Tunnel excavation device for centrifugal model test and test method

Abstract

The invention belongs to the field of centrifugal model tests, and particularly relates to a tunnel excavation device for a centrifugal model test and a test method.The tunnel excavation device comprises a model box, a positioning system, an excavation simulation system and a power system, the model box comprises a bottom plate and four side plates, the positioning system is provided with a middle partition plate assembly, and the middle partition plate assembly is arranged in the model box; the model box is divided into an excavation half area and a monitoring half area, the excavation simulation system comprises an organic glass tube and a stainless steel tube, one end of the organic glass tube is sealed, the other end of the organic glass tube is hollow, the sealed end of the organic glass tube is fixed to the front side plate, and the organic glass tube is embedded in the stainless steel tube in a sliding mode. A through hole allowing the stainless steel pipe to penetrate is formed in the middle of the middle partition plate assembly, a threaded rod is fixed in the end, away from the front side plate, of the stainless steel pipe, the power system is provided with a stainless steel wire, and the threaded rod is in transmission connection with the power system through the stainless steel wire. According to the method, the stress characteristics of the tunnel lining and the damage form of the excavation face during tunnel excavation can be truly restored.

Description

Technical Field

[0001] The invention belongs to the field of centrifugal model tests, and in particular relates to a tunnel excavation device and a testing method for centrifugal model tests. Background Art

[0002] Tunnel engineering is a building built underground or underwater or in a mountain, with railways or roads for motor vehicles to pass. In order to study the stress and deformation characteristics of tunnels under different geological conditions, indoor test simulation research is often required, and centrifuge model test, as a better test technology, is widely used in various geotechnical engineering simulation tests. This technology is to place the model in a high-speed rotating centrifuge, simulate different gravity fields by controlling the speed, and then reduce the model to 1 / n of the prototype. Since the centrifuge model test can simulate the stress field of the prototype and the materials used are the same as the prototype, the stress-strain and deformation instability laws of the model are almost exactly the same as those of the prototype. Centrifuge model test technology has become the preferred test method for solving complex geotechnical problems due to its reliability, time and cost-effectiveness.

[0003] Although my country's geotechnical centrifugal testing technology started late, it has developed rapidly in the past two or three decades. Centrifugal simulation test technology has also made great progress. The performance of centrifuges has become better and better, the power has become larger and larger, and the performance of various auxiliary equipment has become more and more perfect. In addition, in order to meet the requirements of various tests, researchers have developed various auxiliary test devices. Taking tunnel excavation as an example, the patent with the authorization number "CN215599161U" and the name "A simulation test device for underwater tunnel excavation in a high centrifugal field" discloses a test device for simulating tunnel excavation. The test device includes a model box, a tunnel model tube, a segmented air bag, an air valve and other devices. The device simulates the size and thickness of the tunnel excavation surface by controlling the gas content in the air bag in segments. However, the device has the following main shortcomings: (1) Under high gravity fields, the strength of the airbag is often insufficient and it is more likely to rupture; (2) The sealing of the connection between the airbag and the air valve is also difficult to ensure, and leakage is very likely to occur under high gravity fields, which may lead to test failure; (3) The gas in the airbag will be unevenly distributed under the action of high gravity fields. Taking a circular tunnel as an example, there will be more gas at the bottom and less gas at the top, which makes it difficult to simulate the actual cross-sectional shape of a tunnel.

[0004] Therefore, how to develop a test device that can simulate the entire process of tunnel excavation is an urgent problem to be solved in centrifuge model testing. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention discloses a tunnel excavation device and a test method for centrifugal model test. The present invention uses a driving motor to pull a stainless steel sleeve to simulate stratum loss, realizes segmented excavation of tunnels under high gravity fields, and solves the problem of accurate control of stratum loss rate. To achieve the above-mentioned purpose, the present invention specifically discloses the following technical solutions:

[0006] A tunnel excavation device and test method for centrifugal model test, including a model box, a positioning system, an excavation simulation system and a power system. The model box is a box structure with an opening on the top, including a bottom plate and four side plates. The positioning system is provided with a middle partition assembly, and the middle partition assembly is arranged in the model box to divide the model box into an excavation half area and a monitoring half area. The excavation simulation system includes an organic glass tube and a stainless steel tube, one end of the organic glass tube is sealed and the other end is hollow, the sealed end of the organic glass tube is fixed to the front side plate of the model box, and the organic glass tube is slidably nested in the stainless steel tube. A through hole for the stainless steel tube to pass through is provided in the middle of the middle partition assembly, and a threaded rod is fixed inside the end of the stainless steel tube away from the front side plate. The power system is provided with stainless steel wire, and the threaded rod is connected to the power system through the stainless steel wire transmission.

[0007] Furthermore, the model box is made of aerospace aluminum alloy, and a rectangular hollow area is provided in the middle of the front side plate of the model box. A plexiglass plate is installed in the rectangular hollow area for observing and recording the displacement and deformation of the soil during the test. The front end of the plexiglass tube is sealed and fixed to the plexiglass plate by bolts.

[0008] Furthermore, a groove is provided in the middle of the left and right side plates of the model box, and plug-in protrusions are provided at both ends of the plug-in of the middle partition assembly, and the middle partition assembly is plugged into the groove through the plug-in protrusions.

[0009] Furthermore, the positioning system also includes a fixed threaded rod and a support platform. A fixed threaded rod vertically fixed to the bottom plate of the model box is arranged directly behind the middle partition assembly. The support platform is arranged at the top end of the fixed threaded rod. An arc groove concentric with the through hole is arranged on the top of the support platform.

[0010] Furthermore, the power system includes a driving motor, a guide wheel bracket, a guide wheel, a fixed pulley and a stainless steel wire. The rear side plate of the model box is provided with a reserved hole, the guide wheel bracket is installed on the outer surface of the rear side plate through the reserved hole, the guide wheel is rotatably set on the guide wheel bracket, the driving motor is set on the bottom plate of the model box, the fixed pulley is fixedly installed on the output shaft of the driving motor, the center of the stainless steel pipe, the guide wheel and the fixed pulley are maintained in the same vertical plane, one end of the stainless steel wire is fixedly connected to the threaded rod, and the other end of the stainless steel wire is wrapped around and passed through the guide wheel and is wound in the fixed pulley.

[0011] Furthermore, the reserved holes are three vertically arranged long holes, and the guide wheel bracket is arranged in the long holes on the left and right sides by adjusting bolts, and the installation height of the guide wheel bracket is changed by adjusting the bolts.

[0012] Furthermore, the bottom plate of the model box is provided with a model box fixing hole for fixing the model box on the centrifuge.

[0013] Furthermore, the tops of the left and right side panels of the excavation half of the model box are provided with reserved holes for brackets for installing sensor brackets, and the tops of the left and right side panels of the monitoring half of the model box are provided with installation holes for high-definition cameras for installing high-definition cameras.

[0014] Furthermore, it also includes soil pressure sensors, pore water pressure sensors, inclinometers and tunnel lining sensors, wherein the soil pressure sensors, pore water pressure sensors, inclinometers and tunnel lining sensors are all pre-buried in the soil of the excavation half area, and the strain gauges of the tunnel lining sensors are posted on the surface of the plexiglass tube.

[0015] A test method for tunnel excavation for centrifugal model testing, using the above test device, includes the following steps:

[0016] S1. Determine the tunnel burial depth, select the corresponding middle partition assembly and the corresponding cross-sectional form of the middle partition assembly according to the burial depth, and adjust the support platform and the directional wheel bracket to a matching height;

[0017] S2. The soil is buried in the excavated half area of ​​the model box, and the buried height of the soil is the elevation of the bottom surface of the tunnel;

[0018] S3. Bury the sensors inside the soil. According to the test conditions, bury the soil pressure sensor, pore water pressure sensor and inclinometer inside the soil;

[0019] S4. Install the tunnel lining sensor and stick the strain gauge on the plexiglass tube according to the test conditions;

[0020] S5. Assemble the excavation simulation system, fix the plexiglass tube and the plexiglass plate together with bolts and nuts, nest the plexiglass tube inside the stainless steel tube, and fix the threaded rod to one end of the stainless steel tube;

[0021] S6. Assemble the power system and connect the drive motor and the stainless steel pipe through stainless steel wire;

[0022] S7. Bury the remaining soil at a depth that is appropriate for the test conditions and cover the tunnel excavation system with suitable test soil;

[0023] S8. Install the sensor bracket, and fix the sensor bracket with the laser displacement meter installed above the excavation half area;

[0024] S9. Start the test, hoist the model box to the centrifuge host and fix it with bolts, turn on the centrifuge, turn on the sensor acquisition equipment, turn on the high-definition camera to observe the excavation status, start the drive motor, wait until the excavation reaches the target position, turn off the motor, turn off the centrifuge host, and end the test.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention can simulate the real stress environment of the tunnel by means of the centrifugal force generated by the high-speed rotation of the centrifuge. The device of the present invention can truly restore the stress characteristics of the tunnel lining and the damage form of the excavation surface during tunnel excavation;

[0027] 2. The middle partition assembly of the present invention can be freely assembled and customized to different tunnel cross-sections to simulate the excavation process of a highway tunnel (horseshoe cross-section) and a subway tunnel (circular cross-section). In addition, tunnels with different buried depths can be simulated by changing the position of the first middle partition;

[0028] 3. The driving motor of the present invention is driven by electricity, and the speed of the driving motor can be changed by changing the voltage, thereby achieving different excavation speeds;

[0029] 4. The present invention can simulate different stratum loss rates by changing the thickness of the stainless steel pipe in the excavation system, and explore the influence of the stratum loss rate on tunnel instability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the main structure of the tunnel excavation device of the present invention;

[0031] Figure 2 A top view of the tunnel excavation device of the present invention;

[0032] Figure 3 This is a schematic diagram of the back structure of the tunnel excavation device of the present invention;

[0033] Figure 4 This is a schematic diagram of the support platform structure of the present invention;

[0034] Figure 5 This is a schematic diagram of the plug-in connection of the partition assembly in the present invention;

[0035] Figure 6 This is a schematic diagram of the structure of the first middle partition of the present invention;

[0036] Figure 7 This is a schematic diagram of the structure of the second middle partition of the present invention;

[0037] Figure 8 This is a schematic diagram of the connection between the organic glass tube and the organic glass plate of the present invention;

[0038] Fig. 9 This is a schematic diagram of the installation of the guide wheel bracket of the present invention;

[0039] Fig.10 This is a schematic diagram of the model box of the present invention in the working state of the centrifuge.

[0040] Among them, 1: bolts and nuts; 2: plexiglass plate; 3: model box fixing holes; 4: plexiglass tube; 5: middle partition assembly; 5a: first middle partition; 5b: second middle partition; 6: stainless steel tube; 7: high-definition camera; 8: stainless steel wire; 9: reserved holes; 10: 304 high-strength threaded rod; 11: reserved holes; 12: guide wheel; 13: support platform; 14: fixed pulley; 15: drive motor; 16: guide wheel bracket; 17: fixed threaded rod. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Example 1

[0043] like Figure 1-10 As shown, the present invention provides a tunnel excavation device for centrifugal model testing, including a model box, a positioning system, a power system, a positioning system, and an excavation simulation system.

[0044] The model box in the present invention is composed of high-strength aerospace aluminum alloy. The model box is used to fill the test soil and serve as the basic platform for the power system, positioning system and excavation simulation system, including four side panels and a bottom plate. Four circular holes and a rectangular hole for observation are opened on the front side panel. The organic glass plate 2 is fixed to the rectangular hole of the front side panel by bolts and nuts 1, which is convenient for observing and recording the displacement and deformation of the soil during the test. A model box fixing hole 3 is opened on the bottom plate for fixing the model box on the centrifuge host. The positioning system is provided with a middle partition assembly 5, which is arranged in the model box to separate the model box into an excavation half area and a monitoring half area. The excavation half area is used to bury the test soil, and the monitoring half area is used to monitor the progress of the test. The top of the left and right side panels of the excavation half area is provided with a bracket reserved hole 9 for the installation of the sensor bracket. The top of the left and right side panels of the monitoring half area of ​​the model box is provided with a high-definition camera installation hole for the installation of the high-definition camera 7. In this embodiment, the high-definition camera 7 is fixed on the left side panel of the monitoring half area, and a reserved hole 11 is opened on the rear side panel.

[0045] Specifically, the excavation simulation system includes an organic glass tube 4 and a stainless steel tube 6. The organic glass tube 4 is used to simulate the tunnel lining, and one end of the organic glass tube is sealed and the other end is hollow. The stainless steel tube 6 is used to simulate the stratum loss of the tunnel excavation. The sealed end of the organic glass tube 4 is fixed to the organic glass plate 2 by bolts and nuts 1, and the tube body of the organic glass tube 4 is slidably nested in the stainless steel tube 6. A through hole for the stainless steel tube 6 to pass through is provided in the middle of the middle partition assembly 5. The stainless steel tube 6 is symmetrically provided with mounting holes at one end away from the front side plate. The 304 high-strength threaded rod 10 passes through the mounting hole of the stainless steel tube 6 and is locked and fixed by nuts. The power system is provided with stainless steel wire 8, and the 304 high-strength threaded rod 10 is connected to the power system through the stainless steel wire 8.

[0046] The positioning system also includes a fixed threaded rod 17 and a support platform 13. A fixed threaded rod 17 vertically fixed to the bottom plate of the model box is arranged directly behind the middle partition assembly 5. The support platform 13 is arranged at the top end of the fixed threaded rod, and an arc groove concentric with the through hole is arranged on the top of the support platform 13.

[0047] The power system includes a driving motor 15, a guide wheel bracket 16, a guide wheel 12, a fixed pulley 14 and a stainless steel wire 8. The guide wheel bracket 16 is installed on the outer surface of the rear side plate through the reserved hole 9. The guide wheel 12 is rotatably set on the guide wheel bracket 16, wherein the center of the stainless steel pipe 6, the center of the middle partition assembly 5 and the center of the fixed pulley 14 need to maintain the same horizontal line. The driving motor 15 is set on the bottom plate of the model box, and the fixed pulley 14 is fixedly installed on the output shaft of the driving motor 15. The center of the stainless steel pipe 6, the guide wheel 12 and the fixed pulley 14 are maintained in the same vertical plane. One end of the stainless steel wire 8 is fixedly connected to the 304 high-strength threaded rod 10, and the other end of the stainless steel wire 8 is wrapped around and passes through the guide wheel 12 and is wound in the fixed pulley 14. The power system is powered by the driving motor 15 to drag the stainless steel pipe 6 to move.

[0048] As a preferred embodiment of the present invention, a groove is provided in the middle of the front and rear side panels, plug-in protrusions are provided on both sides of the middle partition assembly 5, and the middle partition assembly 5 and the left and right side panels are combined through a "concave and convex" mortise and tenon structure.

[0049] Furthermore, the middle partition assembly 5 includes a first middle partition 5a and a second middle partition 5b. The through hole for the stainless steel pipe 6 to pass through is set on the first middle partition 5a, and different hole positions can be opened according to the tunnel section form. The second middle partition 5b is arranged at the upper and lower ends of the first middle partition 5a. By reasonably assembling the middle partition assembly 5, the height adjustment of the through hole can be achieved.

[0050] As a preferred embodiment of the present invention, the reserved holes 11 are three vertically arranged long holes, the guide wheel bracket 16 is arranged in the long holes on the left and right sides by adjusting bolts, and the installation height of the guide wheel bracket 16 is changed by adjusting bolts, the stainless steel wire 8 is passed through the middle long hole, and the guide wheel bracket 16 can flexibly adjust the appropriate height according to the reserved space of the reserved holes 11.

[0051] As a preferred embodiment of the present invention, it also includes an earth pressure sensor, a pore water pressure sensor, an inclinometer and a tunnel lining sensor. The earth pressure sensor, the pore water pressure sensor, the inclinometer and the tunnel lining sensor are all pre-buried in the soil of the excavation half area, and the strain gauge of the tunnel lining sensor is posted on the surface of the organic glass tube 4.

[0052] Example 2

[0053] This embodiment discloses a test method for tunnel excavation using the test device in the above example to simulate the centrifugal model test, comprising the following steps:

[0054] S1. Determine the buried depth of the tunnel, select the appropriate middle diaphragm assembly 5 and the corresponding cross-sectional form of the middle diaphragm assembly 5 according to the buried depth, assemble the middle diaphragm assembly 5 to a suitable height, and adjust the support platform 13 and the directional wheel bracket 16 to a suitable height;

[0055] S2. Bury the soil in the excavated half of the model box, and the buried height of the soil is the elevation of the bottom surface of the tunnel. Bury the sensors inside the soil. According to the test conditions, bury the soil pressure sensors, pore water pressure sensors, inclinometers and other sensing equipment that may be used inside the soil;

[0056] S3, install the tunnel lining sensor, and stick the strain gauge on the organic glass tube 4 according to the test conditions;

[0057] S4, assemble the excavation simulation system, fix the plexiglass tube 4 and the plexiglass plate 2 together by bolts and nuts 1, nest the plexiglass tube 4 inside the stainless steel tube 6, and pass the 304 high-strength threaded rod 10 through the mounting hole of the stainless steel tube 6, and lock and fix it with nuts;

[0058] S5, assemble the power system, install the fixed pulley 14 on the output shaft of the driving motor 15, and connect the fixed pulley 14 and the stainless steel pipe 6 through the stainless steel wire 8 through the guide wheel 12, and ensure that the stainless steel pipe 6 and the guide wheel 12 are on the same horizontal line;

[0059] S6. Bury the remaining soil at a depth that is appropriate for the test. Bury the remaining soil according to the test conditions and cover the tunnel excavation system with suitable test soil.

[0060] S7, installing the sensor bracket, installing the sensor bracket with the laser displacement meter on the model box through the bracket reserved hole 9, and fixing it above the excavation half area;

[0061] S8, start the test, hoist the model box to the centrifuge host (such as Fig.10 As shown), turn on the centrifuge, turn on the sensor acquisition equipment, turn on the high-definition camera to observe the excavation status, start the drive motor 15, wait until the excavation reaches the target position, turn off the drive motor 15, turn off the centrifuge host, and end the test.

[0062] The key to the success of this test device is whether the drive motor 15 can provide a sufficiently large pulling force. The force on the tunnel during the pulling process is mainly the friction caused by the surrounding soil. Assume that the tunnel diameter is 10cm. The tunnel depth is 15cm, the tunnel length is 30cm, and the surrounding soil is sand (density is 1.8×10 3 kg / m 3 ), the similarity ratio is 50. Then the earth pressure above the tunnel is:

[0063] F=mg=pvg=1.8×10 3 ×0.1×0.15×0.3×10=81kN (1) The friction force is:

[0064] f=μF=0.1×81=8.1kN (2)Then the friction force under the action of 50 times the centrifugal force is:

[0065] f 50 =N×f=50×8.1=405kN(3)Simplify the circular tunnel into a square tunnel, then the friction force f on the four surfaces is 总 for:

[0066] f 总 =4×f 50 =4×405=1620kN(4)

[0067] Take Weisheng 75ZY, a drive motor available on the market, as an example. The motor torque M is 610kg / cm, which is approximately equal to 6100kN / cm. The motor shaft radius is 1.5cm, so the torque N that the motor can provide is 4066kN, N>f 总 , it can be seen that in theoretical terms, the drive motor can pull the stainless steel pipe.

[0068] In fact, considering factors such as the passive earth pressure coefficient and the circular cross-section of the tunnel, the friction force on the tunnel should be completely smaller than this value. In addition, in order to ensure that the tunnel model is pulled out smoothly, Vaseline will be applied to the outside of the steel cylinder to reduce the friction coefficient.

[0069] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A tunnel excavation device for centrifugal model testing, characterized in that: It includes a model box, a positioning system, an excavation simulation system and a power system. The model box is a box structure with an opening on the top, including a bottom plate and four side plates. The positioning system is provided with a middle partition assembly, and the middle partition assembly is arranged in the model box to divide the model box into an excavation half area and a monitoring half area. The excavation simulation system includes an organic glass tube and a stainless steel tube. One end of the organic glass tube is sealed and the other end is hollow. The sealed end of the organic glass tube is fixed to the front side plate of the model box, and the organic glass tube is slidably nested in the stainless steel tube. A through hole for the stainless steel tube to pass through is provided in the middle of the middle partition assembly, and a threaded rod is fixed inside the end of the stainless steel tube away from the front side plate. The power system is provided with a stainless steel wire, and the threaded rod is connected to the power system through the stainless steel wire transmission.

2. A tunnel excavation device for centrifugal model testing according to claim 1, characterized in that: The model box is made of aerospace aluminum alloy. A rectangular hollow area is provided in the middle of the front side plate of the model box. A plexiglass plate is installed in the rectangular hollow area for observing and recording the displacement and deformation of the soil during the test. The front end of the plexiglass tube is sealed and fixed to the plexiglass plate by bolts.

3. A tunnel excavation device for centrifugal model testing according to claim 1, characterized in that: A groove is arranged in the middle of the left and right side plates of the model box, and plug-in protrusions are arranged at both ends of the plug-in middle partition assembly, and the middle partition assembly is plugged into the groove through the plug-in protrusions.

4. A tunnel excavation device for centrifugal model testing according to claim 1, characterized in that: The positioning system also includes a fixed threaded rod and a support platform. A fixed threaded rod vertically fixed to the bottom plate of the model box is arranged directly behind the middle partition assembly. The support platform is arranged at the top end of the fixed threaded rod. The top of the support platform is provided with an arc groove concentric with the through hole.

5. The tunnel excavation device for centrifugal model testing according to claim 1, characterized in that: The power system includes a driving motor, a guide wheel bracket, a guide wheel, a fixed pulley and a stainless steel wire. The rear side plate of the model box is provided with a reserved hole. The guide wheel bracket is installed on the outer surface of the rear side plate through the reserved hole. The guide wheel is rotatably arranged on the guide wheel bracket. The driving motor is arranged on the bottom plate of the model box. The fixed pulley is fixedly installed on the output shaft of the driving motor. The center of the stainless steel pipe, the guide wheel and the fixed pulley are maintained in the same vertical plane. One end of the stainless steel wire is fixedly connected to the threaded rod, and the other end of the stainless steel wire is wrapped around and passes through the guide wheel and is wound in the fixed pulley.

6. A tunnel excavation device for centrifugal model testing according to claim 5, characterized in that: The reserved holes are three vertically arranged long holes, and the guide wheel bracket is arranged in the long holes on the left and right sides by adjusting bolts, and the installation height of the guide wheel bracket is changed by adjusting the bolts.

7. A tunnel excavation device for centrifugal model testing according to claim 1, characterized in that: The bottom plate of the model box is provided with a model box fixing hole for fixing the model box on the centrifuge.

8. The tunnel excavation device for centrifugal model testing according to claim 1, characterized in that: The top of the left and right side plates of the excavation half area of ​​the model box are provided with bracket reserved holes for installing the sensor bracket, and the top of the left and right side plates of the monitoring half area of ​​the model box are provided with high-definition camera installation holes for installing the high-definition camera.

9. A tunnel excavation device for centrifugal model testing according to claim 1, characterized in that: It also includes soil pressure sensors, pore water pressure sensors, inclinometers and tunnel lining sensors. The soil pressure sensors, pore water pressure sensors, inclinometers and tunnel lining sensors are all pre-buried in the soil of the excavation half area, and the strain gauges of the tunnel lining sensors are posted on the surface of the organic glass tube.

10. A testing method using the tunnel excavation device for centrifugal model testing according to any one of claims 1 to 9, characterized in that: The steps are as follows: S1. Determine the tunnel burial depth, select the corresponding middle partition assembly and the corresponding cross-sectional form of the middle partition assembly according to the burial depth, and adjust the support platform and the directional wheel bracket to a matching height; S2. The soil is buried in the excavated half area of ​​the model box, and the buried height of the soil is the elevation of the bottom surface of the tunnel; S3. Bury the sensors inside the soil. According to the test conditions, bury the soil pressure sensor, pore water pressure sensor and inclinometer inside the soil; S4. Install the tunnel lining sensor and stick the strain gauge on the plexiglass tube according to the test conditions; S5. Assemble the excavation simulation system, fix the plexiglass tube and the plexiglass plate together with bolts and nuts, nest the plexiglass tube inside the stainless steel tube, and fix the threaded rod to one end of the stainless steel tube; S6. Assemble the power system and connect the drive motor and the stainless steel pipe through stainless steel wire; S7. Bury the remaining soil at a depth that is appropriate for the test conditions and cover the tunnel excavation system with suitable test soil; S8. Install the sensor bracket, and fix the sensor bracket with the laser displacement meter installed above the excavation half area; S9. Start the test, hoist the model box to the centrifuge host and fix it with bolts, turn on the centrifuge, turn on the sensor acquisition equipment, turn on the high-definition camera to observe the excavation status, start the drive motor, wait until the excavation reaches the target position, turn off the motor, turn off the centrifuge host, and end the test.

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