Calculation method for shear force and rotation angle of rigid pipe joints affected by uneven deformation of underlying soil

Abstract

The present invention belongs to the technical field of pipeline engineering, and particularly relates to a calculation method for the shear force and rotation angle of a rigid pipeline joint affected by uneven deformation of the bottom soil. First, calculate the overburden pressure per unit length of the rigid pipeline along the longitudinal direction; then calculate the total vertical displacements generated at the joint of the rigid pipelines on both sides respectively; based on the compression deformation stiffness of the rubber gasket at the pipeline joint, calculate the shear force of the pipeline joint; according to the moment balance condition of the pipeline segments on both sides, calculate the rotation angle of the pipeline joint. The method for calculating the shear force and rotation angle of the rigid pipeline joint in the present invention can measure the influence of soil deformation on the pipeline joint, so as to ensure the long-term stability of the pipeline system.

Description

Technical Field

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

[0002] With the continuous acceleration of the urbanization process, the construction and maintenance of the underground pipeline system have increasingly become key facilities to ensure the normal operation of the city. The pipeline joint is a weak link in the pipeline structure and is more vulnerable to the influence of external loads. Once the seal fails, leakage will occur, leading to more extensive damage. At present, in the design of underground pipelines, although there are certain load calculation standards and methods, most of them are only applicable to continuous pipelines. The design and evaluation of pipeline joints are crucial, which directly affect the overall stability and safety of the pipeline system.

[0003] When uneven deformation occurs in the bottom soil mass of the pipeline, the pipeline may experience local deformation or inclination. Especially in rigid pipelines, this kind of deformation often concentrates at the pipeline joint part. Due to the structural characteristics of the rigid pipeline joint, the rigidity at the joint restricts the degree of freedom of its deformation, which will lead to stress concentration at the joint, increasing the risk of cracks or damage at the joint. Uneven deformation may also cause local bending or compression of the pipeline, affecting the overall stability and sealing performance of the pipeline. Especially under long-term service conditions, it may lead to the failure or leakage of the pipeline joint. Summary of the Invention

[0004] Object 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 pipeline joint under the influence of uneven deformation of the bottom soil mass, in order to determine the influence of soil deformation on the pipeline joint and ensure the long-term stability of the pipeline system.

[0005] In order to achieve the above object of the invention, the technical solution adopted by the present invention is as follows:

[0006] A calculation method for the shear force and rotation angle of a rigid pipeline joint affected by uneven deformation of the bottom soil mass, comprising the following steps:

[0007] S1: Calculate the overburden pressure per unit length along the longitudinal direction of the rigid pipeline;

[0008] S2: Calculate the total vertical displacements generated at the joint by the rigid pipelines on both sides respectively;

[0009] S3: Calculate the pipeline joint shear force based on the compression deformation stiffness of the rubber gasket at the pipeline joint;

[0010] S4: Calculate the pipeline joint rotation angle according to the moment balance condition of the pipeline segments on both sides;

[0011] S5: Determine whether the obtained shear force and rotation angle of the pipe joint simultaneously satisfy the allowable shear force value and the allowable rotation angle value of the joint, so as to obtain the safety state of the current pipe joint.

[0012] Specifically, in step S1, the overburden pressure on the rigid pipe per unit length in the longitudinal direction is calculated by formula (1) F :

[0013] (1);

[0014] In formula (1), D is the diameter of the rigid pipe, in m;

[0015] H is The buried depth of the rigid pipe, in m;

[0016] γ is The unit weight of soil, in kN / m 3 ;

[0017] is the soil arch coefficient, and the value range is 1.2 - 1.5.

[0018] Specifically, in step S2, the total vertical displacement generated by the left pipe segment at the joint; among them, is the vertical displacement generated by the left pipe under the action of the overburden pressure; is the net vertical displacement generated by the left pipe segment under the action of the joint shear force; is the vertical displacement generated at the joint due to the rotation of the left pipe segment;

[0019] The total vertical displacement generated by the right pipe segment at the joint; among them, is the vertical displacement generated by the right pipe under the action of the overburden pressure; is the net vertical displacement generated by the right pipe segment under the action of the joint shear force; is the vertical displacement generated at the joint due to the rotation of the right pipe segment.

[0020] Specifically, under the action of the overburden pressure, the vertical displacement generated by the left pipe and the vertical displacement generated by the right pipe are respectively calculated by formula (2) and formula (3):

[0021] (2);

[0022] (3);

[0023] In the formula, Fis the overburden pressure per unit length of the rigid pipeline in the longitudinal direction;

[0024] is the spring stiffness of the soil around the left pipeline segment, with the unit of kN / m 2 ;

[0025] is the spring stiffness of the soil around the right pipeline segment, with the unit of kN / m 2 .

[0026] Specifically, according to the moment equilibrium condition of the left pipeline segment, Equation (4) can be obtained:

[0027] (4);

[0028] In the formula, is the pipeline joint shear force, with the unit of kN, is the rotation angle of the left pipeline segment, with the unit of rad; is the length of the left pipeline segment, with the unit of m.

[0029] Furthermore, Equation (5) can be obtained:

[0030] (5);

[0031] Since the left pipeline segment rotates, the vertical displacement generated at the joint is calculated by Equation (6):

[0032] (6);

[0033] Under the action of the joint shear force, the net vertical displacement generated by the left pipeline segment is calculated by Equation (7):

[0034] (7).

[0035] Specifically, the total vertical displacement generated by the left pipeline segment at the joint is calculated by the following Equation (8):

[0036] (8).

[0037] According to the moment equilibrium condition of the right pipeline segment, Equation (9) can be obtained:

[0038] (9);

[0039] In the formula, is the pipeline joint shear force, with the unit of kN; is the rotation angle of the right pipeline segment, with the unit of rad; is the length of the right pipeline segment, with the unit of m;

[0040] Furthermore, Equation (10) can be obtained:

[0041] (10);

[0042] The vertical displacement generated at the joint due to the rotation of the right pipeline segment is calculated by Equation (11):

[0043] (11);

[0044] Under the action of the joint shear force, the net vertical displacement generated by the right pipeline segment is calculated by Equation (12):

[0045] (12).

[0046] Specifically, the total vertical displacement generated by the right pipeline segment at the joint is calculated by the following Equation (13):

[0047] (13).

[0048] Specifically, in step S3, according to the deformation coordination relationship at the pipeline joint position, Equation (14) can be obtained:

[0049] (14);

[0050] In the formula, is the total vertical displacement generated by the left pipeline segment at the joint, with the unit of m; is the total vertical displacement generated by the right pipeline segment at the joint, with the unit of m; is the compression amount of the rubber gasket at the pipeline joint, with the unit of m, and it is calculated by the following Equation (15):

[0051] (15);

[0052] In the formula, is the compression deformation stiffness of the rubber gasket at the pipeline joint, with the unit of kN / m;

[0053] The total vertical displacement generated by the left pipeline segment at the joint is calculated by the following Equation (8):

[0054] (8);

[0055] The total vertical displacement generated by the right pipeline segment at the joint is calculated by the following Equation (13):

[0056] (13);

[0057] Substitute Equation (8), Equation (13) and Equation (15) into Equation (14) to obtain the calculation of the pipeline joint shear force Formula (16):

[0058] (16).

[0059] Specifically, in step S4, according to the moment balance condition of the left pipeline section, formula (4) can be obtained:

[0060] (4);

[0061] In the formula, is the shear force of the pipeline joint, with the unit of kN, is the rotation angle of the left pipeline section, with the unit of rad; is the length of the left pipeline section, with the unit of m;

[0062] Furthermore, formula (5) can be obtained:

[0063] (5);

[0064] According to the moment balance condition of the right pipeline section, formula (9) can be obtained:

[0065] (9);

[0066] In the formula, is the shear force of the pipeline joint, with the unit of kN; is the rotation angle of the right pipeline section, with the unit of rad; is the length of the right pipeline section, with the unit of m;

[0067] Furthermore, formula (10) can be obtained:

[0068] (10);

[0069] Finally, the pipeline joint rotation angle is calculated through formula (17):

[0070] (17).

[0071] In step S5, if the calculated pipeline joint rotation angle is less than the allowable value of the joint rotation angle, and the calculated pipeline joint shear force is less than the allowable value of the joint shear force, then the current pipeline joint is in a safe state; if the calculated pipeline joint rotation angle is greater than the allowable value of the joint rotation angle, or the calculated pipeline joint shear force is greater than the allowable value of the joint shear force, then the current pipeline joint has failed and needs corresponding repair treatment.

[0072] Beneficial effects:

[0073] By accurately calculating the shear force and rotation angle of the pipeline joint, the present invention can effectively consider the influence of uneven soil deformation on the pipeline joint, improve the accuracy and rationality of the pipeline joint design, thereby reducing the risk of joint failure 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 the pipeline during long-term operation 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 the pipeline joint, helps to select appropriate design schemes, and optimize the construction process to ensure the 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 to ensure that the repaired pipeline system can withstand greater loads and external influences and avoid failure again. Generally speaking, 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

[0074] The following further detailed description of the present invention will be made in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0075] Figure 1 It is a schematic diagram of the present invention's pipeline buried below the ground.

[0076] Figure 2 It is a schematic diagram of the present invention's pipeline affected by uneven deformation of the bottom soil. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0077] The present invention can be better understood according to the following embodiments.

[0078] Combined with Figure 1 and Figure 2 , the present invention provides a method for calculating the shear force and rotation angle of a rigid pipeline joint under the influence of uneven deformation of the bottom soil, so as to determine the influence of soil deformation on the pipeline joint and ensure the long-term stability of the pipeline system.

[0079] Specifically, it includes the following steps:

[0080] S1: Calculate the overburden pressure per unit length of the rigid pipeline along the longitudinal direction;

[0081] S2: Calculate the total vertical displacements generated at the joint of the rigid pipelines on both sides respectively;

[0082] S3: Calculate the pipeline joint shear force based on the compression deformation stiffness of the rubber gasket at the pipeline joint;

[0083] S4: Calculate the pipeline joint rotation angle according to the moment balance condition of the pipeline segments on both sides.

[0084] First, the diameter of the buried rigid pipeline isD (m), the buried depth is H (m), the unit weight of soil is γ (kN / m 3 ). Figure 2 It is a schematic diagram of the pipeline affected by uneven deformation of the bottom soil body.

[0085] (1) Calculate the shear force of the pipeline joint

[0086] The overburden pressure on the pipeline per unit length in the longitudinal direction F , can be calculated by the following formula:

[0087] (1);

[0088] In the formula, is the soil arch coefficient, and the value range is 1.2 - 1.5.

[0089] Under the action of the overburden pressure, the vertical displacement generated by the left pipeline and the vertical displacement generated by the right pipeline are respectively:

[0090] (2);

[0091] (3);

[0092] In the formula, is the spring stiffness of the soil around the left pipeline section (kN / m 2 ); is the spring stiffness of the soil around the right pipeline section (kN / m 2 ).

[0093] According to the moment balance condition of the left pipeline section, we can get:

[0094] (4);

[0095] In the formula, is the shear force of the pipeline joint (kN), is the rotation angle (rad) of the left pipeline section; is the length of the left pipeline section, in meters.

[0096] Further, we can get:

[0097] (5);

[0098] The vertical displacement generated at the joint due to the rotation of the left pipeline section is:

[0099] (6);

[0100] In addition, under the action of the joint shear force, the net vertical displacement generated by the left pipeline segment is:

[0101] (7).

[0102] The total vertical displacement generated by the left pipeline segment at the joint can be calculated by the following formula:

[0103] (8).

[0104] According to the moment balance condition of the right pipeline segment, it can be obtained that:

[0105] (9);

[0106] In the formula, is the joint shear force of the pipeline, with the unit of kN; is the rotation angle of the right pipeline segment, with the unit of rad; is the length of the right pipeline segment, with the unit of m.

[0107] Furthermore, it can be obtained that:

[0108] (10);

[0109] The vertical displacement generated by the right pipeline segment at the joint due to rotation is:

[0110] (11);

[0111] In addition, under the action of the joint shear force, the net vertical displacement generated by the right pipeline segment is:

[0112] (12).

[0113] The total vertical displacement generated by the right pipeline segment at the joint can be calculated by the following formula:

[0114] (13).

[0115] According to the deformation coordination relationship at the pipeline joint position, it can be obtained that: (14);

[0116] In the formula, is the total vertical displacement generated by the left pipeline segment at the joint, with the unit of m; is the total vertical displacement generated by the right pipeline segment at the joint, with the unit of m; is the compression amount (m) of the rubber gasket at the pipeline joint, which can be calculated by the following formula:

[0117] (15);

[0118] In the formula, is the compression deformation stiffness (kN / m) of the rubber gasket at the pipe joint.

[0119] Substitute formulas (8), (13), and (15) into formula (14) to obtain formula (16) for calculating the shear force of the pipe joint :

[0120] (16).

[0121] (2) Calculate the rotation angle of the pipe joint

[0122] According to formulas (5) and (10), the rotation angle of the pipe joint can be obtained as: (17).

[0123] Taking a buried rigid pipe at a certain location as an example, the diameter of the reinforced concrete pipe D is 0.94 m, the burial depth H is 6.1 m, and the compression deformation stiffness of the rubber gasket at the pipe joint is 500 kN / m. The lengths of the left and right pipe segments ( l L and l R ) are both 3 m. The soil spring stiffnesses k L and k R are 23500 kN / m 2 and 47000 kN / m 2 respectively, the unit weight of the soil is 22 kN / m 3 , and the soil arch coefficient is taken as 1.43.

[0124] (1) Calculate the shear force of the pipe joint

[0125] According to formula (1), it can be obtained:

[0126] ;

[0127] According to formula (16), it can be obtained:

[0128]

[0129] (2) Calculate the rotation angle of the pipe joint

[0130] According to formula (18), it can be obtained:

[0131] .

[0132] (3) Verification

[0133] According to the existing test method (Qin Xiaogang. Research on the Interaction between Socket-Type Rigid Pipe Culverts and Soil under Extreme Stratum Loads [D]. Southeast University, 2018.), the joint rotation angle of the pipeline is measured. Table 1 shows the comparison between the measured values of the test 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 measured values of the experiment is less than 5%, indicating that the shear force and rotation angle of the underground rigid pipeline joint calculated by this method under the influence of uneven deformation of the bottom soil are reliable and effective.

[0134] Table 1 Comparison between Test Values and Calculated Values of the Method of the Present Patent

[0135]

[0136] The present invention provides an idea and method for calculating the shear force and rotation angle of a rigid pipeline joint affected by uneven deformation of the bottom soil. There are many methods and ways to specifically implement this technical solution. The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined 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: judging whether the obtained shear force and rotation angle of the pipe joint simultaneously meet the allowable value of the joint shear force and the allowable value of the rotation angle, thereby obtaining the safety state of the current pipe joint; 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, ranging from 1.2 to 1.5; 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; is the vertical displacement of the right pipe section at the joint due to the rotation; 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）； 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）。 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: 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 .

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: 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）。 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 total vertical displacement of the left pipe section at the joint is calculated by the following formula (8): （8）。 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 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）。 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 right pipe section at the joint is calculated by the following formula (13): （13）。

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