Suspension tunnel pipe joint test model and method for measuring connection force of joints of suspension tunnel pipe joint test model

Abstract

The invention relates to a floating tunnel pipe joint test model and a method for measuring the connecting force of joints of the floating tunnel pipe joint test model, and belongs to the technical field of cross-sea channels. The test model comprises a plurality of pipe joints connected through joints; the adjacent pipe joints are connected through flexible materials, annular connecting pieces, rectangular connecting pieces and splicing rings arranged at the ends of the pipe joints in a sleeving mode, grooves matched with the rectangular connecting pieces are formed in the inner sides of the splicing rings, and matched groove holes are formed in the grooves, the rectangular connecting pieces and the annular connecting pieces respectively. And the embedded block is sequentially clamped into the slotted holes of the splicing ring, the rectangular connecting piece and the annular connecting piece to connect the splicing ring, the rectangular connecting piece and the annular connecting piece. The measuring method comprises the following steps: installing a strain gauge on the rectangular connecting piece to measure the strain at the pipe joint joint; stress is solved according to Hooke's law, and bending moment and torque are calculated according to a bending stress formula and a torsional stress formula. The rigidity of the joint can be changed through the detachable rectangular connecting pieces made of different materials, the problem of stress concentration at the joint is solved, and the stress at the joint of the pipe joints is more uniform.

Description

Technical Field

[0001] The invention belongs to the technical field of cross-sea channels and relates to a suspended tunnel pipe segment test model and a method for measuring the connection force of a joint thereof. Background Art

[0002] In recent years, the construction of cross-sea channel projects has gradually developed towards the deep and large strait waters. As a new type of cross-sea transportation structure, underwater floating tunnels are environmentally friendly, less restricted by water depth conditions, less affected by weather, and flexible in layout compared to traditional cross-sea channels. In order to promote the actual construction process of floating tunnels, scholars have carried out many model tests on underwater floating tunnels, and discussed various parameters that affect the dynamic characteristics of tunnels, such as anchor cable stiffness, buoyancy-to-weight ratio, and joint stiffness. Among them, the stiffness of the pipe joint is an important parameter in the design of the underwater floating tunnel structure. In the numerical model test, the change of joint stiffness within a certain range will affect the three-dimensional dynamic response characteristics of the tunnel. In the existing model test research, the influence of pipe joint stiffness and joint force is often ignored, and the increase in joint stiffness caused by the direct connection between the joint device and the tunnel is ignored. The pipe joint part is often simplified, which cannot fully reflect the dynamic response of the underwater floating tunnel in the actual environment and the synergistic mechanism of multiple structural parameters. In the actual structure, the stiffness at the pipe joint is discontinuous, and stress concentration is easily generated at the stiffness discontinuity. Considering the structural safety, it is necessary to measure the connection force at the joint. If a simple circular ring device is used to replace the variable stiffness pipe joint, it will be very difficult to measure the joint force. The strain gauge can only measure the local load and it is difficult to calculate the target load. In addition, the commonly used six-component force sensor will destroy the stiffness properties of the pipe joint, resulting in a large error between the measured load and the target value.

[0003] In response to the above problems, it is necessary to further explore and verify the influence law of pipe joint stiffness and obtain reliable joint force data. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a suspended tunnel pipe segment test model and a method for measuring the joint connection force thereof, wherein the joint stiffness is variable, the stress concentration problem at the joint is reduced, and the force at the pipe segment connection is more uniform.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A suspended tunnel pipe segment test model comprises a plurality of pipe segments connected by joints; adjacent pipe segments are connected by flexible materials, annular connectors are arranged between the pipe segments and the flexible materials; a rectangular connector is arranged on the outer periphery of the flexible material; the joint comprises a splicing ring sleeved on the end of the pipe segment, a groove matching the rectangular connector is provided on the inner side of the splicing ring, matching slots are respectively provided on the groove, the rectangular connector and the annular connector; an embedded block is sequentially clamped into the slots of the splicing ring, the rectangular connector and the annular connector to connect the splicing ring, the rectangular connector and the annular connector.

[0007] Optionally, an anchor cable is provided on the pipe segment.

[0008] Optionally, the flexible material is a foam material.

[0009] Optionally, the rectangular connector is made of one or more of steel, plexiglass, nylon, aluminum plate, and acrylic plate.

[0010] Optionally, the rectangular connecting piece is detachably arranged on the outer periphery of the flexible material.

[0011] Optionally, four rectangular connecting members are provided and are evenly distributed on the periphery of the flexible material.

[0012] Optionally, a rubber membrane for water sealing is provided on the free end of the pipe segment.

[0013] Optionally, the embedded block is a screw.

[0014] A method for measuring the connection force of a suspended tunnel pipe joint using any of the above-mentioned test models comprises the following steps:

[0015] S1, assemble the test model, arrange anchor cables at 1 / 4 and 3 / 4 of each pipe segment, and install strain gauges on each rectangular connector to measure the strain at the pipe segment joints;

[0016] S2, use the obtained strain value to calculate the stress according to Hooke's law, and then use the bending stress formula and torsional stress formula to calculate the bending moment and torque.

[0017] Optionally, in step S1, four rectangular connectors are located at the upper, lower, left and right positions of the flexible material, respectively, wherein the two rectangular connectors at the upper and lower positions are the first measurement units, and the two rectangular connectors at the left and right positions are the second measurement units; the strain value measured by the first measurement unit is recorded as ε + , the strain value of the second measuring unit is recorded as ε = ;

[0018] In step S2, the strain caused by the tension P at the pipe joint is ε P , the strain caused by the bending moment M is ε M , then:

[0019]

[0020] According to the above formula, we can solve ε P and ε M , and then solve the tension P and bending moment M by the following formula:

[0021]

[0022] Where E is the structural elastic modulus of the strain gauge, A is the cross-sectional area of ​​the strain gauge, and W m is the bending section coefficient of the strain gauge.

[0023] The shear strain is measured using a strain gauge rosette according to the following formula:

[0024]

[0025] Where α is the angle between the measurement direction and the x-axis (the direction angle is defined in a two-dimensional plane); ε α Represents the strain in the direction α, which is based on the strain in the angle direction of the strain rosette measurement; ε x represents the normal strain in the x-axis direction (axial strain along the x-axis); ε y represents the normal strain in the y-axis direction (axial strain along the y-axis); γ xy is the shear strain between the x-axis and the y-axis, indicating the relative angle change between the deformation in the x-axis direction and the y-axis direction;

[0026] When α=45 degrees, we have

[0027]

[0028] Solved

[0029] ε x =ε 0° , ε y =ε -45° -ε 0° +ε 45° , γ xy =ε -45° -ε 45° (5)

[0030] The following formula is further obtained from the constitutive relationship, and then the torque T is obtained:

[0031]

[0032] Where G is the structural shear modulus, W t is the torsional section coefficient; τ is the shear stress, that is, the internal force per unit area acting on the shear surface inside the material; γ is the shear strain, which describes the angular change of the material under the action of shear force and is defined as the deformation change angle per unit length; σ is the normal stress, that is, the internal force per unit area acting on the cross section of the material.

[0033] The beneficial effects of the present invention are:

[0034] The present invention proposes a suspended tunnel pipe joint test model that is convenient for measuring connection force. The rectangular connector in the joint can be replaced with a variety of materials to achieve the purpose of variable joint stiffness. This device can arrange sensors and strain gauges between two pipe joints, and can accurately and conveniently measure pipe joint forces under a variety of stiffnesses for scaled model test research.

[0035] By superimposing the bending properties of the four rectangular connectors, the pipe joint with a stiffness of 5% to 100% can be flexibly simulated. Strain rosettes and strain gauges are installed on the joint connectors between pipe joints to measure and calculate the bending moment and torque at the joint. Accurate and comprehensive joint force data can be obtained to study the stress concentration problem at the joint.

[0036] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0038] Figure 1 This is a schematic diagram of the explosion of the pipe joint;

[0039] Figure 2 It is the side view of the overall test model;

[0040] Figure 3 It is the cross-sectional view of the pipe joint;

[0041] Figure 4 It is a schematic diagram after the pipe joint is connected;

[0042] Figure 5 Marking diagram of the moment of inertia and dimension calculation parameters of rectangular connectors;

[0043] Figure 6 Strain gauge arrangement diagram for measuring bending moment;

[0044] Figure 7 The α-angle strain rosette is used to measure the bending moment and torque;

[0045] Figure 8 Schematic diagram of the three-dimensional strain rosette.

[0046] Figure numerals: 1 anchor cable, 2 pipe segment, 3 flexible material, 4 rectangular connecting piece, 5 annular connecting piece, 6 rubber membrane, 7 groove, 8 splicing ring, 9 embedded block. DETAILED DESCRIPTION

[0047] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0048] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0049] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0050] See also Figures 1 to 8, is a suspended tunnel pipe segment test model, including a plurality of pipe segments 2 connected by joints; adjacent pipe segments 2 are connected by flexible materials 3, and an annular connector 5 is provided between the pipe segment 2 and the flexible material 3; a rectangular connector 4 is provided on the outer periphery of the flexible material 3; the joint includes a splicing ring 8 sleeved on the end of the pipe segment 2, and a groove 7 matching with the rectangular connector 4 is provided on the inner side of the splicing ring 8, and matching slots are provided on the groove 7, the rectangular connector 4, and the annular connector 5 respectively; an embedded block 9 is sequentially inserted into the slots of the splicing ring 8, the rectangular connector 4, and the annular connector 5 to connect the splicing ring 8, the rectangular connector 4, and the annular connector 5. The annular connector 5 is actually a thickened cover plate at the end of the pipe segment 2, which can be connected to the cross section of the pipe segment 2, on the one hand to ensure the water tightness inside the pipe segment 2, and on the other hand to provide connection support for the rectangular connector 4.

[0051] The embedding block 9 is preferably a screw. An anchor cable 1 is arranged at 1 / 4 and 3 / 4 of each pipe section 2. A rubber membrane 6 for water sealing is arranged on the free end of the pipe section 2.

[0052] The flexible material 3 is preferably a foam material. With respect to the internal gap of the connector, in order to ensure that the connector part meets the geometrical similarity to ensure the Morrison force, the joint of the pipe section 2 is wrapped with foam material to meet the geometrical similarity between the joint and the pipe body.

[0053] Four rectangular connecting pieces 4 are detachably provided and evenly distributed on the outer circumference of the flexible material 3 .

[0054] The splicing ring 8 and the end of the tube body are connected to form an integrated structure by bolts or waterproof glue. A positioning groove 7 is provided on the splicing ring 8 for placing the rectangular connector 4. At the same time, excessive deformation of the connector is limited to improve the structural stability. The splicing ring 8, the end of the tube body, the rectangular connector 4, and the annular connector 5 can be connected by the embedded block 9. Compared with the pure lifting ear connection method, the connection method of the present invention can reduce the stress concentration problem at the bolt connection between the lifting ear and the tube body. For example, if the test tube body adopts relatively brittle materials such as plexiglass, bolts directly punching holes on the lifting ears can easily damage the end of the tube body and affect the watertightness. Replacing the local lifting ears with connecting rings can make the force on the end of the tube body more uniform.

[0055] The entire test model consists of connectors that can take into account vertical and horizontal bending stiffness and foam materials with a certain thickness that do not provide additional stiffness. The equivalent stiffness change of the joint of the pipe section 2 is achieved by changing the material of the rectangular connector 4 to change the moment of inertia of the connector. Specifically, the moment of inertia provided by the connector can be calculated based on the connector position parameters and geometric dimensions. By changing different connector materials to provide different elastic moduli E, a series of bending stiffness EI and axial stiffness EA are obtained, thereby achieving a change in the connection stiffness at the joint of the connected pipe section 2. The moment of inertia under this setting is calculated by the following formula, and the relevant parameters are marked as follows Figure 5, where y and z are the distances between the axes of the rectangular connector 4 in two directions respectively, and a1, b1, a2, and b2 are the sizes of the rectangular connector 4 respectively.

[0056]

[0057] According to the horizontal and vertical bending stiffness of the pipe body, the elastic modulus of the material and the corresponding percentage of joint stiffness, the size of the joint connector in the scaled test can be calculated by the above formula. Considering the size of the model pipe body and the normal sensor size, it is analyzed from the previous calculation results that when the connection stiffness is 100%, the connector material should be steel, and when the connection stiffness is the rest, acrylic plate should be used.

[0058] Based on the setting of the variable stiffness joint, the material of the rectangular connector 4 can be steel plate, organic glass, nylon, aluminum plate, acrylic plate and other materials.

[0059] A method for measuring the connection force of a suspended tunnel pipe joint using any of the above-mentioned test models comprises the following steps:

[0060] S1, assemble the test model, arrange anchor cables 1 at 1 / 4L and 3 / 4L of each pipe segment 2, install strain gauges on each rectangular connector 4, and measure the strain at the joint of the pipe segment 2;

[0061] The four rectangular connectors 4 are respectively located at the upper part, the lower part, the left part and the right part of the flexible material 3, wherein the two rectangular connectors 4 at the upper part and the lower part are the first measurement units, and the two rectangular connectors 4 at the left part and the right part are the second measurement units;

[0062] The strain value measured by the first measuring unit is recorded as ε + , the strain value of the second measuring unit is recorded as ε - .

[0063] like Figure 7 As shown, the strain gauges arranged along the x-axis and z-axis directions respectively measure the bending strain when the tube section is bent around the z-axis and the y-axis, and the strain gauge combination is arranged at an angle of ±45° (relative to the axial direction of the tube body) to measure the torsional strain at the top / bottom.

[0064] S2, use the obtained strain value to calculate the stress according to Hooke's law, and then use the bending stress formula and torsional stress formula to calculate the bending moment and torque.

[0065] like Figure 6 As shown, the strain caused by the tension P at the joint of pipe segment 2 is ε P , the strain caused by the bending moment M is ε M , then:

[0066]

[0067] According to the above formula, we can solve ε P and ε M , and then solve the tension P and bending moment M by the following formula:

[0068]

[0069] Where E is the structural elastic modulus of the strain gauge, A is the cross-sectional area of ​​the strain gauge, and W m is the bending section coefficient of the strain gauge.

[0070] like Figure 7 As shown, the shear strain is measured using a strain gauge rosette according to the following formula:

[0071]

[0072] Where α is the angle between the measurement direction and the x-axis (the direction angle is defined in a two-dimensional plane); ε α Represents the strain in the direction α, which is based on the strain in the angle direction of the strain rosette measurement; ε x represents the normal strain in the x-axis direction (axial strain along the x-axis); ε y represents the normal strain in the y-axis direction (axial strain along the y-axis); γ xy is the shear strain between the x-axis and the y-axis, indicating the relative angle change between the deformation in the x-axis direction and the y-axis direction;

[0073] When α=45 degrees, we have

[0074]

[0075] Solved

[0076] ε x =ε 0° , ε y =ε -45° -ε 0° +ε 45° , γ xy =ε -45° -ε 45° (5)

[0077] The following formula is further obtained from the constitutive relationship, and then the torque T is obtained:

[0078]

[0079] Where G is the structural shear modulus, W tis the torsional section coefficient; τ is the shear stress, that is, the internal force per unit area acting on the shear surface inside the material; γ is the shear strain, which describes the angular change of the material under the action of shear force and is defined as the deformation change angle per unit length; σ is the normal stress, that is, the internal force per unit area acting on the cross section of the material.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A suspended tunnel pipe segment test model, characterized in that: The invention comprises a plurality of pipe sections (2) connected by joints; adjacent pipe sections (2) are connected by flexible materials (3), and an annular connecting piece (5) is arranged between the pipe sections (2) and the flexible materials (3); a rectangular connecting piece (4) is arranged on the outer periphery of the flexible material (3); the joint comprises a splicing ring (8) sleeved on the end of the pipe section (2), a groove (7) matching with the rectangular connecting piece (4) is provided on the inner side of the splicing ring (8), and matching slots are respectively provided on the groove (7), the rectangular connecting piece (4) and the annular connecting piece (5); an embedded block (9) is sequentially inserted into the slots of the splicing ring (8), the rectangular connecting piece (4) and the annular connecting piece (5) to connect the splicing ring (8), the rectangular connecting piece (4) and the annular connecting piece (5).

2. The suspended tunnel segment test model according to claim 1 is characterized in that: An anchor cable (1) is arranged on the pipe section (2).

3. The suspended tunnel segment test model according to claim 1 is characterized in that: The flexible material (3) is a foam material.

4. The suspended tunnel segment test model according to claim 1, characterized in that: The rectangular connecting piece (4) is made of a material selected from the group consisting of steel, organic glass, nylon, aluminum plate, and acrylic plate.

5. The floating tunnel segment test model according to claim 1 is characterized in that: The rectangular connecting piece (4) is detachably arranged on the outer periphery of the flexible material (3).

6. The floating tunnel segment test model according to claim 1 is characterized by: Four rectangular connecting pieces (4) are provided and are evenly distributed on the outer periphery of the flexible material (3).

7. The floating tunnel segment test model according to claim 1 is characterized by: A rubber membrane (6) for water sealing is arranged on the free end of the pipe section (2).

8. The suspended tunnel pipe segment test model according to claim 1 is characterized by: The embedded block (9) is a screw.

9. A method for measuring the connection force of pipe joints in a floating tunnel using the test model according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, assemble the test model, arrange anchor cables (1) at 1 / 4 and 3 / 4 of each pipe segment (2), and install strain gauges on each rectangular connector (4) to measure the strain at the joint of the pipe segment (2); S2, use the obtained strain value to calculate the stress according to Hooke's law, and then use the bending stress formula and torsional stress formula to calculate the bending moment and torque.

10. The method for measuring the connection force of a floating tunnel pipe joint according to claim 9, characterized in that: In step S1, four rectangular connectors (4) are respectively located at the upper part, the lower part, the left part and the right part of the flexible material (3), wherein the two rectangular connectors (4) at the upper part and the lower part are the first measurement units, and the two rectangular connectors (4) at the left part and the right part are the second measurement units; the strain value measured by the first measurement unit is recorded as ε + , the strain value of the second measuring unit is recorded as ε - ; In step S2, the strain caused by the tension P at the joint of pipe segment (2) is ε P , the strain caused by the bending moment M is ε M , then: According to the above formula, we can solve ε P and ε M , and then solve the tension P and bending moment M by the following formula: Where E is the structural elastic modulus of the strain gauge, A is the cross-sectional area of ​​the strain gauge, and W m is the bending section coefficient of the strain gauge. The shear strain is measured using a strain gauge rosette according to the following formula: Where α is the angle between the measurement direction and the x-axis (the direction angle is defined in a two-dimensional plane); ε α Represents the strain in the direction α, which is based on the strain in the angle direction of the strain rosette measurement; ε x represents the normal strain in the x-axis direction (axial strain along the x-axis); ε y represents the normal strain in the y-axis direction (axial strain along the y-axis); γ xy is the shear strain between the x-axis and the y-axis, indicating the relative angle change between the deformation in the x-axis direction and the y-axis direction; When α=45 degrees, we have Solved e x =e 0° ,he y =e -45° -e 0° +e 45° ,c xy =e -45° -e 45° (5) The following formula is further obtained from the constitutive relationship, and then the torque T is obtained: Where G is the structural shear modulus, W t is the torsional section coefficient; τ is the shear stress, that is, the internal force per unit area acting on the shear surface inside the material; γ is the shear strain, which describes the angular change of the material under the action of shear force and is defined as the deformation change angle per unit length; σ is the normal stress, that is, the internal force per unit area acting on the cross section of the material.

Images