RU2516984C1 - Method of pipe laying in rock and half-rock at longitudinal slopes - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: in the method a pipe trench is developed, the trench bottom is prepared by levelling and subsequent removing local snouts of rocks and local depression in the trench bottom. Then sand bags are laid by continuous packing on the prepared trench bottom and a pipeline is laid over the sand bags. Sand-bag stoppings are formed on top of the pipeline in the shape of prisms which bases are protruded towards the slope side. The trench is filled by mineral ground from the dump and top soil on top of it. Arrangement of sand-bag stoppings in the area between the pipeline and rock in the trench provides significant reduction in soil removal.

EFFECT: reducing damage of the pipeline insulating layer, increasing speed and reducing costs.

6 cl, 3 dwg

Description

The invention relates to the field of the oil industry and can be used for laying pipelines in rocky and semi-rocky soils with a slope of the terrain.

When laying pipelines in the direction of a slope of more than 20%, it is necessary to provide for the installation of anti-erosion screens and lintels made of both natural soil (for example, clay lintels) and artificial materials. This follows, for example, from SNiP 2.05.06-85 “Main pipelines”. Jumpers are designed to prevent leaching of soil in the area around the pipeline, which serves as a supporting basis for the latter. In addition, due to the movement of solid particles of the soil during leaching, mechanical damage to the outer shell of the pipeline, the insulation coating, is possible, which affects its service life.

As a rule, anti-erosion towels are used as a substrate for pipelines, which, as practice shows, does not provide the proper low level of soil leaching.

From the USSR author's certificate No. 1651004 (published on 05/23/1991; IPC F16L 1/028), a method is known for laying an underground pipeline, including digging a trench, laying a pipeline into it, installing flexible carpets, forming transverse partitions and filling the trench with soil. Digging trenches is carried out with the formation of transverse ledges on its bottom and walls. A flexible carpet of filter material is spread along the bottom profile of the trench. Piping is laid on this carpet. After that, they lay another carpet of the same material on the pipeline and the walls of the trench with its establishment in the ledges and the formation of transverse partitions at the maximum cross-section of the trench. Trenches are filled in sections between the partitions in series, starting from the bottom of each inclined section of the trench, with the laying of transverse partitions on the end surface of the sprinkled soil. The aim of the invention is to increase the reliability of laying pipelines on inclined sections.

A disadvantage of the known solution is the complexity of the installation process, as well as a fairly low level of protection of the laid pipeline from leaching of the soil.

RF patent for invention No. 2062936 (published on June 27, 1996; IPC F16L 1/028) discloses an anti-erosion system for a pipeline laid on a slope. The system contains a set of drainage barriers, each of which includes a cloth filter made of non-woven synthetic material and its entrapment in a trench. Each of the filter sheets has the shape of a funnel facing the slope with a neck opening diameter equal to the diameter of the pipe, while the longitudinal edges of the filter cloth in the neck part of the funnel are overlapping each other, and in the receiving part they are bent to accommodate the trench at the bottom, walls and burs . The fastening of each filter in the trench is formed by a clamp that tightens the cloth on the pipe along one of its transverse edges and is removed from the trench or quarry by soil placed on the cloth inside the neck part and on the surface of the receiving part of the funnel. The technical result is to simplify the construction of an erosion control system.

The disadvantage of this solution is also the complexity of the process of laying the pipeline, including the installation of clamps. The protection against soil leaching according to this solution is higher than that proposed in A.S. USSR No. 1651004, however, is not designed for use in rocky and semi-rock soils.

The RF patent for invention No. 2218505 (published December 10, 2003; IPC F16L 1/028) discloses a method for preventing soil erosion by filling the pipeline on slopes. On a slope, a trench is torn, laid on its bottom, walls and berm anti-erosion towels made of non-woven synthetic material, and laid on them a pipeline. In the open trench, filters are created from anti-erosion towels by forming a funnel from each towel, the neck of which is located down the slope, covers the pipeline laid in the trench and is fixed. The fastening of each of the towels is carried out with backfill soil from the top of the slope. Dumping is carried out with the formation of an angle of natural slope of the soil in the zone of the filter funnel, leaving the lower edge of the panel free. The filter funnel is formed by overlapping the lower longitudinal edges of the towering bed with natural slope of the backfill and tying the edges of the cloth around the pipeline to form a gap between the neck of the funnel and the pipeline to allow the flow of groundwater along the slope of the trench and to regulate the flow rate over the cross section of the trench. The upper part of the funnel, formed by overlapping the longitudinal edges of erosion control towels, is located above the groundwater level in the trench. The result is an increase in the reliability of the pipeline by preventing leaching of the soil of the trench dump by surface waters.

This solution also has the above disadvantages.

As the closest analogue of the studied technical solution, the method of ballasting an underground pipeline according to the RF patent for invention No. 2153119 (published on July 20, 2000; IPC F16L 1/028) can be selected. The method consists in laying out on the surfaces of the pipeline laid in the trench, the bottom and the walls of the trench of a flexible carpet with the formation of longitudinal pockets filled with soil and interacting with the pipeline surface of the partitions with zones free of soil and the subsequent filling of the trench. Separate panels are used as a flexible carpet, and partitions are formed after filling pockets by pulling the flexible carpet around the pipeline and being pinched by clamps at the ends of the panels in areas free from soil. The latches are made in the form of a soil-filled tank formed by a flexible carpet covering the partitions, soil-free zones of the trench and its berm, the flexible carpet being connected to the partitions in their upper part by transverse welds. After backfilling, the soil is first covered with the longitudinal edges of the overlapping carpet, and then over the longitudinal ones, it is overlapped with transverse edges with an overlap, connecting the transverse edges with a weld. The method increases the stability of the soil in the trench against leaching, provides a ballasting effect in the area of the partitions, increases the reliability of the partitions and laying in general during operation.

The presence of partitions helps to reduce the rate of leaching of the soil. However, the disadvantage of the prototype is the complexity and complexity of the process of laying the pipeline, the use of additional tools designed to fix the protective material (flexible carpet).

The objective of the considered technical solution is to simplify the process of laying the pipeline on longitudinal slopes with a simultaneous increase in soil stability in the trench against leaching. As a result of preventing soil leaching around the pipeline, the level of protection of the insulation coating of the pipeline from exposure to moving solid soil particles is also increased, which is especially important when laying pipelines in rocky and semi-rock soils.

The problem is solved in that the method of laying the pipeline at the bottom of the trench in rocky and semi-rocky soils on a longitudinal slope includes the development of a trench, the leveling of local protrusions of rock and local recesses of the bottom of the trench, elimination of local protrusions and deepenings of the soil of the bottom of the trench to prepare the bottom of the trench, backfill of the trench bottom recesses is carried out with a dump soil containing at least 30% of incoherent mineral aggregate, continuous laying of sandbags on the prepared bottom of the trench and installing the pipeline on sandbags on top of the pipeline covering forming webs from its sandbags shaped prism base are elongated in the direction of the slope, and the mineral filling the trench with excavated soil, and on top of it - the soil-plant soil layer.

The device of jumpers from sandbags in the area between the pipeline and the rock formations of the trench makes it possible to significantly reduce soil leaching and, therefore, reduce damage to the insulation coating of pipelines. In addition, this method is faster and more profitable from an economic point of view in comparison with methods known in the art for preventing soil leaching.

The invention will now be described in more detail with reference to the drawings.

Figure 1 shows a General view of the trench with a pipe laid in it.

Figure 2 shows a cross section of a trench with a pipe laid in it.

Figure 3 shows a top view of the trench with the pipeline laid in it.

On a longitudinal slope (1), a trench is torn out. When developing trenches with preliminary loosening by a mechanized method, it is preferable to provide a steepness of slopes of 1: 0.3, and when developing trenches with preliminary loosening - by a blasting method - 1: 0.5.

At the bottom (2) of the trench, by means of leveling, the presence of local protrusions and local depressions (3) of the rock formations requiring elimination is detected. Elimination of local protrusions and recesses (3) of the bottom soil (2) of the trench can be carried out by attachments of excavators, such as a rock bucket, hydraulic hammer, ripper, cutter, etc., or by overhead charges.

Preferably, if for pipelines with a diameter of 1000 to 1100 mm, the width of the prepared bottom (2) of the trench is from 2.3 to 2.8 m.

The recesses (3) of the bottom (2) of the trench are preferably filled with a dump soil containing at least 30% of an incoherent mineral aggregate, which ensures greater soil stability.

On the prepared bottom (2) of the trench, continuous packing of bags (4) with sand is carried out. Bags (4) are made of polyester yarns according to GOST 30090 (length 80 cm, width 46 cm, weight with sand 50 kg), which guarantees a service life of at least 40 years, and filling them with sand is economically viable.

On the prepared bottom (2), trenches with bags (4) with sand are laid in the pipeline (5), enclosed in an insulating coating (6).

Next, on top of the pipeline (5), the lintels (7) covering it from sandbags (4) are laid. The jumpers (7) are stacked in the form of prisms, the bases of which must be extended towards the slope to increase stability. Preferably, if for pipelines with a diameter of 1000 to 1100 mm, the step L of laying the lintels (7) is from 18 to 22 m. The height of the lintels (7) is preferably chosen so that the depth from the surface (8) of the earth is about 0.3 m.

Next, fill the trench with mineral soil (9) dump. Backfill should be done with a bulldozer or a single-bucket excavator when working with anchoring mechanisms, and the backfill soil to the top of the trench should not contain solid inclusions larger than 300 mm.

A soil-plant layer (10) of soil is poured over the mineral soil (9).

The inventive method provides a high degree of protection against leaching of soil in the area around the pipeline laid in rocky and semi-rocky soils, and, therefore, its greater stability and protection from abrasive particles of the soil. In addition, the use of sandbags as jumpers that protect against leaching is cost-effective and does not require the use of additional means for fixing them in a trench, typical of the prototype and other solutions known from the prior art.

Claims (6)

1. A method of laying a pipeline at the bottom of a trench in rocky and semi-rocky soils on a longitudinal slope, including
trench development
leveling out local protrusions of rocks and local deepenings of the bottom of the trench,
elimination of local protrusions and deepenings of the soil of the bottom of the trench for preparing the bottom of the trench, and backfilling of the recesses of the bottom of the trench is carried out with a dump soil containing at least 30% of an incoherent mineral aggregate,
continuous laying of sandbags on the prepared bottom of the trench,
installation of the pipeline on sandbags,
forming on top of the pipeline bridges covering it from sandbags in the form of prisms, the bases of which are elongated towards the slope, and
filling the trench with mineral soil from the dump, and on top of it -
soil-vegetable layer of soil. 2. The method of laying the pipeline according to claim 1, characterized in that the elimination of local protrusions and deepenings of the soil of the bottom of the trench is carried out by attachments of excavators or overhead charges. 3. The method of laying the pipeline according to claim 1, characterized in that for pipelines with a diameter of 1000 mm to 1100 mm, the width of the prepared base of the trench is from 2.3 to 2.8 m, and the step of laying the lintels is from 18 to 22 m. 4. The method of laying the pipeline according to claim 1, characterized in that the bags made of polyester threads are laid. 5. The method of laying the pipeline according to claim 1, characterized in that when developing trenches with preliminary loosening by a mechanized method, the slope slope is 1: 0.3. 6. The method of laying the pipeline according to claim 1, characterized in that when developing trenches with preliminary loosening by the blasting method, they provide a slope of 1: 0.5.

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