A test device and method for simulating deep tunnel excavation

Abstract

The present invention discloses a test device for simulating deep-buried tunnel excavation, which belongs to the field of deep-buried tunnels and underground engineering technology. The device includes a model box, a high-ground stress loading system, a tunnel excavation simulation system, and a DIC and sensor monitoring system. The present invention can realize the simulation of deep-buried shield tunnel excavation. The mechanical expansion and contraction device adopts a rigid design of an oil cylinder driving the main shaft to extend and retract. The simulation of the tunnel excavation process is more accurate, the test operation is simple, and its expansion and contraction parameters are simple and controllable, effectively restoring the working conditions of stratum contraction and compensatory grouting during deep-buried shield excavation. After the simulated tunnel excavation is completed, the degree of stratum deformation recorded by the DIC monitoring device and the stress change of the foundation soil monitored by the sensor can be used to analyze the degree of disturbance of the foundation soil caused by the tunnel excavation, thereby realizing the verification of the soil arch effect of the tunnel excavation.

Description

Technical Field

[0001] The invention belongs to the technical field of deep-buried tunnels and underground engineering, and particularly relates to a test device and method for simulating deep-buried tunnel excavation. Background Art

[0002] Deep tunnel construction is an important means of alleviating urban traffic congestion and improving the urban environment. The deep underground environment is characterized by high water pressure and high stress, making tunnel construction in this environment difficult and risky. Currently, the static design of deep tunnel structures still uses the same design methods for shallow tunnel structures. This raises two major issues: First, the basic theories and calculation methods for shallow tunnel structure design are based on the ground response patterns caused by shallow tunnel excavation, and their applicability to deep tunnels is unknown. Second, the impact mechanism of deep tunnel construction on the surrounding environment is unclear, making it difficult to accurately predict the impact of deep excavation disturbances on the surrounding environment, posing a threat to the safety of adjacent underground structures.

[0003] Physical model testing is an effective means of investigating the soil arching effect during deep tunnel excavation and the interaction mechanisms between tunnels and soil. Existing shield tunnel excavation experimental devices often simulate shallow tunnel excavation by pumping liquid and air from the excavation area. However, these methods cannot effectively simulate the uniform ground contraction caused by tunnel overexcavation. Furthermore, they cannot reproduce the actual ground stress levels or determine the internal force variations in the tunnel. Furthermore, they cannot replicate the effects of seepage on the stress and strain of the ground surrounding the tunnel and the soil arching effect in actual projects.

[0004] Therefore, in order to address the problems faced by deep-buried shield tunnels with "high water pressure and high ground stress" during design and construction, there is an urgent need for a device that can effectively simulate the uniform shrinkage of the stratum, highly restore the true stratum stress level, and restore the actual stratum seepage conditions, so as to provide support for the calculation method of stratum stress and deformation caused by deep-buried tunnel excavation and the structural load design method. Summary of the Invention

[0005] The purpose of the embodiments of the present invention is to provide a simulated deep-buried tunnel excavation test device and method, which can overcome the defects of existing tunnel excavation simulation devices that cannot achieve excavation and seepage field simulation under high water pressure and high stress conditions, thereby solving at least one technical problem involved in the background technology.

[0006] In order to solve the above-mentioned technical problems, the present invention is achieved as follows:

[0007] An embodiment of the present invention provides a simulated deep tunnel excavation test device, comprising a model box, a high ground stress loading system, a tunnel excavation simulation system, a DIC and sensor monitoring system, wherein:

[0008] The model box includes a box body, a model box top cover arranged on the top of the box body, and a loading member configured on the model box top cover for pressurizing the soil in the model box;

[0009] The high ground stress loading system includes a base platform arranged at the bottom of the model box, a portal frame arranged on the base platform, a hydraulic servo cylinder arranged on the portal frame, and an actuator arranged below the hydraulic servo cylinder and used to drive the loading component;

[0010] The tunnel excavation simulation system includes a mechanical expansion and contraction device with a front end inserted into the box body and capable of generating expansion and contraction deformation, a seepage pipe network sleeved on the mechanical expansion and contraction device, a telescopic drive cylinder connected to the rear end of the mechanical expansion and contraction device, and a displacement meter provided at the rear end of the mechanical expansion and contraction device;

[0011] The DIC and sensor monitoring system includes a sensor disposed inside the box, a DIC monitoring device disposed outside the box for visually monitoring the interior of the box, and a data acquisition and processing system connected to the sensor and the DIC monitoring device.

[0012] Optionally, a transparent observation window is provided on the front wall of the box, and the DIC monitoring device is arranged facing the transparent observation window.

[0013] Optionally, the loading component includes a guide rod assembled in the center of the top cover of the model box, a loading push plate arranged at the bottom of the guide rod and located in the box body, and a rubber cover plate arranged at the bottom of the loading push plate.

[0014] Optionally, a dust ring, an axial seal, a guide belt, an oil storage groove and a radial seal are provided between the guide rod and the top cover of the model box.

[0015] Optionally, a water inlet and an air inlet are provided on the top cover of the model box; a water outlet is provided at the bottom of the box body, and a circular hole for installing the mechanical expansion and contraction device is provided on the rear wall of the box body.

[0016] Optionally, the mechanical expansion and contraction device includes a telescopic main shaft, a lock core linked to the telescopic main shaft, and fins connected to the lock core to produce expansion or contraction.

[0017] Optionally, the model box also includes a sensor terminal fixed to the upper middle part of the front wall of the box body through a flange, the sensor terminal includes a column body and two forked column heads located at the top of the column body, each of the column heads is provided with a terminal block that can be connected to multiple sensor data lines, and the column body is provided with an air inlet channel for controlling the water level inside the box to be lower than the height of the terminal block.

[0018] Optionally, the model box also includes a liftable roller arranged on the base platform to enable the box body to be raised and lowered, and the liftable roller includes a slider connected to the box body, a roller rotatably connected to the bottom of the slider, and a screw nut arranged on the slider for adjusting the height of the slider.

[0019] Optionally, the seepage pipe network includes eight longitudinal pipes arranged in the circumferential direction of the mechanical expansion and contraction device, three annular pipes for connecting the eight longitudinal pipes, and a main drainage pipe connecting the longitudinal pipes and the annular pipes, the main drainage pipe is connected to the water outlet, and the seepage pipe network is provided with 23 water inlets, and replaceable fine-pore screens are installed on the water inlets.

[0020] The present invention also provides a method for using the simulated deep tunnel excavation test device, comprising the following steps:

[0021] Step S1, preparing sand and calibrating the sensor;

[0022] Step S2: Install the portal frame in the middle of the front section of the base platform, then install the hydraulic servo cylinder at the top center axis of the portal frame, and debug the actuator below the hydraulic servo cylinder;

[0023] Step S3, completing sensor wiring through the sensor terminals on the upper front side of the box, and then setting up the DIC monitoring device at an appropriate observation position in front of the transparent observation window;

[0024] Step S4: Push the model box to the rear end of the base platform, insert the mechanical expansion and contraction device into the box through the circular hole in the rear wall of the box, and connect the tail end of the telescopic main shaft of the mechanical expansion and contraction device to the external telescopic drive cylinder. During the insertion process, wrap the seepage pipe network around the surface of the mechanical expansion and contraction device, connect the drainage main pipe at the bottom of the seepage pipe network to the drainage port of the box, and install a flow meter and flow valve on the external drainage main pipe. Some sensors can be installed on the surface of the mechanical expansion and contraction device according to experimental requirements.

[0025] Step S5: Fill the model box with the prepared sand and soil in layers according to the calculated amount, lay the sensors simultaneously, and lay the rubber cover on top of the soil;

[0026] Step S6: Install the loading push plate, guide rod and model box cover on the top of the model box, adjust the lifting roller at the bottom of the model box, push the model box to the appropriate position, and then connect the guide rod and the actuator;

[0027] Step S7: Connect the water source to the water inlet of the model box top cover and adjust the soil seepage flow rate using a flow meter and a flow valve. Connect the air compressor to the pressure stabilizing device and then connect the air supply channel to the air inlet to adjust the air pressure in the box to a preset value. Adjust the control mode of the servo control system to the "force-displacement" mode, set the pressurization rate according to the test requirements, and control the actuator to apply the load to the loading push plate to the target value.

[0028] In step S8, the telescopic drive cylinder is switched to the reverse gear position, and the displacement meter fixed at the end of the telescopic main shaft is read to control the telescopic amount of the telescopic main shaft to a preset value, thereby achieving the target value of the formation loss rate to realize shield tunnel excavation; during the simulated excavation process of the mechanical expansion and contraction device, data is collected through the DIC monitoring and sensor monitoring system.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. This invention can simulate deep-buried shield tunnel excavation. The mechanical expansion and contraction device uses a rigid design with a cylinder-driven main shaft extension and retraction. This allows for higher-precision simulation of the tunnel excavation process, simplifies test operation, and allows for simple and controllable expansion and contraction parameters, effectively recreating the conditions of ground contraction and compensatory grouting during deep-buried shield tunneling.

[0031] 2. This invention utilizes a seepage pipe network mounted on the surface of a mechanical expansion and contraction device, combined with air pressure regulation, to restore the seepage field in the surrounding strata during tunnel excavation. The seepage pipe network is designed with a suitable anti-blocking screen structure, and the seepage flow rate can be precisely adjusted using a flow valve and flow meter.

[0032] 3. After simulated tunnel excavation is completed, this method can analyze the degree of disturbance to the foundation soil caused by tunnel excavation based on the ground deformation recorded by the DIC monitoring device and the stress changes in the foundation soil monitored by the sensor, thereby verifying the soil arching effect caused by tunnel excavation.

[0033] 4. The high-in-situ stress loading system of this invention can simultaneously apply 1 MPa of vertical earth pressure and 1 MPa of air pressure. The loading system features both displacement and force control modes, with precisely adjustable loading speeds. The actuators are equipped with built-in magnetostrictive displacement sensors that accurately measure displacement changes, as well as detachable spoke-type load sensors that precisely measure the applied load, effectively reproducing the in-situ stress surrounding deep tunnels. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0035] Figure 1 A schematic diagram of the overall structure of the simulated deep tunnel excavation test device provided by the present invention;

[0036] Figure 2 A schematic structural diagram of the liftable roller provided by the present invention;

[0037] Figure 3 A schematic diagram of the sealing structure of the model box top cover and the guide rod provided by the present invention;

[0038] Figure 4 A schematic structural diagram of a circular hole provided by the present invention;

[0039] Figure 5 A schematic structural diagram of the transparent observation window provided by the present invention;

[0040] Figure 6 A schematic structural diagram of the sensor terminal provided by the present invention;

[0041] Figure 7 A schematic diagram of the longitudinal section structure of the mechanical expansion and contraction device provided by the present invention;

[0042] Figure 8 A schematic cross-sectional view of the mechanical expansion and contraction device provided by the present invention;

[0043] Figure 9 A schematic diagram of the installation of the seepage pipe network provided by the present invention;

[0044] Figure 10 for Figure 9 Schematic diagram of the enlarged structure at A in the middle;

[0045] Figure 11 This is a corresponding relationship diagram between the telescopic main shaft displacement and the formation loss rate provided by the present invention. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0047] The terms "first," "second," and the like in the specification and claims of the present invention are used to distinguish similar objects, and are not used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present invention can be implemented in an order other than that illustrated or described herein, and that the objects distinguished by "first," "second," and the like are generally of the same type, and do not limit the number of objects. For example, the first object can be one or more. In addition, the term "and / or" in the specification and claims refers to at least one of the connected objects, and the character " / " generally indicates that the objects connected are in an "or" relationship.

[0048] An embodiment of the present invention provides a test device for simulating deep tunnel excavation, comprising a model box, a high ground stress loading system, a tunnel excavation simulation system, and a DIC and sensor monitoring system.

[0049] See Figure 1 As shown, the model box includes a box body 7, a model box top cover 19 arranged on the top of the box body 7, and a loading component configured on the model box top cover 19 for pressurizing the soil in the model box.

[0050] The high ground stress loading system includes a base platform 1 arranged at the bottom of the model box, a portal frame 2 set on the base platform 1, a hydraulic servo cylinder 3 set on the portal frame 2, and an actuator 4 set below the hydraulic servo cylinder 3 and used to drive the loading component.

[0051] Recombination Figure 2 As shown, the model box also includes a liftable roller 6 set on the base platform 1 to enable the box body 7 to be raised and lowered. The liftable roller 6 has two adjustment modes: raising and lowering. It includes a slider 602 connected to the box body 7, a roller 603 rotatably connected to the bottom of the slider 602, and a screw nut 601 set at the center axis of the slider 602 for adjusting the height of the slider 602. With the above structure, due to the limited height of the portal frame 2, it is impossible to open the model box top cover 19 in the portal frame area to perform operations inside the box. Experimental preparation work needs to be carried out in the rear half of the base platform 1. The liftable roller 6 facilitates the preparation of foundation soil and the installation of the device.

[0052] The loading component includes a guide rod 21 assembled in the center of the model box top cover 19, a loading push plate 20 arranged at the bottom of the guide rod 21 and located in the box body 7, and a rubber cover 18 arranged at the bottom of the loading push plate 20.

[0053] Recombination Figure 3As shown, the guide rod 21 is installed at the central axis position of the box top cover 19, and a dust ring 2101, an axial seal 2102, a guide belt 2103, an oil storage groove 2104 and a radial seal 2105 are provided between the rod body and the model box top cover 19. In this way, it can be ensured that the load applied by the actuator 4 is loaded in the vertical direction, while avoiding sandblasting of the soil to the gap of the guide rod 21, eliminating the possibility of water rusting the guide rod 21, extending the life of the loading system, and ensuring the safety of the device structure.

[0054] The model box top cover 19 is provided with a water inlet 22 and an air inlet 24; the bottom of the box body 7 is provided with a water outlet 12. Figure 4 As shown, the rear wall of the box body is provided with a circular hole 29, and the circular hole 29 is equipped with a hole plug 2901 with a radial sealing ring 2903 and an axial sealing ring 2902.

[0055] Recombination Figure 5 As shown, a transparent observation window 28 is provided on the front wall of the box body 7 . The transparent observation window 28 includes a high-transmittance POM plate 35 and a radial seal 34 between the box body 7 and the transparent observation window 28 .

[0056] Recombination Figure 6 As shown, the model box also includes a sensor terminal 8 fixed to the upper middle part of the front wall of the box body 7 through a flange 803. The sensor terminal 8 includes a column body and two forked column heads located at the top of the column body. Each of the column heads is provided with a terminal board 801 that can be connected to multiple sensor data lines 802. The column body is provided with an air inlet channel 31 for controlling the water level inside the box body 7 to be lower than the height of the terminal board 801.

[0057] The tunnel excavation simulation system includes a mechanical expansion and contraction device 9 whose front end is inserted into the interior of the box 7 and can produce expansion and contraction deformation, a seepage pipe network 10 mounted on the mechanical expansion and contraction device 9, a telescopic drive cylinder 15 connected to the tail end of the mechanical expansion and contraction device 9, and a displacement meter 16 arranged at the tail end of the mechanical expansion and contraction device 9.

[0058] Recombination Figure 7 and Figure 8 As shown, the mechanical expansion and contraction device 9 includes a telescopic main shaft 901, a lock core 903 linked to the telescopic main shaft 901, and fins 902 connected to the lock core 903 to generate expansion or contraction.

[0059] By adopting the above structure, the mechanical expansion and contraction device 9 can realize tunnel excavation. Through the telescopic drive cylinder 15 outside the box body 7 and the displacement meter 16 at the rear end of the telescopic main shaft 901, the deformation of the mechanical expansion and contraction device 9 can be accurately controlled at the same time, and the excavation degree can be restored with high precision.

[0060] Recombination Figure 9 and Figure 10 As shown, the seepage pipe network 10 includes eight longitudinal pipes 101 arranged in the circumferential direction of the mechanical expansion and contraction device, three annular pipes 102 for connecting the eight longitudinal pipes 101, and a drainage main pipe 103 connecting the longitudinal pipes 101 and the annular pipes 102. The drainage main pipe 103 is connected to the water outlet 12. The seepage pipe network is provided with 23 water inlets, and a replaceable fine-pore screen 11 is installed on the water inlet.

[0061] By installing replaceable fine-mesh screens 11 at the water inlet of the seepage pipe network 10, with eight screens evenly distributed across each annular pipe 102, the fine-mesh screens effectively address pipe blockage issues, as ground seepage can cause soil particles to migrate. The water inlet drives the fine-mesh screens to rotate 360°, directing water in the soil along the desired seepage direction. This allows for simple control of the total drainage flow rate, restoring the seepage field around deep shield tunnels.

[0062] At the bottom of the seepage pipe network 10 is a main drainage pipe 103, which flows from the water outlet 12 of the box body 7 to the outside of the box body 7. A flow meter 13 and a flow valve 14 are installed on the main drainage pipe 103. The flow meter 13 is used to measure the total drainage flow rate in the seepage field in real time. If the flow rate does not reach the set value, the flow rate is adjusted through the flow valve 14 on the pipe section.

[0063] The seepage pipe network 10 can be used in conjunction with the mechanical expansion and contraction device 9. A water source and a pressurized air source are introduced into the top of the box 7. When the actuator 4 is vertically loaded, the flow rate is adjusted by controlling the flow valve 14 to achieve the restoration of the seepage field during the excavation of the deep-buried shield tunnel, thereby exploring the influence mechanism of stratum seepage on the soil arch effect of tunnel excavation.

[0064] The DIC and sensor monitoring system includes a sensor 17 disposed inside the box 7, a DIC monitoring device 27 disposed outside the box 7 and facing the transparent observation window 28 for visually monitoring the interior of the box 7, and a data acquisition and processing system 33 connected to the sensor 17 and the DIC monitoring device 27.

[0065] Specifically, the data line of the sensor 17 is divided into two sections. The first section is connected to the inside of the sensor terminal 8 from the box 7, and the second section extends from the sensor terminal 8 to the data acquisition and processing system 33; the DIC monitoring device 27 is arranged at a certain distance from the transparent observation window 28.

[0066] By adopting the above structure, the data line of the sensor 17 can be integrated into the terminal board 801 of the sensor terminal 8, avoiding the confusion of the wiring inside the box 7, affecting the operation of the mechanical expansion and contraction device 9, and interfering with the restoration of the soil stress state.

[0067] Please combine Figure 11 As shown, the present invention also provides a method for using the simulated deep tunnel excavation test device as described above, comprising the following steps:

[0068] Step S1, prepare sand and calibrate the sensor 17;

[0069] Specifically, sand is prepared by the sand rain method, and clay is prepared by the remolded soil preparation device; the sensor 17 is calibrated by the calibration tank and the data acquisition system.

[0070] Step S2: Install the portal frame 2 in the middle of the front section of the base platform 1, then install the hydraulic servo cylinder 3 at the top center axis of the portal frame 2, and debug the actuator 4 below the hydraulic servo cylinder 3 through the servo control system 5;

[0071] It should be noted that after the actuator 4 is installed, it needs to be adjusted to a minimum displacement state to facilitate its connection with the guide rod 21 .

[0072] Step S3: Connect the sensor 17 via the sensor terminals 8 on the upper front side of the box, then install the DIC monitoring device 27 at an appropriate observation position in front of the transparent observation window 28, and complete the debugging of all monitoring instruments using the DIC and sensor monitoring system 33;

[0073] Step S4: Push the model box to the rear end of the base platform 1, insert the mechanical expansion and contraction device 9 into the box body 7 through the circular hole 29 on the rear wall of the box body 7, and connect the tail end of the telescopic main shaft 901 of the mechanical expansion and contraction device 9 to the external telescopic drive cylinder 15. During the insertion process, the seepage pipe network 10 is wrapped around the surface of the mechanical expansion and contraction device 9, and the drainage main pipe 103 at the bottom of the seepage pipe network 10 is connected to the drainage port 12 of the box body 7. The external drainage main pipe 103 is installed with a flow meter 13 and a flow valve 14. Some sensors 17 can be installed on the surface of the mechanical expansion and contraction device 9 according to experimental requirements.

[0074] It should be noted that before the mechanical expansion and contraction device 9 is inserted into the circular hole 29 , silicone grease needs to be evenly applied to the inner wall of the hole.

[0075] Step S5: Fill the model box with the prepared sand in layers according to the calculated amount, simultaneously lay the sensor 17, and lay the rubber cover 18 on top of the soil;

[0076] It should be noted that before filling the soil into the model box in layers, a geotextile needs to be laid at the bottom of the box to prevent fine particles of soil from clogging the drainage port 12 of the box 7 .

[0077] Step S6: Install the loading push plate 20, the guide rod 21 and the model box cover 19 on the top of the model box. Adjust the liftable roller 6 at the bottom of the model box to push the model box to the appropriate position and then connect the guide rod 21 to the actuator 4.

[0078] It should be noted that when sealing the box body 7, an appropriate amount of sealing silicone grease may be applied to the sealing ring at the joint between the top of the box body 7 and the top cover 19 of the model box according to the relevant requirements of the test air tightness.

[0079] Step S7: Connect the water source 23 to the water inlet 22 of the model box top cover, and adjust the soil seepage flow rate through the flow meter 13 and the flow valve 14; connect the air compressor 26 to the pressure stabilizing device 25, and then connect the air supply channel to the air inlet 24 to adjust the air pressure in the box to a preset value; adjust the control mode of the servo control system 5 to the "force-displacement" mode, set the pressurization rate according to the test requirements, and control the actuator 4 to apply the load to the loading push plate 20 to the target value;

[0080] It should be noted that the telescopic drive cylinder 15 has three gears: forward, reverse, and neutral. When in the reverse gear, the telescopic main shaft 901 of the mechanical expansion and contraction device 9 moves toward the exterior of the housing 7, and in conjunction with the lock cylinder 903, the internal fins 902 contract, reducing the device's outer diameter. When in the forward gear, the telescopic main shaft 901 of the mechanical expansion and contraction device 9 moves toward the interior of the housing 7, and in conjunction with the lock cylinder 903, the internal fins 902 expand, increasing the device's outer diameter.

[0081] In step S8, the telescopic drive cylinder 15 is switched to the reverse gear position, and the displacement meter 16 fixed at the end of the telescopic main shaft 901 is read to control the telescopic amount of the telescopic main shaft 901 to a preset value, thereby achieving the target value of the formation loss rate to realize shield tunnel excavation; during the simulated excavation process of the mechanical expansion and contraction device 9, the DIC monitoring and sensor monitoring system 33 collects data, and thus the corresponding relationship between the displacement of the telescopic main shaft 901 and the formation loss rate can be obtained. For details, see Figure 11 As shown;

[0082] Step S9: After adjusting the loading force of the servo control system 5 to zero, the device is disassembled from top to bottom, and the box is cleaned accordingly to prepare for the next round of testing.

[0083] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0084] Furthermore, it should be noted that the scope of the methods and systems of the present invention is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in reverse order, depending on the functions involved. For example, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Furthermore, features described with reference to certain examples may be combined in other examples.

[0085] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A test device for simulating deep tunnel excavation, characterized in that: It includes a model box, a high ground stress loading system, a tunnel excavation simulation system, a DIC and sensor monitoring system, including: The model box includes a box body, a model box top cover arranged on the top of the box body, and a loading member configured on the model box top cover for pressurizing the soil in the model box; The high ground stress loading system includes a base platform arranged at the bottom of the model box, a portal frame arranged on the base platform, a hydraulic servo cylinder arranged on the portal frame, and an actuator arranged below the hydraulic servo cylinder and used to drive the loading component; The tunnel excavation simulation system includes a mechanical expansion and contraction device with a front end inserted into the box body and capable of generating expansion and contraction deformation, a seepage pipe network sleeved on the mechanical expansion and contraction device, a telescopic drive cylinder connected to the rear end of the mechanical expansion and contraction device, and a displacement meter provided at the rear end of the mechanical expansion and contraction device; The DIC and sensor monitoring system includes a sensor disposed inside the box, a DIC monitoring device disposed outside the box for visually monitoring the interior of the box, and a data acquisition and processing system connected to the sensor and the DIC monitoring device.

2. The simulated deep tunnel excavation test device according to claim 1, characterized in that: A transparent observation window is provided on the front wall of the box body, and the DIC monitoring device is arranged facing the transparent observation window.

3. The simulated deep tunnel excavation test device according to claim 1, characterized in that: The loading component includes a guide rod assembled at the center of the top cover of the model box, a loading push plate arranged at the bottom of the guide rod and located in the box body, and a rubber cover plate arranged at the bottom of the loading push plate.

4. The simulated deep tunnel excavation test device according to claim 3, characterized in that: A dust ring, an axial seal, a guide belt, an oil storage groove and a radial seal are provided between the guide rod and the top cover of the model box.

5. The simulated deep tunnel excavation test device according to claim 1 or 2, characterized in that: The top cover of the model box is provided with a water inlet and an air inlet; the bottom of the box body is provided with a water outlet, and the rear wall of the box body is provided with a circular hole for installing the mechanical expansion and contraction device.

6. The simulated deep tunnel excavation test device according to claim 1, characterized in that: The mechanical expansion and contraction device includes a telescopic main shaft, a lock core linked to the telescopic main shaft, and fins connected to the lock core to generate expansion or contraction.

7. The simulated deep tunnel excavation test device according to claim 1, characterized in that: The model box also includes a sensor terminal fixed to the upper middle part of the front wall of the box body through a flange. The sensor terminal includes a column body and two forked column heads located at the top of the column body. Each of the column heads is provided with a terminal block that can be connected to multiple sensor data lines. The column body is provided with an air intake channel for controlling the water level inside the box to be lower than the height of the terminal block.

8. The simulated deep tunnel excavation test device according to claim 1, characterized in that: The model box also includes a liftable roller arranged on the base platform to enable the box body to be raised and lowered. The liftable roller includes a slider connected to the box body, a roller rotatably connected to the bottom of the slider, and a screw nut arranged on the slider for adjusting the height of the slider.

9. The simulated deep tunnel excavation test device according to claim 5, characterized in that: The seepage pipe network includes eight longitudinal pipes arranged in the circumferential direction of the mechanical expansion and contraction device, three annular pipes for connecting the eight longitudinal pipes, and a main drainage pipe connecting the longitudinal pipes and the annular pipes. The main drainage pipe is connected to the water outlet. The seepage pipe network is provided with 23 water inlets, and replaceable fine-pore screens are installed on the water inlets.

10. A method for using the simulated deep tunnel excavation test device according to any one of claims 1 to 9, characterized in that: The steps include: Step S1, prepare sand and calibrate the sensor; Step S2: Install the portal frame in the middle of the front section of the base platform, then install the hydraulic servo cylinder at the top center axis of the portal frame, and debug the actuator below the hydraulic servo cylinder; Step S3, completing sensor wiring through the sensor terminals on the upper front side of the box, and then setting up the DIC monitoring device at an appropriate observation position in front of the transparent observation window; Step S4: Push the model box to the rear end of the base platform, insert the mechanical expansion and contraction device into the box through the circular hole in the rear wall of the box, and connect the tail end of the telescopic main shaft of the mechanical expansion and contraction device to the external telescopic drive cylinder. During the insertion process, wrap the seepage pipe network around the surface of the mechanical expansion and contraction device, connect the drainage main pipe at the bottom of the seepage pipe network to the drainage port of the box, and install a flow meter and flow valve on the external drainage main pipe. Some sensors can be installed on the surface of the mechanical expansion and contraction device according to experimental requirements. Step S5: Fill the model box with the prepared sand and soil in layers according to the calculated amount, lay the sensors simultaneously, and lay the rubber cover on top of the soil; Step S6: Install the loading push plate, guide rod and model box cover on the top of the model box, adjust the lifting roller at the bottom of the model box, push the model box to the appropriate position, and then connect the guide rod and the actuator; In step S7, a water source is connected to the water inlet of the model box top cover, and the soil seepage flow rate is adjusted using a flow meter and a flow valve. The air compressor is connected to the pressure stabilizing device, and then the air supply channel is connected to the air inlet to adjust the air pressure in the box to a preset value. The control mode of the servo control system is adjusted to "force-displacement" mode, and the pressurization rate is set according to the test requirements. The actuator is controlled to apply the load to the loading push plate to the target value. In step S8, the telescopic drive cylinder is switched to the reverse gear position, and the displacement meter fixed at the end of the telescopic main shaft is read to control the telescopic amount of the telescopic main shaft to a preset value, thereby achieving the target value of the formation loss rate to realize shield tunnel excavation; during the simulated excavation process of the mechanical expansion and contraction device, data is collected through the DIC monitoring and sensor monitoring system.

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