Test device and method for simulating excavation of deep tunnel

Abstract

The invention discloses a test device for simulating excavation of a deep tunnel, and belongs to the technical field of deep tunnels and underground engineering. The device comprises a model box, a high ground stress loading system, a tunnel excavation simulation system and a DIC and sensor monitoring system. According to the invention, deep-buried shield tunnel excavation simulation can be realized, the mechanical expansion and contraction device adopts a rigid design that the oil cylinder drives the main shaft to stretch out and draw back, the precision of the simulated tunnel excavation process is higher, the test operation is simple and convenient, the expansion and contraction parameters are simple and controllable, and the working conditions of stratum contraction and compensation grouting during deep-buried shield tunneling are effectively restored; after tunnel excavation simulation is finished, the disturbance degree of tunnel excavation on foundation soil can be analyzed according to the stratum deformation degree recorded by the DIC monitoring device and the foundation soil stress change condition monitored by the sensor, and the tunnel excavation soil arching effect verification is achieved.

Description

Technical Field

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

[0002] Deep tunnel construction is an important means to alleviate urban traffic congestion and improve the urban environment. The deep underground environment has the characteristics of "high water pressure and high stress". Tunnel construction in this environment is difficult and risky. At present, the static design of deep tunnel structures still adopts the design method of shallow tunnel structures. This has caused two major problems: first, the basic theory and calculation method of shallow tunnel structure design are based on the stratum response law caused by shallow tunnel excavation, and its applicability in deep tunnels is unknown; second, the impact mechanism of deep tunnel construction on the surrounding environment is unclear, and the impact of deep excavation disturbance on the surrounding environment is difficult to accurately predict, threatening the safety of adjacent underground structures.

[0003] Physical model tests are an effective means to explore the soil arching effect of deep tunnel excavation and the interaction mechanism between tunnel and soil. Existing shield tunnel excavation experimental devices mostly simulate the shallow tunnel excavation process by pumping liquid and gas from the excavation area. This method cannot effectively simulate the uniform shrinkage of the stratum caused by tunnel over-excavation. On the other hand, it cannot restore the stress level of the real stratum, nor can it obtain the change of the internal force of the tunnel. In addition, it cannot restore the influence of seepage on the stress and strain of the stratum around the tunnel and the soil arching effect in actual engineering.

[0004] Therefore, in order to address the problems faced by deep-buried shield tunnels with "high water pressure and high ground stress" in their design and construction, there is an urgent need for a set of devices that can effectively simulate the uniform shrinkage of the strata, 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] The embodiment of the present invention provides a simulated deep buried tunnel excavation test device, including a model box, a high ground stress loading system, a tunnel excavation simulation system, a DIC and a sensor monitoring system, wherein:

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

[0009] The high ground stress loading system comprises 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 member;

[0010] The tunnel excavation simulation system comprises a mechanical expansion and contraction device whose front end is inserted into the box body and can generate 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 arranged 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 inside 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 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.

[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 opening or contraction.

[0017] Optionally, the model box also includes a sensor terminal fixed to the upper middle portion of the front wall of the box body through a flange, the sensor terminal including 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 cables, 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 disposed on the base platform to enable the box to be lifted and lowered, the liftable roller including a slider connected to the box, a roller rotatably connected to the bottom of the slider, and a screw nut disposed on the slider for adjusting the height of the slider.

[0019] Optionally, the seepage pipe network includes eight longitudinal pipes arranged in a circumferential direction around the mechanical expansion and contraction device, three annular pipes used to connect the eight longitudinal pipes, and a main drainage pipe connecting the longitudinal pipes and the transverse 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, installing the portal frame at the middle of the front section of the base platform, then installing the hydraulic servo cylinder at the top center axis of the portal frame, and debugging the actuator under the hydraulic servo cylinder;

[0023] Step S3, completing sensor wiring through the sensor terminal 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 on 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 a flow valve on the outer 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, filling the sand and soil prepared for the test into the model box in layers according to the calculated amount, laying sensors simultaneously, and laying a rubber cover on the top of the soil;

[0026] Step S6, installing the loading push plate, the guide rod and the upper cover of the model box on the top of the model box, and pushing the model box to a proper position by adjusting the liftable roller at the bottom of the model box, and then connecting the guide rod and the actuator;

[0027] Step S7, connect the water source to the water inlet of the top cover of the model box, and adjust the soil seepage flow rate through the flow meter and the flow valve; connect the air compressor to the pressure stabilizing device and then connect the air transmission channel to the air inlet, and adjust the air pressure in the box to a preset value; adjust the control mode of the servo control system, switch 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] Step S8, switch the telescopic drive cylinder to the reverse gear position, read the displacement meter reading fixed at the end of the telescopic main shaft, control the telescopic amount of the telescopic main shaft to a preset value, and then achieve the target value of the formation loss rate to realize shield tunnel excavation; collect data through the DIC monitoring and sensor monitoring system during the simulated excavation process of the mechanical expansion and contraction device.

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

[0030] 1. The present invention can realize the simulation of deep-buried shield tunnel excavation. The mechanical expansion and contraction device adopts a rigid design of oil cylinder driving the main shaft to expand and contract. The simulation of the tunnel excavation process is more accurate, the test operation is simple, and the expansion and contraction parameters are simple and controllable, which effectively restores the working conditions of stratum contraction and compensatory grouting during deep-buried shield excavation.

[0031] 2. The present invention can restore the seepage field in the surrounding strata during tunnel excavation by assembling a seepage pipe network on the surface of the mechanical expansion and contraction device in cooperation with air pressure regulation; the seepage pipe network is designed with a relevant anti-blocking screen structure, and the seepage flow rate can be accurately adjusted through a flow valve and a flow meter;

[0032] 3. After the simulated tunnel excavation is completed, the present invention can analyze the disturbance degree of the tunnel excavation on the foundation soil according to the stratum deformation degree recorded by the DIC monitoring device and the stress change of the foundation soil monitored by the sensor, so as to verify the soil arch effect of the tunnel excavation;

[0033] 4. The high ground stress loading system of the present invention can realize simultaneous loading of 1MPa vertical soil pressure and 1MPa air pressure. The loading system has two modes: displacement and force control. The loading speed is precisely adjustable. The actuator is equipped with a built-in magnetostrictive displacement sensor that can accurately measure its displacement change. It is also equipped with a detachable spoke-type load sensor that can accurately measure the size of its applied load, so as to highly restore the ground stress around the deep buried tunnel. 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. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

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

[0036] Figure 2 A schematic diagram of the structure 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 diagram of the structure of a circular hole provided by the present invention;

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

[0040] Figure 6 A schematic diagram of the structure 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 diagram of the cross-sectional structure of the mechanical expansion and contraction device provided by the present invention;

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

[0044] Fig.10 for Fig. 9 A schematic diagram of the enlarged structure at A in the middle;

[0045] Fig.11 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 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 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.

[0047] The terms "first", "second", etc. 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 sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

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

[0049] See also 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 arranged on the base platform 1, a hydraulic servo cylinder 3 arranged on the portal frame 2, and an actuator 4 arranged 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 disposed on the base platform 1 to lift the box body 7, and the liftable roller 6 has two adjustment modes: raising and lowering, and 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 disposed 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, the model box top cover 19 cannot be opened in the portal frame area to perform operations inside the box, and experimental preparation work needs to be performed 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 at 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 plate 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 arranged 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, and at the same time, the soil sandblasting to the gap of the guide rod 21 is avoided, the possibility of water rusting the guide rod 21 is eliminated, the service life of the loading system is extended, and the safety of the device structure is guaranteed.

[0054] The model box top cover 19 is provided with a water inlet 22 and an air inlet 24; the box body 7 is provided with a water outlet 12 at the bottom. 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, which has 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 , and the transparent observation window 28 includes a high-transparency POM plate 35 and a radial seal 34 between the box body 7 .

[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, and 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, and 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 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 driving cylinder 15 connected to the rear end of the mechanical expansion and contraction device 9, and a displacement meter 16 arranged at the rear 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 opening 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 Fig. 9 and Fig.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 main drainage pipe 103 connecting the longitudinal pipes 101 and the transverse pipes 102, the main drainage pipe 103 is connected to the water outlet 12, and the seepage pipe network is provided with 23 water inlets, and replaceable fine-pore screens 11 are installed on the water inlets.

[0061] By setting a replaceable fine-mesh screen 11 on the water inlet of the seepage pipe network 10, that is, eight screens are evenly installed on each ring pipe 102. Since the formation seepage will cause the soil particles to migrate, the use of fine-mesh screens can effectively solve the problem of pipe blockage. The water inlet drives the fine-mesh screen to rotate 360 ​​degrees, so that the water in the soil flows along the set seepage direction. By simply controlling the total drainage flow, the seepage field around the deep-buried shield tunnel is restored.

[0062] The bottom of the seepage pipe network 10 is a drainage main pipe 103, which is connected to the outside of the box body 7 from the water outlet 12 of the box body 7. A flow meter 13 and a flow valve 14 are installed on the drainage main pipe 103. The flow meter 13 is used to measure the total drainage flow of the seepage field in real time. When the flow does not reach the set value, the flow is adjusted by 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 a 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 Fig.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, preparing sand and calibrating the sensor 17;

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

[0070] Step S2, installing the portal frame 2 at the middle of the front section of the base platform 1, then installing the hydraulic servo cylinder 3 at the top center axis of the portal frame 2, and debugging the actuator 4 under 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, complete the wiring of the sensor 17 through the sensor terminal 8 on the upper front side of the box, then set up the DIC monitoring device 27 at an appropriate observation position in front of the transparent observation window 28, and use the DIC and sensor monitoring system 33 to complete the debugging of all monitoring instruments;

[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 from 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, wrap the seepage pipe network 10 around the surface of the mechanical expansion and contraction device 9, and connect the drainage main pipe 103 at the bottom of the seepage pipe network 10 to the drainage port 12 of the box body 7. The outer drainage main pipe 103 is equipped with a flow meter 13 and a flow valve 14. According to experimental requirements, some sensors 17 can be installed on the surface of the mechanical expansion and contraction device 9;

[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, filling the sand prepared for the test into the model box in layers according to the calculated amount, laying the sensor 17 at the same time, and laying the rubber cover 18 on the top of the soil;

[0076] It should be noted that before the soil is filled into the model box in layers, a geotextile needs to be laid at the bottom of the box to prevent fine particles from blocking 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 upper cover 19 on the top of the model box, and push the model box to a proper position by adjusting the liftable roller 6 at the bottom of the model box, and then connect the guide rod 21 and 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 top cover of the model box, 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 transmission 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, switch 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, backward, and neutral. When adjusted to the backward gear, the telescopic main shaft 901 of the mechanical expansion and contraction device 9 moves toward the outside of the box body 7, and the internal fins 902 shrink under the linkage with the lock core 903, and the outer diameter of the device decreases; when adjusted to the forward gear, the telescopic main shaft 901 of the mechanical expansion and contraction device 9 moves toward the inside of the box body 7, and the internal fins 902 open under the linkage with the lock core 903, and the outer diameter of the device increases.

[0081] Step S8, switch the telescopic drive cylinder 15 to the reverse gear position, cooperate with reading the displacement meter 16 fixed at the end of the telescopic main shaft 901, control the telescopic amount of the telescopic main shaft 901 to a preset value, and then achieve 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 then the corresponding relationship between the displacement of the telescopic main shaft 901 and the formation loss rate can be obtained, see Fig.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 tests.

[0083] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0084] In addition, it should be noted that the scope of the methods and systems in the embodiments of the present invention is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, 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 modes, which are merely illustrative rather than 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 within the protection of the present invention.

Claims

1. A test device for simulating deep tunnel excavation, characterized in that: It includes model box, high ground stress loading system, tunnel excavation simulation system, DIC and sensor monitoring system, among which: The model box comprises a box body, a model box top cover arranged on the top of the box body, and a loading member arranged on the model box top cover for pressurizing the soil in the model box; The high ground stress loading system comprises 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 member; The tunnel excavation simulation system comprises a mechanical expansion and contraction device whose front end is inserted into the box body and can generate 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 arranged 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 inside 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 comprises 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 arranged 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, and 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 board 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 board.

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 lifted 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 used to connect the eight longitudinal pipes, and a main drainage pipe connecting the longitudinal pipes and the transverse 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, preparing sand and calibrating the sensor; Step S2, installing the portal frame at the middle of the front section of the base platform, then installing the hydraulic servo cylinder at the top center axis of the portal frame, and debugging the actuator under the hydraulic servo cylinder; Step S3, completing sensor wiring through the sensor terminal at the upper front side of the box body, 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 on 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 a flow valve on the outer drainage main pipe. Some sensors can be installed on the surface of the mechanical expansion and contraction device according to experimental requirements; Step S5, filling the sand prepared for the test into the model box in layers according to the calculated amount, laying sensors simultaneously, and laying a rubber cover on the top of the soil; Step S6, installing the loading push plate, the guide rod and the upper cover of the model box on the top of the model box, and pushing the model box to a proper position by adjusting the liftable roller at the bottom of the model box, and then connecting the guide rod and the actuator; Step S7, connect the water source to the water inlet of the top cover of the model box, and adjust the soil seepage flow rate through the flow meter and the flow valve; connect the air compressor to the pressure stabilizing device and then connect the air transmission channel to the air inlet, and adjust the air pressure in the box to the preset value; adjust the control mode of the servo control system, switch 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; Step S8, switch the telescopic drive cylinder to the reverse gear position, read the displacement meter reading fixed at the end of the telescopic main shaft, control the telescopic amount of the telescopic main shaft to a preset value, and then achieve the target value of the formation loss rate to realize shield tunnel excavation; collect data through the DIC monitoring and sensor monitoring system during the simulated excavation process of the mechanical expansion and contraction device.

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