Sharp curve shield tunneling pushing test device and use method thereof

Abstract

The invention discloses a sharp curve shield tunneling pushing test device and a use method thereof. The sharp curve shield tunneling pushing test device comprises a tunnel model and a shield head model which are arranged in a model box, and a soil sample is filled to simulate an underground soil layer; the tunnel model is of an equal-proportion-reduced shield tunnel structure, one end of the tunnel model is tightly attached to the reaction wall baffle, one side of the other end of the tunnel model is connected with the shield head model through a connecting hinge, and the other side of the other end of the tunnel model abuts against the stepping motor. The stepping motor is used for simulating a shield jack during curve shield tunneling pushing, is fixedly connected with the shield head model, and pushes the tunnel model through the dowel bar to enable the tunnel model to rotate relative to the shield head model; the surface of the tunnel model is provided with various monitoring sensors including strain gauges and soil pressure cells. During testing, data is collected through the testing device and then processed. According to the invention, the technical blank of on-machine simulation of the centrifugal test for the urgent curve shield tunneling is filled up, and an effective means is provided for indoor research of the urgent curve shield tunneling of municipal administration, so that the engineering risk is reduced, the construction safety is guaranteed, and the engineering budget is optimized.

Description

Technical Field

[0001] This invention relates to the field of geotechnical centrifuge testing technology, and in particular to a test device for pushing the jacking of shield tunnels on steep curves and its usage method. Background Technology

[0002] In existing technologies, the simulation of shield tunneling in geotechnical centrifuge tests mainly relies on equivalent simulation methods such as flexible face tunneling, airbag method, dissolved organic matter method, and drainage method. Although micro-shield tunneling machines have been applied to centrifuge test research, they are costly and can only push the tunnel in straight lines at low g values ​​(≤25g) (continuous tunneling is possible, but only in straight lines at low g values, and cannot achieve sharp curves), and cannot achieve continuous pushing in high g value (≥50g) environments, resulting in distortion of the ground stress field. For shield tunneling on sharp curves with small radii of curvature, more complex construction parameters and mechanical behaviors are involved (such as asymmetric jack action and dynamic soil removal and disposal at the shield head). Existing methods monitor construction parameters or ground response in isolation, without constructing a complete response chain of tunneling thrust-soil balance-segment loading-surface settlement, which seriously restricts the accuracy of predicting risks in sharp curve construction.

[0003] Therefore, how to fill the technical gap in machine simulation of centrifugal tests for steep curve shield tunneling, provide an effective means for indoor research on shield tunneling curves, thereby reducing engineering risks, ensuring construction safety, and optimizing project budgets has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the present invention provides a test device for pushing the jacking of shield tunneling on sharp curves and its method of use. The purpose is to fill the technical gap in the in-machine simulation of centrifugal test of shield tunneling on sharp curves, provide an effective means for indoor research on shield tunneling on sharp curves in municipal engineering, thereby reducing engineering risks, ensuring construction safety and optimizing project budget.

[0005] To achieve the above objectives, the present invention discloses a test device for pushing the jack of a shield tunneling machine on a steep curve, comprising a tunnel model, a shield head model, a connecting hinge, a stepper motor, a piston, a reaction wall baffle, and various monitoring sensors set in a model box, and filling it with soil samples to simulate underground soil layers;

[0006] The tunnel model is a scaled-down shield tunnel structure. The overall materials and dimensions are determined according to the simulated field conditions and similarity criteria of the geotechnical centrifuge test. One end is tightly attached to the reaction wall baffle, and one side of the other end is connected to the shield head model through the connecting hinge. The other side of the other end abuts against the stepper motor.

[0007] The connecting hinge is a hinge structure, which allows the tunnel model and the shield head model to rotate relative to each other;

[0008] The stepper motor is used to simulate the shield jack during curved shield tunneling. It is fixedly connected to the shield head model and pushes the tunnel model through the force transmission rod to make the tunnel model rotate relative to the shield head model.

[0009] The piston is provided on the side of the shield head model facing away from the tunnel model;

[0010] The piston is connected to the shield head model by a sliding joint and can reciprocate along the pushing direction of the force transmission rod;

[0011] The reaction wall baffle is fixed to the box wall of the model box;

[0012] The surface of the tunnel model is equipped with various monitoring sensors, including strain gauges and earth pressure cells.

[0013] Preferably, a latex film is fitted at the connection between the tunnel model and the shield head model, and the latex film covers the gap between the tunnel model and the shield head model, the connecting hinge, and the stepper motor.

[0014] Preferably, the side of the reaction wall baffle facing away from the tunnel model is in close contact with the wall of the model box.

[0015] Preferably, the model box is a steel rigid box.

[0016] Preferably, the tunnel model has a ring of strain gauges and a ring of earth pressure cells on the sidewall near the end that connects with the shield head model;

[0017] The strain gauge ring comprises four strain gauges evenly distributed around the axis of the tunnel model;

[0018] The earth pressure cells in one ring include four earth pressure cells evenly distributed around the axis of the tunnel model.

[0019] The strain gauge is located between the earth pressure cell and the shield head model.

[0020] Preferably, inclination holes are provided symmetrically about the axis of the tunnel model on both sides, on both sides of the shield head model, and on both sides extending along the length of the tunnel model towards the outside of the shield head model. A laser displacement sensor is provided at the position above each inclination hole on the corresponding soil surface.

[0021] Each of the aforementioned inclinometer holes is used to measure the horizontal displacement of the soil around the tunnel along its depth, and a fixed inclinometer is placed in the middle of each hole.

[0022] Each of the laser displacement sensors is suspended above the soil surface and arranged symmetrically perpendicular to the axis of the tunnel model to monitor the settlement displacement of the soil surface.

[0023] This invention also provides a method for using the test device for pushing the jacks during steep curve shield tunneling, comprising the following steps:

[0024] Step 1: Fill the model box with soil sample and use a centrifuge to accelerate it to the target g value. Stop the centrifuge after the soil sample has consolidated.

[0025] Step 2: After the soil sample has been consolidated, bury the tunnel model and shield head model to the target depth, install various monitoring sensors, and then connect the various monitoring sensors to the computer.

[0026] Step 3: Accelerate the centrifuge to the target g value and wait for the data collected by the various monitoring sensors to stabilize;

[0027] Step 4: Start the stepper motor to rotate the shield head model relative to the tunnel model, and record the data from various monitoring sensors, as well as the angle R1 of the shield head model's rotation relative to the tunnel model;

[0028] Step 5: After the angle R1 of the shield head model relative to the tunnel model reaches the maximum target angle R2, stop pushing, and continuously record the data of the various monitoring sensors during the process;

[0029] Step 6: Process the recorded data.

[0030] Preferably, the calculation model test stepper motor advance distance L is used to determine whether the target angles R1 and R2 are in place. The calculation method is as follows:

[0031]

[0032] In the formula: Δ is the segment wedge shape, in mm; D0 is the outer diameter of the segment ring, in mm; B is the segment ring width, in mm; R min α is the radius of curvature, in mm; α is the universal ring assembly angle, in °.

[0033] The pushing angle and pushing distance are calculated according to the wedge amount and the outer diameter of the segment using the following formula:

[0034]

[0035]

[0036] In the formula: θ is the segment annular wedge shape, and the unit is °; The stepper motor propulsion distance in the model test is in meters; N is the target g value in the geotechnical centrifuge test, i.e., the similarity ratio.

[0037] The beneficial effects of this invention are:

[0038] This invention overcomes the challenge of continuous jacking at high g values ​​and overcomes the shortcomings of existing methods that cannot study the process of tunneling on sharp curves (including asymmetric thrust and dynamic excavation support) in a controlled high gravity field environment. It enables risk assessment and parameter optimization before construction, and has the advantages of reducing engineering risks and ensuring construction safety.

[0039] This invention establishes a variable curvature control system, breaking through the bottleneck that equivalent simulation technologies such as the flexible surface method / airbag method cannot reproduce the complex mechanical behavior of sharp curves. Based on real-time feedback of curvature radius (≤3D), the jack advance distance is dynamically adjusted (accuracy ±2%) to accurately simulate the dynamic deflection of the shield head.

[0040] This invention constructs a dynamic simulation method for soil extraction and disposal, which can solve the problem that existing geotechnical centrifuge test methods cannot simulate the asymmetric jack pushing and shield head dynamic soil extraction and disposal process in curved shield tunneling, and realize the accurate simulation study of the mechanical response of steep curve shield tunneling.

[0041] This invention integrates the entire response chain monitoring process, overcoming the shortcomings of existing technologies in reproducing key issues such as soil-structure interaction, ground disturbance, and segment stress and deformation under steep curve tunneling in indoor tests. It provides direct and reliable test data for the design and construction of steep curve shield tunnels.

[0042] This invention solves the problem of insufficient verification data and questionable accuracy of traditional simplified models and numerical simulations under steep curve conditions, and provides an economical, efficient and controllable indoor research approach to support the theoretical development and engineering application of steep curve shield tunneling technology.

[0043] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0044] Figure 1 The diagram shows a top-view schematic of the connection structure between the tunnel model and the shield head model in one embodiment of the present invention.

[0045] Figure 2 The diagram shows a top-view schematic of the connection structure between the tunnel model and the shield head model after the stepper motor starts pushing the tunnel.

[0046] Figure 3 This diagram illustrates the structure of a shield tunneling jacking test device for steep curves according to an embodiment of the present invention.

[0047] Figure 4 This diagram illustrates the arrangement of various monitoring sensors in one embodiment of the present invention.

[0048] Figure 5 This diagram illustrates the arrangement of strain gauges, earth pressure cells, inclinometer holes, and laser displacement sensors in one embodiment of the present invention.

[0049] Figure 6 A flowchart illustrating the method of using the shield tunneling jacking test device in a sharp curve according to an embodiment of the present invention is shown.

[0050] Figure 7 This diagram illustrates the principle of data processing in one embodiment of the present invention.

[0051] The components include: 1. Tunnel model, 2. Shield head model, 3. Connecting hinge, 4. Stepper motor, 5. Piston, 6. Latex membrane, 7. Reaction wall baffle, 8. Various monitoring sensors, 81. Strain gauge, 82. Earth pressure cell, 9. Model box, 10. Laser displacement sensor, and 11. Inclinometer hole. Detailed Implementation

[0052] Example: Figures 1 to 5 As shown, the steep curve shield tunneling push test device includes a tunnel model 1, a shield head model 2, a connecting hinge 3, a stepper motor 4, a piston 5, a reaction wall baffle 7, and various monitoring sensors 8, all set in a model box 9, and is filled with soil samples to simulate underground soil layers.

[0053] Tunnel Model 1 is a scaled-down shield tunnel structure. The overall materials and dimensions are determined according to the simulated field conditions and similarity criteria of the geotechnical centrifuge test. One end is tightly attached to the reaction wall baffle 7, and one side of the other end is connected to the shield head model 2 through the connecting hinge 3. The other side of the other end abuts against the stepper motor 4.

[0054] The connecting hinge 3 is a hinge structure that allows the tunnel model 1 and the shield head model 2 to rotate relative to each other. In practical applications, the tunnel model 1 and the shield head model 2, which can rotate relative to each other, can open to the corresponding angle to meet the curvature radius and arc requirements of the curved shield tunnel.

[0055] Stepper motor 4 is used to simulate the shield jack during curved shield tunneling. It is fixedly connected to shield head model 2 and pushes tunnel model 1 through force transmission rod to make tunnel model 1 rotate relative to shield head model 2. In practical applications, controlling stepper motor 4 to push tunnel model 1 to open connecting hinge 3.

[0056] Piston 5 is provided on the side of shield head model 2 facing away from tunnel model 1;

[0057] Piston 5 is connected to shield head model 2 by a sliding joint and can move back and forth along the pushing direction of the force transmission rod. In practical applications, the presence of piston 5 facilitates the entry of soil into the shield head model 2 during tunneling, completing the soil removal and disposal process.

[0058] The reaction wall baffle 7 is fixed to the box wall of the model box 9;

[0059] The surface of tunnel model 1 is equipped with various monitoring sensors 8, including strain gauges 81 and earth pressure cells 82.

[0060] In practical applications, the measured results correspond one-to-one with the deployed sensors. The results output by strain gauge 81 are the deformation of tunnel model 1 under load, the results output by earth pressure cell 82 are the compression of the soil around tunnel model 1, the results obtained by inclinometer 11 are the horizontal displacement of the soil around tunnel model 1 along the depth, and the results measured by laser displacement sensor 10 are the changes in surface soil settlement.

[0061] In some embodiments, a latex film 6 is fitted at the connection between the tunnel model 1 and the shield head model 2, and the latex film 6 covers the gap between the tunnel model 1 and the shield head model 2, the connecting hinge 3 and the stepper motor 4.

[0062] In practical applications, the gap between the tunnel model 1 and the shield head model 2, the connecting hinge 3, and the stepper motor 4 are wrapped with latex film 6 to prevent soil from falling into the gap and tunnel interior during the test due to the angle opening.

[0063] In some embodiments, the side of the reaction wall baffle 7 facing away from the tunnel model 1 is in close contact with the wall of the model box 9.

[0064] In practical applications, the reaction wall baffle 7 is built inside the model box 9 and contacts the tunnel model 1, providing the shield tunneling reaction force during the test, so that the stepper motor 4 pushes the tunnel model 1 through the force transmission rod to generate a reaction force to push the shield head forward.

[0065] In some embodiments, the model box 9 is a steel reinforced box.

[0066] In some embodiments, the tunnel model 1 has a ring of strain gauges 81 and a ring of earth pressure cells 82 on the side wall near the end that is connected to the shield head model 2.

[0067] A ring of strain gauges 81 includes four strain gauges 81 evenly distributed around the axis of the tunnel model 1;

[0068] The earth pressure cells 82 consist of four earth pressure cells 82 evenly distributed around the axis of the tunnel model 1.

[0069] A ring of strain gauges 81 is located between a ring of earth pressure cells 82 and the shield head model 2.

[0070] In some embodiments, inclination holes 11 are provided symmetrically about the axis of tunnel model 1 on both sides of tunnel model 1, both sides of shield head model 2, and both sides extending along the length of tunnel model 1 towards the outside of shield head model 2. A laser displacement sensor 10 is provided at the position above the corresponding soil surface for each inclination hole 11.

[0071] Each inclinometer hole 10 is used to measure the horizontal displacement of the soil around the tunnel along the depth, and a fixed inclinometer is placed in the middle of each hole.

[0072] Each laser displacement sensor 10 is suspended above the soil surface and symmetrically arranged perpendicular to the axis of the tunnel model 1 to monitor the settlement displacement of the soil surface. Figure 5 As shown, inclined planes 11 are symmetrically arranged about the axis of tunnel model 1 on both sides of tunnel model 1, both sides of shield head model 2, and both sides extending along the length of tunnel model 1 towards the outside of shield head model 2. They are detected by laser displacement sensors 10, respectively, corresponding to the soil-structure interaction, ground disturbance and segment stress deformation before the shield arrives, during the shield passes, and after the shield passes, so as to realize the whole process monitoring of the steep curve shield advancement.

[0073] like Figure 6 As shown, the present invention also provides a method for using the test device for pushing the jacking of shield tunnels on steep curves, comprising the following steps:

[0074] Step 1: Fill the model box 9 with soil sample and use a centrifuge to accelerate it to the target g value. Stop the centrifuge after the soil sample has consolidated.

[0075] Step 2: Bury the tunnel model 1 and shield head model 2 into the consolidated soil sample to the target depth, install various monitoring sensors 8, and then connect the various monitoring sensors 8 to the computer.

[0076] Step 3: Accelerate to the target g value using a centrifuge and wait for the data collected by various monitoring sensors 8 to stabilize;

[0077] Step 4: Start the stepper motor 4 to rotate the shield head model 2 relative to the tunnel model 1, and record the data from various monitoring sensors 8, as well as the angle R1 of the rotation of the shield head model 2 relative to the tunnel model 1;

[0078] Step 5: After the angle R1 of the shield head model 2 relative to the tunnel model 1 reaches the maximum target angle R2, stop the jacking, and continuously record the data of various monitoring sensors 8 during the process;

[0079] Step 6: Process the recorded data.

[0080] In some embodiments, the calculation model test stepper motor advances a distance L, and the target angles R1 and R2 are determined based on the calculated stepper motor advance distance L. The calculation method is as follows:

[0081]

[0082] In the formula: Δ is the segment wedge shape, in mm; D0 is the outer diameter of the segment ring, in mm; B is the segment ring width, in mm; R min α is the radius of curvature, in mm; α is the universal ring assembly angle, in °.

[0083] The pushing angle and pushing distance are calculated according to the wedge amount and the outer diameter of the segment using the following formula:

[0084]

[0085]

[0086] In the formula: θ is the segment annular wedge shape, and the unit is °; The stepper motor propulsion distance in the model test is in meters; N is the target g value in the geotechnical centrifuge test, i.e., the similarity ratio.

[0087] The principle of the above technology is as follows: single-ring jacking is carried out according to different radii of curvature. The angle between the completed tunnel model and the shield head model is controlled by the advance distance of the stepper motor remotely. The asymmetric jacking simulation of shield tunneling jacks on the engineering site is realized in conjunction with the connecting hinge. The larger the advance distance of the stepper motor, the larger the opening of the connecting angle, and the smaller the radius of curvature on the engineering site.

[0088] In practical applications, such as Figure 7 As shown, θ1 has a larger radius of curvature, so V1 requires a smaller amount of soil; θ2 has a smaller radius of curvature, so V2 requires a larger amount of soil.

[0089] The calculation method for the wedge amount Δ of the tunnel segment has been fully disclosed in the technical document "Research on the Calculation Method of the Wedge Amount of the General Ring Tunnel Segment of Metro Shield Tunnel" published in 2019. The authors are Zhang Wenjun, Zhu Zhankui, Zhang Qi, et al., published in Tunnel Construction (Chinese and English) 2019, 39(5): 746-753.

[0090] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A test device for pushing the jacking of a shield tunnel on a sharp curve; characterized in that, The model includes a tunnel model (1), a shield head model (2), a connecting hinge (3), a stepper motor (4), a piston (5), a reaction wall baffle (7), and various monitoring sensors (8) set in a model box (9), and is filled with soil samples to simulate underground soil layers; The tunnel model (1) is a scaled-down straight shield tunnel structure. The overall material and size are determined according to the simulated field conditions and similarity criteria of the geotechnical centrifuge test. One end is in close contact with the reaction wall baffle (7), and one side of the other end is connected to the shield head model (2) through the connecting hinge (3). The other side of the other end abuts against the stepper motor (4). The connecting hinge (3) is a hinge structure, which allows the tunnel model (1) and the shield head model (2) to rotate relative to each other; The stepper motor (4) is used to simulate the shield jack during the tunneling of a curved shield tunnel. It is fixedly connected to the shield head model (2) and pushes the tunnel model (1) through the force transmission rod to make the tunnel model (1) rotate relative to the shield head model (2). The piston (5) is provided on the side of the shield head model (2) facing away from the tunnel model (1); The piston (5) is connected to the shield head model (2) by a sliding pair and can reciprocate along the pushing direction of the force transmission rod; The reaction wall baffle (7) is fixed to the box wall of the model box (9); The surface of the tunnel model (1) is equipped with various monitoring sensors (8) including strain gauges (81) and earth pressure cells (82).

2. The steep curve shield tunneling jacking test device as described in claim 1, characterized in that, A latex film (6) is fitted at the connection between the tunnel model (1) and the shield head model (2), and the latex film (6) covers the gap between the tunnel model (1) and the shield head model (2), the connecting hinge (3) and the stepper motor (4).

3. The steep curve shield tunneling jacking test device as described in claim 1, characterized in that, The side of the reaction wall baffle (7) facing away from the tunnel model (1) is in close contact with the wall of the model box (9).

4. The steep curve shield tunneling jacking test device as described in claim 1, characterized in that, The model box (9) is a steel reinforced box.

5. The steep curve shield tunneling jacking test device as described in claim 1, characterized in that, The tunnel model (1) has a ring of strain gauges (81) and a ring of earth pressure cells (82) on the side wall near the end connected to the shield head model (2). The strain gauge (81) consists of four strain gauges (81) evenly distributed around the axis of the tunnel model (1). The earth pressure cells (82) in one ring consist of four earth pressure cells (82) evenly distributed around the axis of the tunnel model (1). The strain gauge (81) is located between the earth pressure cell (82) and the shield head model (2).

6. The steep curve shield tunneling jacking test device as described in claim 1, characterized in that, Inclinometer holes (11) are provided symmetrically about the axis of the tunnel model (1) on both sides of the tunnel model (1), on both sides of the shield head model (2), and on both sides extending along the length of the tunnel model (1) towards the shield head model (2) to the outside of the shield head model (2). A laser displacement sensor (10) is provided at the position above each inclinometer hole (11) on the corresponding soil surface. Each of the aforementioned inclinometer holes (10) is used to measure the horizontal displacement of the soil around the tunnel along the depth, and a fixed inclinometer is placed in the middle of each hole; Each of the laser displacement sensors (10) is suspended above the soil surface and arranged symmetrically perpendicular to the axis of the tunnel model (1) to monitor the settlement displacement of the soil surface.

7. The method of using the steep curve shield tunneling jacking test device as described in claim 1, characterized in that, Includes the following steps: Step 1: Fill the model box (9) with soil sample and use a centrifuge to accelerate to the target g value. Stop the centrifuge after the soil sample has been consolidated. Step 2: Bury the tunnel model (1) and shield head model (2) into the consolidated soil sample to the target depth and install various monitoring sensors (8). Then connect the various monitoring sensors (8) to the computer. Step 3: Accelerate to the target g value using the centrifuge and wait for the data collected by the various monitoring sensors (8) to stabilize; Step 4: Start the stepper motor (4) to rotate the shield head model (2) relative to the tunnel model (1), and record the data of the various monitoring sensors (8) and the angle R1 of the rotation of the shield head model (2) relative to the tunnel model (1); Step 5: After the angle R1 of the shield head model (2) relative to the tunnel model (1) reaches the maximum target angle R2, stop pushing, and continuously record the data of the various monitoring sensors (8) during the process; Step 6: Process the recorded data.

8. The method of using the steep curve shield tunneling jacking test device as described in claim 7, characterized in that, The calculation method is as follows: The stepper motor advances a distance L in the test model. Based on this distance L, the target angles R1 and R2 are determined to be in place. ； In the formula: Δ is the segment wedge shape, in mm; D0 is the outer diameter of the segment ring, in mm; B is the segment ring width, in mm; R min α is the radius of curvature, in mm; α is the universal ring assembly angle, in °. The pushing angle and pushing distance are calculated according to the wedge amount and the outer diameter of the segment using the following formula: ； ； In the formula: θ is the segment annular wedge shape, and the unit is °; The stepper motor propulsion distance in the model test is in meters; N is the target g value in the geotechnical centrifuge test, i.e., the similarity ratio.

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