Manufacturing method of cross-fault tunnel model for simulating high confining pressure and high ground stress environment

Abstract

The invention provides a manufacturing method of a cross-fault tunnel model for simulating a high confining pressure and high ground stress environment, and the method comprises the following steps: S1, manufacturing layered shear boxes which comprise a plurality of first shear boxes and a plurality of second shear boxes which are connected through universal connecting pieces; the first shearing box comprises a first cavity, and the second shearing box comprises a second cavity; s2, the first cavity and the second cavity are filled with foam expansive concrete, and a fault rock model for simulating the tunnel excavation position is obtained; s3, a surrounding rock hole is formed in the middle of the fault rock model to simulate the tunnel excavation process, and a surrounding rock hole model is obtained; and S4, a tunnel model is placed in the surrounding rock hole, the space between the tunnel model and the surrounding rock hole is filled with a polyurethane expansion material, and the cross-fault tunnel model simulating the high confining pressure and high ground stress environment is obtained. According to the method, the stress state of the tunnel in complex geological environments such as high confining pressure and high ground stress is more truly represented.

Description

Technical Field

[0001] The present invention belongs to the field of geotechnical engineering, and particularly relates to a cross-fault tunnel model capable of simulating high confining pressure and high in-situ stress environments and a manufacturing method thereof. Background Art

[0002] With the large-scale development and construction of tunnels in China, how to truly simulate the stress state of tunnels underground in the laboratory has become an urgent problem to be solved in the field of civil engineering technology. During the tunnel construction process, it is often necessary to cross faults, and the influence of fault activities on tunnels is extremely complex. Especially in high confining pressure and high in-situ stress environments, the stability problem of tunnels is particularly prominent. Traditional laboratory simulation methods often fail to accurately reflect these complex geological conditions, resulting in a large difference between the experimental results and the actual engineering situation. Traditional laboratory simulation methods often cannot accurately reproduce the stress state of tunnels under complex geological environments such as high confining pressure and high in-situ stress. For example, in the prior art, the patent document with the application number 201810162269.8 provides a layered shear model soil box and a method for measuring the strain of the soil in the model soil box. The main body of the model soil box is composed of stacked layered frames. There are sliding grooves, rollers and bow-shaped steel sheets between adjacent two frames, and a reaction force loading device is also provided to simulate the overlying load of the soil.

[0003] The above-mentioned model soil box simulates the overlying load through the reaction force loading device, and cannot uniformly apply high in-situ stress to the soil. The deformation and confining pressure inside the soil are not the same everywhere, and there will be local stress concentration, and it cannot truly reflect the high confining pressure and high in-situ stress states of tunnels in the actual environment. Therefore, providing a cross-fault tunnel model capable of truly simulating high confining pressure and high in-situ stress environments and a manufacturing method thereof is of great significance for improving the design and construction levels of tunnel engineering. Summary of the Invention

[0004] To solve the above deficiencies, the present application provides a manufacturing method for a cross-fault tunnel model simulating high confining pressure and high in-situ stress environments. Through designing a specific model structure and manufacturing process, this method can accurately simulate the stress state of tunnels under high confining pressure and high in-situ stress environments.

[0005] Specifically, the method includes the following steps: S1: Manufacture a layered shear box, which includes a plurality of first shear boxes and a plurality of second shear boxes connected by universal joints; the first shear box includes a first cavity, and the second shear box includes a second cavity; S2: Fill the first cavity and the second cavity with foam expanded concrete to obtain a fault rock model simulating the tunnel excavation position; S3: Open a surrounding rock hole in the middle of the fault rock model to simulate the tunnel excavation process, and obtain a surrounding rock hole model; S4: Place the tunnel model into the surrounding rock hole, and fill the space between the tunnel model and the surrounding rock hole with polyurethane expanding material. The polyurethane expanding material applies pressure to the tunnel model to simulate the high confining pressure environment of the tunnel. The foam expanding concrete expands under the constraint of the first shear box and the second shear box to simulate the high in-situ stress environment of the tunnel, obtaining a cross-fault tunnel model under the simulated high confining pressure and high in-situ stress environment.

[0006] Further, S2 includes: S2.1: Determine the addition amount of the foam concrete expanding agent in the foam concrete according to the in-situ stress at the tunnel excavation location to obtain the prepared foam expanding concrete. The magnitude of the in-situ stress is determined by the in-situ stress detection data at the tunnel excavation location, and the addition amount of the foam concrete expanding agent is determined by the concrete stress-strain curve. S2.2 Stir the prepared foam expanding concrete, pour the stirred foam expanding concrete into the layered shear box, and wait for the foam concrete to cure and harden to obtain the fault rock model.

[0007] Further, the foam expanding concrete is the foam expanding concrete added with the HCSA expanding agent produced by Wuhan Sanyuan Special Building Materials Co., Ltd.

[0008] Further, in S4, the expanding material is polyurethane expanding material, and the addition amount of the polyurethane expanding material is determined by the magnitude of the confining pressure of the lining. The magnitude of the confining pressure is determined by the tunnel confining pressure calculation method in the "Code for Design of Highway Tunnels (Volume 1, Civil Engineering Manual)".

[0009] Further, strain gauges are arranged in both the multi-fault rock model and the tunnel model.

[0010] Further, the first shear box is surrounded by several fixedly connected first side plates; the second shear box is surrounded by several detachably connected second side plates; the universal joint is arranged at the connection of the first side plates or the second side plates. The first side plates enclose the first cavity, and the second side plates enclose the second cavity.

[0011] Further, the universal joint includes a universal ball and an upper ball groove and a lower ball groove for accommodating the universal ball. The upper ball groove is arranged at the top connection of the first side plates or the second side plates, and the lower ball groove is arranged at the bottom connection of the first side plates or the second side plates. The radii of the upper ball groove and the lower ball groove are greater than the radius of the universal ball, and the total depth of the upper ball groove and the lower ball groove is less than the diameter of the universal ball.

[0012] Further, both the first side plates and the second side plates are acrylic plates, and the second side plates are detachably connected by bolts.

[0013] Further, a plurality of the second shear boxes are arranged in the middle of the layered shear box.

[0014] Further, a frame is arranged around the layered shear box. The frame includes an upper bottom plate frame, a lower bottom plate frame, and columns connecting the upper bottom plate frame and the lower bottom plate frame. Upper bottom plate mounting holes are provided on the upper bottom plate frame, and a lower bottom plate is fixedly arranged in the lower bottom plate frame.

[0015] The beneficial technical effects of the present application are as follows: This method not only considers the influence of the rock deposition process on tunnel excavation, but also simulates the high confining pressure environment by applying pressure with expansion materials, and uses the expansion of foam-expanded concrete under the constraint of the shear box to simulate the high in-situ stress environment, thereby realizing a comprehensive simulation of the true stress state of the tunnel. In addition, by arranging strain gauges, the deformation of the tunnel model and the surrounding rock model can be monitored in real time, providing more reliable data support for tunnel design and construction. By simulating a cross-fault tunnel under high confining pressure and high in-situ stress environments, the stability and safety of the tunnel under such complex geological conditions can be evaluated more accurately, providing a reliable basis for subsequent various tests.

[0016] Compared with the traditional laboratory simulation method, the method of the present application more truly reproduces the stress state of the tunnel under complex geological environments such as high confining pressure and high in-situ stress, thus greatly improving the accuracy and reliability of the experimental results.

[0017] In addition, the designs of the layered shear box and foam-expanded concrete provided by the present application are not only simple in structure, easy to manufacture and operate, but also have high flexibility and adjustability, and can simulate the stress state of the tunnel under different geological conditions according to actual needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 : Flow chart of the method for manufacturing a cross-fault tunnel model under high confining pressure and high in-situ stress environments of the present application; Figure 2 : Overall structural schematic diagram of the layered shear box of the present application; Figure 3 : Top view structural schematic diagram of the layered shear box of the present application; Figure 4 : Structural schematic diagram of the layered shear box of the present application filled with foam-expanded concrete; Figure 5 : Structural schematic diagram of the frame around the layered shear box of the present application; Figure 6 : Detailed structural schematic diagram of the frame around the layered shear box of the present application; Figure 7: Schematic diagram of the first shear box structure of this application; Figure 8 : Schematic diagram of the second shear box structure of this application; Figure 9 : Schematic diagram of the second side plate of the second shear box of this application; Figure 10 : Schematic diagram of the universal joint of this application; Figure 11 : Schematic diagram of the bottom surface of the first shear box of this application; Figure 12 : Schematic diagram of the physical object of the foamed expanded concrete loaded into the layered shear box of this application; In the above figure: 1 First shear box, 101 First side plate, 2 Second shear box, 201 Second side plate, 3 Universal joint, 301 Universal ball, 302 Upper ball groove, 303 Lower ball groove, 4 Foamed expanded concrete accommodation cavity, 5 Frame, 501 Upper bottom plate, 502 Lower bottom plate, 503 Upper bottom plate frame, 504 Lower bottom plate frame, 505 Support pillar, 6 Foamed expanded concrete, 7 Surrounding rock hole, 8 Tunnel model. Specific embodiments

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0020] In all embodiments of the present invention, unless otherwise specifically defined, the terms are explained as follows.

[0021] High in-situ stress: The stress generated by the self-weight of the overlying rock layers in the deep underground rocks, usually increasing with the increase of depth.

[0022] Rock deposition: The sedimentary sequence process of rocks formed by geological processes such as weathering, transportation, and accumulation in the surface or near-surface environment. During the simulation of the rock deposition process, in this application, foamed expanded concrete is poured into the cavity of the layered shear box, and the expansion characteristics of the concrete are used to simulate the dense packing state of rock deposition.

[0023] Lining: In the field of civil engineering, especially in geotechnical engineering and tunnel engineering, lining refers to a permanent support structure built with materials such as masonry, concrete, or reinforced concrete around the perimeter of a tunnel, cavern, or other underground excavation project to prevent the deformation or collapse of the surrounding rock, as well as to isolate water, prevent weathering, and support the surrounding rock.

[0024] Lining confining pressure: the pressure exerted on the lining structure by the rock mass surrounding it after tunnel excavation.

[0025] With the large-scale development and construction of tunnels in my country, how to simulate the stress state of tunnels underground in the laboratory has become an urgent problem to be solved in the field of civil engineering technology. In the process of tunnel construction, it is often necessary to cross faults, and the impact of fault activity on tunnels is extremely complex, especially in high confining pressure and high ground stress environments, the stability of tunnels is particularly prominent. Traditional laboratory simulation methods are often difficult to accurately reflect these complex geological conditions, resulting in a large difference between experimental results and actual engineering conditions. Traditional laboratory simulation methods are often unable to accurately reproduce the stress state of tunnels under complex geological environments such as high confining pressure and high ground stress. For example, in the prior art, the patent document with application number 201810162269.8 provides a layered shear model soil box and a method for measuring the strain of soil in the model soil box. The model soil box body is composed of layered frames stacked together, and a slide, rollers and bow-shaped steel sheets are provided between two adjacent frames. A reaction loading device is also provided to simulate the overlying load on the soil.

[0026] The above-mentioned model soil box simulates the overburden load through the reaction loading device, which cannot uniformly apply high geostress to the soil. The deformation and confining pressure inside the soil are not the same everywhere, and there will be local stress concentration, which cannot reflect the high confining pressure and high geostress stress state of the tunnel in the real environment. Therefore, providing a cross-fault tunnel model and its production method that can truly simulate the high confining pressure and high geostress environment is of great significance to improving the design and construction level of tunnel engineering.

[0027] To solve the above shortcomings, the present application provides a method for making a cross-fault tunnel model simulating a high confining pressure and high ground stress environment. The method can accurately simulate the stress state of the tunnel under a high confining pressure and high ground stress environment by designing a specific model structure and manufacturing process.

[0028] In some embodiments, Figures 1-12 As shown, the specific technical solution of this application is: S1: manufacturing a layered shear box, wherein the layered shear box comprises a plurality of first shear boxes 1 and a plurality of second shear boxes 2 connected by a universal connector 3; the first shear box 1 comprises a first cavity, and the second shear box 2 comprises a second cavity; like Figure 3 As shown, a plurality of first shear boxes 1 and second shear boxes 2 are stacked, and the first cavity and the second cavity together form a foam expansion concrete containing cavity 4.

[0029] S2: Filling the first cavity and the second cavity with foam expansion concrete 6 to obtain a fault rock model simulating the tunnel excavation location; S3: Open a surrounding rock hole 7 in the middle of the fault rock model to simulate the tunnel excavation process and obtain a surrounding rock hole model; S4: Place the tunnel model 8 into the surrounding rock hole 7. The space between the tunnel model 8 and the surrounding rock hole 7 is filled with polyurethane expansion material, and the polyurethane expansion material applies pressure to the tunnel model 8 to simulate the high confining pressure environment of the tunnel. The foam expanded concrete 6 expands under the constraint of the first shear box 1 and the second shear box 2 to simulate the high in-situ stress environment of the tunnel, and a cross-fault tunnel model under the simulated high confining pressure and high in-situ stress environment is obtained.

[0030] Through the above steps, this application constructs a cross-fault tunnel model capable of simulating the high confining pressure and high in-situ stress environment. During the production process, the design of the mutual dislocation between the layered shear boxes is used to simulate the fault activity, and the use of the foam expanded concrete 6 under the constraint of the layered shear boxes accurately reproduces the tightly packed state of rock deposition. The tunnel excavation process is simulated by opening holes in the multi-fault rock model.

[0031] An expansion material is filled between the tunnel model 8 and the surrounding rock hole 7 because it can apply pressure to the tunnel model, thereby simulating the high confining pressure environment that the tunnel bears underground. In this embodiment, the confining pressure is determined by referring to the confining pressure calculation method in the "Code for Design of Highway Tunnels (Volume 1, Civil Engineering Manual)".

[0032] At the same time, the foam expanded concrete 6 expands under the constraint of the shear box, effectively simulating the influence of the high in-situ stress environment on the tunnel.

[0033] The simulation method of this application not only overcomes the limitations of traditional laboratory simulation methods, such as the inability to uniformly apply high in-situ stress and the inability to truly reflect the stress state of the tunnel under high confining pressure and high in-situ stress environments, but also provides a more accurate and reliable simulation means. This is of great significance for improving the design and construction levels of tunnel engineering and helps engineers better predict the behavior of tunnels under actual geological conditions.

[0034] In some embodiments, the S2 includes, S2.1 Determine the cement grade of the foam concrete, the addition amount of the foam concrete expansion agent, and the addition amount of the foam according to the in-situ stress at the tunnel excavation location to obtain the prepared foam concrete; S2.2 Stir the prepared foam concrete and pour the stirred foam concrete into the layered shear box.

[0035] According to the depth and location of the concrete tunnel to be simulated in the experiment, the density of the rock at this depth, the shear wave velocity of the rock at this depth, the in-situ stress distribution in the rock, and the magnitude of the in-situ stress, determine the cement grade to be used, the addition amount of the foam concrete expander, and the addition amount of the foam. In the experiment, there will be different depths, and several different addition amounts of the concrete expander can be determined according to the in-situ stress data at different depths to simulate different magnitudes of in-situ stress. According to the rock density and strength at the actual depth, change the addition amount of the foam in the foam concrete, which can change the density and strength of the foam concrete. The more foam is added, the lower the strength and density. Then add fly ash, silica fume, and slag powder to both increase the strength of the concrete material and reduce the density of the concrete material. Add SAP to supply water to the concrete material in a closed environment. SAP needs to absorb water one hour in advance before concrete mixing. According to the ratio of 1:50, 1 part of SAP is added to 50 parts of water. After it is saturated with water, it is put into the material. SRA is used to inhibit the dry shrinkage of the concrete. Finally, before the experiment, configure it according to the soil body data to be simulated, and then add water and stir it in the normal concrete mixing method. Then pour the stirred concrete into the layered shear box.

[0036] Use the stress-strain curve of the selected grade of concrete to determine the concrete strength required to achieve the required in-situ stress magnitude, and determine the formula of the foam concrete according to this strength. During the experiment, by adjusting the formula of the foam concrete, the in-situ stress state at different depths and positions can be simulated, so as to further verify the mechanical properties of the tunnel model in a high confining pressure and high in-situ stress environment. It provides a more scientific basis for the design and construction of tunnel engineering.

[0037] In some embodiments, the selected foam-expanded concrete is the foam-expanded concrete added with the HCSA expander produced by Wuhan Sanyuan Special Building Materials Co., Ltd.

[0038] In some embodiments, the expansion material in S4 is the polyurethane expansion material, and the addition amount of the polyurethane expansion material is determined by the magnitude of the confining pressure of the lining.

[0039] The polyurethane expansion material has high strength, high adhesion and good elasticity, and can effectively simulate the real lining confining pressure situation. When connecting, first, the polyurethane expansion material needs to be evenly applied on the outer wall of the tunnel model, and then it is inserted into the surrounding rock hole. After the polyurethane expansion material is cured, the high confining pressure simulation of the tunnel model can be realized. In actual operation, the magnitude of the lining confining pressure can be accurately controlled by adjusting the addition amount of the polyurethane expansion material, so as to meet the simulation requirements of different confining pressure conditions in the experiment. In addition, the use of the polyurethane expansion material can also enhance the connection stability between the tunnel model and the surrounding rock hole model, ensuring the accuracy of the experimental results.

[0040] In some embodiments, strain gauges are provided in both the multi-fault rock model and the tunnel model.

[0041] The strain gauges are provided to monitor the strain conditions of the tunnel model and the rock model during the simulation experiment. Through the feedback data of the strain gauges, the deformation and stress states of the tunnel model under different in-situ stress and confining pressure conditions can be accurately measured and analyzed. These data are crucial for evaluating the stability and safety of the tunnel structure and provide strong support for the design and optimization of tunnel engineering. At the same time, the setting of the strain gauges can also achieve real-time monitoring of the tunnel model during the simulation experiment, ensuring the accuracy and reliability of the experimental results.

[0042] In some embodiments, as Figures 2-12 shown, the layered shear box includes a plurality of first shear boxes 1 and a plurality of second shear boxes 2 connected by universal connectors 3. The first shear box 1 is surrounded by a plurality of fixedly connected first side plates 101; the second shear box 2 is surrounded by a plurality of detachably connected second side plates 201; the universal connectors 3 are arranged at the joints of the first side plates 101 or the second side plates 201. A cavity 4 is formed by the first side plates 101 and the second side plates 201. An upper bottom plate 501 and a lower bottom plate 502 are respectively arranged on the upper opening 401 and the lower opening 402 of the cavity 4; Foam-expanded concrete 6 is poured into the cavity 4. When the foam concrete expands, the first side plates 101 or the second side plates 201, as well as the upper bottom plate 501 and the lower bottom plate 502, will generate uniform and isotropic high in-situ stress on the foam concrete.

[0043] It can be understood that when the foam concrete in the present application expands, it will fill the entire cavity 4. And due to the expansion characteristics of the foam concrete, it will exert uniform pressure on the first side plates 101, the second side plates 201, the upper bottom plate 501, and the lower bottom plate 502. This pressure simulates high in-situ stress, making the foam-expanded concrete in the cavity in a stress state similar to that of rocks deep underground.

[0044] The numbers of the first shear boxes 1 and the second shear boxes 2 can be adjusted according to experimental requirements to simulate rock deposition processes of different scales and complexities. For example, when simulating a shallower sedimentary layer, a smaller number of shear boxes can be used; while when simulating a deeper sedimentary layer or a complex geological structure containing multiple sedimentary layers, the number of shear boxes can be increased.

[0045] The universal connectors 3 not only allow relative movement between the first shear boxes 1 and the second shear boxes 2 to simulate shear deformation during the rock deposition process.

[0046] In some embodiments, as Figure 10 andFigure 11 As shown, the universal joint 3 includes a universal ball 301, an upper ball groove 302 and a lower ball groove 303 for accommodating the universal ball. The upper ball groove 302 is arranged at the top connection of the first side plate 101 or the second side plate 201, and the lower ball groove 303 is arranged at the bottom connection of the first side plate 101 or the second side plate 201. The radii of the upper ball groove and the lower ball groove are larger than that of the universal ball, and the total depth of the upper ball groove 302 and the lower ball groove 303 is smaller than the diameter of the universal ball 301.

[0047] The universal joint 3 allows relative movement between the shear boxes in multiple directions, thus more realistically simulating the complex shear deformation caused by crustal movement or geological activities during the underground rock deposition process. This design enables the layered shear box to simulate a more real and complex geological environment.

[0048] In some embodiments, the radii of the upper ball groove 302 and the lower ball groove 303 are set to be twice as large as the radius of the universal ball 301, and the sum of the depths of the lower circular grooves of the upper ball groove 302 and the lower ball groove 303 is 1 mm smaller than the diameter of the universal ball 301.

[0049] This not only ensures that the shear boxes can move relative to each other through the universal joint but also prevents them from separating from each other. At the same time, such a design also makes the entire layered shear box structure more stable and able to withstand greater stress without being damaged.

[0050] In some embodiments, as Figures 7-9 shown, both the first side plate and the second side plate are acrylic plates.

[0051] Using acrylic plates enables experimenters to clearly observe the expansion process of the foam-expanded concrete in the cavity 4 and the relative movement between the shear boxes, thus facilitating the experimenters to observe and record the experimental results. In addition, acrylic plates also have good transparency and corrosion resistance, which can ensure the accuracy and reliability of the experiment.

[0052] The first shear box 1 is integrally formed with the first side plate 101, and the second shear box 2 is surrounded by a detachable second side plate 201.

[0053] The first shear box 1 is surrounded by the first side plate 101. The first side plate 101 is made of acrylic transparent material, and the first side plates 101 are integrally formed and fixedly connected to form a whole structure for simulating a relatively hard rock layer. Such a design enables the first shear box 1 to maintain good integrity and stability when subjected to high ground stress and shear action.

[0054] As Figure 8As shown, the second shear box 2 in this embodiment is formed by second side plates 201 that are detachably connected by bolts. Such a design facilitates experimenters to adjust the structure and size of the second shear box according to experimental requirements. For example, when simulating the rock deposition process containing soft interlayers or fracture zones, experimenters can simulate the distribution and characteristics of the soft interlayers or fracture zones by disassembling or adjusting the position and quantity of the second side plates 201.

[0055] In this embodiment, the first shear box 1 and the second shear box 2 are made of acrylic plates with a thickness of 5 cm to ensure that the shear boxes around the periphery are absolutely rigid during the expansion stage of concrete curing and hardening and will not be damaged by the expansion of the concrete.

[0056] In some embodiments, a plurality of the second shear boxes 2 are arranged in the middle of the layered shear box.

[0057] In this embodiment, the second shear box 2 is arranged in the layered shear box. After the foam-expanded concrete in the layered shear box is cured, the second shear box 2 is removed to allow the foam-expanded concrete to have an arbitrary deformation range, so as to simulate the fracture zone in the rock formation and more realistically reflect the complex situation during the underground rock deposition process. At the same time, this design also provides more experimental flexibility and operability for experimenters, and they can adjust the position and quantity of the second shear box according to specific experimental requirements to achieve the best simulation effect.

[0058] In some embodiments, as Figure 6 shown, a frame 5 is arranged outside the layered shear box. The frame includes an upper bottom plate frame 503, a lower bottom plate frame 504, and columns 505 connecting the upper bottom plate frame 503 and the lower bottom plate frame. Mounting holes corresponding to the upper bottom plate 501 are arranged on the upper bottom plate frame 503, and the upper bottom plate frame 503 is detachably connected to the upper bottom plate 501 through the mounting holes. The lower bottom plate is fixedly connected to the upper bottom plate frame and the lower bottom plate frame.

[0059] The frame 5 can provide additional support and fixation for the layered shear box to ensure the stability and safety of the layered shear box during the experiment. In this embodiment, the upper bottom plate frame 503, the lower bottom plate frame 504, and the columns 505 are all made of steel bars. The lower bottom plate 504 and the columns 505 are fixedly connected by welding. The connection between the upper bottom plate 501 and the upper bottom plate frame 503 is detachable. By the detachable connection between the mounting holes on the upper bottom plate frame 503 and the upper bottom plate 501, experimenters can conveniently install and disassemble the layered shear box for experimental operations.

[0060] In summary, the present invention provides a layered shear box for use in conjunction with foamed expanded concrete. By adopting a specially designed universal joint, relative movement can occur between the first shear box and the second shear box in multiple directions, thereby simulating the complex shear deformation during the underground rock deposition process. At the same time, by pouring foamed expanded concrete into the cavity and utilizing its expansion characteristics to simulate the high in-situ stress and the tightly packed state of rock deposition, the experimental results are made more realistic and reliable.

[0061] In addition, the layered shear box in the present invention can also simulate the fracture zone in the rock formation through the quantity and position settings of the first shear box and the second shear box, more realistically reflecting the complex conditions during the underground rock deposition process.

[0062] The cross-fault tunnel model for simulating high confining pressure and high in-situ stress environments in this application can provide effective data support for subsequent various tests. For example, the tunnel model of this application can be placed on a shaking table to simulate the tunnel response under seismic action, and observe the deformation and stress conditions of the tunnel model under seismic waves. By adjusting parameters such as the frequency and amplitude of the seismic waves, different levels of seismic action can be simulated, thereby evaluating the seismic performance of the tunnel structure under different seismic conditions. Through the above experiments, the stability and safety of the tunnel under different seismic intensities can be evaluated. The shaking table can simulate seismic motions with different frequencies and amplitudes, thus truly reflecting the impact of earthquakes on the tunnel. During the experiment, key indicators such as the deformation of the tunnel, the degree of damage to the lining structure, and the response characteristics of the surrounding rock can be observed and recorded. These data can provide important reference bases for the seismic design and reinforcement of the tunnel.

[0063] This simulation method not only helps engineers better understand the behavior of the tunnel under seismic action, but also provides a scientific basis for the seismic design of tunnel engineering. At the same time, the simulation method of this application can also be combined with other test means, such as seepage tests and temperature stress tests, to comprehensively evaluate the performance of the tunnel structure under different environments.

[0064] In summary, this application provides a method for fabricating a cross-fault tunnel model for simulating high confining pressure and high in-situ stress environments. This method not only solves the limitations of traditional simulation means in simulating the stress state of tunnels under complex geological conditions, but also realizes the accurate simulation of the mechanical characteristics of tunnels under extreme geological conditions through fine design and experimental steps. The tunnel model fabrication method of the present invention has high flexibility and operability, and can adjust the parameters and structure of the model according to specific experimental requirements to meet the simulation needs under different experimental conditions.

Claims

1. A method for making a cross-fault tunnel model simulating a high confining pressure and high ground stress environment, characterized in that: The method comprises the following steps: S1: manufacturing a layered shear box, the layered shear box comprising a plurality of first shear boxes (1) and a plurality of second shear boxes (2) connected via a universal connector (3); the first shear box (1) comprises a first cavity, and the second shear box (2) comprises a second cavity; S2: filling the first cavity and the second cavity with foam expansion concrete (6) to obtain a fault rock model simulating a tunnel excavation location; S3: opening a surrounding rock hole (7) in the middle of the fault rock model to simulate the tunnel excavation process, thereby obtaining a surrounding rock hole model; S4: placing a tunnel model (8) into the surrounding rock hole (7), filling the space between the tunnel model (8) and the surrounding rock hole (7) with a polyurethane expansion material, and applying pressure to the tunnel model (8) by the polyurethane expansion material to simulate the high confining pressure environment of the tunnel; the foam expansion concrete (6) expands under the constraints of the first shear box (1) and the second shear box (2) to simulate the high ground stress environment of the tunnel, thereby obtaining a cross-fault tunnel model under a simulated high confining pressure and high ground stress environment.

2. The method for making a cross-fault tunnel model simulating a high confining pressure and high ground stress environment according to claim 1, characterized in that: The S2 includes: S2.1: Determine the amount of foam concrete expansion agent added to the foam concrete according to the ground stress at the tunnel excavation location to obtain the configured foam expansion concrete; the ground stress is determined by the ground stress detection data at the tunnel excavation location, and the amount of foam concrete expansion agent added is determined by the concrete stress-strain curve; S2.2 Stir the prepared foam expansion concrete, pour the stirred foam expansion concrete into the layered shear box, and wait for the foam expansion concrete to cure and harden to obtain the fault rock model.

3. The method for making a cross-fault tunnel model simulating a high confining pressure and high ground stress environment according to claim 1, characterized in that: The foamed expansive concrete (6) is foamed expansive concrete to which HCSA expansive agent produced by Wuhan Sanyuan Special Building Materials Co., Ltd. is added.

4. The method for making a cross-fault tunnel model simulating a high confining pressure and high ground stress environment according to claim 1, characterized in that: The amount of the polyurethane expansion material added is determined by the confining pressure, and the confining pressure is determined by the tunnel confining pressure calculation method in the "Highway Tunnel Design Code Volume 1 (Civil Construction Manual)".

5. The method for making a cross-fault tunnel model simulating a high confining pressure and high ground stress environment according to claim 1, characterized in that: Strain gauges are provided in both the fault rock model and the tunnel model.

6. The method for making a cross-fault tunnel model simulating a high confining pressure and high ground stress environment according to claim 1, characterized in that: The first shear box (1) is surrounded by a plurality of fixedly connected first side panels (101); the second shear box (2) is surrounded by a plurality of detachably connected second side panels (201); the universal connector (3) is arranged at the connection between the first side panel (101) or the second side panel (201); the first side panel (101) surrounds the first cavity, and the second side panel (201) surrounds the second cavity.

7. The method for making a cross-fault tunnel model simulating a high confining pressure and high ground stress environment according to claim 6, characterized in that: The universal connecting member (3) comprises a universal ball (301) and an upper ball groove (302) and a lower ball groove (303) for accommodating the universal ball (301); the upper ball groove (302) is arranged at the top connection of the first side plate (101) or the second side plate (201); the lower ball groove (303) is arranged at the bottom connection of the first side plate (101) or the second side plate (201); the radii of the upper ball groove (302) and the lower ball groove (303) are greater than the radius of the universal ball (301); and the total depth of the upper ball groove (302) and the lower ball groove (303) is less than the diameter of the universal ball (301).

8. The method for making a cross-fault tunnel model simulating a high confining pressure and high ground stress environment according to claim 7, characterized in that: The first side plate (101) and the second side plate (201) are both acrylic plates, and the second side plates (201) are detachably connected via bolts.

9. The method for making a cross-fault tunnel model simulating a high confining pressure and high ground stress environment according to claim 1, characterized in that: A plurality of the second shear boxes (2) are arranged in the middle of the layered shear box.

10. The method for making a cross-fault tunnel model simulating a high confining pressure and high ground stress environment according to claim 8, characterized in that: A frame (5) is arranged around the layered shear box, the frame comprising an upper bottom plate frame (503), a lower bottom plate frame (504) and a support (505) connecting the upper bottom plate frame (503) and the lower bottom plate frame (504), an upper bottom plate mounting hole is arranged on the upper bottom plate frame (503), and a lower bottom plate (502) is fixedly arranged in the lower bottom plate frame.

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