RUSSIAN JOINT STOCK COMPANY
  GAZPROM

SYSTEM OF REGULATORY DOCUMENTS IN CONSTRUCTION

CONSTRUCTION RULES
  MAIN GAS PIPELINES

CONSTRUCTION RULES FOR CONSTRUCTION
  LINEAR PART OF GAS PIPELINES

PRODUCTION OF LAND WORKS

SP 104-34-96

Approved by RAO Gazprom

(Order of September 11, 1996, No. 44)

Moscow

1996

SP 104-34-96

Set of rules

Code of practice for the construction of gas pipelines

C ode of the regulations on contstruction of trunk gas pipelines

Date of introduction October 1, 1996

Earthworks

Developed by the Highly Reliable Pipeline Transport Association, RAO Gazprom, AO Rosneftegazstroy, VNIIST AO, NGS-Orgproektekonomika JSC.

Edited by

acad. B.E. Patona, Cand. tech. sciences V.A. Dinkova. prof. O.M. Ivantsova

INTRODUCTION

In this Code of Rules (SP), in order to ensure year-round construction and the possibility of flow-mechanized implementation of the whole complex of construction and installation works, especially in difficult conditions, compliance with the design parameters of pipeline elements during installation and the requirements for the reliability of their operation during operation, modern progressive organization methods and technologies for production work, quality control and acceptance earthworks  in various climatic and soil zones.

The Code of Practice summarizes the results of research and design development, as well as the best practices for excavation work accumulated by construction organizations in domestic and foreign practice in the construction of linear facilities.

This joint venture proposes new ways of constructing trunk pipelines in difficult climatic conditions, reflects methods for developing trenches, constructing embankments, drilling holes and bore holes for pile supports, filling trenches taking into account the design parameters of pipelines, the specifics of drilling and blasting operations, including including parallel installation of multi-line highways in various sections of the route.

This joint venture is intended for specialists in construction and design organizations involved in earthworks during the construction of the linear part of pipelines, as well as in the development of projects for the organization of construction and work (PIC and PPR).

Terminology

A trench is a recess, usually of considerable length and relatively small width, intended for laying a laid pipeline. The trench as a temporary earthen structure is developed in certain parameters depending on the diameter of the pipeline under construction and can be arranged with slopes or with vertical walls.

Dump is usually called soil laid along the trench during its development by earth-moving machinery.

Embankments - earthworks intended for laying pipelines at the intersection of low or difficult terrain, as well as for building a roadway along them or mitigating the profile of the route when planning a construction strip by means of additional dumping of soil.

Excavations - earthworks constructed by cutting soil while softening the longitudinal profile of the route and laying roads along the pipeline construction strip.

Half-half-half-embankments - earthworks that combine the features of a excavation and embankment, intended for laying pipelines and roads on steep slopes (mainly transverse slopes).

Ditches - structures in the form of linear excavations, usually arranged to drain the construction strip, they are often called drainage or drainage. Ditches, which are used to intercept and divert water flowing from an upstream territory and arranged on the sloping side of the earthworks, are called upland. Ditches that serve to drain water and located along both borders of the recesses or roads are called ditches.

The ditches laid during the construction of pipelines (by land) in the swamps along the borders of the right of way and used to store water are called fire ditches.

Cavaliers are called embankments sprinkled from excess soil formed during the development of excavations, and located along the latter.

Reserves are usually called excavations, the soil of which is used to fill nearby embankments. The reserve is separated from the embankment of the embankment by a protective berm.

A quarry is a specially developed excavation for the use of soil when filling embankments and located at a considerable distance from them.

The channel is a recess of considerable length and filled with water. Canals are usually arranged during the construction of pipelines in swamps and wetlands and serve as a trench for laying the pipeline by the alloy method or as a main channel of the drainage system of the drainage system.

The structural elements of the trench are the profile of the trench, the soil dump, the roller above the trench (after filling it with soil). The structural elements of the embankment are the subgrade, ditches, cavaliers and reserves.

The profile of the trench, in turn, has the following characteristic elements: bottom, walls, edges.

The embankments have: base, slopes, sole and edges of slopes, ridge.

A bed is a layer of loose, usually sandy soil (10–20 cm thick), poured to the bottom of a trench in rocky and frozen soils to protect against mechanical damage to the insulation coating when laying the pipeline in a trench.

Powder - a layer of soft (sandy) soil, poured over a pipe laid in a trench (20 cm thick), before filling it with loose rocky or frozen soil to the design elevation of the ground.

Overburden - a mineral soft topsoil lying over mainland rock, subject to priority removal (opening) from the construction strip, for subsequent effective development of rocky soil using the blasting method.

Boreholes are cylindrical cavities in soil with a diameter of up to 75 mm and a depth of not more than 5 m, formed by drilling rigs for placing explosive charges when loosening strong soils using the blast-hole drilling method (for constructing trenches).

Wells are cylindrical cavities in the soil with a diameter of more than 76 mm and a depth of more than 5 m, formed by drilling machines to place explosive charges in them during drilling and blasting operations, both for loosening the soil and for blasting when dumping shelves in mountainous areas.

A comprehensive sequential method is a method for developing trenches mainly in high-strength permafrost soils for ballasted pipelines with a diameter of 1420 mm, which consists in sequential passage through the trench section of several types of bucket-wheel trench excavators, or bucket-wheel excavators of the same type with different working body parameters for constructing a trench of a design profile (up to 3´ 3m).

Technological gap - the front distance between the grips of the production of certain types of work of the construction process of the linear part of the main pipeline within the right-of-way (for example, the technological gap between preparatory and excavation works, between welding and installation and insulation and laying, and during excavation in rocky soil between the teams for stripping, drilling, blasting and excavation of excavation trenches in the soil loosened by the explosion).

Operational quality control of work - a continuous technological process of quality control, carried out in parallel with the execution of any construction and installation operation or process, is carried out in accordance with the technological cards for operational quality control developed for all types of works on the construction of the linear part of main pipelines.

The technological map of operational control of the quality of earthworks reflects the main provisions on the technology and organization of operational control, technological requirements for machines, defines the main processes and operations, the indicators to be monitored that are typical for earthworks, the composition and types of control, as well as the forms of performance documentation, in which the results of control are recorded.

  1. General Provisions

1.1 . The technology of the whole complex of earthworks, including the engineering preparation of the construction strip, to comply with the required dimensions and profiles of earthworks, as well as regulated tolerances in the excavation, should be carried out in accordance with the Project, developed taking into account the requirements of existing normative documents:

¨   “Main pipelines” (SNiP III-42-80);

¨   “Organization of construction production” (SNiP 3.01.01-80);

¨   “Earthworks. Foundations and foundations ”(SNiP 3.02.01-87);

¨   “Norms of land allotment for trunk pipelines” (SN-452-73) Fundamentals of land legislation of the USSR and Union Republics;

¨   “Construction of trunk pipelines. Technology and organization ”(BCH 004-88, Minneftegazstroy, P, 1989);

¨   RF Law on Environmental Protection;

¨   Technical Rules for blasting on the surface (M., Nedra, 1972);

¨   Instructions on the technology for blasting in frozen pounds near existing steel underground trunk pipelines (VSN-2-115-79);

¨   This Code of Practice.

A detailed development of the technology and organizational measures is carried out in the preparation of technological maps and work projects for specific production processes, taking into account the specifics of the relief and soil conditions of each section of the pipeline route.

1.2 . Excavation  should be carried out with quality requirements and with mandatory operational control of all technological processes. It is recommended that all subdivisions for the production of earthworks be provided with cards for operational quality control, which are developed in the development of PIC and PPR, with schemes of complex mechanization for the construction of trunk pipelines by design organizations of the industry.

1.3 . Excavation work must be carried out in compliance with the Safety Rules, industrial sanitation and the latest achievements in the field of labor protection.

The whole complex of earthworks during the construction of pipelines is carried out in accordance with the projects for the organization of construction and work.

1.4 . The technology and organization of earthwork should provide for the flow of their production, year-round implementation, including on complex sections of the route, without a significant increase in their complexity and cost, while maintaining the given pace of work. The exception is work on permafrost soils and wetlands of the Far North, where work is recommended to be done only during freezing.

1.5 . Management and guidance on labor protection, as well as responsibility for ensuring conditions for compliance with labor protection requirements in specialized units, are recommended to be assigned to managers, chiefs and chief engineers of these organizations. At the work sites, the responsibility for complying with these requirements lies with the heads of sections (columns), superintendents and foremen.

1.6 . Construction machinery and equipment for earthworks must comply with the technical conditions of operation, taking into account the conditions and nature of the work performed; in northern areas with low air temperatures, it is recommended to mainly use machines and equipment in the northern version.

1.7 . During the construction of the main pipelines, the lands provided for temporary use must be brought into compliance with the requirements of the project on-farm land management of the respective land users:

· in the production of earthworks, it is not recommended to use techniques and methods that facilitate the washing out, blowing and sweeping of soils and soils, the growth of ravines, erosion of sand, the formation of mudflows and landslides, salinization, waterlogging of soils and other forms of loss of fertility;

·   when draining the right of way by the method of open drainage, the discharge of drainage water into the population’s water supply sources, medicinal water resources, places of recreation and tourism should not be allowed.

  2. Earthworks. Land reclamation works

2.1 . The removal and restoration of the layer within the construction strip is recommended to be carried out in accordance with a special project for land restoration.

2.2 . The land restoration project should be developed by design organizations taking into account the specifics of specific sections of the route and be coordinated with land users of these sections.

2.3 . The fertile lands are brought into a suitable condition, as a rule, during the construction work on the pipeline, and if this is impossible, no later than within a year after the completion of the whole complex of works (as agreed with the land user). All work must be completed within the period of allotment of land for construction.

2.4 . In the project of land reclamation in accordance with the conditions for the presentation of land for use and taking into account local climatic features, the following should be defined:

¨   boundaries of land along the pipeline route, in which restoration is necessary;

¨   the thickness of the removed fertile soil layer for each plot to be recultivated;

Fig. Schematic diagram of the right of way in the construction of trunk pipelines

A - the minimum width of the strip in which the fertile soil layer is removed (the width of the trench along the top plus 0.5 m in each direction)

¨   the width of the reclamation zone within the ROW;

¨   dump location for temporary storage of the removed fertile soil layer;

¨   methods for applying a fertile soil layer and restoring its fertility;

¨   permissible excess of the applied fertile soil layer over the level of undisturbed lands;

¨   methods of compaction of loosened mineral soil and the fertile layer after filling the pipeline.

2.5 . Work on the removal and application of the fertile soil layer (technical reclamation) is carried out by the construction organization; restoration of soil fertility (biological reclamation, including fertilizing, sowing grasses, restoration of moss cover in the northern regions, plowing of fertile soils and other agricultural work) is carried out by land users at the expense of funds provided by the estimate for restoration included in the consolidated construction estimate.

2.6 . When developing and coordinating a land reclamation project for a pipeline laid parallel to an existing gas pipeline, one should take into account its actual position in the plan, the actual occurrence depth and technical condition, and based on these data, design decisions to ensure the safety of the existing pipeline and the safety of work in accordance with “Instructions for the production of works in the security zone of trunk pipelines” and the current safety regulations.

2.7 . When laying a pipeline parallel to an existing pipeline, it should be borne in mind that the operating organization must indicate the location of the axis of the existing pipeline on the ground before starting work, identify and mark with danger signs (areas of insufficient depth and sections of the pipeline in unsatisfactory condition) with special warning signs. During the period of work near the existing pipelines or at the intersection with them, the presence of representatives of the operating organization is necessary. Executive documentation for hidden work should be compiled according to the forms given inBCH 012-88, part II.

2.8 . The technology of work on the technical restoration of disturbed lands during the construction of trunk pipelines consists in removing the fertile soil layer before starting construction work, transporting it to the place of temporary storage and applying it to the restored land at the end of construction work.

2.9 . In the warm season, the removal of the fertile soil layer and its transfer to the dump should be carried out by a rotary reclaimer type ETR 254-05, as well as bulldozers (type D-493A, D-694, D-385A, D-522, DZ-27C) with transverse strokes with a layer thickness of up to 20 cm and transverse - with a layer thickness of more than 20 cm. With a thickness of the fertile layer of 10 - 15 cm, it is recommended to use graders to remove and move it to the dump.

2.10 . The removal of the fertile soil layer should be carried out for the entire design thickness of the reclamation layer, if possible, in one pass or layer by layer in several passes. In all cases, one must not allow mixing of the fertile soil layer with mineral soil.

Excess mineral soil formed as a result of displacement of the volume when laying the pipeline in a trench, in accordance with the project, can be evenly distributed and planned on the strip of the removed fertile soil layer (before applying the latter) or taken out of the construction strip to places specially indicated for this.

Excess mineral soil is transported according to two schemes:

1 . After filling the trench, the mineral soil with a bulldozer or motor grader is evenly distributed over the strip to be recultivated, then, after its compaction, the soil is cut off with scraper (type D-357M, D-511C, etc.) to the required depth in such a way as to ensure a permissible excess of the applied level fertile soil layer above the surface of undisturbed lands. The soil is transported by scrapers to the places specified in the design;

2 . Mineral soil after leveling and compaction is cut off and moved along the strip with a bulldozer and laid in order to increase the efficiency of its loading onto vehicles in special collars up to 1.5 - 2.0 m high with a volume of up to 150 - 200 m 3 from where it is equipped with single-bucket excavators (type EO- 4225, equipped with a bucket with a straight shovel or grab), or single-bucket frontal loaders (type TO-10, TO-28, TO-18) are loaded into dump trucks and transported outside the construction strip to places specially indicated in the project.

2.11 . If, at the request of land users, the project also provides for the export of a fertile soil layer outside the construction strip to special temporary dumps (for example, on especially valuable lands), then removal and transportation of it to a distance of up to 0.5 km should be carried out by scrapers (type DZ-1721).

When transporting soil to a distance of more than 0.5 km, dump trucks (type MAZ-503B, KRAZ-256B) or other machines should be used.

In this case, it is recommended to load the fertile layer (also previously shifted to the shoulders) on dump trucks with frontal loaders (type TO-10, D-543), as well as single-bucket excavators (type EO-4225) equipped with a bucket with a straight shovel or grab. Payment for all specified works should be provided for in an additional estimate.

2.12 . The removal of the fertile soil layer, as a rule, is carried out before the onset of stable negative temperatures. In exceptional cases, by agreement with land users and bodies that monitor land use, fertile soil can be removed in winter conditions.

When carrying out work to remove the fertile soil layer in the winter, it is recommended that the frozen fertile soil layer be developed with bulldozers (type DZ-27S, DZ-34C, International Harvester TD-25C) with preliminary loosening with three-toothed cultivators (type DP-26C, DP -9C, U-RK8, U-RKE, International Harvester TD-25C), cultivators of the Caterpillar brand (model 9B) and others.

Loosening should be carried out to a depth not exceeding the thickness of the removed fertile soil layer.

When loosening the soil with tractor cultivators, it is recommended to use a longitudinally rotary technological scheme.

In winter, rotary trench excavators (type ETR-253A, ETR-254, ETR-254AM, ETR-254AM-01, ETR-254-05, ETR-307, ETR-309) can be used to remove and move the fertile soil layer.

The immersion depth of the rotor should not exceed the thickness of the removed fertile soil layer.

2.13 . The pipeline is filled with mineral soil at any time of the year immediately after it is laid. For this, rotary trenchers and bulldozers can be used.

In the warm season, after filling the pipeline with mineral soil, it is compacted with vibrational seals of the D-679 type, pneumatic rollers or multiple (three to five times) passages of caterpillar tractors over the pipeline filled with mineral soil. Compaction of mineral soil in this way is performed before filling the pipeline with the transported product.

2.14 . In winter, artificial compaction of mineral soil is not performed. Soil acquires the necessary density after thawing for three to four months (natural compaction). The compaction process can be accelerated by moistening (soaking) the soil with water in a covered trench.

The same sealing method can be recommended when there is a product in the pipeline during the reclamation period.

2.15 . Application of the fertile soil layer should be done only in the warm season (at normal humidity and sufficient bearing capacity of the soil for the passage of cars). For this, bulldozers are used, working in transverse strokes, moving and leveling the fertile soil layer. This method is recommended to be used when the thickness of the fertile layer is more than 0.2 m. The final layout can be performed by longitudinal passages of motor graders.

2.16 . If it is necessary to transport the fertile soil layer to the place of its application from dumps located outside the construction strip and removed from it by a distance of up to 0.5 km, scrapers (type DZ-1721) can be used. With a transportation distance exceeding 0.5 km, the fertile soil layer is delivered by dump trucks, followed by leveling it with bulldozers that work crosswise or longitudinally.

Leveling the fertile soil layer can also be done by motor graders (type DZ-122, DZ-98V, equipped in front with a knife blade).

Bringing the land to a usable condition is carried out during the work, and if this is impossible, no later than within a year after completion of the work.

2.17 . Control over the correct performance of work in accordance with the land restoration project is carried out by state control bodies over the use of land on the basis of a regulation approved by the Government. The transfer to the land users of the restored lands should be documented in an act in the prescribed manner.

  3. Earthworks under normal conditions

3.1 . The technological parameters of the earthworks used in the construction of trunk pipelines (width, depth and slopes of the trench, the cross section of the embankment and the steepness of its slopes, the parameters of the holes and boreholes) are set depending on the diameter of the pipeline being laid, the method of fixing it, the terrain, and soil conditions and are determined project. The dimensions of the trench (depth, width along the bottom, slopes) are set depending on the purpose and external parameters of the pipeline, the type of ballasting, soil characteristics, hydrogeological and relief terrain conditions.

The specific parameters of earthworks are determined by working drawings.

The depth of the trench is determined from the conditions for protecting the pipeline from mechanical damage when moving vehicles, construction and agricultural vehicles through it. The depth of the trench when laying the main pipelines is taken equal to the diameter of the pipe plus the required amount of backfill of soil above it and is assigned by the project. Moreover, it should be (respectively SNiP 2.05.06-85) not less than:

·   with a diameter of less than 1000 mm ................................................................................... 0.8 m;

·   with a diameter of 1000 mm and more ................................................................................ 1,0 m;

·   on swamps or peat soils to be drained ................................. 1.1 m;

·   in sand dunes, counting from the lower elevations of the inter-arch bases ... 1.0 m;

·   in rocky soils, marshland in the absence of passage

motor vehicles and agricultural machinery ..................................................... 0.6 m

The minimum width of the trench is assigned to the SNiP from the bottom and taken at least:

¨ D   + 300 mm - for pipelines with a diameter up to 700 mm;

¨   1,5 D   - for pipelines with a diameter of 700 mm and more, taking into account the following additional requirements:

for pipelines with a diameter of 1200 and 1400 mm when digging trenches with slopes no steeper than 1: 0.5, the width of the trench along the bottom can be reduced to a valueD + 500 mm, where D   - conditional diameter of the pipeline.

When excavating soil using earth-moving machines, it is recommended to take the width of the trench equal to the width of the cutting edge of the working body of the machine, adopted by the construction organization project, but not less than the above.

When ballasting the pipeline with weighting materials or securing with anchor devices, the width of the trench along the bottom must be taken at least 2.2D , and for a pipeline with thermal insulation is set by the project.

The width of the trench along the bottom in the curved sections from the knees of forced bending is recommended to be taken equal to two times the value in relation to the width in straight sections.

3.2 . By the beginning of trenching, it is recommended to obtain:

·   written permission for the right to carry out earthwork in the area of \u200b\u200bunderground utilities, issued by the organization responsible for the operation of these utilities;

·   excavation project, the development of which uses standard technological maps;

·   job assignment to the crew of the excavator (if the work is carried out in conjunction with bulldozers and cultivators, then the drivers of these machines) to carry out the work.

3.3 . Before developing a trench, it is necessary to reconstruct the axis of the trench. When developing a trench with a single-bucket excavator, trenches are placed along the axis of the trench in front of the machine and behind along the already dug trench. When digging with a rotary excavator, a vertical sight is installed on the front of it, which allows the driver, focusing on the installed landmarks, to keep to the design direction of the route.

3.4 . The profile for the trench must be performed so that the laid pipeline along the entire length of the lower generatrix is \u200b\u200bin close contact with the bottom of the trench, and at the turning angles it is located along the line of elastic bending.

3.5 . At the bottom of the trench should not be left fragments of steel rocks, gravel, hard lumps of clay and other objects and materials that could damage the insulation of the laid pipeline.

3.6 . The development of the trench is made by a single-bucket excavator:

¨   in areas with marked hilly terrain (or severely rugged), interrupted by various (including water) obstacles;

¨   in rocky soils loosened by a blasting method;

¨   on the sections of the curves of the pipeline inserts;

¨   when working in soft soils with the inclusion of boulders;

¨   in areas of high humidity and swamps;

¨   in flooded soils (in rice fields and irrigated lands);

¨   in places where it is impossible or impractical to use rotary excavators;

¨   in difficult areas specifically defined by the project.

To develop wide trenches with slopes (in heavily flooded, loose, unstable soils), single-bucket excavators equipped with draglines are used in the pipeline construction. Earth-moving machinery is equipped with a reliable sound alarm system. The signal system should be familiar to all work crews serving these machines.

In areas with a quiet topography, on gentle hills, on the soft foothills and on the soft lingering slopes of the mountains, work can be carried out by rotary trench excavators.

3.7 . Trenches with vertical walls can be developed without fastening in soils of natural humidity with an undisturbed structure in the absence of groundwater to a depth (m):

·   in bulk sandy and gravelly soils ......... no more than 1;

·   in sandy loam ....................................................................... no more than 1.25;

·   in loam and clay ................................................... no more than 1,5;

·   in especially dense non-rocky soils ....................... no more than 2.

When developing trenches of great depth, it is necessary to arrange slopes of various laying depending on the composition of the soil and its moisture content (table).

Table 1

Permissible steepness of slopes of trenches

3.8 . In overmoistened, clay soils with rain, snow (melt) and ground waters, the steepness of the slopes of pits and trenches is reduced compared to that indicated in Table.   to the angle of repose. Reducing the steepness of the slopes, the work designer draws up an act. Forest-like and bulk soils become unstable during waterlogging, and wall fastening is used in their development.

3.9 . The steepness of the slopes of the trenches for the pipeline and pits for the installation of pipe fittings is taken according to the working drawings (in accordance with table. ) The steepness of the slopes of the trench in the areas of swamps is taken as follows (tab. ):

table 2

The steepness of the slopes of the trench in the areas of swamps

3.10 . Soil development methods are determined depending on the parameters of the earthworks and the amount of work, geotechnical characteristics of soils, soil classification according to the difficulty of development, local construction conditions, the presence of earth-moving machinery in construction organizations.

3.11 . In linear work during the digging of trenches for pipelines, in accordance with the working drawings, pits are developed for cranes, condensate collectors and other technological units 2 m in size in all directions from the welded joint of the pipeline with valves.

Under technological breaks (overlaps), pits are developed with a depth of 0.7 m, a length of 2 m and a width of at least 1 m in each direction from the pipe wall.

During the construction of the linear part of pipelines by the in-line method, soil excavated from the trench is laid in a dump on one side (left in the direction of work) of the trench, leaving the other side free for movement of vehicles and construction and installation works.

3.12 . To avoid collapse of excavated soil in the trench, as well as collapse of the walls of the trench, the base of the dump of excavated soil should be located depending on the state of the soil and weather conditionsbut not closer than 0.5 m from the edge of the trench.

Collapsed soil in the trench can be cleaned by an excavator with a clamshell bucket immediately before laying the pipeline.

3.13 . The development of trenches with a single-bucket excavator with a backhoe is carried out in accordance with the project without the use of manual cleaning of the bottom (this is achieved by the rational distance of advancement of the excavator and dragging the bucket along the bottom of the trench), which ensures the elimination of scallops at the bottom of the trench.

3.14 . The development of trenches by dragline is carried out by frontal or side faces. The choice of development method depends on the size of the trenches at the top, the location of the pound dump, and the working conditions. Wide trenches, especially on swampy and soft soils, are developed, as a rule, by side passages, and usual ones by frontal passages.

When constructing trenches, it is recommended that the excavator be installed from the bottom edge at a distance that ensures the safe operation of machines (outside the prism of the collapse of the soil): for excavators - draglines with a bucket of 0.65 m 3, the distance from the edge of the trench to the axis of movement of the excavator (with lateral excavation) should be at least 2.5 m. On unstable weak soils, wooden slans are placed under the chassis of the excavator or work with mobile foam sledges.

When developing trenches with one-bucket excavators with a backhoe and dragline, it is allowed to search the soil up to 10 cm; under-harvesting is not permitted.

3.15 . In areas with a high level of groundwater standing, the development of trenches is recommended to start from lower places to ensure water flow and drain overlying areas.

3.16 . To ensure the stability of the walls of the trench during operations in low-stability soils with rotary excavators, the latter are equipped with special slopes that allow you to develop trenches with slopes (slope 1: 0.5 or more).

3.17 . Trenches, the depth of which exceeds the maximum digging depth of an excavator of this brand, are developed by excavators in combination with bulldozers.

Earthworks in rocky soils in flat and mountainous conditions

3.18 . Earthwork during the construction of trunk pipelines in rocky soils in flat terrain with slopes of up to 8 °include the following operations and are performed in a specific sequence:

·   removing and moving to a dump for storing a fertile layer or opening a layer covering rocky soils;

·   loosening of rock by a blasting or mechanical method with its subsequent layout;

·   development of a loosened soil with a single-bucket excavator;

·   bed device from soft ground  at the bottom of the trench.

After laying the pipeline in the trench, the following works are performed:

¨ dusting the pipeline with loose soft soil;

¨   device jumpers in the trench on the longitudinal slopes;

¨   filling the pipeline with rocky soil;

¨   reclamation of the fertile layer.

3.19 . After removing the fertile layer to ensure uninterrupted and more productive work of drillers and drilling equipment on loosening rocky soil, the overburden is removed until the rock is exposed. In areas with a soft soil layer thickness of 10 - 15 cm or less, it can not be removed.

When cone drilling charging holes and wells, soft soil is removed only for the purpose of preserving it or using it for bedding or powdering the pipeline.

3.20 . Stripping works are usually carried out with bulldozers. If necessary, these works are allowed to be carried out by single-bucket or bucket-wheel excavators, trenchers, using them both independently and in combination with bulldozers (combined method).

3.21 . The removed soil is laid on a berm trench in order to be able to use it for the device of bed and powder. The dump of loosened rocky soil is located behind the overburden dump.

3.22 . With a small thickness of rock or in case of severe fracturing, loosening is recommended to be carried out with a tractor cultivator.

3.23 . Loosening of rocky soils is carried out mainly by means of short-blown blasting, in which charging wells (holes) are arranged on a square grid.

In exceptional cases, the application of the instant blasting method (with wide trenches and pits) of the hole (borehole) should be staggered.

3.24 . Refinement of the estimated mass of charges and adjustment of the grid location of the holes is carried out by test explosions.

3.25 . Blasting operations must be carried out in such a way that the rock is loosened to the design level of the trench (taking into account the arrangement of the sand bed by 10 - 20 cm) and would not require re-blasting for its completion.

To the same extent this applies to the device shelves explosive way.

When loosening the soil by the explosive method, it is also necessary to ensure that the pieces of loosened soil do not exceed 2/3 of the size of the excavator bucket intended for its development. Pieces large sizes  destroy overhead charges.

3.26 . Before the development of the trench, a rough layout of loosened rocky soil is performed.

3.27 . When laying the pipeline to protect its insulation coating from mechanical damage about unevenness, the bottom of the trench makes a bed of soft soil with a thickness of at least 0.1 m above the protruding parts of the base.

The bed is made of imported or local overburden soft soil.

3.28 . For the construction of the bed, they mainly use rotary trench and single bucket excavators, and in some cases rotary trenchers, which develop soft overburden, located in the strip next to the pipeline trench, at the carriageway, and pour it to the bottom of the trench.

3.29 . The soil brought in by dump trucks and dumped near the pipe (from the side opposite the dump from the trench) is placed and leveled at the bottom of the trench using a single-bucket excavator equipped with a dragline, scraper, backhoe, or scraper or belt devices. With a sufficient width of the trench (for example, in the areas of pipeline ballasting or in sections of the turn of the route), leveling of the spilled soil along the bottom of the trench can be carried out by small-sized bulldozers.

3.30 . To protect the insulation coating of the pipeline from damage by pieces of rock when backfilling over the pipe, it is recommended to arrange a powder of soft overburden or imported soil with a thickness of at least 20 cm above the upper generatrix of the pipe. Piping of the pipeline is carried out by the same technique as the filling under the pipeline.

In the absence of soft soil, the backfill and powder can be replaced by a continuous lining device made of wooden battens or straw, reed, foam, rubber and other mats. In addition, the backfill can be replaced by laying bags filled with soft soil or sand at the bottom of the trench at a distance of 2 - 5 m from each other (depending on the diameter of the pipeline) or with a foam-foam bed (spraying the mortar before laying the pipeline).

3.31 . Earthworks during the construction of pipelines in rocky soils in mountainous areas include the following technological processes:

·   arrangement of temporary roads and access roads to the highway;

·   stripping works;

·   device shelves;

·   the development of trenches on the shelves;

·   backfilling of trenches and design of the roller.

3.32 . When passing the pipeline along steep longitudinal slopes, they are planned by cutting the soil and reducing the angle of elevation. These works are carried out along the entire width of the strip with bulldozers, which, cutting the soil, move from top to bottom and push it to the foot of the slope outside the limits of the construction strip. The profile of the trench is recommended to be placed not in bulk, but in mainland soil. Therefore, the device embankment is possible mainly in the area of \u200b\u200bpassage of transport vehicles.

Shelf device

3.33 . When passing routes along a slope with a transverse steepness of more than 8 °, a shelf should be arranged.

The design and parameters of the shelves are assigned depending on the diameter of the pipes, the size of the trenches and dumps, the type of machines used and the methods of work and are determined by the project.

3.34 . The stability of the half-shelve-shelf depends on the characteristics of the bulk soil and the soil of the slope, the slope of the slope, the width of the bulk, the state of the vegetation cover. For shelf stability, it is torn off with a slope of 3 - 4% in the direction of the slope.

3.35 . In areas with a transverse slope of up to 15 °, the development of notches for shelves in uncrag and loosened rocky soils is carried out by transverse passages of bulldozers perpendicular to the axis of the track. Finalization of the shelf and its layout in this case is carried out by longitudinal passages of the bulldozer with layer-by-layer excavation of the soil and moving it into half-mounds.

Soil excavation during the installation of shelves in areas with a transverse slope of up to 15 ° can also be carried out by longitudinal passages of the bulldozer. At first, the bulldozer kills and develops the soil at the transition line with half-recesses to half-embankment. After cutting the soil in the first prism at the outer edge of the shelf and moving it to the bulk part of the shelf, the soil of the next prism remote from the transition to the half-burial prism (towards the direction of the inside of the shelf) is developed, and then in the following prisms located in the mainland - until the half-profile is fully developed .

For large volumes of excavation, two bulldozers are used, which are developing the shelves on both sides with longitudinal passages towards each other.

3.36 . In areas with a transverse slope of more than 15 °, shovel excavators equipped with a straight shovel are used to develop loosened or non-rocky soil when arranging shelves. The excavator develops the soil within the half-excavation and pours it into the bulk of the shelf. During the initial development of the shelf, it is recommended to anchor it with a bulldozer or tractor. The final refinement and layout of the shelf is carried out by bulldozers.

3.37 . When arranging shelves and digging trenches in mountainous areas, tractor rippers or a drilling and blasting method of development can be used for loosening non-separable rock.

3.38 . During the operation of the tractor cultivator, it is taken into account that its efficiency increases if the direction of the working stroke is taken from top to bottom for slope and loosening is carried out with the choice of the longest stroke length.

3.39 . The methods of drilling holes and boreholes, as well as the methods of loading and blasting charges when installing shelves in mountainous areas and trenches on shelves are similar to the methods used to develop trenches in rocky soils on flat terrain.

3.40 . Excavation of the development of trenches on the shelves is recommended to be carried out ahead of the removal of pipes to the track.

Trenches on shelves in soft soils and highly weathered rock formations are developed by single-bucket and rotary excavators without loosening. In areas with dense rocky soils, before excavation of the trench, the soil is loosened using a blasting method.

Earth-moving machinery, when developing trenches, move along a carefully planned shelf; at the same time, shovel excavators move in the same way as during the construction of trenches in rocky soils on flat terrain, on a flooring made of metal or wooden shields.

3.41 . The dump of soil from the trench is usually located at the edge of the slope of the half-notch on the right side of the shelf during the development of the trench. If the soil dump is located in the drive zone, then for the normal operation of construction vehicles and mechanisms, the soil is planned on a shelf and rammed with bulldozers.

3.42 . On sections of the route with longitudinal slopes of up to 15 °, the development of trenches, if there are no transverse slopes, is carried out by single-bucket excavators without special preliminary measures. When working on longitudinal slopes from 15 to 36 °, preliminary excavation of the excavator is carried out. The number of anchors and the method of fixing them are determined by calculation, which should be part of the project of work.

When working on longitudinal slopes of more than 10 °, to determine the stability of the excavator, it is checked for spontaneous shear (slip) and, if necessary, anchored. Tractors, bulldozers, winches are used as anchors on steep slopes. The restraints are placed on the top of the slope on horizontal platforms and connected to the excavator by a cable.

3.43 . On longitudinal slopes up to 22 °, soil development with a single-bucket excavator is allowed in the direction both from bottom to top and from top to bottom along the slope.

In areas with a slope of more than 22 °, to ensure the stability of single-bucket excavators, it is allowed: with a straight shovel, work only in the direction from top to bottom along the slope with the bucket forward in the course of work, and with a backhoe shovel, only from top to bottom down the slope with the bucket back in the course of work.

The development of trenches on longitudinal slopes up to 36 ° in soils that do not require loosening is performed by single-bucket or rotary excavators, in previously loosened soils, by single-bucket excavators.

The operation of bucket wheel excavators is permitted on longitudinal slopes up to 36 ° when moving them from top to bottom. For slopes from 36 to 45 °, their anchoring is used.

The work of single-bucket excavators with a longitudinal slope of more than 22 ° and rotary excavators of more than 45 ° is performed by special techniques according to the design of the work.

The development of the trench with bulldozers is carried out on longitudinal slopes up to 36 °.

The arrangement of trenches on steep slopes from 36 ° and above can also be carried out by the trough method using scraper installations or bulldozers.

Backfilling trenches in the mountains

3.44 . Backfill of a pipeline laid in a trench on shelves and on longitudinal slopes is carried out similarly to backfilling in rocky soils on flat terrain, i.e. with a preliminary arrangement of the bed and powdering the pipeline with soft soil or replacing these operations with a lining. Lining can be made of polymer roll materials, foamed polymers, concrete coating. It is forbidden to use rotting materials for lining (cane mats, wooden slats, lumbering waste, etc.).

If the soil of the dump is planned on the shelf, then the final filling of the pipeline with rocky soil is carried out by a bulldozer or rotary trencher, the remaining soil is leveled along the construction strip. In the event that the soil is located on the edge from the side of the slope of the half-excavation, then for this purpose single-bucket excavators are used, as well as frontal bucket loaders.

3.45 . The final filling of the pipeline on the longitudinal slopes is usually carried out by a bulldozer, which moves along or at an angle to the trench, and can also be carried out from top to bottom along the slope by a trencher with its mandatory anchoring on slopes above 15 °. On slopes of more than 30 ° in places where the use of mechanisms is not possible, backfilling can be done manually.

3.46 . To backfill the pipeline laid in trenches, developed by the trough method on steep slopes when the soil dump is located at the bottom of the slope, scraper trenchers or scraper winches are used.

3.47 . To prevent flushing of the soil when backfilling the pipeline on steep longitudinal slopes (above 15 °), a jumper is recommended.

Features of earthwork in winter conditions

3.48 . Excavation in winter is associated with a number of difficulties. The main ones are soil freezing to various depths and the presence of snow cover.

When predicting the freezing of soil to a depth of more than 0.4 m, it is advisable to protect the soil from freezing, in particular, by loosening the soil with single or multipoint cultivators.

3.49 . In some places of a small area, it is possible to protect the soil from freezing by warming it with wood residues, sawdust, peat, applying a layer of polystyrene, as well as non-woven rolled synthetic materials.

3.50 . To reduce the duration of thawing of frozen ground and in order to maximize the use of earthmoving machinery in warm weather, it is recommended to remove snow from the future trench strip during the establishment of positive temperatures.

Winter trenching

3.51 . In order to avoid the introduction of trenches with snow and freezing of the soil dump during winter work, the rate of development of trenches should correspond to the rate of insulation and laying. The technological gap between the digging and insulation-laying columns is recommended no more than two-day productivity of the digging columns.

The methods for developing trenches in the winter are prescribed depending on the time of excavation, the characteristics of the soil and the depth of freezing. The choice of the technological scheme of earthworks in winter should include the preservation of snow cover on the soil surface until the beginning of the development of trenches.

3.52 . With a soil freezing depth of up to 0.4 m, the development of trenches is carried out as in normal conditions: with a bucket-wheel or single bucket excavator equipped with a backhoe bucket with a bucket capacity of 0.65 - 1.5 m 3.

3.53 . When the depth of freezing of the soil is more than 0.3 - 0.4 m, before developing it with a single-bucket excavator, the soil is loosened mechanically or by a blasting method.

3.54 . When using the blasting method for loosening frozen soils, work on the development of trenches is carried out in a certain sequence.

The trench strip is divided into three captures:

¨   zone for drilling, charging and blasting holes;

¨   planning area;

¨   excavation area for loose soil.

The distance between the grips should ensure the safe conduct of work on each of them.

Drilling of boreholes is carried out by screw augers, rotary hammers and self-propelled drilling machines.

3.55 . When developing frozen soil using tractor cultivators with a capacity of 250 - 300 hp Trench development works are carried out according to the following schemes:

1 . With a soil freezing depth of up to 0.8 m, a soil cultivator loosens the soil to the entire freezing depth, and then it is developed with a single-bucket excavator. The excavation of loose soil in order to avoid repeated freezing must be carried out immediately after loosening.

2 . With a freezing depth of up to 1 m, work can be carried out in the following sequence:

·   loosen the soil with a rack-mounted cultivator in several passes, then select it with a bulldozer along the trench;

·   the remaining soil, having a freezing thickness of less than 0.4 m, is developed by a single-bucket excavator.

The trough-like trench in which the excavator operates is arranged with a depth of not more than 0.9 m (for an EO-4121 type excavator) or 1 m (for an E-652 excavator or similar foreign excavators) to ensure that the back of the excavator rotates when unloading the bucket.

3 . With a freezing depth of up to 1.5 m, work can be carried out similarly to the previous scheme with the difference that the soil in the trough before passage of the excavator must be loosened with a rack-mounted cultivator.

3.56 . The development of trenches in strong frozen and permafrost soils with an active layer freezing depth of more than 1 m can be carried out by a complex combined sequential method, i.e. the passage of two or three different types of bucket wheel excavators.

First, a trench of a smaller profile is developed, and then it is increased to design parameters using more powerful excavators.

In complex sequential operation, you can use either different brands of rotary excavators (for example, ETR-204, ETR-223, and then ETR-253A or ETR-254) or excavators of the same model equipped with working bodies of different sizes (for example, ETR-309).

Before the first excavator passes, the soil, if necessary, is loosened with a heavy tractor cultivator.

3.57 . To develop frozen and other dense soils, buckets of rotary excavators should be equipped with teeth reinforced with wear-resistant surfacing or reinforced with carbide plates.

3.58 . With a significant depth of thawing (more than 1 m), the soil can be developed by two rotary excavators. In this case, the first excavator develops the upper layer of thawed soil, and the second - a layer of frozen soil, laying it behind a dump of thawed soil. For the development of water-saturated soil, you can also use a bucket excavator equipped with a backhoe.

3.59 . During the period of maximum thawing of the frozen layer (with a thawing depth of 2 m or more), the trench is developed by conventional methods, either in ordinary or in marshy soils.

3.60 . Before laying the pipeline in a trench, the base of which has irregularities in frozen soil, a bed 10 cm high is made at the bottom of the trench from thawed loose or finely loosened frozen soil.

3.61 . When thawing frozen soil (30 - 40 cm) for subsequent loosening of the frozen layer, it is advisable to first remove it with a bulldozer or a bucket excavator, and then perform the work according to the same schemes as for frozen soils.

Filling the pipeline

3.62 . To protect the insulation coating of the pipeline laid in the trench, backfilling is made by loosened soil. If the backfill soil on the parapet is frozen, then it is advisable to sprinkle the laid pipeline to a height of at least 0.2 m from the top of the pipe with imported soft thawed snow or loosened, mechanically or drilling and blasting frozen ground. Further filling the pipeline with frozen soil is carried out with bulldozers or rotary trenchers.

Earthworks in swamps and wetlands

3.63 . A bog (from a construction point of view) is an excessively moistened part of the earth’s surface covered with a layer of peat with a thickness of 0.5 m or more.

Areas with significant water saturation with a peat deposit thickness of less than 0.5 m are waterlogged.

Areas covered with water and without peat coating are waterlogged.

3.64 . Depending on the cross-country ability of construction equipment and the complexity of the construction and installation works during the construction of pipelines, swamps are classified into three types:

First - swamps entirely filled with peat, allowing the work and repeated movement of swamp equipment with a specific pressure of 0.02 - 0.03 MPa (0.2 - 0.3 kG / cm 2) or the operation of conventional equipment using shields, slans, or temporary roads providing a decrease in the specific pressure on the surface of the reservoir to 0.02 MPa (0.2 kG / cm 2).

Second  - swamps entirely filled with peat, allowing the work and movement of construction equipment only along shields, slans or temporary technological roads, providing a decrease in specific pressure on the surface of the deposit to 0.01 MPa (0.1 kG / cm 2).

Third  - swamps filled with spreading peat and water with a floating peat crust (rafting) and without rafting, allowing the operation of special equipment on pontoons or conventional equipment with floating equipment.

Development of trenches for underground pipeline laying in swamps

3.65 . Depending on the type of swamp, laying method, construction time and equipment used, the following schemes for excavating in marshy areas are distinguished:

¨   pre-peat trenches;

¨   the development of trenches using special equipment, shields or shales that reduce the specific pressure on the soil surface;

¨   the development of trenches in the winter;

¨   development of trenches by explosion.

Construction on the swamps should begin after a thorough examination.

3.66 . The development of pre-peat trenches is used at a peat layer depth of up to 1 m with an underlying base having a high bearing capacity. Preliminary removal of peat to mineral soil is carried out by a bulldozer or excavator. The width of the recess formed in this case should ensure the normal operation of the excavator, moving along the surface of the mineral soil and developing a trench to full depth. The trench is arranged with a depth of 0.15 - 0.2 m below the design level, taking into account the possible trenching of the slopes of the trench in the period from the moment of development to the laying of the pipeline. When using an excavator for peeling, the length of the created front of work is taken 40-50 m.

3.67 . The development of trenches using special equipment, shields or shales that reduce the specific pressure on the soil surface is used in marshy areas with a peat deposit thickness of more than 1 m and having a low bearing capacity.

To develop trenches on soft soils, swamp excavators equipped with a backhoe or dragline should be used.

The excavator can also develop trenches while being on the sledges, which move through the swamp with a winch and are located on mineral soil. Instead of a winch, one or two tractors can be used.

3.68 . The development of trenches in the summer should be ahead of the insulation of the pipeline, if it is carried out in the field. Lead time depends on the characteristics of the pounds and should not exceed 3 to 5 days.

3.69 . The feasibility of laying pipelines through long swamps in the summer should be justified by technical and economic calculations and determined by the construction organization project.

Deep and long swamps with low bearing capacity of the peat cover should be covered in winter, and small small swamps and wetlands in the summer season.

3.70 . IN winter period  as a result of freezing the soil to the full (design) depth of the trench development, the bearing capacity of the soil increases significantly, which allows the use of conventional earthmoving equipment (bucket-wheel and single-bucket excavators) without the use of shales.

In areas with deep freezing of peat, work should be performed in a combined way: loosening the frozen layer using the blasting method and excavating the soil to the design level with a single-bucket excavator.

3.71 . The development of trenches in swamps of all types, especially in impassable swamps, it is advisable to carry out the explosive method. This method is economically justified in those cases when it is very difficult to carry out work from the surface of the swamp, even using special equipment.

3.72 . Depending on the type of swamp and the size of the required trench, various development options for their explosive methods are used.

In open and slightly forested bogs, when developing channels with a depth of 3 - 3.5 m, a width of up to 15 m, a peat layer thickness of up to 2/3 of the depth of the trench, elongated cord charges from waste pyroxylin powders or waterproof ammonites are used.

When laying a pipeline in deep swamps covered with forests, it is advisable to develop trenches up to 5 m deep, using concentrated charges placed along the axis of the trench. In this case, there is no need for preliminary clearance of the track from the forest. Concentrated charges are placed in charging funnels, which, in turn, are formed by small borehole or concentrated charges. To do this, waterproof ammonites are usually used in cartridges with a diameter of up to 46 mm. The depth of the charging funnel is taken into account the laying of the center of the main concentrated charge at 0.3 - 0.5 channel depths.

When developing trenches up to 2.5 m deep and 6 to 8 m wide at the top, it is efficient to use borehole charges from waterproof explosives. This method can be used in swamps.I   and type II, both with and without forest. Wells (vertical or inclined) are located along the axis of the trench at a calculated distance from each other in one or two rows depending on the design width of the bottom of the trench. The diameter of the wells is 150-200 mm. Inclined boreholes at an angle of 45-60 ° to the horizon are used if necessary, directed ejection of soil on one side of the trench.

3.73 . The choice of explosives, the mass of the charge, the depth, the location of the charges in the plan, the methods of blasting, as well as the organizational and technical preparation for drilling and blasting operations and testing of explosives, materials are described in the "Technical rules for blasting on the surface" and in the Methodology for calculating explosive parameters for the construction of canals and trenches in the swamps ”(M., VNIIST, 1970).

Backfill in the swamps

3.74 . The methods of performing work when filling trenches in swamps in the summertime depend on the type and structure of the swamps.

3.75. In the swamps I   and types II, backfill is carried out either by swamp bulldozers, when such machines are ensured, or by dragline excavators on the broadened or normal course, moving along shales on dumps of soil, pre-planned by two passages of the bulldozer.

3.76 . The excess soil obtained during backfill is placed in a trench roller, the height of which is determined taking into account precipitation. If there is not enough soil to fill the trench, it should be developed by an excavator from side reserves, which should be laid from the axis of the trench at a distance of at least three depths.

3.77 . In deep marshes with a flowing peat texture, inclusion of sapropelite or coating with alloys (marshesIII type), after laying the pipeline on a solid foundation, you can not fill it up.

3.78 . Backfilling of trenches in swamps in winter is usually carried out with bulldozers on broadened tracks.

Ground pipelines in the embankment

3.79 . The method of construction of embankments is determined by the construction conditions and the type of earthmoving machinery used.

The soil for filling the embankment in irrigated areas and in swamps is developed in nearby quarries located in elevated places. Soil in such quarries, as a rule, is more mineralized and therefore more suitable for the construction of a stable embankment.

3.80 . Soil mining in quarries is carried out by scrapers or single-bucket or bucket-wheel excavators with simultaneous loading into dump trucks.

3.81 . When filling the embankment swamps with a mound, a floating crust (rafting) of small thickness (not more than 1 m) is not removed, but immersed to the bottom. Moreover, if the thickness of the crust is less than 0.5 m, the embankment is poured directly onto the raft without making longitudinal slots in the ravine.

When the thickness of the alloy is more than 0.5 m, longitudinal slots can be arranged in the alloy, the distance between which should be equal to the bottom of the future earth embankment.

3.82 . The formation of slots should be carried out by an explosive method. Powerful rafts before the start of dumping are destroyed by explosions of small charges laid in a checkerboard pattern on a strip equal to the bottom of the earth strip.

3.83 . Embankments through swamps with low bearing capacity are constructed from imported soil with preliminary peat out at the base. In swamps with a bearing capacity of 0.025 MPa (0.25 kG / cm 2) or more, embankments can be emptied without peeling directly on the surface or along the brushwood. In the swampsIII   type embankments are poured mainly on the mineral bottom due to the extrusion of peat mass by soil mass.

3.84 . It is recommended to build embankments with peat in swamps with a peat cover thickness of not more than 2 m. Peat can be carried out by excavators equipped with dragline, or by explosive method. The feasibility of peat is determined by the project.

3.85 . In swamps and other irrigated areas with water flow across the embankment, the filling is carried out from well-draining coarse-grained and gravelly sands, gravel or specially culverts are arranged.

3.86 . It is recommended to fill the embankment in a certain sequence:

· the first layer (25-30 cm higher than the swamp), delivered by dump trucks, is poured in a pioneer way of sliding. The soil is unloaded at the edge of the swamp, and then moves towards the embankment arranged by a bulldozer. Depending on the length of the swamp and access conditions, the embankment is erected from one or both banks of the swamp;

·   the second layer (up to the design mark of the bottom of the pipe) is poured in layers with a seal immediately along the entire length of the transition;

·   the third layer (up to the design mark of the embankment) is poured after laying the pipeline.

Leveling the soil on the embankment is carried out by a bulldozer, backfilling of the laid pipeline - with single-bucket excavators.

3.87 . The embankments during the erection are sprinkled taking into account the subsequent precipitation of the soil; precipitation is set by the project depending on the type of soil.

3.88 . The filling of embankments during preliminary removal of peat at the base is carried out in a pioneer way from the “head”, and without peeling out both from the head part and from the laid road located along the axis of the pipeline.

Earthwork during the construction of concrete pipelines, ballasted or weighted

3.89 . Excavation work on the construction of a pipeline ballasted with reinforced concrete weights or a concrete pipeline is characterized by increased volumes of work and can be performed both in summer and in winter.

3.90 . With the underground method of laying the concrete gas pipeline trenches, it is necessary to develop the following parameters:

¨   trench depth - match the design and be no less thanD n + 0.5 m (D n   - the outer diameter of the concrete gas pipeline, m);

¨   the width of the trench along the bottom in the presence of slopes of 1: 1 or more - not lessD n + 0.5 m.

When developing a trench for a pipeline alloy, its width along the bottom is recommended at least 1.5D n

3.91 . The minimum clearance between the cargo and the wall of the trench when ballasting the pipeline with reinforced concrete weighting materials should be at least 100 mm or the width of the trench along the bottom when ballasting with goods or securing with anchor devices is recommended at least 2.2D n

3.92 . In view of the fact that the pipelines concrete or ballasted with reinforced concrete cargo are laid in swamps, wetlands and waterlogged areas, the methods of excavation are similar to excavation in swamps (depending on the type of swamps and season).

3.93 . To develop trenches for pipelines of large diameters (1220, 1420 mm), concrete-coated or ballasted with reinforced concrete cargoes, the following method can be used: a bucket-wheel excavator tears a trench in the first pass with a width equal to about half of the required width of the trench, then the soil returns to its place with a bulldozer; Then, by the second pass of the excavator, the soil is selected on the remaining unripe part of the trench and again returned to the trench with a bulldozer. After that, the loosened soil for the entire profile is selected with a single-bucket excavator.

3.94 . When laying the pipeline in the areas of the predicted watering ballasted by reinforced concrete cargoes, in winter conditions the method of group installation of cargoes on the pipeline can be used. In this regard, the trench can be developed in the usual way, and its broadening to the group of cargoes should be done only in certain areas.

Earthwork in this case is carried out as follows: by a rotary or one-bucket (depending on the depth and strength of frozen soil) excavator trench trenches of normal (for a given diameter) width; then the sections of the trench where the cargo groups are to be installed are covered with soil. In these places, wells are drilled along the sides of the developed trench for explosive charges in one row, so that after blasting the total width of the trench in these places would be sufficient for the installation of weighting loads. Then the soil, loosened by the explosion, is taken out by a single-bucket excavator.

3.95 . The filling of a pipeline concrete-coated or ballasted with weighting materials is carried out using the same methods as for filling a pipeline in swamps or frozen soils (depending on the conditions of the route and the time of year).

Features of the technology of earthworks when laying gas pipelines with a diameter of 1420 mm in permafrost soils

3.96 . The selection of technological schemes for the construction of trenches in permafrost soils is carried out taking into account the depth of freezing of the soil, its strength characteristics and the time it takes to complete the work.

3.97 . The arrangement of trenches in the autumn-winter period at a depth of freezing of the active layer from 0.4 to 0.8 m with the help of single-bucket excavators of the type EO-4123, ND-150 is carried out after preliminary soil loosening with rack-mounted cultivators of the D-355, D-354 type and others that produce loosening the soil to the entire depth of freezing in one technological technique.

With a freezing depth of up to 1 m, it is loosened by the same cultivators in two passes.

With a greater depth of freezing, the development of trenches by single-bucket excavators is performed after preliminary loosening of the soil by a blasting method. Holes and wells in the trench strip are drilled using drilling machines such as BM-253, MBSh-321, Kato and others in one or two rows that are charged with explosives and explode. At a depth of freezing of the active soil layer of up to 1.5 m, its loosening for the development of trenches, especially those located no further than 10 m from existing structures, is carried out using the blasting method; with the depth of freezing of the soil more than 1.5 m - by the downhole method.

3.98 . When constructing trenches in permafrost soils in winter with freezing them at the entire depth of development, both in swamps and in other conditions, it is advisable to use mainly bucket-wheel trench excavators. Depending on the strength of the developed soil for the installation of trenches, the following technological schemes are used:

·   in permafrost soils with a strength of up to 30 MPa (300 kG / cm 2), trenches are developed in one technological process by rotary excavators of the ETR-254, ETR-253A, ETR-254A6 ETR-254AM, ETR-254-05 bottom width 2.1 m and a maximum depth of up to 2.5 m; ETR-254-S - bottom width 2.1 m and depth up to 3 m; ETR-307 or ETR-309 - 3.1 m wide along the bottom and 3.1 m deep.

If it is necessary to develop trenches of greater depth (for example, for ballasted gas pipelines with a diameter of 1420 mm), the same excavators previously using tractor rippers and bulldozers of the D-355A or D-455A type develop a trough-like excavation with a width of 6 - 7 m and a depth of up to 0.8 m ( depending on the required design depth of the trench), then in this excavation using the appropriate types of rotary excavators for a given diameter of the pipeline, a design profile trench is developed for one technological passage.

·   in permafrost soils with a strength of up to 40 MPa (400 kGf / cm 2), the development of wide-profile trenches for laying loaded pipelines with a diameter of 1420 mm by UBO-type reinforced concrete cargo in sections from 2.2 to 2.5 m deep and 3 m wide is carried out by an ETR-type rotary trench excavator -307 (ETR-309) in one pass, or by a complex combined and sequential method.

The development of trenches in such areas by the flow complex-combined method, at first along the edge of one side of the trench with an ETR-254-01 type trench excavator with a working body width of 1.2 m, a pioneer trench is being developed, which is filled up with a D-355A, D-455A or DZ bulldozer -27C. Then, at a distance of 0.6 m from it, a second trench with a width of 1.2 m is developed by an ETR-254-01 type rotary excavator, which is also covered with loose soil using the same bulldozers. The final development of the design profile of the trench is carried out by a single-bucket excavator of the ND-1500 type, which simultaneously with the selection of pioneer trench soil loosened by rotary excavators also develops a ground pillar between them.

The use of rotary excavators of the ETR-241 or 253A type instead of the ETR-254-01 for fragments of the second pioneer trench can serve as a variant of this scheme in areas of soils with a strength of up to 25 MPa (250 kG / cm 2). In this case, there is practically no work on the development of the pillar.

·   when developing trenches of such parameters in permafrost soils with a strength of 40 to 50 MPa (400 to 500 kG / cm 2), tractor-mounted rack-type cultivators of the D-355, D-455 type for preliminary loosening are additionally included in the complex of earthmoving machines (according to the previous scheme) the top most durable soil to a depth of 0.5 - 0.6 m before the work of bucket wheel excavators.

·   for the development of trenches in soils of higher strength - more than 50 MPa (500 kgf / cm 2), when loosening and excavating a ground pillar with a single-bucket excavator is very difficult, it is necessary to loosen it before using single-bucket excavators using the blasting method. For this purpose, a series of boreholes are drilled in the body of the pillar by drilling machines of the BM-253, BM-254 type through 1.5 - 2.0 m to a depth exceeding the design depth of the trench by 10 - 15 cm, which are charged with explosive charges by loosening and explode. After that, excavators of the type ND-1500 excavate all the loosened soil to obtain the design profile of the trench.

·   trenches for loaded pipelines with reinforced concrete weights (UBO type) with a depth of 2.5 to 3.1 m are developed in a specific technological sequence.

In areas with soil strengths up to 40 MPa (400 kgf / cm 2) and more, tractor-mounted cultivators on the basis of D-355A or D-455A are first loosened in the upper permafrost layer of soil in a strip 6 - 7 m wide to a depth of 0.2 - 0 , 7 m depending on the required final depth of the trench. After removing the loosened soil with bulldozers in the obtained trough-like excavation by an ETR-254-01 type trench excavator, a pioneer slot-trench 1.2 m wide is developed along the boundary of the design trench. After filling this slot with the excavated loosened soil, at a distance of 0.6 m from the edge the second pioneer trench is cut by another ETR-254-01 type rotary excavator, which is also filled with bulldozers of the D-355, D-455 type. Then, with a single-bucket excavator of the ND-1500 type, a trench of the full design profile is developed simultaneously with the pillar soil.

·   in areas of highly icy high-strength permafrost soils with a cutting resistance of more than 50 - 60 MPa (500 - 600 kgf / cm 2), the development of trenches should be carried out with preliminary soil loosening using the blasting method. At the same time, depending on the required depth of the trenches, drilling holes in a staggered manner in 2 rows using machines of the BM-253, BM-254 type should be carried out in a trough-shaped recess from a depth of 0.2 (with a trench depth of 2.2 m) to 1.1 m (at a depth of 3.1 m). To eliminate the need for work on the device of a trough-like excavation, it is advisable to introduce drilling machines of the MBSh-321 type.

3.99 . On sections of the route in permafrost soils with weak ice content, where gas pipelines are ballasted with mineral soil using LPS devices, the trench parameters are recommended to be taken: the width of the bottom is not more than 2.1 m, the depth depending on the amount of backfill and the presence of a heat-insulating screen - from 2.4 up to 3.1 m.

The development of trenches in such areas up to 2.5 m deep in soils with a strength of 30 MPa (300 kG / cm 2) is recommended to be carried out on a full profile by rotary trench excavators of the ETR-253A or ETR-254 type. Trenches up to 3 m deep in such soils can be developed by ETR-254-02 and ETR-309 rotary excavators.

In soils with a strength of more than 30 MPa (300 kG / cm 2), mechanized earth-moving complexes for the implementation of the technological scheme described above should be includedadditional tractor rack-mounted cultivators of the D-355 typeA or D-455A for preliminary loosening of the most durable upper layer of permafrost soil to a depth of 0.5 - 0.6 m before the development of the trench profile by bucket-wheel excavators of the indicated brands.

In areas with soil strengths up to 40 MPa (400 kG / cm 2), it is also possible to use a technological scheme with sequential penetration and development of a trench profile along the axis of the route with two rotary excavators: first ETR-254-01 with a rotor width of 1.2 m, and then ETR-253A, ETR-254 or ETR-254-02, depending on the required depth of the trench in this section.

For the effective development of wide trenches of ballastable gas pipelines with a diameter of 1420 mm in durable permafrost soils, a sequentially complex method is recommended by two powerful rotary trench excavators of the ETR-309 type (with different parameters of the working body), in which the first excavator is equipped with replaceable unified working bodies with a width of 1.2¸   1.5 and 1.8 ¸   2.1 m, first cuts through a pioneer trench ~ 1.5 m wide, and then a second excavator equipped with two mounted side rotor cutters, moving in series, finalizes it to the design dimensions 3´ 3 m required to accommodate the pipeline with ballasting devices.

In soils with a strength of more than 35 MPa (350 kgf / cm 2), it is necessary to include the preliminary loosening of the upper frozen soil layer to a depth of 0.5 m in the indicated sequentially combined technological scheme with tractor rack-mounted cultivators of the D-355A or D-455A type.

3.100 . In areas with extremely hard permafrost soils with a strength of 50 MPa or more (500 kgf / cm 2), the development of trenches with such parameters is recommended to be carried out with single-bucket excavators of the ND-1500 type with preliminary loosening of the frozen layer by the blasting method. For drilling holes to the full depth (up to 2.5 - 3.0 m), it is necessary to use drilling machines of the BM-254 and MBSh-321 types.

3.101 . In all cases, when carrying out excavation work on the construction of trenches in these soil conditions in the summer period, in the presence of a thawed topsoil, it is removed from the trench strip using bulldozers, after which work on the construction of trenches is carried out according to the technological schemes given above, taking into account the design profile of the trench and the strength of permafrost soil in this area.

When thawing the top soil layer in the event of its transition to a plastic or fluid state, which makes it difficult to carry out excavation work on loosening and developing the underlying permafrost soil, this soil layer is removed with a bulldozer or a single-bucket excavator, and then the permafrost soil is developed using the methods described above, depending on its strength.

Embankments on permafrost soils, as a rule, should be constructed from imported soil mined in quarries. In this case, it is not recommended to take the soil for the embankment in the strip of gas pipeline construction.

A quarry should be arranged (if possible) in loose-frozen soils, since a change in their temperature does not significantly affect their mechanical strength.

During the construction process, the embankment should be dumped taking into account its subsequent settlement. In this case, an increase in its height is established: when performing work in the warm season and filling the embankment with mineral soil - by 15%, when performing work in the winter and filling the embankment with frozen soil - by 30%.

3.102 . The filling of a pipeline laid in a trench made in permafrost soils is carried out as usual, if after laying the pipeline immediately after the development of the trench and the device for backfilling (if necessary), the soil of the dump did not freeze. In case of freezing of the soil of the dump in order to avoid damage to the insulating coating of the pipeline, it must be sprinkled with imported melt fine-grained soil or finely loosened frozen soil to a height of at least 0.2 m from the top of the pipe.

Further filling of the pipeline is carried out with a pound of a dump using a bulldozer or, preferably, a rotary trencher, which is able to develop a dump with freezing to a depth of 0.5 m.When the soil dump is deeper frozen, it must first be loosened mechanically or by a blasting method. When filling with frozen soil above the pipeline, a soil roller is arranged taking into account its precipitation after thawing.

Drilling and installation of piles for overhead pipelines

3.103 . The method of construction of pile foundations is prescribed depending on the following factors:

¨   frozen ground conditions of the route;

¨   time of year;

¨   production technology and the results of technical and economic calculations.

Pile foundations for the construction of pipelines in areas of permafrost soils are erected, as a rule, from factory-made piles.

3.104 . The construction of pile foundations is carried out depending on soil conditions in the following ways:

·   driving piles directly into plastic-frozen soil or into previously developed leader wells (drilled method);

·   installation of piles in pre-thawed soil;

·   installation of piles into pre-drilled and flooded wells with a special solution;

·   installing piles using a combination of the above methods.

Pile driving into the frozen stratum can only be carried out in high-temperature plastic-frozen soils having a temperature above -1° C. Driving piles into such soils with coarse and solid inclusions up to 30% is recommended after drilling leader wells, which are formed by immersing special leader pipes (with a cutting edge at the bottom and a hole in the upper side). The diameter of the leader well is 50 mm smaller than the smallest cross-sectional area of \u200b\u200bthe pile.

3.105 . The technological sequence of operations for installing piles in previously developed leader wells is as follows:

¨   the leader piles the piling mechanism to the design level;

¨   the leader with the core is removed by an excavator winch, which with the leader pipe moves to the next well, where the whole process is repeated;

¨   in the formed leader well, the pile is clogged with a second piling mechanism.

3.106 . In the presence of coarse inclusions in the soils (more than 40%), leader drilling is impractical, since the initial effort to extract the leader increases significantly and core is shedding back into the well.

3.107 . In heavy clays and loams, the use of bored piles is also impractical due to the fact that the core in the pipe is jammed and not forced out of the leader.

Leader wells can be arranged by thermomechanical, shock-rope, or other drilling.

3.108 . In cases where it is impossible to use bored piles, they are immersed in wells previously drilled by thermomechanical, mechanical or shock-rope drilling machines.

The technological sequence of operations when drilling wells with shock-rope drilling machines is as follows:

· arrange a platform for installing the unit, which should be strictly horizontal. This is especially important when drilling wells on slopes, when planning the site for installing the unit and for smooth access to it is carried out by a bulldozer by snow cobbing and watering it (to freeze the top layer); in the summer, the site is planned with a bulldozer;

·   drill a hole with a diameter 50 mm larger than the largest transverse size of the pile;

·   the well is poured heated to 30 - 40° With a sand-clay solution in the volume of about 1/3 of the well, based on the total filling of the space between the pile and the wall of the well (the solution is prepared directly on the track in mobile boilers using drill cuttings with the addition of fine-grained sand in an amount of 20-40% of the mixture volume; water for zhelonirovaniya it is desirable to deliver hot to mobile tanks or heat it in the process of work);

·   install a pile into the well with a pipe layer of any brand.

When the pile is immersed at the design elevation, the solution must be squeezed to the surface of the earth, which serves as evidence of the complete filling of the space between the walls of the well and the surface of the pile by the solution. The process of drilling a well and immersing piles in a drilled well should not last more than 3 days. in winter and more than 3-4 hours in summer.

3.109 . The technology for drilling wells and installing piles using thermomechanical drilling machines is described in the “Instructions for the technology of drilling wells and installing piles in frozen soils using thermomechanical drilling machines” (VSN 2-87-77, Minneftegazstroy).

3.110 . The duration of the freezing process of piles with permafrost soil depends on the season of work, the characteristics of frozen soil, soil temperature, construction of the pile, the composition of the sand-clay mortar and other factors and should be indicated in the design of the work.

Backfill trench

3.111 . Before starting work on filling the pipeline in any soil, it is necessary:

¨   check the design position of the pipeline;

¨   check the quality and, if necessary, repair the insulation coating;

¨   to carry out the work envisaged by the project to protect the insulation coating from mechanical damage (planning the bottom of the trench, laying the bed, dusting the pipeline with loose soil);

¨   arrange entrances for the delivery and maintenance of the excavator and bulldozer;

¨   Obtain written permission from the customer to backfill the laid pipeline;

¨ to give out a task assignment to the operator of a bulldozer or trencher (or to the crew of a single-bucket excavator if backfilling is carried out by an excavator).

3.112 . It is recommended to fill up the trench immediately after laying work (after ballasting the pipeline or fixing it with anchor devices).

3.113 . When filling the pipeline in rocky and frozen soils, the safety of the pipes and isolation from mechanical damage is ensured by the device sprinkling over the laid pipeline from soft (thawed) sandy soil to a thickness of 20 cm above the upper generatrix of the pipe, or by the protective coatings provided by the project.

3.114 . Pipeline filling under normal conditions is carried out mainly by rotary-type bulldozers and trenchers.

3.115 . Bulldozers fill the pipeline with: rectilinear, oblique parallel, oblique and combined passages. In cramped conditions of the construction strip, as well as in places with a reduced right-of-way, the work is performed by oblique parallel and oblique passages with a bulldozer or rotary trencher.

3.116 . If there are horizontal curves in the pipeline, the curved section is first filled up, and then the rest. Moreover, the filling of the curved section begins from its middle, moving alternately to its ends.

3.117 . In areas with vertical pipeline curves (in ravines, gullies, on hills, etc.), backfill is carried out from top to bottom.

3.118 . With large volumes of backfill, trenchers are advisable to use in combination with bulldozers. In this case, the filling is first carried out with a trencher, which, at the first pass, has maximum productivity, and then the remaining part of the blade is moved into the trench with bulldozers.

3.119 . The dragline laid in the trench of the pipeline is filled with dragline in cases where the operation of the equipment in the area where the blade is located is impossible, or at large distances of filling with soil. In this case, the excavator is located on the side of the trench opposite the dump, and the soil for backfill is taken from the dump and showered in the trench.

3.120 . After backfilling, on non-reclaimed lands, a soil roller is arranged above the pipeline in the form of a regular prism. The height of the roller should coincide with the value of the possible precipitation of soil in the trench.

On the cultivated lands in the warm season after filling the pipeline with mineral soil, it is compacted with pneumatic rollers or tracked tractors with multiple passes (three to five times) over the filled pipeline. Compaction of mineral soil in this way is performed before filling the pipeline with the transported product.

  4. Quality control and acceptance of earthwork

4.1 . The quality control of earthworks consists in the systematic observation and verification of the compliance of the work performed with the design documentation, the requirements of the joint venture in compliance with the tolerances (given in table.-5

The thickness of the layer of powder from soft soil above the pipe (with subsequent filling with rocky or frozen soil)