Discrimination method for shield tunnel segment ring joint leakage risk based on contact stress measurement

Abstract

The present application relates to a kind of shield tunnel segment ring joint leakage risk discrimination method based on contact stress measurement, comprising 1) the establishment of elastic sealing pad hyperelastic body finite element model;2) the establishment of elastic sealing pad water split numerical model;3) groundwater leakage pressure and the average contact stress relationship of sealing pad are fitted;4) real-time monitoring the contact stress of contact surface;5) obtain the joint waterproof pressure according to the measured joint basis pressure;6) calculate the groundwater pressure acting on shield segment joint;7) preliminary identification;8) the preliminary judgment condition is corrected, can be used as the basis of tunnel long-term operation maintenance.It is advantageous that the contact stress condition of shield tunnel joint can be mastered in real time, which has intuitive judgment for shield tunnel joint waterproof risk control and operation maintenance, and has important significance;Concept is clear, cost is low, operation is convenient, easy for field staff to apply, also provides basis and method for post-tunnel operation.

Description

TECHNICAL FIELD

[0001] The application is a shield tunnel segment ring joint leakage risk discrimination method based on contact stress measurement, belonging to the technical field of underground engineering construction. BACKGROUND

[0002] The shield tunnel method has become the mainstream method of urban tunnel construction and has been widely used in the construction of subway tunnels in more than 40 large and medium-sized cities in China. However, while pursuing high-speed construction, it also brings many problems, among which the segment joint leakage problem is common, which brings many hidden dangers to the safety of subway operation. When the shield is excavated, the jacks act on the rear assembled segments to provide the advancing thrust for the excavation of the shield machine, and at the same time, the thrust is transmitted to the segment ring joint, which increases the rubber contact stress of the segment ring joint and improves the waterproof performance of the segment ring joint. With the completion of the shield excavation project, the release of the thrust will gradually relax the rubber contact stress of the ring joint, reducing the waterproof performance of the segment ring joint. At the same time, with the increase of the operation life of the subway tunnel, the rubber aging of the elastic sealing pad will accelerate year by year, which will also reduce its sealing performance year by year. The safety of tunnel, especially underwater tunnel, needs regular security checks, but it cannot be ensured that there will be no major risks. SUMMARY

[0003] The application provides a shield tunnel segment ring joint leakage risk discrimination method based on contact stress measurement, which aims to overcome the above-mentioned defects, apply film area pressure sensor technology, facilitate the implementation of control of tunnel joint waterproof safety, and thus realize real-time judgment of tunnel segment joint leakage risk and more intuitive and accurate judgment of the waterproof ability of shield tunnel joints during the operation period.

[0004] The technical solution of the application is a shield tunnel segment ring joint leakage risk discrimination method based on contact stress measurement, which comprises the following steps:

[0005] S1, selecting an elastic sealing pad, establishing an elastic sealing pad hyperelastic body finite element model, and determining the average contact stress P of the sealing pad contact surface under different opening amounts and misalignment amounts c ;

[0006] S2, establishing a numerical analysis of the water splitting number of the elastic sealing pad, and determining the underground water leakage pressure P of the elastic sealing pad under different opening amounts and misalignment amounts u ;

[0007] S3, fitting the sealing coefficient K between the underground water leakage pressure and the average contact stress of the sealing pad, and the relationship formula P u = K·P c ;

[0008] S4, install a thin film pressure sensor on the contact surface of the elastic sealing gasket and a monitoring signal transmission device to monitor the contact stress P of the contact surface in real time cm ;

[0009] S5, substitute the average contact stress into the relationship formula P um = K·P cm to obtain the joint waterproof pressure P um ;

[0010] S6, calculate the groundwater pressure P w ;

[0011] S7, according to K = P um / P w , preliminarily determine the waterproof risk of the shield segment joint: if K≥2.0, the waterproof of the segment joint is in a safe area; if 1.6≤K<2.0, the waterproof of the segment joint is in a low-risk area; if 1.3≤K<1.6, the waterproof of the segment joint is in a medium-risk area; if K<1.3, the waterproof of the segment joint is in a high-risk area, and corresponding measures are recommended according to the determination level in practice;

[0012] S8, review and investigate the leakage of the field shield tunnel segment joint, and correct the preliminary determination according to the leakage and development of the segment joint, which can be used as a basis for long-term operation and maintenance of the tunnel.

[0013] The step S4 includes the following specific steps:

[0014] S4.1, select a contact segment joint, and attach a thin film pressure sensor to the rubber sealing gasket surface in the segment joint groove before each segment is assembled, so that the thin film pressure sensor covers the rubber sealing gasket contact surface;

[0015] S4.2, after the segment is assembled or during the operation of the tunnel, set the data acquisition box, signal receiver and signal strength amplifier near the segment joint to be monitored, connect the data acquisition box, signal receiver, cloud platform server and industrial controller in sequence through wireless signals, connect the thin film pressure sensor previously buried on the sealing gasket contact surface of the joint through wires and the data acquisition box, and finally transmit the data to the industrial controller through the signal receiver, cloud platform server in sequence, to obtain the contact stress P cm of the contact surface.

[0016] In steps S1 and S2, the opening amount of the sealing gasket is 12mm, 10mm, 8mm, 6mm, 4mm, 2mm and 0mm, and the misalignment amount of the sealing gasket is 6mm and 0mm.

[0017] In the steps S1 and S2, the contact stress under different opening amounts and misalignment amounts can be determined by the grid mapping technology in the ABAQUS software, and the underground water leakage pressure under different opening amounts and misalignment amounts can be determined by the fluid pressure permeation load calculation method of the ABAQUS software.

[0018] In the step S3, the sealing coefficient K is fitted, a plurality of rubber sealing pad load tests and water pressure leakage tests are performed, and the reliability of the fitted sealing pad coefficient K is determined, and the formula is as follows:

[0019] Misalignment amount 1: P u =(A1+B1δ+C1δ 2 +D1δ 3 )P c

[0020] Misalignment amount 2: P u =(A2+B2δ+C2δ 2 +D2δ 3 )P c

[0021] In the formula, δ represents the opening amount, A1, B1, C1, D1, A2, B2, C2 and D2 are undetermined coefficients of the fitted formula.

[0022] In the step S4, the thin film pressure sensor used should be calibrated in advance, and the voltage-pressure calibration function file of each buried thin film pressure sensor is obtained, so that the measured contact stress P cm of the sealing pad is obtained by subsequent signal transmission to the industrial controller.

[0023] The present application has the following beneficial effects:

[0024] 1) The contact stress of the shield tunnel joint can be grasped in real time, which has important significance for the intuitive judgment of the waterproof risk control and operation and maintenance of the shield tunnel joint.

[0025] 2) The judgment method provided by the present application has clear concept, low cost and convenient operation, and is convenient for field workers to apply, and also provides basis and method for later tunnel operation and maintenance. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the finite element model of the elastic sealing pad established by the present application;

[0027] Figure 2 is the compression numerical model result graph of the elastic sealing pad calculated by the present application;

[0028] Figure 3 is the waterproof failure numerical model result graph of the elastic sealing pad calculated by the present application;

[0029] Figure 4 This is a schematic diagram of the monitoring and information transmission based on the thin-film pressure sensor of the present invention;

[0030] Figure 5 This is the fitting curve of the sealing coefficient K of the system gasket of the present invention;

[0031] Figure 6 This is a flowchart of a method for judging the leakage risk of shield tunnel segment ring joints based on the actual measurement of contact stress at the segment ring joints;

[0032] Labeling instructions: 1. Segment, 2. Elastic sealing gasket, 3. Thin-film pressure sensor, 4. Wire, 5. Data acquisition box, 6. Tunnel boring machine, 7. Signal receiver, 8. Signal strength gainer, 9. Cloud platform server, 10. Industrial controller. Detailed Implementation

[0033] A method for judging the leakage risk of shield tunnel segment ring joints based on the measured contact stress of segment ring joints, the analysis steps of which are as follows: 1) By establishing a finite element model of the elastic sealing gasket hyperelastic body, the average contact stress P of the sealing gasket contact surface under different opening and misalignment amounts is determined. c 2) By establishing a numerical analysis of water fracturing of the elastic sealing gasket, the groundwater leakage pressure P under different opening and misalignment amounts was determined. u ;3) To determine the sealing coefficient K and the relationship P between the groundwater leakage pressure and the average contact stress of the sealing gasket. u =K·P c 4) By installing a thin-film pressure sensor and a monitoring signal transmission device on the contact surface of the elastic sealing gasket, the contact stress P of the contact surface can be monitored in real time. cm ;5) Substitute the average contact stress and groundwater leakage pressure into the formula P um =K·P cm Calculate the joint waterproofing pressure P based on the measured joint foundation pressure. um 6) Calculate the groundwater pressure P acting on the shield tunnel segment joints based on the tunnel's burial depth and groundwater depth. w 7) According to K=P um / P wThe waterproof risk of the shield segment joint is preliminarily judged: if K≥2.0, it is considered that the waterproof of the segment joint is in a safe area; if 1.6≤K<2.0, it is considered that the waterproof of the segment joint is in a low-risk area; if 1.3≤K<1.6, it is considered that the waterproof of the segment joint is in a medium-risk area; if K<1.3, it is considered that the waterproof of the segment joint is in a high-risk area. In the project, corresponding measures can be taken according to the judgment level; 8) The leakage of the shield tunnel segment joint is tested and investigated in detail, and the preliminary judgment is corrected according to the leakage and development of the segment joint, which can be used as the basis for long-term operation and maintenance of the tunnel.

[0034] The gasket opening amount is 12mm, 10mm, 8mm, 6mm, 4mm, 2mm, 0mm, and the gasket misalignment amount is 6mm, 0mm. The first step to determine the contact stress under different opening amounts and misalignment amounts can be determined by the grid mapping technology in ABAQUS software. The second step to determine the groundwater leakage pressure under different opening amounts and misalignment amounts can be determined by the fluid pressure permeation load calculation method of ABAQUS software.

[0035] The third step is to calculate the sealing coefficient K, which is a variable about the opening amount and the misalignment amount. The P u =K·P c is obtained by fitting:

[0036] Misalignment amount 6mm: P u =(A1+B1δ+C1δ 2 +D1δ 3 )P c (1)

[0037] Misalignment amount 0mm: P u =(A2+B2δ+C2δ 2 +D2δ 3 )P c (2)

[0038] Where δ represents the opening amount, A1, B1, C1, D1, A2, B2, C2, D2 are the undetermined coefficients of the fitting formula.

[0039] The method of real-time monitoring the contact stress P cm of the contact surface in the fourth step can be obtained by real-time measurement of the thin film pressure sensor. The thin film pressure sensor used should be calibrated in advance to obtain the voltage-pressure calibration function file of each buried thin film pressure sensor, which is prepared for subsequent signal transmission to the industrial controller to obtain the measured contact stress P cm of the gasket.

[0040] The seventh step is to preliminarily judge the waterproof risk of the shield segment joint, and further modification is needed according to the leakage of the shield tunnel segment joint on site, so as to be more in line with the actual situation.

[0041] Embodiment 1

[0042] The technical solutions of the present application will be further described below with reference to the drawings

[0043] As shown in the accompanying Figures 1-6 , taking a tunnel in Nanjing as an example: 1) the elastic sealing pad is selected from HD4422A type of ethylene-propylene-diene rubber sealing pad of Jiangyin Haida Rubber and Plastic Co., Ltd.; 2) according to the buried depth of the shield tunnel and the buried depth of underground water, the maximum underground water pressure P w of the shield segment joint is calculated = 0.79 MPa.

[0044] S1, the HD4422A type of ethylene-propylene-diene rubber sealing pad of Jiangyin Haida Rubber and Plastic Co., Ltd. is selected. By establishing the finite element model of the super-elastic body of the elastic sealing pad, the average contact stress P c of the sealing pad contact surface under different opening amounts and misalignment amounts is determined; as shown in Table 1.

[0045] Table 1

[0046]

[0047] S2, by establishing the numerical analysis of the water splitting number of the HD4422A type of elastic sealing pad, the underground water leakage pressure P u under different opening amounts and misalignment amounts is determined.

[0048] Table 2

[0049]

[0050]

[0051] S3, the sealing coefficient K between the underground water leakage pressure and the average contact stress of the sealing pad and the relationship P u = K·P c is determined, which is a variable about the opening amount and the misalignment amount, and the calculation formula of P u = K·P c obtained by fitting is:

[0052] Misalignment amount 6mm: P u = (1.998-0.232δ+0.033δ 2 -0.00177δ 3 )P c (3)

[0053] Misalignment amount 0mm: Pu =(1.747-0.093δ+0.0186δ) 2 -0.00132δ 3 )P c (4)

[0054] Meanwhile, based on the load test and water pressure leakage test of the elastic sealing gasket, the average error of the sealing coefficient K value is about 11.7%, which shows that the fitting formula has good reliability.

[0055] S4, as attached Figure 4 As shown, by installing a thin-film pressure sensor 3 and a monitoring signal transmission device on the contact surface of the elastic sealing gasket 2, the contact stress P of the contact surface is monitored in real time. cm ;

[0056] S4.1 Select the joint of the contact tube segment 1. Before assembling each tube segment 1, attach the thin film pressure sensor 3 to the surface of the rubber sealing gasket 2 in the groove of the tube segment joint, so that the thin film pressure sensor 3 covers the contact surface of this part of the rubber sealing gasket 2.

[0057] S4.2 After segment 1 is assembled, or during the entire tunnel operation period, the data acquisition box 5, signal receiver 7, and signal strength gainer 8 are installed near the segment joint to be monitored. The data acquisition box 5, signal receiver 7, cloud platform server 9, and industrial controller 10 are sequentially connected via wireless signal. The thin-film pressure sensor 3, pre-embedded on the contact surface of the sealing gasket 2 within the joint, is connected to the data acquisition box 5 via wire 4. Finally, the data is transmitted sequentially to the industrial controller 10 via the signal receiver 7 and cloud platform server 9 to obtain the contact stress P of the contact surface. cm .

[0058] S8. Conduct detailed testing and investigation on the water leakage at the joints of the shield tunnel segments. Based on the leakage and its development, revise the preliminary judgment and use it as a basis for the long-term operation and maintenance of the tunnel.

[0059] S5, Substitute into the relationship between average contact stress and groundwater leakage pressure P um =K·P cm Calculate the joint waterproofing pressure P based on the measured joint contact stress. um ;

[0060] S6. Calculate the groundwater pressure P acting on the shield tunnel segment joints based on the tunnel's burial depth and groundwater depth. w =0.79MPa;

[0061] S7. According to K=P um / P wP < 1.027 MPa. In the project, corresponding measures can be taken according to the discrimination level; cm If K≥2.0, it can be considered that the segment joint waterproof is in the safe area, at this time the measured average contact stress P cm should be greater than 1.58 MPa; if 1.6≤K<2.0, it can be considered that the segment joint waterproof is in the low risk area, at this time the measured average contact stress should satisfy 1.265 MPa≤P cm <1.58 MPa; if 1.3≤K<1.6, it can be considered that the segment joint waterproof is in the medium risk area, at this time the measured average contact stress should satisfy 1.027 MPa≤P cm <1.265 MPa; if K<1.3, it can be considered that the segment joint waterproof is in the high risk area, at this time the measured average contact stress should satisfy P cm <1.027 MPa. In the project, corresponding measures can be taken according to the discrimination level;

[0062] In step S4, the used film pressure sensor should be calibrated in advance to obtain the voltage-pressure calibration function file of each buried film pressure sensor, so as to obtain the measured contact stress P cm of the sealing gasket for subsequent signal transmission to the industrial controller.

Claims

1. A shield tunnel segment ring joint leakage risk discrimination method based on contact stress measurement, characterized in that The method comprises the following steps: S1, select elastic sealing gasket, establish elastic sealing gasket hyperelastic finite element model, determine the average contact stress of the sealing gasket contact surface under different opening amounts and misalignment amounts ; S2, establish the numerical analysis of the water wedge of the elastic sealing gasket, determine the underground water leakage pressure under different opening amounts and misalignment amounts ; S3, fitting a sealing coefficient between both the groundwater leakage pressure and the average contact stress of the sealing gasket K , both relationship equations ; S4, install a thin film pressure sensor and a monitoring signal transmission device on the contact surface of the elastic sealing gasket to monitor the contact stress of the contact surface in real time ; S5, substitute the average contact stress and the groundwater leakage pressure relationship formula Obtain the joint waterproof pressure according to the measured joint foundation pressure ; S6、According to the buried depth of the shield tunnel and the buried depth of groundwater, the groundwater pressure acting on the shield segment joint is calculated P w ; S7、According to Preliminary discrimination of the waterproof risk of the shield segment joint: if , the waterproof of the segment joint is in the safe area; if , the waterproof of the segment joint is in the low-risk area; if , the waterproof of the segment joint is in the medium-risk area; If K <1.3, the pipe joint waterproof is in a high-risk area; S8, review and research the leakage situation of the field shield tunnel segment joint, and correct the preliminary judgment according to the leakage and development of the segment joint, which can be used as the basis for long-term operation and maintenance of the tunnel.

2. The method according to claim 1, characterized in that The step S4 comprises the following specific steps: S4.1, selecting a contact segment joint, and attaching a thin film pressure sensor on the rubber sealing gasket surface in the segment joint groove before assembling each segment, so that the thin film pressure sensor covers the contact surface of the rubber sealing gasket; S4.2, after the completion of the segment assembly or during the tunnel operation, the data acquisition box, signal receiver and signal strength gain device are arranged near the segment joint to be monitored, the data acquisition box, signal receiver, cloud platform server and industrial controller are sequentially connected through wireless signals, the film pressure sensor previously buried on the contact surface of the sealing pad in the joint is connected with the data acquisition box through the wire, and finally the data is transmitted to the industrial controller through the signal receiver, cloud platform server in sequence, so that the contact stress of the contact surface is obtained .

3. The method according to claim 1, characterized in that In the steps S1 and S2, the opening amounts of the sealing gaskets are respectively 12mm, 10mm, 8mm, 6mm, 4mm, 2mm and 0mm, and the misalignment amounts of the sealing gaskets are respectively 6mm and 0mm.

4. The shield tunnel segment joint leakage risk identification method based on contact stress measurement according to claim 1, characterized in that In the steps S1 and S2, the contact stress under different opening amounts and misalignment amounts is determined by the grid mapping technology in the ABAQUS software, and the groundwater leakage pressure under different opening amounts and misalignment amounts is determined by the fluid pressure penetration load calculation method of the ABAQUS software.

5. The method for judging the risk of shield tunnel segment joint leakage based on the measured contact stress according to claim 1, characterized in that In the step S3, the sealing coefficient K is fitted, a plurality of rubber sealing gasket load tests and water pressure leakage tests are performed, and the reliability of the fitted sealing gasket coefficient K is determined, and the formula is: ； ； In the formula δ represent the opening amount, A1, B1, C1, D1, A2, B2, C2, and D2 are undetermined coefficients of the fitting formula, respectively.

6. The method for judging the risk of shield tunnel segment joint leakage based on the measured contact stress according to claim 1, characterized in that The step S4, using the film pressure sensor should be prior calibration test, obtain each buried film pressure sensor voltage-pressure calibration function file, for subsequent signal transmission to the industrial controller to get the gasket measured contact stress Get ready.

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