Method for calculating shearing force and corner of rigid pipeline joint influenced by uneven deformation of bottom soil body

Abstract

The invention belongs to the technical field of pipeline engineering, and particularly relates to a method for calculating the shear force and the corner of a rigid pipeline joint influenced by uneven deformation of a bottom soil body, which comprises the following steps of: firstly, calculating the overlying soil pressure of a rigid pipeline along the longitudinal unit length; then total vertical displacement generated by the rigid pipelines on the two sides at the joint is calculated; calculating the shearing force of the pipeline joint based on the compression deformation rigidity of the rubber gasket at the pipeline joint; according to the moment balance conditions of the pipeline sections on the two sides, the pipeline joint corner is calculated. According to the method for calculating the shearing force and the corner of the rigid pipeline joint, the influence of soil deformation on the pipeline joint can be measured, so that the long-term stability of a pipeline system is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of pipeline engineering, and in particular relates to a method for calculating the shear force and rotation angle of a rigid pipeline joint affected by uneven deformation of bottom soil. Background Art

[0002] With the continuous acceleration of urbanization, the construction and maintenance of underground pipeline systems have become increasingly critical facilities to ensure the normal operation of cities. Pipeline joints are the weak link in the pipeline structure and are more susceptible to external loads. Once the seal fails, it will cause leakage and cause greater damage. At present, in the design of underground pipelines, although there are certain load calculation standards and methods, most methods are only for continuous pipelines. The design and evaluation of pipeline joints is crucial, which directly affects the overall stability and safety of the pipeline system.

[0003] When the soil at the bottom of the pipeline deforms unevenly, the pipeline may experience local deformation or tilt, especially in rigid pipelines, where such deformation is often concentrated at the pipe joints. Due to the structural characteristics of rigid pipe joints, the rigidity of the joints limits their freedom of deformation, which can lead to stress concentration at the joints and increase the risk of cracks or damage to the joints. Uneven deformation may also cause local bending or compression of the pipeline, affecting the overall stability and sealing performance of the pipeline, and may cause failure or leakage of the pipe joints, especially under long-term service conditions. Summary of the invention

[0004] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for calculating the shear force and rotation angle of a rigid pipe joint under the influence of uneven deformation of the bottom soil, in order to determine the influence of soil deformation on the pipe joint and ensure the long-term stability of the pipe system.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows: A method for calculating shear force and rotation angle of a rigid pipe joint affected by uneven deformation of bottom soil comprises the following steps: S1: Calculate the overburden pressure per unit length of the rigid pipe in the longitudinal direction; S2: Calculate the total vertical displacement of the rigid pipes on both sides at the joints; S3: Calculate the shear force of the pipe joint based on the compression deformation stiffness of the rubber gasket at the pipe joint; S4: Calculate the rotation angle of the pipe joint according to the moment balance conditions of the pipe sections on both sides; S5: Determine whether the obtained pipe joint shear force and rotation angle simultaneously meet the joint shear force allowable value and the rotation angle allowable value, thereby obtaining the safety state of the current pipe joint.

[0006] Specifically, in step S1, the overburden pressure per unit length of the rigid pipe along the longitudinal direction is calculated by formula (1): F : (1); In formula (1), D is the diameter of the rigid pipe, in m; H is The buried depth of the rigid pipeline, in m; γ is Soil weight, unit: kN / m 3 ; is the soil arch coefficient, and its value range is 1.2~1.5.

[0007] Specifically, in step S2, the total vertical displacement of the left pipe section at the joint is ;in, is the vertical displacement of the left pipeline caused by the overlying soil pressure; is the net vertical displacement of the left pipe section under the shear force of the joint; is the vertical displacement of the left pipe section at the joint due to rotation; Total vertical displacement of the right pipe segment at the joint ;in, is the vertical displacement of the right pipeline caused by the overlying soil pressure; is the net vertical displacement of the right pipe section under the shear force of the joint; It is the vertical displacement of the right pipe section at the joint due to the rotation.

[0008] Specifically, under the overburden pressure, the vertical displacement of the left pipeline and the vertical displacement of the right pipe They are calculated by formula (2) and formula (3) respectively: (2); (3); In the formula, F is the overburden pressure per unit length of the rigid pipe in the longitudinal direction; is the spring stiffness of the soil around the left pipe section, in kN / m 2 ; is the spring stiffness of the soil around the right pipe section, in kN / m 2 .

[0009] Specifically, according to the moment balance condition of the left pipeline section, equation (4) can be obtained: (4); In the formula, is the shear force of the pipe joint, in kN, is the rotation angle of the left pipe section, in rad; is the length of the left pipe section in meters.

[0010] Furthermore, we can get formula (5): (5); Since the left pipe section rotates, the vertical displacement generated at the joint is calculated by formula (6): (6); Under the action of the joint shear force, the net vertical displacement of the left pipe section is calculated by formula (7): (7).

[0011] Specifically, the total vertical displacement of the left pipe section at the joint is calculated by the following formula (8): (8).

[0012] According to the moment balance condition of the right pipe section, equation (9) can be obtained: (9); In the formula, is the shear force of the pipe joint, in kN; is the rotation angle of the right pipe segment, in rad; is the length of the right pipe section, in meters; Furthermore, we can get formula (10): (10); The vertical displacement of the right pipe section at the joint due to rotation is calculated by formula (11): (11); Under the action of the joint shear force, the net vertical displacement of the right pipe section is calculated by formula (12): (12).

[0013] Specifically, the total vertical displacement of the right pipe section at the joint is calculated by the following formula (13): (13).

[0014] Specifically, in step S3, according to the deformation coordination relationship at the pipe joint position, equation (14) can be obtained: (14); In the formula, is the total vertical displacement of the left pipe section at the joint, in m; is the total vertical displacement of the right pipe section at the joint, in m; is the compression amount of the rubber gasket at the pipe joint, in m, which is calculated by the following formula (15): (15); In the formula, is the compression deformation stiffness of the rubber gasket at the pipe joint, in kN / m; The total vertical displacement of the left pipe section at the joint is calculated by the following formula (8): (8); The total vertical displacement of the right pipe section at the joint is calculated by the following formula (13): (13); Substituting formula (8), formula (13) and formula (15) into formula (14), we can obtain the calculated shear force of the pipe joint: Formula (16): (16).

[0015] Specifically, in step S4, according to the moment balance condition of the left pipeline section, equation (4) can be obtained: (4); In the formula, is the shear force of the pipe joint, in kN, is the rotation angle of the left pipe section, in rad; is the length of the left pipe section, in meters; Furthermore, we can get formula (5): (5); According to the moment balance condition of the right pipe section, equation (9) can be obtained: (9); In the formula, is the shear force of the pipe joint, in kN; is the rotation angle of the right pipe segment, in rad; is the length of the right pipe section, in meters; Furthermore, we can get formula (10): (10); Finally, the pipe joint angle is calculated by formula (17): (17).

[0016] In step S5, if the calculated pipe joint angle is less than the allowable value of the joint angle, and the calculated pipe joint shear force is less than the allowable value of the joint shear force, the current pipe joint is in a safe state; if the calculated pipe joint angle is greater than the allowable value of the joint angle, or the calculated pipe joint shear force is greater than the allowable value of the joint shear force, the current pipe joint has been damaged and failed, and corresponding repair processing is required.

[0017] Beneficial effects: The present invention can effectively consider the influence of uneven deformation of soil on pipe joints by accurately calculating the shear force and rotation angle of pipe joints, improve the accuracy and rationality of pipe joint design, thereby reducing the risk of joint damage and ensuring the overall stability and safety of the pipeline system. By evaluating the shear force and rotation angle of the joint, the stability of long-term operation of the pipeline can also be improved, the service life can be extended and the later maintenance cost can be reduced. In addition, the present invention provides theoretical support for the structural optimization of pipe joints, helps to select appropriate design schemes, and optimizes the construction process to ensure sealing performance and anti-deformation ability. For pipelines that have undergone uneven deformation, the present invention can also provide data support for repair and reinforcement, ensuring that the repaired pipeline system can withstand greater loads and external influences and avoid failure again. In general, the present invention provides a theoretical basis for pipeline design, construction, maintenance and repair, ensuring the long-term stability, safety and reliability of the pipeline system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0019] Figure 1 It is a schematic diagram of the pipeline of the present invention being buried under the ground.

[0020] Figure 2 It is a schematic diagram of the pipeline of the present invention being affected by the uneven deformation of the bottom soil. DETAILED DESCRIPTION

[0021] The present invention can be better understood with reference to the following examples.

[0022] Combination Figure 1 and Figure 2 The present invention provides a method for calculating the shear force and rotation angle of a rigid pipe joint under the influence of uneven deformation of the bottom soil, so as to determine the influence of soil deformation on the pipe joint and ensure the long-term stability of the pipe system.

[0023] The specific steps include: S1: Calculate the overburden pressure per unit length of the rigid pipe in the longitudinal direction; S2: Calculate the total vertical displacement of the rigid pipes on both sides at the joints; S3: Calculate the shear force of the pipe joint based on the compression deformation stiffness of the rubber gasket at the pipe joint; S4: Calculate the rotation angle of the pipe joint according to the moment balance conditions of the pipe sections on both sides.

[0024] First, the diameter of the buried rigid pipeline is D (m), the burial depth is H (m), soil weight is γ (kN / m 3 ). Figure 2 Schematic diagram of the pipeline being affected by uneven deformation of the bottom soil.

[0025] (1) Calculation of shear force at pipe joints Overburden pressure per unit length of the pipeline F , can be calculated by the following formula: (1); In the formula, is the soil arch coefficient, and its value range is 1.2~1.5.

[0026] The vertical displacement of the left pipeline under the overburden pressure and the vertical displacement of the right pipe They are: (2); (3); In the formula, is the spring stiffness of the soil around the left pipe segment (kN / m 2 ); is the spring stiffness of the soil around the right pipe segment (kN / m 2 ).

[0027] According to the moment balance condition of the left pipe section, we can get: (4); In the formula, is the shear force of the pipe joint (kN), is the rotation angle of the left pipe segment (rad); is the length of the left pipe section in meters.

[0028] Further, we can get: (5); The vertical displacement of the left pipe section at the joint due to rotation is: (6); In addition, under the action of the joint shear force, the net vertical displacement of the left pipe section is: (7).

[0029] The total vertical displacement of the left pipe section at the joint can be calculated using the following formula: (8).

[0030] According to the moment balance condition of the right pipe section, we can get: (9); In the formula, is the shear force of the pipe joint, in kN; is the rotation angle of the right pipe segment, in rad; is the length of the right pipe section, in meters.

[0031] Further, we can get: (10); The vertical displacement of the right pipe section at the joint due to rotation is: (11); In addition, under the action of the joint shear force, the net vertical displacement of the right pipe section is: (12).

[0032] The total vertical displacement of the right pipe section at the joint can be calculated using the following formula: (13).

[0033] According to the deformation coordination relationship at the pipe joint position, it can be obtained: (14); In the formula, is the total vertical displacement of the left pipe section at the joint, in m; is the total vertical displacement of the right pipe section at the joint, in m; is the compression amount of the rubber gasket at the pipe joint (m), which can be calculated using the following formula: (15); In the formula, is the compression deformation stiffness of the rubber gasket at the pipe joint (kN / m).

[0034] Substituting formulas (8), (13) and (15) into formula (14), we can obtain the calculated shear force of the pipe joint: Formula (16): (16).

[0035] (2) Calculate the pipe joint angle According to formulas (5) and (10), the pipe joint angle can be obtained as: (17).

[0036] Taking a buried rigid pipeline as an example, the diameter of the reinforced concrete pipe is D is 0.94 m, the buried depth H is 6.1 m, and the compression deformation stiffness of the rubber gasket at the pipe joint is is 500 kN / m, the length of the left and right pipe sections ( l L and l R ) are 3m, soil spring stiffness k L and k R 23500 kN / m respectively 2 and 47000 kN / m 2 , soil weight is 22 kN / m 3 , the soil arch coefficient is taken as 1.43.

[0037] (1) Calculation of shear force at pipe joints According to formula (1), we can get: ; According to formula (16), we can get:

[0038] (2) Calculate the pipe joint angle According to formula (18), we can get: .

[0039] (3) Verification According to the existing test method (Qin Xiaogang. Study on the interaction between socket-type rigid pipe culvert and soil under extreme stratum load [D]. Southeast University, 2018.), the rotation angle of the pipe joint is measured. Table 1 is a comparison between the experimental measured values ​​and the calculated values ​​of the method of the present invention. It can be seen from the table that the error between the calculated values ​​of this method and the experimental measured values ​​is less than 5%, indicating that the shear force and rotation angle of the underground rigid pipe joint affected by the uneven deformation of the bottom soil calculated by this method are reliable and effective.

[0040] Table 1 Comparison of experimental values ​​and calculated values ​​by this patent method

[0041] The present invention provides a method and idea for calculating the shear force and rotation angle of a rigid pipe joint affected by the uneven deformation of the bottom soil. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A method for calculating shear force and rotation angle of a rigid pipe joint affected by uneven deformation of the bottom soil, characterized in that: The steps include: S1: Calculate the overburden pressure per unit length of the rigid pipe in the longitudinal direction; S2: Calculate the total vertical displacement of the rigid pipes on both sides at the joints; S3: Calculate the shear force of the pipe joint based on the compression deformation stiffness of the rubber gasket at the pipe joint; S4: Calculate the rotation angle of the pipe joint according to the moment balance conditions of the pipe sections on both sides; S5: Determine whether the obtained pipe joint shear force and rotation angle simultaneously meet the joint shear force allowable value and the rotation angle allowable value, thereby obtaining the safety state of the current pipe joint.

2. The method for calculating shear force and rotation angle of a rigid pipe joint affected by uneven deformation of the bottom soil according to claim 1, characterized in that: In step S1, the overburden pressure per unit length of the rigid pipe along the longitudinal direction is calculated by formula (1): F : （1）； In formula (1), D is the diameter of the rigid pipe, in m; H is The buried depth of the rigid pipeline, in m; γ is Soil weight, unit: kN / m 3 ; is the soil arch coefficient, and its value range is 1.2~1.

5.

3. The method for calculating shear force and rotation angle of a rigid pipe joint affected by uneven deformation of the bottom soil according to claim 2, characterized in that: In step S2, the total vertical displacement of the left pipe section at the joint ;in, is the vertical displacement of the left pipeline caused by the overlying soil pressure; is the net vertical displacement of the left pipe section under the shear force of the joint; is the vertical displacement of the left pipe section at the joint due to rotation; Total vertical displacement of the right pipe segment at the joint ;in, is the vertical displacement of the right pipeline caused by the overlying soil pressure; is the net vertical displacement of the right pipe section under the shear force of the joint; It is the vertical displacement of the right pipe section at the joint due to the rotation.

4. The method for calculating shear force and rotation angle of a rigid pipe joint affected by uneven deformation of the bottom soil according to claim 3, characterized in that: The vertical displacement of the left pipeline under the overburden pressure and the vertical displacement of the right pipe They are calculated by formula (2) and formula (3) respectively: （2）； （3）； In the formula, F is the overburden pressure per unit length of the rigid pipe in the longitudinal direction; is the spring stiffness of the soil around the left pipe section, in kN / m 2 ; is the spring stiffness of the soil around the right pipe section, in kN / m 2 .

5. The method for calculating shear force and rotation angle of a rigid pipe joint affected by uneven deformation of bottom soil according to claim 4, characterized in that: According to the moment balance condition of the left pipe section, equation (4) can be obtained: （4）； In the formula, is the shear force of the pipe joint, in kN, is the rotation angle of the left pipe section, in rad; is the length of the left pipe section, in meters; Furthermore, we can get formula (5): （5）； Since the left pipe section rotates, the vertical displacement generated at the joint is calculated by formula (6): （6）； Under the action of the joint shear force, the net vertical displacement of the left pipe section is calculated by formula (7): （7）。 6. The method for calculating shear force and rotation angle of a rigid pipe joint affected by uneven deformation of the bottom soil according to claim 5, characterized in that: The total vertical displacement of the left pipe section at the joint is calculated by the following formula (8): （8）。 7. The method for calculating shear force and rotation angle of a rigid pipe joint affected by uneven deformation of bottom soil according to claim 6, characterized in that: According to the moment balance condition of the right pipe section, equation (9) can be obtained: （9）； In the formula, is the shear force of the pipe joint, in kN; is the rotation angle of the right pipe segment, in rad; is the length of the right pipe section, in meters; Furthermore, we can get formula (10): （10）； The vertical displacement of the right pipe section at the joint due to rotation is calculated by formula (11): （11）； Under the action of the joint shear force, the net vertical displacement of the right pipe section is calculated by formula (12): （12）。 8. The method for calculating shear force and rotation angle of a rigid pipe joint affected by uneven deformation of the bottom soil according to claim 7, characterized in that: The total vertical displacement of the right pipe section at the joint is calculated by the following formula (13): （13）。 9. The method for calculating shear force and rotation angle of a rigid pipe joint affected by uneven deformation of bottom soil according to claim 1, characterized in that: In step S3, according to the deformation coordination relationship at the pipe joint position, equation (14) can be obtained: （14）； In the formula, is the total vertical displacement of the left pipe section at the joint, in m; is the total vertical displacement of the right pipe section at the joint, in m; is the compression amount of the rubber gasket at the pipe joint, in m, which is calculated by the following formula (15): （15）； In the formula, is the compression deformation stiffness of the rubber gasket at the pipe joint, in kN / m; The total vertical displacement of the left pipe section at the joint is calculated by the following formula (8): （8）； The total vertical displacement of the right pipe section at the joint is calculated by the following formula (13): （13）； Substituting formula (8), formula (13) and formula (15) into formula (14), we can obtain the calculated shear force of the pipe joint: Formula (16): （16）。 10. The method for calculating shear force and rotation angle of a rigid pipe joint affected by uneven deformation of bottom soil according to claim 1, characterized in that: In step S4, according to the moment balance condition of the left pipeline section, equation (4) can be obtained: （4）； In the formula, is the shear force of the pipe joint, in kN, is the rotation angle of the left pipe section, in rad; is the length of the left pipe section, in meters; Furthermore, we can get formula (5): （5）； According to the moment balance condition of the right pipe section, equation (9) can be obtained: （9）； In the formula, is the shear force of the pipe joint, in kN; is the rotation angle of the right pipe segment, in rad; is the length of the right pipe section, in meters; Furthermore, we can get formula (10): （10）； Finally, the pipe joint angle is calculated by formula (17): （17）。

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