A test method for stress relaxation of sealing gasket-segment groove contact surface

Abstract

The present application discloses a test method for stress relaxation of the contact surface of the sealing gasket and the groove of the pipe segment, comprising the following steps: using numerical simulation to obtain the extrusion effect of the sealing gasket on the groove and determine the contact path; drawing the contact stress distribution curve on the path and using the numerical integration method to obtain the closing pressure of the sealing gasket on the groove; conducting a mechanical compression performance test of the sealing gasket and using a thin film pressure sensor to obtain the closing pressure value on the contact surface of the sealing gasket and the groove under a specified deformation; comparing the curve integral calculation value with the pressure sensor measurement value and fitting the calibration coefficient; fixing the sealing gasket in a clamping device with a specific deformation amount, placing it in an aging furnace for aging, and reading the measurement value of the thin film pressure sensor in real time; according to the calibration coefficient and the real-time measurement value, obtaining the contact stress changes of each column foot of the sealing gasket and the contact edge with the groove. The present invention realizes the real-time monitoring of the stress relaxation process of the sealing gasket and the groove contact surface during the aging process.

Description

Technical Field

[0001] The invention relates to a mechanical property testing method for a shield tunnel joint sealing gasket, in particular to a testing method for stress relaxation of a sealing gasket-segment groove contact surface. Background Art

[0002] As tunnel construction continues to develop towards greater depth and greater water pressure, higher requirements are placed on the waterproof performance of tunnel segment joints. In the existing joint waterproofing system, the contact stress generated by the compression deformation of the sealing gasket set in the segment groove is used to resist the intrusion of groundwater. Specifically, the contact stress of the sealing gasket includes two types: the contact stress between the sealing gaskets and the contact stress between the sealing gaskets and the grooves.

[0003] Existing tests on the mechanical properties of gaskets mainly focus on the contact stress between gaskets, and there are few studies on the contact stress between the column foot and the gasket groove. The only studies on the contact stress between the gasket and the groove mostly use numerical simulation methods, and almost no experimental methods. In addition, existing studies on the aging stress relaxation of gaskets do not involve stress relaxation at the column foot. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a testing method for stress relaxation of the sealing gasket-segment groove contact surface, which has a good guiding role in studying the stress relaxation of tunnel joint sealing gaskets after aging.

[0005] In order to solve the above technical problems, the technical solution of the present invention is: a method for testing stress relaxation of the contact surface of a sealing gasket and a pipe segment groove, comprising the following steps:

[0006] (1) The extrusion effect of the gasket on the groove under a specified deformation is obtained through numerical simulation, and the contact path between the gasket and the groove is determined;

[0007] (2) Draw the contact stress distribution curve on the path and use the numerical integration method to obtain the closing pressure of the sealing gasket on the groove;

[0008] (3) Conducting a mechanical compression performance test of the sealing gasket, placing a thin film pressure sensor between the pressure plate and the groove plate, and obtaining the closing pressure value on the sealing gasket-groove contact surface under a specified deformation through the thin film pressure sensor;

[0009] (4) Compare the curve integral calculation value with the pressure sensor measurement value to calculate the calibration coefficient;

[0010] (5) The sealing gasket is connected by bolts and fixed in the clamping device with a specific deformation amount, the clamping device is placed in a high-temperature furnace for aging, and the measurement value of the thin film pressure sensor is read in real time;

[0011] (6) The contact stress changes at each column foot and the contact edge with the groove of the sealing gasket during the aging process are obtained through the calibration method in steps 4 and 5 and the real-time measurement value of the sensor.

[0012] Furthermore, the extrusion effect of step (1) means obtaining the surface that may come into contact with the groove of the pipe segment during the compression process through the deformation cloud map.

[0013] Furthermore, the path of step (2) is a surface that may come into contact with the groove of the tube segment during the compression process described in claim 2.

[0014] Furthermore, when studying the stress loss at the contact surface between the gaskets under aging, the path of step (2) is the contact surface between the gaskets.

[0015] Furthermore, the thin film pressure sensor in step (3) is arranged between the upper pressure plate and the upper groove plate, or between the lower pressure plate and the lower groove plate, and the pressure sensor can be distributed or single-point.

[0016] Furthermore, the calibration coefficient calculation method in step (4) is:

[0017] ∫S 22 dl=ασA

[0018] In the formula, S 22 is the stress component along the compression direction on the working surface of the sealing gasket and the groove; l is the actual distance of the path; α is the calibration coefficient, and its value is 1 in theory; σ is the stress measurement value obtained in the thin film pressure sensor under the specified opening amount; A is the pressure area of ​​the groove plate.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention adopts a method combining numerical simulation experiments, gasket mechanical compression performance tests and aging experiments, which can effectively solve the problem that measuring points cannot be arranged at the column base in the gasket mechanical compression test, and can effectively monitor the stress changes of the gasket during the aging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A flow chart of the testing method for stress relaxation at the aging column foot of the sealing gasket provided by the present invention.

[0021] Figure 2 A sealing gasket-groove contact path extraction diagram provided in an embodiment of the present invention.

[0022] Figure 3 A stress cloud diagram on the sealing gasket-groove contact path provided by an embodiment of the present invention.

[0023] Figure 4 An opening amount clamping device with a pressure sensor provided in an embodiment of the present invention.

[0024] Figure 5 This is a diagram of application scenarios under different opening amounts provided in Example 1 of the present invention.

[0025] Figure 6 This is an application scenario diagram for the opening + misalignment condition provided in Example 2 of the present invention.

[0026] Explanation of the reference numerals: 1 is an elastic sealing gasket; 2 is a sealing gasket-groove contact path; 3 is a pressure plate; 4 is a groove plate; 5 is a thin film pressure sensor; 6 is a thin film pressure sensor data acquisition device; 7 is a high temperature furnace. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0028] like Figure 1 As shown, Figure 1 The flowchart of the present invention is as follows:

[0029] Example 1, aging conditions under different opening deformations:

[0030] (1) Through numerical simulation, the extrusion effect of the gasket on the groove under the specified opening deformation is obtained, and the gasket-groove contact path (such as Figure 2 As shown in the figure, when compressed to the specified opening amount, it can be seen that the surfaces in contact with the groove are the bottom of the column foot and the two side surfaces.

[0031] (2) Draw the contact stress distribution curve on the path, and use the numerical integration method to obtain the closing pressure of the sealing gasket on the groove. Draw the path along the contact surface obtained in step 1, such as Figure 2 As shown, the stress curve at the reading path is Figure 3 As shown, the total vertical pressure value ∫S is obtained by integrating and summing 22 dl.

[0032] (3) Carry out the mechanical compression performance test of the sealing gasket, place the thin film pressure sensor between the pressure plate and the groove plate, and obtain the closing pressure value on the sealing gasket-groove contact surface under the specified opening deformation through the thin film pressure sensor, such as Figure 4 As shown, the measured value of the thin film pressure sensor is σ, and the upper surface area of ​​the groove plate is A, from which it can be concluded that the total pressure is σA.

[0033] (4) Compare the curve integral calculation value with the pressure sensor measurement value to calculate the calibration coefficient, such as Figure 4 As shown, ∫S22 dl=ασA is the calculation formula, and the calibration coefficient α is obtained.

[0034] (5) The sealing gasket is connected by bolts and fixed in the clamping device with a specific deformation amount. The clamping device is placed in a high-temperature furnace for aging, and the measurement value of the thin film pressure sensor is read in real time.

[0035] (6) The calibration coefficients obtained through the above steps and the real-time measurement values ​​of the sensors are used to obtain the changes in contact stress at each column foot of the sealing gasket and at the contact edge with the groove during the aging process.

[0036] Example 2, aging conditions under different opening + staggering:

[0037] (1) Through numerical simulation, the extrusion effect of the gasket on the groove under the specified opening + misalignment deformation is obtained, and the gasket-groove contact path is determined.

[0038] (2) Draw the contact stress distribution curve on the path, and use the numerical integration method to obtain the closing pressure of the sealing gasket on the groove. Draw the path along the contact surface obtained in step 1, read the stress curve at the path, and integrate and sum to obtain the total vertical pressure value ∫S 22 dl.

[0039] (3) Carry out the mechanical compression performance test of the sealing gasket, place the film pressure sensor between the upper pressure plate and the upper groove plate, and adjust the misalignment by adjusting the position of the upper and lower groove plates. The closing pressure value on the sealing gasket-groove contact surface under the specified opening deformation is obtained by the film pressure sensor, where the measurement value of the film pressure sensor is σ, and the upper surface area of ​​the groove plate is A, from which the total pressure can be obtained as σA.

[0040] (4) Compare the curve integral calculation value with the pressure sensor measurement value and fit the corresponding calibration coefficient, such as Figure 4 As shown, ∫S 22 dl=ασA is the calibration formula, and the calibration coefficient α is obtained.

[0041] (5) The sealing gasket adjusted to a specific opening amount + misalignment amount is connected by bolts and fixed in a clamping device with a specific deformation amount. The clamping device is placed in a high-temperature furnace for aging. Taking 90°C as an example, the measured value of the thin film pressure sensor is read in real time. Figure 6 shown.

[0042] (6) According to the calibration coefficients obtained in the above steps and the real-time measurement values ​​of the sensors, the contact stress changes at each column foot of the sealing gasket and at the contact edge with the groove during the aging process are obtained.

Claims

1. A method for testing stress relaxation of the contact surface between a sealing gasket and a segment groove, characterized in that: It is achieved by the following steps: (1) Numerical simulation is used to obtain the extrusion effect of the gasket on the groove under a specified deformation and determine the gasket-groove contact path; (2) Draw the contact stress distribution curve on the path and use the numerical integration method to obtain the closing pressure of the gasket on the groove; (3) Conduct a mechanical compression performance test of the gasket and use a thin film pressure sensor to obtain the compressive stress on the contact surface of the gasket-groove under a specified deformation; (4) Compare the numerical integral calculation value with the pressure sensor measurement value to calculate the calibration coefficient; (5) The sealing gasket is connected by bolts and fixed in the clamping device with a specific deformation amount, the clamping device is placed in a high-temperature furnace for aging, and the measurement value of the thin film pressure sensor is read in real time; (6) According to the calibration coefficients obtained in the above steps and the real-time measurement values ​​of the sensors, the contact stress changes at each column foot of the sealing gasket and at the contact edge with the groove during the aging process are obtained.

2. A method for testing stress relaxation of a sealing gasket-segment groove contact surface according to claim 1, characterized in that: The extrusion effect of step (1) is obtained by using the deformation cloud map to obtain the contact surface with the groove of the pipe segment during the compression process.

3. A method for testing stress relaxation of a sealing gasket-segment groove contact surface according to claim 1, characterized in that: The path of step (2) is the contact surface between the sealing gasket and the groove of the pipe segment during the compression process.

4. A method for testing stress relaxation of a sealing gasket-segment groove contact surface according to claim 1, characterized in that: When studying the stress loss at the contact surface between the gaskets under aging, the path of step (2) is the contact surface between the gaskets.

5. The method for testing stress relaxation of the sealing gasket-segment groove contact surface according to claim 1, characterized in that: The thin film pressure sensor in step (3) is arranged between the upper pressing plate and the upper groove plate, or between the lower pressing plate and the lower groove plate, and the pressure sensor is distributed or single-point.

6. A method for testing stress relaxation of a sealing gasket-segment groove contact surface according to claim 1, characterized in that: The calibration coefficient calculation formula in step (4) is: ∫S 22 dl=ασA In the formula, S 22 is the stress component along the compression direction on the working surface of the sealing gasket and the groove; l is the actual distance of the path; α is the calibration coefficient, and its value is 1 in theory; σ is the stress measurement value obtained in the thin film pressure sensor under the specified opening amount; A is the pressure area of ​​the groove plate.

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