Method of laying underground pipeline in seismic zones

FIELD: construction.

SUBSTANCE: method comprises trenching, laying pipeline in the trench, covering the pipeline with a material for reducing the friction of pipeline, and filling the trench with soil. The covering is made of flexible porous material preliminary impregnated with carbamide-formaldehyde resin. The space is provided between the outer surface of the pipeline and inner surface of the trench.

EFFECT: enhanced reliability.

4 cl, 1 dwg

 

The invention relates to the construction and can be used in the construction of underground pipelines in areas of high seismicity.

Pipelines are in different geographical areas with different topography, climatic conditions, availability of natural and artificial obstacles. It requires absolute reliability of structures such important structures as pipelines, ensure a long and trouble-free operation. This problem is aggravated by the conditions of construction of pipelines in the North, Middle Asia, as well as increasing the diameters of pipelines and operating pressures in them.

With the reliability issues associated conditions of operating pipelines, resulting from the nature of the terrain, the availability of natural and artificial barriers, and technological features.

It is known that the pipelines laid in seismic regions with 7 points and above, should be designed taking into account the additional requirements of normative documents in construction of buildings in these conditions. The laying and operation of pipelines on such soils in many cases is difficult due to permanent damage to the pipes occurring due to the movement of rentowych masses composing these areas.

In some cases, the movement of soil masses cracks, faults, failures and landslides, sometimes moving soil becomes catastrophic dimensions. In other cases, there have been only a small and invisible to the eyes of the soil deformation without cracking and plastic deformation. Movement of the second kind (plastic deformation) occurs much more frequently than the movement of the first kind, and plastic deformation is almost always preceded by movements of the first type.

Most of the damage to the piping on such sites occurs due to plastic deformation and is accompanied by leakage of the pumped product, which is sometimes not immediately, you notice, and resulting from pipeline product saturates the surrounding soil, which leads to greater deformation and more severe damage.

Analysis of engineering solutions that ensure the construction of pipelines in areas of high seismicity, showed that the proposed solution can be roughly classified into the following types:

- the creation of artificial bases of different species under the pipeline, including various supporting elements;

- creating a pipeline of pre-stress due to installation of pipe bends, which when operational p is remedeeh pipeline together with primers ensure the pipeline of new operational forms, what causes it operational voltage, opposite in sign to the pre-Assembly, thereby compensating them.

The prior art method of pipeline construction on landslide slopes, whereby to prevent damage to the pipeline in case of small deformations of the soil pipe is freely suspended from the ceiling of the tunnel, made in the soil (cm. SU 47610 And 30.07.1936). The known solution is difficult, time-consuming and may require significant financial resources.

There is a method of laying a pipeline, ensuring its seismic stability when laying on the soil Foundation with different properties along the length of the pipeline. Between areas characterized by a sharp change in properties of the soil (for example, the site exit subsea pipeline to shore), midway area with a relative ratio of the elastic Foundation, which is determined from the ratio that takes into account the coefficients of the elastic Foundation of all plots, the geometry of the pipeline and its physical-mechanical characteristics (see SU 1303786 A1, 15.04.1987). The method is tedious and does not provide the necessary reliability in mind to take into account a significant number of factors that have a wide range of quantitative characteristics.

A known method of laying underground pipeline in the ground subsidence in the AOR the Ah with high seismicity, the crucial task - improving the reliability of the pipeline by generating additional support for the pipe and its installation in the form of a spatial step of the spiral, absorbing seismic vibrations.

The method is as follows. Tear trench extends it with the formation of longitudinal shelves in the side walls of the trench, and then stack the pipeline, which forms a stepped spiral in plan laid “snake” and based in places turn consistently on the shelf and the bottom of the trench. The horizontal links are placed on the side of the shelf and the bottom of the trench, connecting the horizontal links inclined. After laying and installation of pipe produce the trench (see SU 1492149 A1, 07.07.1989). The method requires a high consumption of metal pipes, difficult to implement and very time-consuming.

Analysis of seismic effects on pipelines helped to establish that the particular transmission of seismic effects on pipelines and the nature of their work significantly depend on the system of pipeline construction and its interaction with the surrounding soil.

In the prior art it is known that the greatest impact on the pipeline have a seismic wave, the propagation direction of which coincides with the direction of the piping. So installed, canabalise the number of damage occurs on pipelines, the direction of which coincides with the direction of seismic wave propagation, the fracture due to the tensile efforts, resulting in trapped in the ground pipelines.

Typically, underground pipelines are not calculated on the action of seismic waves or their components, directed normally to the longitudinal axis of the pipeline.

It is established that the magnitude of the deformations and stresses in the pipe are largely determined by the nature of the interaction between soil and pipe, which in turn depends on the parameters of the seismic waves, the design of the pipeline, physico-mechanical properties of soil, density of the backfill in the trench, transmission friction and other forces from the soil to the pipeline.

It was found that a relatively small displacement of the pipeline structure, ensuring its compliance, does not cause damage to the pipeline.

A known method of laying underground pipelines in earthquake-prone terrain, which consists in laying a pipeline in a trench and the use of special wrappers pipeline trench loose soil or a special material with a low coefficient of adhesion and with a small volume weight (see “Seismic resistance of pipelines and special structures n ftanei and gas industry” Ed. SAVINOV O.A., Moscow, Nauka, 1980, p.102). This decision is closest to the claimed invention.

The known method of pipeline construction ensures its mobility by reducing the degree of crushing of the pipe in the ground.

However, drawing on the pipeline special wrappers in the well-known solution in the field is not high-tech and labor-intensive. In addition, the trench loose soil or a special material with low friction and low volumetric weight will adversely affect the operation of the pipeline at the change of pressure, temperature influences, that is, when the basic operational impacts.

Thus, there is the task of creating a method of underground pipeline, which eliminates pinching of the pipeline in the ground and enables displacement of the soil with respect to the pipeline without significant deformation, destruction, isolation and the pipeline in case of exposure to seismic waves.

This task is solved in that in the method of laying underground pipeline in areas of high seismicity, which consists in the passage of the trench, laying of pipe and backfilling the trench with soil prior to application to the pipeline wrapper for reducing the degree of crushing is Truboprovod in the ground, with a wrapper made of a “sheet rock”, for which the last pre slid under the pipe, bend with overlapping longitudinal edges of the rocky sheet and fasten them overlap with the formation of “rock paper” channel, while between the outer pipe surface and the inner surface of the specified channel to create the calculated value of the gap.

In some cases, of the complete method, “rock sheet made of a flexible porous material in the form of a one or two-layer sheet, which is pre-impregnated with urea-formaldehyde resin with the curing agent, followed by curing, with “rock sheet made of a nonwoven synthetic material (NCM).

The channel is used for laying underground pipe ensures its mobility by reducing the degree of crushing of the pipe in the ground. The execution channel “sheet rock” simplifies the process of construction of underground pipeline, provides the necessary durability of its design. As tires use annealed wire, packing tape and other packaging materials.

On the horizontal rotation angle of the pipeline route should detach the trench with gentle slopes, for which the steepness of the slopes assign lower values of angle eats the state of repose for the soil type.

When the soil backfill prone to rapid seal, you should line the gentle slopes of a material with low coefficient of friction with the soil backfill, such as geotextile material with termopolirovannoe addressed to the soil backfill surface.

The invention is illustrated in the drawing, which depicts laid in a trench the pipeline.

The method is as follows. In an area of high seismicity tear trench 1. To reduce the degree of crushing of the pipe 2 in the ground 3 pipeline pre-put the wrapper 4, which is done from the “sheet rock”, for which the latter is slid under the pipe, bend with overlapping longitudinal edges of the rocky sheet and fasten them overlap with the formation of “rock paper” channel, while between the outer pipe surface and the inner surface of the specified channel to create the calculated value of the gap not exceeding 10-15 mm

“Rock sheet made of a flexible porous material is non-woven synthetic material (NCM) in the form of a one or two-layer sheet, which is pre-impregnated with urea-formaldehyde resin with the curing agent, followed by curing.

Bond edges “sheet rock” is realized by means of bandages 5. As tires use annealed wire is, the packing tape and other packaging materials.

Stack pipe 2 in trench 1 and covered it with soil 3. On sections of the bend pipe 2 tear trench 1 with gentle slopes 6, for which the steepness of the slopes assign lower values of angle of repose for the soil type. When the soil backfill prone to rapid seal line the gentle slopes of 6 material 7 with low coefficient of friction with the soil backfill 3, for example geotextile material with termopolirovannoe addressed to the soil backfill surface. When this soil backfill, the density of which in three years and less than 70% of maternal soil density, should be considered prone to rapid seal.

The use of the channel from the “sheet rock” for laying underground pipeline provides mobility of the pipeline by reducing the degree of crushing in the soil. The execution channel “sheet rock” simplifies the process of construction of underground pipeline, provides the necessary durability of its design.

1. The method of laying underground pipeline in areas of high seismicity, which consists in the passage of the trench, laying of pipe and backfilling the trench with soil prior to application to the pipeline wrappers to reduce frame the crushing of the pipe in the ground, characterized in that the wrapper is made “sheet rock”, for which the latter is slid under the pipe, bend with overlapping longitudinal edges of the rocky sheet and fasten them overlap with the formation of “rock paper” channel, while between the outer pipe surface and the inner surface of the specified channel to create the calculated value of the gap.

2. The method according to claim 1, characterized in that the “rock sheet made of a flexible porous material in the form of one - or two-layer sheet, which is pre-impregnated with urea-formaldehyde resin with the curing agent, followed by curing.

3. The method according to claim 2, characterized in that the “rock sheet made of a nonwoven synthetic material (NCM).

4. The method according to claim 1, characterized in that the longitudinal edges “sheet rock” fasten bandages.

5. The method according to claim 1, characterized in that the horizontal rotation angle of the pipeline route tear trench with gentle slopes, for which the steepness of the slopes assign lower values of angle of repose for the soil type.



 

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