Tunnel excavation test device and method

Abstract

The invention discloses a tunnel excavation test device and method, and relates to the technical field of geotechnical engineering model tests.The tunnel excavation test device comprises a model box, at least one anti-freezing liquid bag and a plurality of freezing pipes, the model box can contain a test soil body, a water injection opening is formed in the bottom of the model box, and the anti-freezing liquid bags and the freezing pipes are both fixedly arranged in the model box; any anti-freezing liquid bag is surrounded by a plurality of freezing pipes, the anti-freezing liquid bags and the freezing pipes are embedded in the test soil body, the anti-freezing liquid bags can contain anti-freezing liquid and can be communicated with the outside of the model box so that the anti-freezing liquid in the anti-freezing liquid bags can be discharged to the outside of the model box, and the freezing pipes can be communicated with the outside of the model box so that the model box can be connected with the model box. The freezing pipe can transmit freezing liquid; according to the invention, artificial frozen stratum tunnel excavation and thaw stratum tunnel excavation can be simulated flexibly, truly and conveniently in a controlled manner.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical engineering model testing, and in particular to a tunnel excavation testing device and method. Background Art

[0002] Artificial freezing is a geotechnical reinforcement technique that uses artificial refrigeration to lower ground temperatures, freezing the water in the soil to form a frozen soil curtain, thereby enhancing the mechanical properties of the ground and reducing permeability. This method offers significant advantages in tunnel construction, particularly in complex geological conditions such as water-rich sand layers and weak, fractured zones. By forming a continuous frozen soil curtain, artificial freezing effectively controls ground deformation during tunnel construction, preventing engineering accidents such as collapse and water inrush, and significantly improving construction safety and reliability.

[0003] In tunnel engineering research, physical model testing has been widely used as an important technical means to study the mechanical properties and deformation patterns of tunnel surrounding rock. Existing tunnel model testing equipment primarily focuses on shield excavation face stability analysis, three-dimensional deformation monitoring during tunnel construction, research on surrounding rock strength characteristics, and surface settlement prediction. However, there is currently a lack of testing equipment capable of conducting tunnel excavation in both artificially frozen and thawed ground. Summary of the Invention

[0004] The purpose of the present invention is to provide a tunnel excavation test device and method to solve the problems existing in the above-mentioned prior art, which can flexibly, realistically and easily controllably simulate tunnel excavation in artificial frozen strata and tunnel excavation in thawed strata.

[0005] To achieve the above object, the present invention provides the following solutions: The present invention provides a tunnel excavation test device, comprising a model box, at least one antifreeze liquid bag and a plurality of freezing pipes. The model box can accommodate test soil. A water inlet is provided at the bottom of the model box. The antifreeze liquid bag and the freezing pipes are both fixedly arranged in the model box. Any antifreeze liquid bag is surrounded by a plurality of freezing pipes. The antifreeze liquid bag and the freezing pipes are both buried in the test soil. The antifreeze liquid bag can accommodate antifreeze liquid. The antifreeze liquid bag can be communicated with the outside of the model box so that the antifreeze liquid in the antifreeze liquid bag can be discharged to the outside of the model box. The freezing pipes can be communicated with the outside of the model box and can transmit freezing liquid.

[0006] Preferably, the model box includes a box body, a front window and a rear window, the top of the box body is open, the front panel of the box body is provided with a front window, the rear panel of the box body is provided with a rear window, the front window is sealed and fixed on the front panel of the box body, the front window can block the front window, the rear window is sealed and fixed on the rear panel of the box body, and the rear window can block the rear window; the front end of the antifreeze liquid bag and the front end of the freezing tube are both fixed on the front window, and the rear end of the antifreeze liquid bag and the rear end of the freezing tube are both fixed on the rear window.

[0007] Preferably, the inner side surface of the front viewing window is flush with the inner side surface of the front panel of the box body, a front tunnel hole and a plurality of front mounting holes are provided on the front viewing window, a front protruding end cover is provided on the outer side surface of the front viewing window to seal and fix around the front tunnel hole, a front accommodating groove is provided on the front protruding end cover, the front accommodating groove is communicated with the front tunnel hole, the front end of the antifreeze liquid bag extends into the front accommodating groove; the front mounting holes correspond one-to-one with the freezing pipes, and the front end of the freezing pipes is fixedly arranged in the front mounting holes inside; the inner side surface of the rear view window is flush with the inner side surface of the rear panel of the box body, and a rear tunnel hole and a plurality of rear mounting holes are provided on the rear view window. A rear protruding end cover is sealed and fixed around the rear tunnel hole on the outer side surface of the rear view window, and a rear accommodating groove is provided on the rear protruding end cover. The rear accommodating groove is connected with the rear tunnel hole, and the rear end of the antifreeze liquid bag extends into the rear accommodating groove; the rear mounting holes correspond one to one with the freezing pipes, and the rear end of the freezing pipes is fixed in the rear mounting holes.

[0008] Preferably, it also includes a through tube, a through hole is opened on the rear protruding end cover, the first end of the through tube is fixedly arranged on the rear end of the antifreeze liquid bag, the interior of the through tube is communicated with the interior of the antifreeze liquid bag, the second end of the through tube passes through the through hole and extends to the outside of the box, the through tube and the through hole are fixedly connected by a threaded seal, and the second end of the through tube can be communicated with the outside of the box.

[0009] Preferably, a flow meter and a valve are provided on the second end of the through-tube, wherein the flow meter can detect the flow of the antifreeze liquid in the through-tube, and the valve can control the on-off of the through-tube.

[0010] Preferably, the through tube is threadedly connected to the through hole; the front protruding end cover includes a front cover plate and a front baffle ring, the front baffle ring is placed between the front cover plate and the outer side surface of the front window, one end of the front baffle ring is communicated with the front tunnel hole, the front cover plate can block the other end of the front baffle ring, the front cover plate, the front baffle ring and the front window are sealed and connected by bolts; the rear protruding end cover includes a rear cover plate and a rear baffle ring, the rear baffle ring is placed between the rear cover plate and the outer side surface of the rear window, one end of the rear baffle ring is communicated with the rear tunnel hole, the rear cover plate can block the other end of the rear baffle ring, the rear cover plate, the rear baffle ring and the rear window are sealed and connected by bolts; the through hole is opened on the rear cover plate.

[0011] Preferably, it also includes a front sealing ring, a front gasket, a rear sealing ring and a rear gasket, a front annular baffle is fixedly provided on the front panel of the box body around the front window, the front gasket is placed between the front annular baffle and the outer side surface of the front window so that the inner side surface of the front window is flush with the inner side surface of the front panel of the box body, the front window, the front gasket and the front annular baffle are bolted, and the front sealing ring is fixed between the front window and the box body; a rear annular baffle is fixedly provided on the rear panel of the box body around the rear window, the rear gasket is placed between the rear annular baffle and the outer side surface of the rear window so that the inner side surface of the rear window is flush with the inner side surface of the rear panel of the box body, the rear window, the rear gasket and the rear annular baffle are bolted, and the rear sealing ring is fixed between the rear window and the box body.

[0012] Preferably, it also includes a diverter, a combiner and a refrigeration unit, the freezing pipe includes an inner pipe and an outer pipe, the first end of the inner pipe is provided with a liquid outlet, the second end of the inner pipe is provided with a liquid inlet, the outer pipe is fixedly sleeved outside the inner pipe, a flow gap is left between the inner side wall of the outer pipe and the outer side wall of the inner pipe, the first end of the outer pipe is closed, the first end of the outer pipe is placed at the liquid outlet, a drainage port is provided on the side wall of the outer pipe, so that the refrigerant enters the inner pipe from the liquid inlet, and then The liquid enters the flow gap from the liquid outlet and finally leaves the outer tube from the drainage port; the liquid supply port of the refrigeration unit is connected with the diverter, and the diverter is connected with all the liquid inlets, and the diverter diverts the refrigerant provided by the liquid supply port of the refrigeration unit into each of the liquid inlets; the return liquid port of the refrigeration unit is connected with the merger, and the merger is connected with all the drainage ports, and the merger merges the refrigerant flowing out of each of the drainage ports into the return liquid port of the refrigeration unit.

[0013] Preferably, it further comprises a plurality of displacement sensors, a plurality of pressure sensors and a plurality of temperature sensors, wherein the displacement sensors, the pressure sensors and the temperature sensors are all fixedly arranged in the model box, the displacement sensors are capable of detecting the soil displacement inside the test soil body, the pressure sensors are capable of detecting the soil pressure inside the test soil body, and the temperature sensors are capable of detecting the soil temperature inside the test soil body; a smooth film is fixedly laid on the inner side surface of the model box, and a lubricating liquid is applied on the surface of the smooth film close to the test soil body.

[0014] The present invention further provides a tunnel excavation test method, using the tunnel excavation test device as described above, comprising: Tunnel excavation simulation in thawing soil: includes the following steps: S11: Set up tunnel excavation test equipment; S12: Prepare the test soil and fill the test soil into the model box; S13: injecting water into the model box through the water injection port; S14: simulate tunnel excavation by draining the antifreeze liquid bag and record all monitoring data during the antifreeze liquid bag drainage process; Simulation of tunnel excavation in artificially frozen ground: includes the following steps: S21: Set up tunnel excavation test equipment; S22: Prepare the test soil and fill the test soil into the model box; S23: injecting water into the model box through the water injection port; S24: circulating a refrigerant in the freezing pipe to freeze the water-containing soil in the area where the freezing pipe is located; S25: After the freezing wall is closed, the antifreeze liquid bag is drained to simulate tunnel excavation, and all monitoring data during the antifreeze liquid bag drainage process are recorded; Tunnel excavation simulation in partially frozen failure strata includes the following steps: S31: Set up tunnel excavation test equipment; S32: Prepare the test soil and fill the test soil into the model box; S33: injecting water into the model box through the water injection port; S34: closing the circulating cold bath or removing the freezing pipe at the freezing failure simulation location to simulate the local freezing failure ground state, and circulating the freezing liquid in the remaining freezing pipes to freeze the water-bearing soil in the area where the freezing pipes are located until the freezing wall of the area to be frozen is completed; S35: After the soil layer enters a state of partial freezing failure, tunnel excavation is simulated by draining the antifreeze liquid bag, and all monitoring data during the antifreeze liquid bag drainage process are recorded.

[0015] Compared with the prior art, the present invention has achieved the following technical effects: The tunnel excavation test device and method provided by the present invention are provided with a model box to accommodate the test soil, an antifreeze liquid bag to accommodate the antifreeze liquid, and a freezing pipe to transmit the freezing liquid, and any antifreeze liquid bag is surrounded by a plurality of freezing pipes, and the antifreeze liquid bag and the freezing pipe are both buried in the test soil. The antifreeze liquid in the antifreeze liquid bag is discharged to the outside of the model box to simulate the excavation of the tunnel, thereby realizing the simulation of the tunnel excavation disturbance. By controlling the step-by-step drainage process of the antifreeze liquid bag, the simulation of the tunnel excavation process of the frozen stratum is made more realistic and controllable. In actual testing, the number, cross-sectional shape and size of the antifreeze liquid bag can be configured according to actual test requirements. The cross-sectional shape of the antifreeze liquid bag includes but is not limited to circular, elliptical and horseshoe-shaped. By selecting antifreeze liquid bags of different cross-sectional types, different sizes and different numbers, different types of tunnel excavation simulations can be realized, and different tunnel sections such as cross-sectional shapes, sizes and multi-chamber arrangements can be simulated. Geometric characteristics, can flexibly, realistically and easily simulate the excavation of tunnels in artificial frozen strata with different cross-sectional geometric characteristics and different freezing conditions, can also flexibly, realistically and easily simulate the excavation of tunnels in thawed soil strata with different cross-sectional geometric characteristics and different groundwater levels, and can achieve water and sand sealing during the entire excavation process, which is suitable for freezing tunnel excavation tests in sandy soil, clay and composite strata, providing a reliable test platform for experimental research on tunnel construction using artificial freezing method, and providing reliable technical means for studying the deformation law of strata induced by tunnel excavation under different freezing conditions, and can be used to simulate the deformation law and stress distribution characteristics of strata induced by tunnel excavation disturbance under different types of artificial frozen soil conditions, providing important technical support for model test research on freezing method construction, which will fill the gap in existing technology and has important theoretical value and engineering significance for promoting the application of artificial freezing method in tunnel engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 A schematic diagram of the tunnel excavation test device provided by the present invention; Figure 2 for Figure 1 A schematic diagram of the box in the tunnel excavation test device is provided; Figure 3 for Figure 1 A schematic diagram of the rear view window in the tunnel excavation test device is provided; Figure 4 for Figure 1A schematic diagram of the antifreeze bladder in the tunnel excavation test device is provided; Figure 5 for Figure 1 A schematic diagram of the rear cover plate in the tunnel excavation test device is provided; Figure 6 for Figure 1 A schematic diagram of the backstop ring in the tunnel excavation test device is provided; Figure 7 for Figure 1 A schematic diagram of the front cover plate in the tunnel excavation test device is provided; Figure 8 for Figure 1 A schematic diagram of the front retaining ring in the tunnel excavation test device is provided; Figure 9 for Figure 1 A schematic diagram of the freezing pipe in the tunnel excavation test device is provided; In the figure: 1-model box, 2-antifreeze liquid bag, 3-freezing pipe, 4-front window, 5-rear window, 6-rear protruding end cover, 7-through tube, 8-flow meter, 9-valve, 10-through hole, 11-front cover plate, 12-front baffle ring, 13-rear cover plate, 14-rear baffle ring, 15-rear annular baffle, 16-water inlet, 17-inner tube, 18-outer tube, 19-liquid outlet, 20-liquid inlet, 21-flow gap, 22-drainage port. DETAILED DESCRIPTION

[0018] 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 the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] The purpose of the present invention is to provide a tunnel excavation test device and method to solve the problems existing in the above-mentioned prior art, which can flexibly, realistically and easily controllably simulate tunnel excavation in artificial frozen strata and tunnel excavation in thawed strata.

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1 like Figures 1 to 9As shown, this embodiment provides a tunnel excavation test device, including a model box 1, at least one antifreeze liquid bag 2 and a plurality of freezing pipes 3. The model box 1 can accommodate test soil. A water inlet 16 is provided at the bottom of the model box 1. The antifreeze liquid bag 2 and the freezing pipes 3 are fixedly arranged in the model box 1. Any antifreeze liquid bag 2 is surrounded by a plurality of freezing pipes 3. The antifreeze liquid bag 2 and the freezing pipes 3 are buried in the test soil. The antifreeze liquid bag 2 can accommodate antifreeze liquid. The antifreeze liquid bag 2 can be connected to the outside of the model box 1 so that the antifreeze liquid in the antifreeze liquid bag 2 can be discharged to the outside of the model box 1. The freezing pipes 3 can be connected to the outside of the model box 1 and the freezing pipes 3 can transmit the freezing liquid.

[0022] The tunnel excavation test device provided in this embodiment is provided with a model box 1 to accommodate the test soil, an antifreeze liquid bag 2 to accommodate the antifreeze liquid, and a freezing pipe 3 to transmit the freezing liquid, and any antifreeze liquid bag 2 is surrounded by a number of freezing pipes 3, and the antifreeze liquid bag 2 and the freezing pipe 3 are all buried in the test soil. The antifreeze liquid in the antifreeze liquid bag 2 is discharged to the outside of the model box 1 to simulate the excavation of the tunnel, thereby realizing the simulation of the tunnel excavation disturbance. By controlling the step-by-step drainage process of the antifreeze liquid bag 2, the simulation of the tunnel excavation process of the frozen stratum is made more realistic and controllable. In actual testing, the number, cross-sectional shape and size of the antifreeze liquid bag 2 can be configured according to actual test requirements. The cross-sectional shape of the antifreeze liquid bag 2 includes but is not limited to circular, elliptical and horseshoe-shaped. By selecting antifreeze liquid bags 2 of different cross-sectional types, different sizes and different numbers, different types of tunnel excavation simulations can be realized, and the cross-sectional shape, size and multi-chamber layout can be simulated. Different tunnel cross-sectional geometric characteristics can flexibly, realistically and easily simulate the excavation of tunnels in artificial frozen strata with different cross-sectional geometric characteristics and different freezing conditions. It can also flexibly, realistically and easily simulate the excavation of tunnels in thawed strata with different cross-sectional geometric characteristics and different groundwater levels, and can achieve water and sand sealing during the entire excavation process. It is suitable for freezing tunnel excavation tests in sandy soil, clay and composite strata, providing a reliable test platform for experimental research on tunnel construction using artificial freezing method, and providing reliable technical means for studying the deformation law of strata induced by tunnel excavation under different freezing conditions. It can be used to simulate the deformation law and stress distribution characteristics of strata induced by tunnel excavation disturbance under different types of artificial frozen soil conditions, providing important technical support for model test research on freezing method construction, which will fill the existing technical gap and have important theoretical value and engineering significance for promoting the application of artificial freezing method in tunnel engineering.

[0023] As a more preferred implementation of this embodiment, the model box 1 includes a box body, a front window 4 and a rear window 5. The top of the box body is open, a front window is provided on the front panel of the box body, and a rear window is provided on the rear panel of the box body. The front window 4 is sealed and fixed on the front panel of the box body, and the front window 4 can block the front window. The rear window 5 is sealed and fixed on the rear panel of the box body, and the rear window 5 can block the rear window. The front end of the antifreeze liquid capsule 2 and the front end of the freezing pipe 3 are fixed on the front window 4, and the rear end of the antifreeze liquid capsule 2 and the rear end of the freezing pipe 3 are fixed on the front window 4. They are all fixed on the rear view window 5, and the front view window 4 and the rear view window 5 are both made of transparent material to facilitate observation of the internal situation of the box; as a more preferred implementation method of this embodiment, the box is a rectangular steel box composed of steel plates and square steels welded and bolted together, and the webs are welded on the outside of each panel of the box to increase the rigidity of the box and resist lateral deformation. An open and close water injection port 16 is reserved at the bottom of the left and right side panels of the box for installing a water injection valve to carry out water inlet and outlet of the box. The front view window 4 and the rear view window 5 can be made of but not limited to transparent materials such as organic glass.

[0024] As a more preferred implementation manner of this embodiment, the inner side surface of the front window 4 is flush with the inner side surface of the front panel of the box body, and a front tunnel hole and several front mounting holes are provided on the front window 4. A front protruding end cover is sealed and fixed around the front tunnel hole, and a front accommodating groove is provided on the front protruding end cover. The front accommodating groove is connected with the front tunnel hole, and the front end of the antifreeze liquid bag 2 extends into the front accommodating groove; the inner side surface of the rear window 5 is flush with the inner side surface of the rear panel of the box body, and a rear tunnel hole and several rear mounting holes are provided on the rear window 5. A rear protruding end cover 6 is sealed and fixed around the rear tunnel hole, and a rear accommodating groove is provided on the rear protruding end cover 6. The rear accommodating groove is connected with the rear tunnel hole, and the rear end of the antifreeze liquid bag 2 extends into the rear accommodating groove, thereby achieving effective water sealing and fixation of the front end and the rear end of the antifreeze liquid bag 2, providing reliable protection for simulated freezing construction and thawing soil excavation tests at different groundwater levels. ; The structures of the front tunnel hole, the front protruding end cover, the rear tunnel hole and the rear protruding end cover 6 can be flexibly adjusted according to the test requirements to adapt to the position, quantity, cross-sectional shape and size of the antifreeze liquid bag 2, and then the different positions, quantities, cross-sectional shapes and sizes of the antifreeze liquid bag 2 can be matched by replacing different front windows 4 and different rear windows 5; the front mounting hole corresponds to the freezing pipe 3 one-to-one, and the front end of the freezing pipe 3 is fixedly arranged in the front mounting hole, and the rear mounting hole corresponds to the freezing pipe 3 one-to-one, and the rear end of the freezing pipe 3 is fixedly arranged in the rear mounting hole to realize the installation of the freezing pipe 3, wherein the outer wall of the freezing pipe 3 needs to be sealed with the inner wall of the front mounting hole and the inner wall of the rear mounting hole. The arrangement of the freezing pipe 3, the front mounting hole and the rear mounting hole is set according to the test requirements, including the arrangement spacing, diameter and arrangement method, which can be adjusted according to the size, shape, position and number of tunnels of the prototype tunnel, so as to achieve stratum freezing according to the test requirements.

[0025] As a more preferred implementation of this embodiment, the tunnel excavation test device provided in this embodiment also includes a through tube 7, a through hole 10 is opened on the rear protruding end cover 6, the first end of the through tube 7 is fixed on the rear end of the antifreeze liquid bag 2, the interior of the through tube 7 is connected with the interior of the antifreeze liquid bag 2, the second end of the through tube 7 passes through the through hole 10 and extends to the outside of the box, the through tube 7 and the through hole 10 are fixedly connected by threaded sealing, and the second end of the through tube 7 can be connected with the outside of the box. The structure is simple and easy to manufacture and use.

[0026] As a more preferred implementation of this embodiment, a flow meter 8 and a valve 9 are provided on the second end of the through-tube 7. The flow meter 8 can detect the flow of antifreeze liquid in the through-tube 7, and the valve 9 can control the on and off of the through-tube 7. The flow meter 8 and the valve 9 are preferably detachable.

[0027] As a more preferred implementation manner of this embodiment, the through tube 7 is threadedly connected to the through hole 10, which can effectively avoid water leakage at the connection between the through tube 7 and the through hole 10, and play a good water sealing role; the front protruding end cover includes a front cover plate 11 and a front baffle ring 12, the front baffle ring 12 is placed between the front cover plate 11 and the outer side of the front window 4, one end of the front baffle ring 12 is connected to the front tunnel hole, the front cover plate 11 can block the other end of the front baffle ring 12, the front cover plate 11, the front baffle ring 12 and the front window 4 are sealed with bolts, which can effectively avoid water leakage at the connection between the front cover plate 11, the front baffle ring 12 and the front window 4, and play a good water sealing role; the rear protruding end cover 6 includes a rear cover Plate 13 and rear retaining ring 14, the rear retaining ring 14 is placed between the rear cover plate 13 and the outer side of the rear window 5, one end of the rear retaining ring 14 is connected to the rear tunnel hole, the rear cover plate 13 can block the other end of the rear retaining ring 14, the rear cover plate 13, the rear retaining ring 14 and the rear window 5 are sealed with bolts, which can effectively avoid water leakage at the connection between the rear cover plate 13, the rear retaining ring 14 and the rear window 5, and play a good water sealing role; a through hole 10 is opened on the rear cover plate 13; as a more preferred implementation method of this embodiment, the front cover plate 11, the front retaining ring 12, the rear cover plate 13 and the rear retaining ring 14 adopt the same transparent material as the front window 4 and the rear window 5, which is convenient for observation during the test.

[0028] As a more preferred implementation manner of this embodiment, the tunnel excavation test device provided by this embodiment also includes a front sealing ring, a front gasket, a rear sealing ring and a rear gasket. A front annular baffle is fixedly provided around the front window on the front panel of the box body, and the front gasket is placed between the front annular baffle and the outer side surface of the front viewing window 4 so that the inner side surface of the front viewing window 4 is flush with the inner side surface of the front panel of the box body. The front viewing window 4, the front gasket and the front annular baffle are bolted together. The front sealing ring is fixedly provided between the front window 4 and the box body, which can effectively prevent water leakage at the connection between the front window 4 and the box body, and play a good water sealing role; a rear annular baffle 15 is fixedly provided around the rear window on the rear panel of the box body, and the rear gasket is placed between the rear annular baffle 15 and the outer side surface of the rear window 5 so that the inner side surface of the rear window 5 is flush with the inner side surface of the rear panel of the box body. The rear window 5, the rear gasket and the rear annular baffle 15 are bolted together, and the rear sealing ring is fixedly provided between the rear window 5 and the box body, which can effectively prevent water leakage at the connection between the rear window 5 and the box body, and play a good water sealing role.

[0029] As a more preferred implementation of this embodiment, the tunnel excavation test device provided in this embodiment also includes a diverter, a combiner and a refrigeration unit. The freezing pipe 3 includes an inner pipe 17 and an outer pipe 18. The first end of the inner pipe 17 is provided with a liquid outlet 19, and the second end of the inner pipe 17 is provided with a liquid inlet 20. The outer pipe 18 is fixedly sleeved outside the inner pipe 17, and a flow gap 21 is left between the inner side wall of the outer pipe 18 and the outer side wall of the inner pipe 17. The first end of the outer pipe 18 is closed, and the first end of the outer pipe 18 is placed at the liquid outlet 19. A drainage port 22 is provided on the side wall of the outer pipe 18 to allow the refrigerant to flow out of the outer pipe 17. The liquid inlet 20 enters the inner tube 17, then enters the flow gap 21 from the liquid outlet 19, and finally leaves the outer tube 18 from the drainage port 22; the liquid supply port of the refrigeration unit is connected with the diverter, and the diverter is connected with all the liquid inlets 20. The diverter diverts the refrigerant provided by the liquid supply port of the refrigeration unit to each liquid inlet 20; the return liquid port of the refrigeration unit is connected with the merger, and the merger is connected with all the drainage ports 22. The merger merges the refrigerant flowing out of each drainage port 22 into the return liquid port of the refrigeration unit, so that the refrigerant circulates between the refrigeration unit and the freezing pipe 3, so as to facilitate the effective water sealing of the model box 1.

[0030] As a more preferred implementation of this embodiment, the tunnel excavation test device provided in this embodiment also includes a plurality of displacement sensors, a plurality of pressure sensors and a plurality of temperature sensors. The displacement sensors, pressure sensors and temperature sensors are all fixedly arranged in the model box 1. The displacement sensor can detect the soil displacement inside the test soil body, the pressure sensor can detect the soil pressure inside the test soil body, and the temperature sensor can detect the soil temperature inside the test soil body, so as to facilitate the detection of the soil condition inside the test soil body; a smooth film is fixedly laid on the inner side surface of the model box 1, and a lubricating liquid is applied to the surface of the smooth film close to the test soil body, which can effectively reduce the boundary effect caused by friction; as a more preferred implementation of this embodiment, the smooth film is made of polystyrene film, which is easy to manufacture and use.

[0031] Example 2 This embodiment provides a tunnel excavation test method, using the tunnel excavation test device in the first embodiment, including: Tunnel excavation simulation in thawing soil: includes the following steps: S11: Set up tunnel excavation test equipment; S12: Prepare the test soil and fill the test soil into the model box 1; S13: injecting water into the model box 1 through the water injection port 16; S14: Simulating tunnel excavation by draining the antifreeze liquid bladder 2, and recording all monitoring data during the draining process of the antifreeze liquid bladder 2; Simulation of tunnel excavation in artificially frozen ground: includes the following steps: S21: Set up tunnel excavation test equipment; S22: Prepare the test soil and fill the test soil into the model box 1; S23: injecting water into the model box 1 through the water injection port 16; S24: Circulating the refrigerant in the freezing pipe 3 to freeze the water-containing soil in the area where the freezing pipe 3 is located; S25: After the frozen wall is closed, drain the antifreeze liquid bag 2 to simulate tunnel excavation, and record all monitoring data during the draining process of the antifreeze liquid bag 2; Tunnel excavation simulation in partially frozen failure strata includes the following steps: S31: Set up tunnel excavation test equipment; S32: Prepare test soil and fill the test soil into the model box 1; S33: injecting water into the model box 1 through the water injection port 16; S34: closing the circulating cold bath or removing the freezing pipe 3 at the freezing failure simulation location to simulate a local freezing failure stratum state, and circulating the refrigerant in the remaining freezing pipes 3 to freeze the water-bearing soil in the area where the freezing pipes 3 are located until the freezing wall of the area to be frozen is completed; S35: After the soil layer enters a partially frozen failure state, the antifreeze liquid bag 2 is drained to simulate tunnel excavation, and all monitoring data during the antifreeze liquid bag 2 drainage process are recorded.

[0032] The tunnel excavation test method provided in this embodiment is to set a model box 1 to accommodate the test soil, set an antifreeze liquid bag 2 to accommodate the antifreeze liquid, set a freezing pipe 3 to accommodate the freezing liquid, and any antifreeze liquid bag 2 is surrounded by a number of freezing pipes 3, and the antifreeze liquid bag 2 and the freezing pipe 3 are all buried in the test soil. The antifreeze liquid in the antifreeze liquid bag 2 is discharged to the outside of the model box 1 to simulate the excavation of the tunnel, thereby realizing the simulation of the tunnel excavation disturbance. By controlling the step-by-step drainage process of the antifreeze liquid bag 2, the simulation of the tunnel excavation process of the frozen stratum is made more realistic and controllable. In actual testing, the number, cross-sectional shape and size of the antifreeze liquid bag 2 can be configured according to actual test requirements. The cross-sectional shape of the antifreeze liquid bag 2 includes but is not limited to circular, elliptical and horseshoe-shaped. By selecting antifreeze liquid bags 2 of different cross-sectional types, different sizes and different numbers, It can realize the simulation of excavation of different types of prototype tunnels, simulate the geometric characteristics of different tunnel sections such as cross-sectional shape, size and multi-chamber arrangement, simulate tunnel excavation flexibly, realistically and easily controlled, and realize water and sand sealing during the whole excavation process. It is suitable for freezing tunnel excavation tests in sandy soil, clay and composite strata, and provides a reliable test platform for experimental research on tunnel construction using artificial freezing method. It provides a reliable technical means for studying the deformation law of strata induced by tunnel excavation under different freezing conditions, and can be used to simulate the deformation law and stress distribution characteristics of strata induced by tunnel excavation disturbance under different types of artificial frozen soil conditions, providing important technical support for model test research on freezing construction of underground engineering, which will fill the gap in existing technology and has important theoretical value and engineering significance for promoting the application of artificial freezing method in tunnel engineering.

[0033] As a more preferred implementation of this embodiment, in S11, S21 and S31, a smooth film is fixedly laid on the inner side of the model box 1, and a lubricating liquid is applied to the surface of the smooth film close to the test soil, which can effectively reduce the boundary effect caused by friction and ensure the clarity of the front window 4 and the rear window 5 after multiple tests; in S12, S22 and S32, when preparing the test soil, similar materials are prepared and mixed according to similar ratios to ensure that the test soil can simulate the physical properties of the actual soil layer, and the test soil is filled into the model box 1. , simulate the actual soil layer, install displacement sensors, pressure sensors and temperature sensors, and monitor the soil conditions inside the test soil in real time; in S13, water is injected into the model box 1 through the water injection port 16 to control the water level to simulate different groundwater levels; in S24, the temperature sensor monitors the soil temperature in real time, and the freezing liquid is low-temperature silicone oil; in S25, after the freezing cycle, when the thickness of the frozen wall meets the test design value, the antifreeze liquid bag 2 is drained to simulate tunnel excavation; in S34, the temperature sensor monitors the soil temperature in real time, and the freezing liquid is low-temperature silicone oil.

[0034] The tunnel excavation test device in Example 1 is suitable for various geotechnical model tests. The test effect of the tunnel excavation test device in Example 1 depends on the specific test type. The tunnel excavation test method provided in this embodiment provides general operating steps applicable to various model tests, and focuses on the versatility of the tunnel excavation test device in Example 1, the feasibility of local freezing application, and the feasibility of freezing failure simulation.

[0035] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A tunnel excavation test device, characterized in that: It includes a model box, at least one antifreeze liquid bag and several freezing pipes. The model box can accommodate test soil. A water inlet is provided at the bottom of the model box. The antifreeze liquid bag and the freezing pipes are fixed in the model box. Any antifreeze liquid bag is surrounded by several freezing pipes. The antifreeze liquid bag and the freezing pipes are buried in the test soil. The antifreeze liquid bag can accommodate antifreeze liquid. The antifreeze liquid bag can be connected to the outside of the model box so that the antifreeze liquid in the antifreeze liquid bag can be discharged to the outside of the model box. The freezing pipes can be connected to the outside of the model box and can transmit freezing liquid.

2. The tunnel excavation test device according to claim 1, characterized in that: The model box includes a box body, a front window and a rear window. The top of the box body is open, the front panel of the box body is provided with a front window, and the rear panel of the box body is provided with a rear window. The front window is sealed and fixed on the front panel of the box body, and the front window can block the front window. The rear window is sealed and fixed on the rear panel of the box body, and the rear window can block the rear window. The front end of the antifreeze liquid bag and the front end of the freezing tube are both fixed on the front window, and the rear end of the antifreeze liquid bag and the rear end of the freezing tube are both fixed on the rear window.

3. The tunnel excavation test device according to claim 2, characterized in that: The inner side surface of the front viewing window is flush with the inner side surface of the front panel of the box body; a front tunnel hole and a plurality of front mounting holes are formed on the front viewing window; a front protruding end cover is sealed and fixedly provided around the front tunnel hole on the outer side surface of the front viewing window; a front accommodating groove is formed on the front protruding end cover, the front accommodating groove is communicated with the front tunnel hole, and the front end of the antifreeze liquid bag extends into the front accommodating groove; the front mounting holes correspond one-to-one with the freezing pipes, and the front ends of the freezing pipes are fixedly provided in the front mounting holes; The inner side surface of the rear view window is flush with the inner side surface of the rear panel of the box body, and a rear tunnel hole and a plurality of rear mounting holes are provided on the rear view window. A rear protruding end cover is sealed and fixed around the rear tunnel hole on the outer side surface of the rear view window, and a rear accommodating groove is provided on the rear protruding end cover. The rear accommodating groove is connected with the rear tunnel hole, and the rear end of the antifreeze liquid bag extends into the rear accommodating groove; the rear mounting holes correspond one-to-one to the freezing pipes, and the rear end of the freezing pipes is fixed in the rear mounting holes.

4. The tunnel excavation test device according to claim 3, characterized in that: It also includes a through tube, a through hole is opened on the rear protruding end cover, the first end of the through tube is fixedly arranged on the rear end of the antifreeze liquid bag, the interior of the through tube is communicated with the interior of the antifreeze liquid bag, the second end of the through tube passes through the through hole and extends to the outside of the box, the through tube and the through hole are fixedly connected by a threaded seal, and the second end of the through tube can be communicated with the outside of the box.

5. The tunnel excavation test device according to claim 4, characterized in that: A flow meter and a valve are provided on the second end of the through-tube. The flow meter can detect the flow of the antifreeze liquid in the through-tube, and the valve can control the on-off of the through-tube.

6. The tunnel excavation test device according to claim 4, characterized in that: The through tube is threadedly connected to the through hole; the front protruding end cover includes a front cover plate and a front baffle ring, the front baffle ring is placed between the front cover plate and the outer side surface of the front window, one end of the front baffle ring is communicated with the front tunnel hole, the front cover plate can block the other end of the front baffle ring, the front cover plate, the front baffle ring and the front window are sealed and connected by bolts; the rear protruding end cover includes a rear cover plate and a rear baffle ring, the rear baffle ring is placed between the rear cover plate and the outer side surface of the rear window, one end of the rear baffle ring is communicated with the rear tunnel hole, the rear cover plate can block the other end of the rear baffle ring, the rear cover plate, the rear baffle ring and the rear window are sealed and connected by bolts; the through hole is opened on the rear cover plate.

7. The tunnel excavation test device according to claim 3, characterized in that: The cam is secured to the front of the box body by means of a latch, and the cam is secured to the rear of the box body by means of a latch, and the latch is secured to the rear of the box body by means of a latch, and the cam is secured to the rear of the box body by means of a latch, and the cam is secured to the rear of the box body by means of a latch, and the cam is secured to the rear of the box body by means of a latch, and the cam is secured to the rear of the box body by means of a latch, and the cam is secured to the rear of the box body by means of a latch, and the cam is secured to the rear of the box body by means of a latch, and the cam is secured to the rear of the box body by means of a latch, and the cam is secured to the rear of the box body by means of a latch, 8. The tunnel excavation test device according to claim 1, characterized in that: It also includes a flow divider, a flow combiner and a refrigeration unit, the freezing pipe includes an inner pipe and an outer pipe, the first end of the inner pipe is provided with a liquid outlet, the second end of the inner pipe is provided with a liquid inlet, the outer pipe is fixedly sleeved outside the inner pipe, a flow gap is left between the inner side wall of the outer pipe and the outer side wall of the inner pipe, the first end of the outer pipe is closed, the first end of the outer pipe is placed at the liquid outlet, a drainage port is provided on the side wall of the outer pipe, so that the refrigerant enters the inner pipe from the liquid inlet, and then flows out from the inner pipe. The liquid outlet enters the flow gap and finally leaves the outer tube from the drainage port; the liquid supply port of the refrigeration unit is connected with the diverter, and the diverter is connected with all the liquid inlets, and the diverter diverts the refrigerant provided by the liquid supply port of the refrigeration unit into each of the liquid inlets; the return liquid port of the refrigeration unit is connected with the merger, and the merger is connected with all the drainage ports, and the merger merges the refrigerant flowing out of each of the drainage ports into the return liquid port of the refrigeration unit.

9. The tunnel excavation test device according to claim 1, characterized in that: It also includes several displacement sensors, several pressure sensors and several temperature sensors, which are all fixedly arranged in the model box. The displacement sensor can detect the soil displacement inside the test soil body, the pressure sensor can detect the soil pressure inside the test soil body, and the temperature sensor can detect the soil temperature inside the test soil body. A smooth film is fixedly laid on the inner side of the model box, and a lubricating liquid is applied to the surface of the smooth film close to the test soil body.

10. A tunnel excavation test method using the tunnel excavation test apparatus according to any one of claims 1 to 9, characterized in that: include: Tunnel excavation simulation in thawing soil: includes the following steps: S11: Set up tunnel excavation test equipment; S12: Prepare the test soil and fill the test soil into the model box; S13: injecting water into the model box through the water injection port; S14: simulate tunnel excavation by draining the antifreeze liquid bag and record all monitoring data during the antifreeze liquid bag drainage process; Simulation of tunnel excavation in artificially frozen ground: includes the following steps: S21: Set up tunnel excavation test equipment; S22: Prepare the test soil and fill the test soil into the model box; S23: injecting water into the model box through the water injection port; S24: circulating a refrigerant in the freezing pipe to freeze the water-containing soil in the area where the freezing pipe is located; S25: After the freezing wall is closed, the antifreeze liquid bag is drained to simulate tunnel excavation, and all monitoring data during the antifreeze liquid bag drainage process are recorded; Tunnel excavation simulation in partially frozen failure strata includes the following steps: S31: Set up tunnel excavation test equipment; S32: Prepare the test soil and fill the test soil into the model box; S33: injecting water into the model box through the water injection port; S34: closing the circulating cold bath or removing the freezing pipe at the freezing failure simulation location to simulate the local freezing failure ground state, and circulating the freezing liquid in the remaining freezing pipes to freeze the water-bearing soil in the area where the freezing pipes are located until the freezing wall of the area to be frozen is completed; S35: After the soil layer enters a state of partial freezing failure, tunnel excavation is simulated by draining the antifreeze liquid bag, and all monitoring data during the antifreeze liquid bag drainage process are recorded.

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