RU2509249C2 - Method to install underground pipeline when crossing active seismotectonic area - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: first borders of the seismotectonic area are defined, and a trench is dug with gentle slopes, the axis of which in plan corresponds to the axis of the pipeline. Then a water-impermeable shell is laid onto levelled bottom and slopes of the trench, and the shell is made from elastic material, on top of which they fill a cushion from a sand filler, afterwards a pipeline is laid onto the cushion, the trench is filled with the sand filler to the height above the pipeline of less than 0.5 of the external diameter of the pipeline. The upper edges of the shell are connected to form a closed shell around the sand filler, and via water-impermeable links that are tightly connected with the pipeline and the shell, they withdraw the pipeline from the sand filler outside the borders of the seismotectonic area. At the same time in the lower part of the sand filler they install a drainage pipe, which is hydraulically communicated with the emergency reservoir, and the pipeline is equipped with a pressure sensor in the pore space of the sand filler and two locking devices, which are arranged on the pipeline, one beyond each border of the seismoactive area. Between the borders of the seismotectonic area the pipeline from outside may be equipped with a layer of specified thickness from foamed material with tightly closed pores.

EFFECT: increased operational reliability of a pipeline, efficient collection of information on leakage of a product from a pipeline within a seismotectonic area and prevention of product spread in adjacent soil areas.

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Description

The invention relates to construction and can be used for underground pipelines transporting mainly oil and oil products, when pipelines cross active seismotectonic zones.

According to clause 5.37 of the Building Norms and Rules currently in force in SNiP 2.05.06-85 *, "on the sections of the intersection of the active pipeline of tectonic faults by the pipeline route, it is necessary to use overhead laying". It is believed that the pipeline installed on the supports and made in the form of a U-shaped compensator will ensure safe operation when the tectonic fault is activated. The dimensions of such a compensator can be very large, which will lead to a significant increase in work. At the same time, the operational reliability of such an onshore pipeline is not great, and in the event of an oil pipeline rupture, a large amount of oil spill will occur, which will lead to significant economic and environmental costs.

It is a well-known method of constructing an underground pipeline, according to which a trench is first torn off, the axis of which in plan corresponds to the axis of the pipeline, and then they are laid in a pipeline trench and filled with trench with soil. When such a pipeline crosses an active seismotectonic zone, seismic tremors produce dangerous effects on the pipeline both in its transverse and longitudinal directions.

For the technical protection of such pipelines from seismic shocks, a number of design solutions and technological methods have been proposed. In this case, special attention is paid to ensuring relatively free movement and deformation of the pipeline while damping the vibrations of the pipeline under various environmental influences (including seismic) (SU 1682709, 10/07/1991; SU 1827494, 07/15/1993; SU 1828839, 23.07. 1993; RU 2197667, 01/27/2003; RU 2220357, 09/10/2003; RU 2262631, 02/20/2005; RU 2264577, 11/20/2005, RU 2363874; 08/10/2009; RU 2363875, 08/10/2009; RU 2363876, 08/10/2009 ; RU 2365802, 08.27.2009).

A disadvantage of the known methods is the use of complex and material-intensive structures, which leads to unjustified costs when laying pipelines. Additionally, in the event of a pipeline rupture, the product will inevitably spill over adjacent soil sections.

A known method of laying an underground pipeline in areas with high seismicity (RU 2250409, 04/20/2005). In this known solution, the pipeline is laid in a trench and filled with soil with preliminary application of wrappers to the pipeline, which are made of “rock sheet” with the formation of the channel. Between the outer surface of the pipeline and the inner surface of the channel create a calculated value gap. The “rock sheet” is made of porous material, and in the sections of the turn of the pipeline route the trench is torn off with gentle slopes.

A pipeline made by this method is not reliable enough when operated in a seismotectonic zone due to the insecurity of preventing product spreading over adjacent soil sections in case of product leakage from the pipeline.

A known method of laying an underground pipeline for terrain with active seismotectonic zones (RU 2241889, 12/10/2004), which is the closest to the claimed solution. The method consists in first tearing off a trench with gentle slopes and a depth of 2.5-4.0 of the outer diameter of the pipeline, while the axis of the trench in plan corresponds to the axis of the pipeline. Then, a pillow of sand filler is poured into the bottom of the trench with a height of at least 0.5 of the outer diameter of the pipeline and the pipeline is laid on the pillow. After that, the trench is covered with sand filler, which is washed river sand of medium size or coarse, not containing dusty or clay fractions or coarse admixture. Sand filler, as an option, together with the pipeline is enclosed in a waterproof shell.

A pipeline made by this method is not sufficiently reliable during operation in the seismotectonic zone due to the insecurity of prompt information in the event of product leakage from the pipeline within the seismotectonic zone and the complexity of work when preventing product spreading on adjacent soil sections in the event of product leakage from the pipeline. When the product flows out of the pipeline under pressure, the pores of the sand filler are filled with the product, and pressure increases inside the waterproof shell. After that, the casing is strained, the soil above the casing swells and if the emergency section of the pipeline is not disconnected in a timely manner, the casing is destroyed and the product spreads over adjacent soil sections with inevitable soil contamination. Additionally, the method does not provide lateral tightness of the shell.

The problem to which the invention is directed, is to increase the operational reliability of the pipeline when it is laid through the active seismotectonic zone with a fault. The technical result from the use of the invention is to quickly obtain information about the leakage of the product from the pipeline within the seismotectonic zone and to prevent the spreading of the product in adjacent soil sections.

The problem is solved, and the technical result is achieved by the fact that in the method of laying an underground pipeline at the intersection of the active seismotectonic zone, the boundaries of the seismotectonic zone are first determined and a trench with gentle slopes is opened, the axis of which in plan corresponds to the axis of the pipeline. Then, on the leveled bottom and slopes of the trench, a waterproof shell made of elastic material is laid on which a pillow of sand filler is poured, after which a pipeline is laid on the pillow, a trench is filled with sand filler to a height above the pipeline of at least 0.5 of the outer diameter of the pipeline. The upper edges of the shell are connected with the formation of a closed shell around the sand filler and through the waterproof lintels that are hermetically connected to the pipeline and the shell, the pipeline is withdrawn from the sand filler beyond the boundaries of the seismotectonic zone. In the lower part of the sand filler, a drainage pipe is placed, which is hydraulically connected with the emergency capacity, and the pipeline is equipped with a pressure sensor in the pore space of the sand filler and two shut-off devices, which are placed on the pipeline one after each boundary of the seismotectonic zone.

Additionally:

- the shell is made with a thickness of at least 2.0 mm;

- the pipeline between the borders of the seismotectonic zone is supplied from the outside with a layer of a given thickness of foam material with hermetically closed pores, while the layer is made mainly of cellular plastic;

- a waterproof jumper is made of rolled polyethylene in the form of a cuff on a pipeline or of cohesive soil in the form of a wall, while the shell is provided with a weakly extensible rim or bandage within the wall;

- the locking device is located in the well directly at the border of the seismotectonic zone.

It is the execution of the shell of an elastic (at least semi-elastic) material that ensures its extensibility, which increases the volume of the container created by the shell, with an increase in pressure in the container in case of leakage of the product from the pipeline. At the same time, a pressure sensor, shut-off devices, a drain pipe and an emergency tank, made according to the indicated rules, ensure the achievement of the previously indicated technical result:

prompt receipt of information on product leakage from the pipeline within the seismotectonic zone and in preventing product spreading to adjacent soil sections.

The method is illustrated by drawings, where Fig. 1 schematically shows a section of a laid underground pipeline at the intersection of a seismotectonic zone, a plan; figure 2 is a section aa in figure 1; figure 3 is a section bB in figure 1.

Example. The underground pipeline 1 is designed to transport oil and oil products (i.e., the oil pipeline) crosses the active seismotectonic zone 2, the boundaries of which are determined by surveys 3 and 4 and which has a width L - the length of the pipeline section in the conditions of this zone 2.

Laying the pipe 1 with an outer diameter D is as follows.

At borders 3 and 4, trench 5 is opened with gentle slopes 6, depth H and width B lower, on top of C. The axis 7 of trench 5 in plan corresponds to axis 8 of pipeline 1. On the leveled bottom 9 and slopes 6 of trench 5 lay an elastic waterproof shell 10, made of rolled material, onto which a pillow 11 is poured from sand filler 12, after which pipe 1 is laid on pillow 11. A trench 5 is filled with sand filler 12 to a height above pipeline 1 of at least 0.5 of the outer diameter of pipeline 1. The upper edges of the shell 10 are connected with about azovaniem closed around the sand filler 12 and the shell 10 through a watertight bridge 13 produce output conduit 1 of sand filler 12 beyond the 3 and 4 seismotectonic zone 2, after which the trench 5 is filled local ground 14 to its entire height H.

The shell 10 is made of rolled polyethylene (film) with a thickness of mainly not less than 2.0 mm Such material is elastic and, given the place of its application and purpose in construction, is usually called a geomembrane. The jumpers 13 are hermetically connected to the pipe 1 and the sheath 10, and they are made of rolled polyethylene (geomembrane) in the form of a cuff on the pipe 1 or from a cohesive soil in the form of a wall 15. In the latter case, the sheath 10 within the wall 15 is provided with a weakly extensible border or bandage 16 of cord fabric (figure 3).

A drain pipe 17 is located in the lower part of the sand filler 12, which is hydraulically hydraulically connected to the emergency tank 20 through the discharge pipe 18 with a valve 19. The pipeline 1 is provided with a pressure sensor in the pore space of the sand filler (not shown) and two shut-off devices 21 located on the pipeline 1 one at a time in wells 22 beyond the boundaries of 3 and 4 of the seismotectonic zone 2, and in the immediate vicinity of the borders of 3 and 4. The pressure sensor can be made, for example, in the form of a pressure gauge located at the outlet the supply pipe 18 in front of the gate valve 19.

The pipeline 1 between the boundaries 3 and 4 of the seismotectonic zone 2 is supplied from the outside with a layer 23 of a predetermined thickness of foam material with hermetically closed pores. This layer 23 is mainly made of cellular plastic (polystyrene foam, polyurethane foam).

Along the pipeline 1, a road embankment 24 is made, on the powders of which are the supports 25 of the power line.

The design of the emergency tank 20 depends on local conditions and may take the form of an open ground tank shielded by a geomembrane or a closed tank.

A feature of the operation of an underground pipeline constructed in accordance with the present invention and as applied to the described embodiment is as follows.

1. If a fault is activated in zone 2, damage to pipeline 1 and subsequent leakage of oil from it into the sand filler 12 containing it can occur. As a result, pressure will continuously increase in the pores of the sand filler 12, and the shell 10 will stretch, which will lead to the increase in oil capacity in a closed shell and swelling of the soil 14 above the pipeline 1 (in Fig.2, swelling of the soil is shown by a dotted line). The latter circumstance allows direct observation of the soil surface to assess the rate of oil leakage, and the stretching of the shell 10 in combination with the gentle slopes 6 of the trench 5 will provide the time necessary to prevent the further development of the accident.

2. The pressure sensor will immediately signal the beginning of the flow of oil from pipeline 1. In this case, by closing the two shut-off devices 20, the emergency section of the pipeline 1 is turned off, and oil from it and sand filling 12 is drained into the emergency tank 20, which prevents oil from spreading over unpaved areas, as well as favorable conditions are created for carrying out 1 repair work on the pipeline.

3. The highly deforming properties of the layer of cellular plastic 23 provide relatively free movement and deformation of the pipeline 1 with simultaneous damping of the vibrations of the pipeline 1 during seismic shocks that produce effects both in the transverse and longitudinal directions, as well as other environmental influences.

This circumstance ensures the achievement of an additional technical result that was not previously indicated: the universality of protecting the pipeline from concentrated deformations of the enclosing rocks, regardless of the nature of the deformation or the direction, while expanding the arsenal of technical means that increase the reliability of the underground pipeline. Moreover, the highly elastic layer 23 of cellular material prevents free flow through oil damage from pipeline 1 to sand filler 12. This circumstance increases the time for shutting down the emergency section and can partially or completely prevent the filling of pores of sand filler 12 with oil, which will also increase the reliability of pipeline 1 and simplify repair work.

Designations

1 - underground pipeline (hereinafter: the pipeline)

2 - active seismotectonic zone (seismotectonic zone)

3 and 4 - boundaries (seismotectonic zone)

5 - trench

6 - slope (trenches)

7 - axis (trenches)

8 - axis (pipeline)

9 - bottom (trenches)

10 - shell

11 - pillow

12 - sand filler

13 - jumper

14 - local soil

15 - wall

16 - bandage

17 - drainage pipe

18 - outlet pipe

19 - valve

20 - emergency capacity

21 - locking device

22 - well

23 - layer of cellular material

24 - road embankment

25 - power transmission towers

L is the length of the pipeline section in a seismotectonic zone

D - Outer diameter of the pipeline

H - trench depth

B - trench width down

C is the width of the trench on top

Claims (8)

1. A method of laying an underground pipeline at the intersection of the active seismotectonic zone, characterized in that the boundaries of the seismotectonic zone are first determined and a trench with shallow slopes is torn, the axis of which corresponds in plan to the axis of the pipeline, then a waterproof shell made of elastic is laid on the leveled bottom and slopes of the trench material onto which a pillow of sand filler is poured, after which a pipeline is laid on the pillow, a trench is poured with sand filler to a height above the pipeline is not less than 0.5 of the outer diameter of the pipeline, the upper edges of the shell are connected to form a closed shell around the sand filler and through the waterproof jumpers that are tightly connected to the pipeline and the shell, the pipeline is withdrawn from the sand filler beyond the boundaries of the seismotectonic zone, while in the lower part sand filler have a drainage pipe, which hydraulically communicate with the emergency capacity, and the pipeline is equipped with a pressure sensor in the pore space p schanogo filler and two closing devices are disposed on the conduit one at each zone boundary Seismotectonic. 2. The method according to claim 1, characterized in that the shell is made of rolled polyethylene with a thickness of at least 2.0 mm 3. The method according to claim 1, characterized in that the pipeline between the boundaries of the seismotectonic zone on the outside is provided with a layer of a given thickness of foam material with hermetically sealed pores. 4. The method according to claim 1, characterized in that the waterproof jumper is made of rolled polyethylene in the form of a cuff on the pipeline. 5. The method according to claim 1, characterized in that the waterproof jumper is made of cohesive soil in the form of a wall. 6. The method according to claim 1, characterized in that the locking device is located in the well directly at the border of the seismotectonic zone. 7. The method according to claim 3, characterized in that the layer is made of cellular plastic. 8. The method according to claim 5, characterized in that within the wall of the shell provide a weakly extensible rim or bandage.

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