An anchor-cable device for ensuring the design position of an underground pipeline when laid in conditions of weak and structurally unstable soils

Abstract

This utility model relates to the construction, operation, and repair of pipelines transporting gas, oil, and other products, and can be used to ensure the stability of underground pipelines in areas with permafrost soils. The technical result of the claimed utility model is to increase the reliability of securing the pipeline in its design position when laid in soft and structurally unstable soils.The said technical result is achieved due to the fact that in the anchor-cable device for ensuring the design position of an underground pipeline when laid in conditions of weak and structurally unstable soils, including anchor elements with fixing clamps made with the possibility of installation on the pipeline, according to the present utility model, each fixing clamp is made in the form of a steel arched horseshoe with lateral bases in which openings are made, with the help of which it is put on the supporting anchor elements, between each pair of anchor elements two cables are stretched, intersecting with each other.

Description

[0001] The utility model relates to the field of construction, operation and repair of pipelines transporting gas, oil and other products, and can be used to ensure the stability of underground pipelines in areas with permafrost soils.

[0002] The degrading behavior of soil conditions during the operational phase of pipelines contributes to their displacement beyond the design specifications, confirming the lack of universal methods for ensuring the stability of sections located in harsh engineering and geological conditions unaffected by soil influences. Currently, the main methods for ensuring the stability of pipelines at design elevations are known. These include various types of load-bearing devices that exert their own force on the pipeline and devices that interact with the soil and ensure pipeline anchorage.Based on the application of existing pipeline ballasting and anchoring devices, as well as operational experience with pipeline mains, it has been established that typical devices primarily support the pipeline section in the longitudinal direction. During pipeline operation, temperature fluctuations and changes in linear expansion lead to transverse pipe movement, which typical devices are unable to fully prevent. To address these challenges, a special system of devices (hereinafter referred to as the anchoring system) is proposed: underground anchor supports coupled with an arched clamp, connected by a cable harness. The interaction of the cable connection system in this design compensates for longitudinal displacement, while the arched clamp and anchor connection to the ground minimize losses of holding capacity in the transverse direction of the pipeline.

[0003] A device for ensuring the design position of an underground pipeline is known [RU 2316630, published February 10, 2008], including bored piles installed in pairs at a specified pitch on either side of the pipeline so that the pile head is above ground level. A metal support is placed under the pipeline, on which loops can be pre-installed. Half a pipe with a larger diameter than the pipeline is used as the metal support. Next, an extended steel cable is passed through the loops of the metal support, bending around the pipe. The ends of the steel cable are secured to the pile heads using tension couplings.

[0004] A device is known for ensuring the design position of an underground pipeline when laid in weak soils [RU 173696, published 06.09.2017], containing a supporting element made of bored piles installed on both sides of the pipeline with tie rods and a clamp put on the pipeline, characterized in that the clamp is made detachable and is made of two halves of a larger diameter pipe fastened with studs, the tie rods are made in the form of two steel cables enveloping the clamp from above and below, with turnbuckles at each end and attached to the bored piles using embedded elements with an eye.

[0005] A common drawback of known devices is the low reliability of fixing the pipeline in the design position due to the lack of force interaction between the anchor supports, which increases the risk of the entire anchor chain of the fixed section failing in the event of a loss of stability of one support.

[0006] The technical result of the claimed utility model is to increase the reliability of fixing the pipeline in the design position when laying in conditions of weak and structurally unstable soils.

[0007] The specified technical result is achieved due to the fact that in the anchor-cable device for ensuring the design position of an underground pipeline when laid in conditions of weak and structurally unstable soils, including anchor elements with fixing clamps made with the possibility of installation on the pipeline, according to the present utility model, each fixing clamp is made in the form of a steel arched horseshoe with lateral bases in which openings are made, with the help of which it is put on the supporting anchor elements, between each pair of anchor elements two cables are stretched, intersecting with each other.

[0008] Thus, the combination of essential features has improved the reliability of securing the pipeline in its design position. The interaction of the cable-based anchoring system within this device compensates for longitudinal displacements, while the arched clamp and anchor adhesion to the ground minimize transverse pipeline movement. Furthermore, the paired connection of the anchor elements maintains the pipeline's design position even if at least one anchor element deviates from its design position.

[0009] The claimed technical solution is explained in more detail using figures and the following description.

[0010] Fig. 1 schematically shows the claimed anchor-cable device.

[0011] Fig. 2 shows view A of Fig. 1.

[0012] Fig. 3 shows the claimed anchor-cable device with a pipeline installed in it.

[0013] Fig. 4 shows a possible exit from the design position of the anchor element.

[0014] An anchor-cable device for ensuring the design position of an underground pipeline 1 when laid in conditions of weak and structurally unstable soils (Fig. 1-4) includes anchor elements 2 with fixing clamps 3, designed with the possibility of installation on the pipeline 1.

[0015] Two steel cables 4 are stretched between each two anchor elements 2, crossing each other in a crisscross pattern. Cables 4 are secured to anchor elements 2 using eye nuts 5 until the tension on cables 4 is reached by dynamometers. The parameters of cables 4 and the fastening pitch are determined by calculation based on the dimensions of pipeline 1, its installation conditions, and the required holding capacity of the section.

[0016] The cables 4 can be provided with clamps 7. On the anchor elements 2, eyes 8 are formed for securing the cables 4.

[0017] Each anchor element 2 is a steel metal pile support, for example, made of steel grade 35KhGSA (other analogs are possible), with a diameter of 1 / 7 from the ratio d опоры / D н .

[0018] Each fixing clamp 3 is made in the form of a steel arched horseshoe with side bases in which holes are made through which the anchor element 2 is passed and stabilized by a nut 6. The fixing clamp 3 is made of steel, for example, grade 17G1S, with a diameter equal to the diameter of the pipeline 1 with an optimal width of 0.2-0.6 m with a wall thickness of 0.025-0.035 m based on the strength calculation and metal content of the product.

[0019] The main purpose of cables 4 is to enhance the holding capacity of the anchor fastening system, as well as to unite all the elements of the device into a single structure, allowing the more mobile parts of the system to be compensated for by less mobile and better secured parts.

[0020] The stability of the device will be ensured not only by the interaction of the anchor elements 2 with the soil and the weight of the fixing clamp 3, but also by the tension of the strapping between the anchor elements 2 and the change in their angle along the horizontal plane in the event of movement of the pipeline 1 under the action of a vertical buoyancy force. A vertical component of the tension force T will arise in the cables 4. y , which depends on the buoyancy force N and the holding capacity of the system P and is determined by the formula

[0021]

[0022] Based on the calculation when selecting the parameters of the fastening system, it is necessary that the stability condition of pipeline 1 be met: the total calculated loads from pipeline 1 and the fastening devices acting downwards are greater than the total loads from the buoyancy force under the pipe section.

[0023] Based on the experimental modeling, a maximum cable tension angle of 5.5 degrees can be recommended for the anchoring system for pipeline 1 with a diameter of 1420 mm. Furthermore, based on the resulting stress of 20.1 MPa in a 10 mm diameter cable with a 1 meter displacement of the right pile, the cable tension force was determined to be approximately 1.58 kN. This means that each pile-cable-pile pair, under the above circumstances, increases the anchoring device's holding capacity by 1.58 kN.

[0024] The claimed device is used as follows.

[0025] Anchor elements 2 are driven into the intended installation locations along the bottom of the trench for the pre-laid pipeline. Anchor elements 2 are driven into the ground by screwing them in using a rotary motion with a mechanized screwing unit. Next, a fixing clamp 3 is mounted on them, the side bases of which rest with the supporting surface on the bottom of the trench. Fixation of clamp 3 to anchor elements 2 is performed using fixing elements (e.g., nuts 6). Next, a cable tie system is installed in a cross-shaped pattern, with cables 4 secured to anchors using eye nuts 5 until the installation torque of tightening cables 4 is reached. To prevent damage to the insulation of pipeline 1, protective mats (not shown in the figures) must be provided at the locations where fixing clamp 3 is installed.

[0026] Pipeline 1 is held in its design position by the adhesion of anchor elements 2 to the ground. When anchor elements 2 are driven into the ground to the required depth and arch clamp 3 is secured to them using a tightening unit, section 1 of pipeline is rigidly fixed to the trench bottom and limited in its free axes. The cable system connecting anchor elements 2 to each other will restrain the anchor pair in the event of its release or anchor rod instability.

[0027] With pipeline section 1 in its design position, this device transfers and distributes shear loads from pipeline 1 to the anchor ties, which in turn distribute them to the soil beneath the underlying section, ensuring the pipeline's stability. When exposed to non-design loads from longitudinal and transverse displacements of the section (e.g., vertical buoyancy or frost heave), and if the anchor pair becomes dislodged, the fixing capacity of arch clamp 3, as well as the movable cable harness, will help compensate for these displacements and prevent their spontaneous pullout, thereby maintaining the design position.

Claims

An anchor-cable device for ensuring the design position of an underground pipeline when laid in conditions of weak and structurally unstable soils, including anchor elements with fixing clamps made with the possibility of installation on the pipeline, characterized in that each fixing clamp is made in the form of a steel arched horseshoe with lateral bases in which openings are made, with the help of which it is placed on the supporting anchor elements, between each pair of anchor elements two cables are stretched, intersecting with each other.

Images