AU2021105214A4

AU2021105214A4 - An Immersed Tube Tunnel Pipe Joint Mechanical Performance Test Device and a Simplified Calculation Method for Stiffness

Info

Publication number: AU2021105214A4
Application number: AU2021105214A
Authority: AU
Inventors: Wei Cao; Guogang FAN; Weiguo He; Zhongsheng Tan; Huagui Zhou
Original assignee: China Railway Liuyuan Group Co Ltd; CRTG Survey and Design Institute Co Ltd
Current assignee: China Railway Liuyuan Group Co Ltd; CRTG Survey and Design Institute Co Ltd
Priority date: 2021-08-10
Filing date: 2021-08-10
Publication date: 2021-10-07
Anticipated expiration: 2029-08-10

Abstract

An immersed tube tunnel pipe joint mechanical performance test device and a simplified calculation method for stiffness. The pipe joint mechanical performance test device is provided with a square balance frame body, and the internal bottom wall of the balance frame body is evenly provided with a resistance reducing device . A limit frame is arranged transversely in the balance frame, and the limit frame is in the same axial direction as the resistance reducing device. A The longitudinal loading device is provided on the side wall of the balance frame body opposite to the balance frame body. The balance frame body is provided with a lateral loading device on the side wall adjacent to the The longitudinal loading device. A vertical loading device is arranged on the bottom wall inside the balance frame body. In the process of the joint experiment of the immersed tube tunnel joints, the present invention can carry out loading from three directions of horizontal, vertical and vertical at the same time or in a single direction. The overall structure is simple, the installation is convenient, the cost is low, and the mechanical properties of the pipe joint can be quickly tested. The simplified calculation method for the stiffness of the pipe joint is based on the test results of the in-plane flexural stiffness and vertical shear stiffness of the pipe joint in the 1:5 pipe joint test model under different axial pressure states. It can quickly determine the mechanical properties of the key components of the immersed tube tunnel joints, and judge whether the immersed tube section joints are safe. 00 Figure1I Figure 2

Description

Figure1I

Figure 2

An Immersed Tube Tunnel Pipe Joint Mechanical Performance Test Device and

a Simplified Calculation Method for Stiffness

Technical Field The invention relates to the technical field of traffic research experiments, in particular to an immersed tube tunnel pipe joint mechanical performance test device and a simplified calculation method for stiffness.

Background Technology China has many rivers and developed water systems. Cities with a population of over one million are built on the rivers, and there is a strong demand for underwater tunnels. The shallow soil on the top of the immersed tube tunnel, the short tunnel length, and the more flexible connection with roads on both sides of the water area can greatly save urban land resources.The immersed tube tunnel is mainly composed of a number of prefabricated basic structural units, which are formed by floating, sinking, and underwater butt joints in the water area. These prefabricated basic structures are simply pipe sections. The connection structure between the pipe sections of an immersed tube tunnel is called a joint. A reliable joint is a key element to ensure the normal operation of an immersed tube tunnel. Therefore, the joint is required to have good shear and bending resistance. In the past, the joints of immersed tube tunnels mainly adopted certain structural measures based on the experience of the builders. There were few studies on the mechanical properties of large-scale (not less than 1:5) joints. There was no corresponding experimental equipment and no method for calculating the joint stiffness of the joints.

Summary of the Invention Aiming at the shortcomings of the prior art, the present invention proposes an immersed tube tunnel joint mechanical performance test device with simple structure, convenient operation and low cost, which is suitable for large-scale joints, and provides a joint stiffness calculation method. The specific technical solutions are as follows: (1) Test device for mechanical properties of pipe joints An immersed tube tunnel pipe joint mechanical performance test device is provided with a square balance frame body (1), and a resistance reducing device (2) is evenly arranged on the inner bottom wall of the balance frame body (1). A limit frame (3) is transversely arranged in the balance frame body (1), and the limit frame (3) has the same axial direction as the resistance reducing device (2). A The longitudinal loading device (4) is provided on the side wall of the balance frame body (1) opposite to the balance frame body (1). The balance frame body (1) is provided with a lateral loading device (5) on the side wall adjacent to The longitudinal loading device(4). A vertical loading device (6) is provided on the bottom wall inside the balance frame body (1). In order to better realize the present invention, it can be further as follows: At least two limit frames (3) are provided, and two ends of the limit frames (3) are slidably connected to the side walls of the balance frame body (1). By moving the limit frame (3), one end of the experimental object can be fixed, at the same time, it can be adjusted according to the size of the experimental object, which expands the application scope of the present invention. The limit frame (3) is composed of two horizontal rods and two vertical rods, wherein the two horizontal rods are opposite to each other. And the two ends are respectively slidably connected with the side wall of the balance frame body (1), and the two vertical rods are arranged oppositely between the two horizontal rods. The overall structure is simple and firm. The lateral loading device (5), The longitudinal loading device (4) and the lateral loading device (5) are all composed of a mounting seat and a jack mechanism, and the jack mechanisms are evenly distributed on the mounting seat. The installation of the mounting seat can uniformly transmit the force of a single jack mechanism to the inner wall of the balance frame body (1), and increase the contact area with the inner wall of the balance frame body (1) to avoid the problem of local excessive force. The resistance reducing device (2) is a steel roller. The structure is simple and the mechanical strength is high. The balance frame body (1) is a reinforced concrete closed frame. The manufacturing cost is low, the overall structure is simple, and the bearing capacity is large. A test method for an immersed tube tunnel pipe joint mechanical performance test device, which is characterized in that the specific steps adopted are: Step 1: The pipe joint model is made, and the pipe joint model is installed in the balance frame body. Step 2: The longitudinal loading device of the bottom plate and the top plate are simultaneously applied with the same load to detect the working condition of the axially compressed pipe section joint model. Step 3: Longitudinal load is applied to the longitudinal loading device of the single-sided bottom plate and top plate to detect the working condition of the joint model of the horizontal bending pipe section. Step 4: The longitudinal loading device of the bottom plate or the top plate is loaded to detect the working condition of the joint model of the vertical bending pipe section. Step 5: The horizontal loading device and the vertical loading device are loaded at the same time to detect the bidirectional shearing condition of the pipe joint model. Step 6: The longitudinal loading device and the lateral loading device are loaded at the same time to detect the horizontal compression and shear conditions of the pipe joint model. Step 7: The longitudinal loading device and the vertical loading device are loaded at the same time to detect the vertical compression and shear conditions of the pipe joint model. In order to better implement this test method, it can be further described that the first step is specifically: 1.1: The pipe joint model is made, and the loading plate is embedded in the pipe joint model. 1.2: The balance frame body is made according to the pipe joint model, and the vertical loading device is arranged.

1.3: The pipe joint model is hoisted into the frame body, and the horizontal and vertical displacement of the pipe joint model is restricted by the limit frame. 1.4: The longitudinal loading device is arranged on the top and bottom plates of the pipe joint model, and lateral loading device is arranged laterally. The beneficial effects of the present invention are as follows: 1. During the joint experiment of immersed tube tunnel joints, loading can be carried out from three directions of horizontal, longitudinal and vertical at the same time or in a single direction, or a combination of several directions to simulate different stress environments , collect the test data of the joint model of the immersed tube tunnel in an all-round way, and get different test data.2. The overall structure is simple, the installation is convenient, and the cost is low, which facilitates the popularization and utilization of the present invention. 3. In the experiment, the internal force self-balance is realized through the cooperation of the horizontal, longitudinal and vertical loading devices and the limit frame, without the need for the reaction force mechanism in the conventional technology. 4. By adjusting the position of the limit frame, it can be adapted to a wider range of experimental objects, which increases the scope of application of the present invention.

Brief Description of Drawings Figure 1 is a schematic diagram of the structure of the present invention. Figure 2 is a schematic diagram of the structure of the limit frame in the present invention. The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, so as to make a clearer and clearer definition of the protection scope of the present invention. As shown in Figure 1 and Figure 2: An immersed tube tunnel joint mechanical performance test device is provided with a reinforced concrete closed square gimbal body 1, and the inner bottom wall of the gimbal body 1 is evenly arranged resistance reduction device 2, the resistance reduction device 2 is a steel roller with lubricating oil. There are two limit frames 3 transversely provided in the balance frame body 1. The limit frame (3) has the same axial direction as the resistance reducing device 2. The limit frame 3 consists of two horizontal rods and two vertical bars. The two vertical rods are arranged opposite to each other, and the two ends are respectively slidably connected with the side wall of the balance frame body 1 by fastening screws, and the two vertical rods are arranged oppositely between the two horizontal rods. A The longitudinal loading device 4 is provided on the side wall of the balance frame body 1 opposite to the balance frame body 1. The balance frame body 1 is provided with a lateral loading device 5 on the side wall adjacent to The longitudinal loading device4. A vertical loading device 6 is provided on the bottom wall inside the balance frame body (1). The lateral loading device 5, the longitudinal loading device 4 and the lateral loading device 5 are all composed of a mounting seat and a jack mechanism, and the jack mechanisms are evenly distributed on the mounting seat. The specific steps used in the immersed tube tunnel pipe joint mechanical performance test device are as follows: Step 1: The pipe joint model is made, and the pipe joint model is installed in the balance frame body. Specifically: 1.1: The pipe joint model is made, and the loading plate is embedded in the pipe joint model. 1.2: The balance frame body is made according to the pipe joint model, and the vertical loading device is arranged. 1.3: The pipe joint model is hoisted into the frame body, and the horizontal and vertical displacement of the pipe joint model is restricted by the limit frame. 1.4: The longitudinal loading device is arranged on the top and bottom plates of the pipe joint model, and lateral loading device is arranged laterally. Step 2: The longitudinal loading device of the bottom plate and the top plate are simultaneously applied with the same load to detect the working condition of the axially compressed pipe section joint model. Step 3: Longitudinal load is applied to the longitudinal loading device of the single-sided bottom plate and top plate to detect the working condition of the joint model of the horizontal bending pipe section. Step 4: The longitudinal loading device of the bottom plate or the top plate is loaded to detect the working condition of the joint model of the vertical bending pipe section. Step 5: The horizontal loading device and the vertical loading device are loaded at the same time to detect the bidirectional shearing condition of the pipe joint model. Step 6: The longitudinal loading device and the lateral loading device are loaded at the same time to detect the horizontal compression and shear conditions of the pipe joint model. Step 7: The longitudinal loading device and the vertical loading device are loaded at the same time to detect the vertical compression and shear conditions of the pipe joint model.

(2) The implementation case of the simplified calculation method for joint

stiffness of pipe joints is as follows: The method will be described in detail below in conjunction with specific implementation cases: 1. The calculation method of the in-plane bending stiffness of the joint is as follows: (1) Calculate the cross-sectional stiffness El of the immersed pipe body from the structural size, material properties and material mechanics algorithm of the immersed pipe body. Sw= (1/kw)EI (2) Calculate the flexural rigidity of the joint according to the following formula, Sw= (1/kw)EI In the formula: Sw-flexural rigidity of joint.

E-The elastic modulus of pipe section concrete (MPa). I-the cross-sectional inertia of the pipe section body (m 4). k.-Characteristic function of joint bending stiffness with axial pressure. kw=bix+ci Among them, the characteristic function kw of the bending stiffness of the joint with the axial pressure is calculated as follows: kw=bix+ci In the formula: bi-Characteristic value of joint flexural stiffness changing with axial pressure, refer to Table 1 for the value. x-The axial pressure variation range, the axial pressure after the pipe section is connected is generally greater than 4000kN. ci-characteristic constant within the range of axial pressure. Table 1 Value table of characteristic value parameters of joint flexural rigidity changing with axial pressure Characteristic value Characteristic Axial pressure bi of stiffness constant ci value x (kN) changing with axial within the range of pressure axialpressure 1 4000<x<5400 -0.144 918 2 5400<x<9000 -0.0531 586.5 3 9000<x<19000 -0.0106 204 The data in Table 1 is based on the data obtained from the super-large-scale immersed pipe joint simulation test conducted by the method disclosed in the Chinese patent A method for detecting the shear structure of the immersed tube tunnel pipe section joint specimen (Patent No.: CN110067270A). (3) Calculate the actual bending moment M of the joint according to the force of the tunnel. (4) When the joint curvature= M/ Sw= M/ (0.0102EI) <allowable curvature [P], the bending deformation in the joint plane meets the requirements. The specific calculation example according to the above method is as follows: After the pipe section is placed and butted, the water pressure at the center of the cross section is kPa and the cross section area of the pipe section is 250m2 , the axial pressure value is x=40x250=100OOkN. When x=1OOOOkN, according to Table 1, query the characteristic value bi=-0.0106 of the change of the plane bending stiffness with the axial pressure and the characteristic constant c 1=204 in the range of axial pressure change of the plane bending stiffness with the axial pressure, then according to kw=bix+c1=-0.0106x10000+204=98, that is: when the axial pressure is 10000KN, the relationship between the bending stiffness SW of the pipe section joint and the bending stiffness El of the body is: Sw= (1/kw)EI=(1/98)EI=0.0102EI Among them, the immersed pipe section body is a regular box structure, and the cross-sectional stiffness El of the pipe section body can be calculated from the structure size, material properties and material mechanics algorithm, and according to the longitudinal force of the tunnel, the actual bending moment M of the immersed pipe section joint is calculated. El and M are the calculation quantities that can be directly obtained according to the calculation methods in the prior art in this field, and will not be repeated here. Calculate the curvature of the joint=M/Sw=M/(0.0102EI) When the joint curvaturep<the allowable curvature [p], the bending deformation in the joint plane meets the requirements. It solves the problem that the curvature cannot be calculated due to the difficulty in determining the bending stiffness of the pipe joints in the past, and it is impossible to judge whether the deformation meets the requirements. 2. The calculation method of the vertical shear stiffness of the joint is as follows: (1) Calculate the shear stiffness GA of the immersed pipe section body from the structural size, material properties and material mechanics algorithm of the immersed pipe section body; SHV=(1/kHv)/GA (2) Calculate the vertical shear stiffness of the joint according to the following formula: SHV=(1/kHv)/GA In the formula: SHV-The vertical shear stiffness of the joint. G-The shear modulus of pipe section concrete (MPa), the value is G=0.4E. A- The concrete area of the cross section of the pipe section (m 4 ). kHv-The characteristic function of the vertical shear stiffness of the joint with the axial pressure. Among them, the characteristic function kHV Ofthe vertical shear stiffness of the joint changing with the axial pressure is calculated as follows: kHv=b 2 X+C 2 In the formula: b 2-The characteristic value of the vertical shear stiffness of the joint changing with the axial pressure, refer to Table 2 for the value. x-The axial pressure variation range, the axial pressure after the pipe sections are connected is generally greater than 4000kN. C2-Characteristic constant within the range of axial pressure Table 2 The parameter value table of the characteristic value of the vertical shear stiffness of the joint with the axial pressure change The characteristic value b2 Characteristic Axial pressure of the vertical shear constant c2 value x (kN) stiffness of the joint within the range of changing with the axial axial pressure pressure 1 4000<x<5400 -0.0483 2429.8 2 5400cx<19000 -0.165 3061

(3) Assuming that the allowable shear deformation of the immersed pipe joint is h, the deformation shear force is Fv=hxSHV; (4) Assuming that the joint is equipped with n vertical shearing pieces, if the average shearing force of each vertical shearing piece is Fv/n<V/y, it is judged that the vertical shearing capacity of the immersed pipe joint meets the requirements. Among them, y is the partial load factor, and V is the difference of the actual external load between the two connected immersed pipe sections. The specific calculation example according to the above method is as follows: Similarly, taking the axial pressure value x=OOOOkN as an example, according to Table 2, query the characteristic value of the vertical shear stiffness of the joint with the axial pressure change b 2 =-0.165, the characteristic constant c2=3061 in the axial pressure range, according to kHv=b2X+C2=-0.165x1OOOO+3061=1411. That is, when the axial pressure is 10000kN, the relationship between the vertical shear stiffness of the pipe section joint SHV and the immersed pipe section body shear stiffness GA is: SHV (/kHv)/GA=(1/1411)GA. Among them, the immersed pipe section body is a regular box structure, and the cross-sectional stiffness GA of the pipe section body can be calculated from the structure size, material properties and material mechanics algorithm. Since the vertical shear resistance of the immersed tube tunnel is mainly bome by the vertical shear key, assuming that the allowable shear deformation of the immersed tube section joint is h, the deformation shear force Fv=hxSHv=hx(1/1411)GA. Among them, the allowable shear deformation of the immersed pipe section joint is h, which is a known amount. Assuming that the joint is equipped with n vertical shear keys, if the average shear force of each vertical shear key Fv/n<V/y, it is judged that the vertical shear resistance of the immersed pipe joint meets the requirements. Among them, V is the difference of the actual external load between the two connected immersed pipe sections, and y is the partial load factor (selected from the Chinese Building Structure Load Code GB50009), which can be calculated or obtained by calculation methods in the prior art in the field, I won't go into details here.

Claims

1. An immersed tube tunnel joint mechanical performance test device, characterized in that a square balance frame body (1) is provided, and a resistance reducing device (2) is evenly arranged on the inner bottom wall of the balance frame body (1). A limit frame (3) is provided laterally in the frame body (1), the limit frame (3) is the same as the axial direction of the resistance reducing device (2). A The longitudinal loading device (4) is provided on the side wall of the balance frame body (1) opposite to the balance frame body (1). The balance frame body (1) is provided with a lateral loading device (5) on the side wall adjacent to The longitudinal loading device(4). A vertical loading device (6) is provided on the bottom wall inside the balance frame body (1).

2. The immersed tube tunnel pipe joint mechanical performance test device according to claim 1, characterized in that the limit frame (3) is provided with at least two, and both ends of the limit frame (3) are slidably connected to the side wall of the balance frame body (1).

3. The immersed tube tunnel pipe joint mechanical performance test device according to claim 1, characterized in that the limit frame (3) is composed of two horizontal rods and two vertical rods, wherein the two horizontal rods are opposite to each other. And the two ends are respectively slidably connected with the side wall of the balance frame body (1), and the two vertical rods are arranged oppositely between the two horizontal rods.

4. The immersed tube tunnel pipe joint mechanical performance test device according to claim 1, characterized in that the lateral loading device (5), The longitudinal loading device (4) and the lateral loading device (5) are all composed of a mounting seat and a jack mechanism, and the jack mechanisms are evenly distributed on the mounting seat.

5. The immersed tube tunnel pipe joint mechanical performance test device according to claim 1, characterized in that the resistance reducing device (2) is a steel roller.

6. The immersed tube tunnel pipe joint mechanical performance test device according to claim 1, characterized in that the balance frame body (1) is a reinforced concrete closed frame.

7. The immersed tube tunnel pipe joint mechanical performance test device according to any one of claims 1 to 6, characterized in that the specific steps adopted are: Step 1: The pipe joint model is made, and the pipe joint model is installed in the balance frame body. Step 2: The longitudinal loading device of the bottom plate and the top plate are simultaneously applied with the same load to detect the working condition of the axially compressed pipe section joint model. Step 3: Longitudinal load is applied to the longitudinal loading device of the single-sided bottom plate and top plate to detect the working condition of the joint model of the horizontal bending pipe section. Step 4: The longitudinal loading device of the bottom plate or the top plate is loaded to detect the working condition of the joint model of the vertical bending pipe section. Step 5: The horizontal loading device and the vertical loading device are loaded at the same time to detect the bidirectional shearing condition of the pipe joint model.

Step 6: The longitudinal loading device and the lateral loading device are loaded at the same time to detect the horizontal compression and shear conditions of the pipe joint model. Step 7: The longitudinal loading device and the vertical loading device are loaded at the same time to detect the vertical compression and shear conditions of the pipe joint model.

8. The immersed tube tunnel pipe joint mechanical performance test device, characterized in that the first step is specifically: 8.1: The pipe joint model is made, and the loading plate is embedded in the pipe joint model. 8.2: The balance frame body is made according to the pipe joint model, and the vertical loading device is arranged. 8.3: The pipe joint model is hoisted into the frame body, and the horizontal and vertical displacement of the pipe joint model is restricted by the limit frame. 8.4: The longitudinal loading device is arranged on the top and bottom plates of the pipe joint model, and lateral loading device is arranged laterally.