Tunnel surrounding rock limit strain simulation device and simulation method based on deformation control

Abstract

The application discloses a tunnel surrounding rock limit strain simulation device and simulation method based on deformation control, the simulation device comprises a model box, a pressurizing device, an excavation simulation device and an information acquisition device, the front and back thickness of the model box is less than one fifth of the left and right width, the upper edge, the left edge and the right edge of the model box are all opened and are respectively provided with the pressurizing device, the excavation simulation device comprises an electric heating melting device and an electric heating controller, the electric heating melting device comprises a center support pipe, a melting ring, a heat insulation sheet and an electric heating wire, the simulation method comprises the following steps: filling the tunnel surrounding rock filler into the model box; obtaining pressure data through three-side pressurizing; melting the melting ring; obtaining stress and strain data and deformation control size data; establishing a surrounding rock stress and strain curve; and analyzing the surrounding rock deformation and failure law and limit strain characteristics under different confining pressures and porosities. The application can realize the simulation test of the deformation of the surrounding rock after excavation in different time and different regions, and the test result is accurate and comprehensive.

Description

Technical Field

[0001] This invention belongs to the field of tunnel simulation test technology, specifically relating to a tunnel surrounding rock ultimate strain simulation device, and more particularly to a tunnel surrounding rock ultimate strain simulation device and simulation method based on deformation control. Background Technology

[0002] Mountainous areas account for more than two-thirds of China's land area, making tunnel engineering an indispensable part of the transportation network. The deformation and stability of the surrounding rock in tunnels is a key and challenging issue in tunnel engineering. Controlling the deformation of the surrounding rock and fully utilizing its self-supporting capacity are crucial technical issues in tunnel construction.

[0003] The core of controlling surrounding rock deformation and fully utilizing its self-supporting capacity lies in clarifying the safety reserve range of the surrounding rock, which can be characterized by the ultimate strain index. Ultimate strain is the strain level around the tunnel where deformation and instability may occur after tunnel excavation, and it is a key indicator for measuring the stability of the surrounding rock. The relative relationship between surrounding rock deformation and ultimate strain can be used to determine the stability and safety reserve of the surrounding rock itself.

[0004] Research on the ultimate strain of tunnel surrounding rock can be mainly divided into two categories: one is based on statistical analysis such as field measurements; the other is based on theoretical research and prediction using model experiments or numerical simulations. Field measurements involve significant investment and time, resulting in high costs; numerical simulations are highly subjective, and the selection of parameters greatly influences the results. Relatively speaking, model experiments are a method that balances cost and accuracy.

[0005] Traditional model experiments on the ultimate strain of tunnel surrounding rock generally adopt a graded loading method, which is contrary to the excavation unloading-stress release process of tunnel excavation. Model test studies also usually use three-dimensional models, which are complex, difficult to control, and have unsatisfactory experimental results. Moreover, they rarely consider the spatial variability of the surrounding rock itself, such as voids.

[0006] The invention application with application number "201310616750.7" discloses an indoor model test device for tunnel excavation, including a model box, a tunnel structure model, a loading device and an excavation device. Rosin rods are installed in the model box, and heating wires are wound around the rosin rods. The rosin rods are melted by heating with the heating wires, so as to simulate the impact of tunnel excavation on the surrounding fill material.

[0007] The aforementioned invention application also has the following drawbacks: the entire model device is too long in the excavation direction, making it impossible to conduct planar model experiments or combine it with the convergence constraint model in tunnel structure design for research, which makes it difficult to accurately study the deformation and failure laws of the surrounding rock; the rosin rod is a single unit, and when it is melted by the heating wire, it can only be melted continuously, and cannot achieve the function of melting in different times, layers, or regions, which makes it impossible to simulate the deformation of the surrounding rock after excavation in different times and regions, so the test results are not accurate and comprehensive enough; there is only a pressure device on the top, so pressure can only be applied from the top, which cannot simulate the confining pressure or the three-dimensional stress field of the tunnel in actual engineering, which also makes it difficult to accurately study the deformation and failure laws of the surrounding rock. Summary of the Invention

[0008] The purpose of this invention is to provide a tunnel surrounding rock ultimate strain simulation device and method based on deformation control in order to solve the above problems. The simulation device can simulate the tunnel excavation unloading-stress release process under different confining pressure conditions in a two-dimensional plane, study the deformation and failure law and ultimate strain characteristics of the surrounding rock, and provide a basis for the safety and stability of tunnel construction and operation.

[0009] The present invention achieves the above objectives through the following technical solutions:

[0010] A tunnel surrounding rock ultimate strain simulation device based on deformation control includes a model box, a pressurizing device, an excavation simulation device, and an information acquisition device. Transparent plates are installed on the front and rear sides of the model box, with a central through-hole at the center of each plate. The front-to-back thickness of the model box is less than one-fifth of its left-to-right width. The model box has openings on its top, left, and right sides, each housing the pressurizing device. The pressurizing device includes electric jacks, a pressure data receiver, and a pressure monitoring host. The signal output terminals of multiple electric jacks are connected to the signal input terminal of the pressure data receiver via wires, and the signal output terminal of the pressure data receiver is connected to the signal input terminal of the pressure monitoring host. The excavation simulation device includes an electrothermal melting device and an electrothermal controller. The electrothermal melting device includes a central support tube, melting rings, heat insulation sheets, and heating wires. Multiple melting rings of different diameters, capable of melting at high temperatures, are sequentially fitted around the central support tube. A heat insulation sheet is provided between each two adjacent melting rings. Multiple heating wires are arranged circumferentially on the surface of each melting ring. All heating wires are connected to the electrothermal controller via wires. The electrothermal melting device is installed inside the model box at a position corresponding to the central through-hole of the transparent plate. The information acquisition device includes earth pressure cells, strain gauges, a stress-strain data receiver, and a stress-strain monitoring host. Multiple earth pressure cells are respectively located inside the model box and on the outer periphery of the electrothermal melting device, evenly distributed circumferentially. Multiple strain gauges are placed inside the model box and positioned between the electrothermal melting device and the four sides of the model box. The signal output terminals of the multiple earth pressure cells and the multiple strain gauges are respectively connected to the signal input terminal of the stress-strain data receiver via wires. The signal output terminal of the stress-strain data receiver is connected to the signal input terminal of the stress-strain monitoring host.

[0011] Preferably, in order to achieve reliable pressure loading, the pressurizing device further includes a reaction beam, a pressure plate, and a movable plate. The reaction beam is installed on the corresponding opening side of the model box, and two electric jacks are installed on the inner side of the reaction beam. The telescopic rods of the two electric jacks are connected to the pressure plate. The movable plate is placed inside the corresponding opening side of the model box and inside the pressure plate. The pressure plate and the movable plate are connected by a force transmission rod.

[0012] Preferably, to achieve reliable heating and melting, the melting ring is a rosin ring made of rosin; to achieve good heat insulation, the heat insulation sheet is asbestos cloth; to facilitate the installation of the electrothermal melting device and the lead wire, both ends of the electrothermal melting device are respectively placed in the central through holes of the two transparent plates, and the central support pipe is a steel pipe with through holes on its wall for the wire to pass through; to facilitate observation of the actual changes in the tunnel surrounding rock filling material in the model box, the transparent plate is a glass plate with longitudinal and transverse scale lines.

[0013] A simulation method using a deformation-controlled tunnel surrounding rock ultimate strain simulation device includes the following steps:

[0014] Step 1: Fill the tunnel surrounding rock filler into the model box, and assemble the model box, pressurization device, excavation simulation device and information acquisition device;

[0015] Step 2: Use three pressurizing devices to pressurize the tunnel surrounding rock filling material on the top, left and right sides of the model box respectively. The same pressure loading method or different pressure loading method on the three sides is adopted. The pressure data after pressurizing the three sides of the model box is collected and recorded by the pressure data receiver and the pressure monitoring host.

[0016] Step 3: Control the heating wire to heat up through the electric heating controller, so that the melting ring of the electric heating melting device begins to melt. The melting method is one of the following: continuous melting from the outside to the inside, intermittent melting from the outside to the inside, continuous melting from the outside to the inside, or intermittent melting from the outside to the inside. Observe the changes in the tunnel surrounding rock filling and the electric heating melting device through the transparent plate.

[0017] Step 4: Collect and record the stress and strain data of the tunnel surrounding rock filler during the melting process of the electrothermal melting device using an information acquisition device;

[0018] Step 5: Extract the pressure data applied by the pressurizing device and the stress-strain data of the tunnel surrounding rock filler, and combine them with the deformation control data of the electrothermal melting device corresponding to each stage of the excavation process by the excavation simulation device to establish the stress-strain curve of the surrounding rock.

[0019] Step 6: Repeat steps 1-5, and use tunnel surrounding rock fillers with different porosities in step 1 and different pressures in step 2 to obtain stress-strain curves of surrounding rock under different confining pressures and porosities. Analyze the deformation and failure law and ultimate strain characteristics of surrounding rock under different confining pressures and porosities, and study the deformation evolution and failure law of surrounding rock during excavation unloading-stress release process.

[0020] Preferably, in order to prepare tunnel surrounding rock fillers with different porosities to achieve a more realistic simulation test effect, in step 1, the geometric similarity ratio between the tunnel surrounding rock filler and the real tunnel soil is 1:50, the gravitational acceleration similarity ratio is 1:1, and the density similarity ratio is 1:1. The tunnel surrounding rock filler is prepared using barite powder, fly ash, cement, and foam particles, and the porosity of the tunnel surrounding rock filler is changed by changing the volume ratio of foam particles.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention reduces the thickness of the model box at both ends, enabling the simulation device to conduct planar model experiments. It can be combined with convergence constraint models in tunnel structure design for research, effectively reflecting the three-dimensional excavation conditions of the tunnel and facilitating accurate study of surrounding rock deformation and failure patterns. The excavation simulation device, composed of a central support pipe, melting ring, heat insulation sheet, and heating wire, allows for various melting methods as needed, including continuous melting from the outside in, intermittent melting from the outside in, and localized continuous melting from the outside in. This ultimately achieves time-sharing, layered, and regional melting capabilities, enabling simulation tests of surrounding rock deformation after excavation in different times and areas. It accurately simulates the excavation unloading-stress release process, providing precise and comprehensive test results. By installing pressurizing devices on the top, left, and right sides of the model box, tunnel excavation conditions under different confining pressures can be simulated, further enhancing the accuracy of the test results. Using the simulation method of this invention, stress-strain curves of surrounding rock under different confining pressures and porosities can be obtained, achieving a more accurate and comprehensive simulation test objective. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural schematic diagram of the tunnel surrounding rock ultimate strain simulation device based on deformation control described in this invention;

[0024] Figure 2 This is a three-dimensional structural diagram of the model box of the tunnel surrounding rock ultimate strain simulation device based on deformation control described in this invention;

[0025] Figure 3 This is a three-dimensional structural diagram of the electrothermal melting device of the tunnel surrounding rock ultimate strain simulation device based on deformation control described in this invention. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings:

[0027] like Figures 1-3As shown, the tunnel surrounding rock ultimate strain simulation device based on deformation control of the present invention includes a model box 1, a pressurizing device, an excavation simulation device, and an information acquisition device. Transparent plates 2 are installed on the front and rear sides of the model box 1, and a central through hole 18 is provided at the center of the transparent plates 2. The front-to-back thickness of the model box 1 (the front-to-back direction is the simulated tunnel excavation direction) is less than one-fifth of its left-to-right width (the left-to-right width and top-to-bottom height are the same in the figure), preferably one-tenth of its left-to-right width. The top, left, and right sides of the model box 1 are all open, and the pressurizing device is installed on each of them. The pressurizing device includes... The device includes electric jacks 6, pressure data receivers 12, and pressure monitoring hosts 13. The signal output terminals of multiple electric jacks 6 are connected to the signal input terminals of the pressure data receivers 12 via wires. The signal output terminals of the pressure data receivers 12 are connected to the signal input terminals of the pressure monitoring hosts 13. The excavation simulation device includes an electrothermal melting device 9 and an electrothermal controller 11. The electrothermal melting device 9 includes a central support tube 94, melting rings 92, heat insulation sheets 91, and heating wires 93. Multiple melting rings 92 of different diameters, capable of melting at high temperatures, are sequentially fitted around the central support tube 94. A heat insulation sheet 91 is provided between each two adjacent melting rings 92. Multiple heating wires 93 are arranged circumferentially on the surface (preferably the outer surface) of each melting ring 92 (they can be placed directly on the outer surface of the melting ring 92 or embedded within it). All heating wires 93 are connected to the electric heating controller 11 via wires (the wires are led out from the through hole of the central support tube 94). The electric heating melting device 9 is installed inside the model box 1 at a position corresponding to the central through hole 18 of the transparent plate 2. The information acquisition device includes an earth pressure cell 8, a strain gauge 3, and a stress-strain data receiver 1. 4. A stress-strain monitoring host 15 is included. Multiple (four shown in the figure) earth pressure cells 8 are respectively placed inside the model box 1 and located on the outer periphery of the electrothermal melting device 9, evenly distributed along the circumference. Multiple (four shown in the figure) strain gauges 3 are placed inside the model box 1 and located between the electrothermal melting device 9 and the four sides of the model box 1. The signal output terminals of the multiple earth pressure cells 8 and the multiple strain gauges 3 are respectively connected to the signal input terminal of the stress-strain data receiver 14 through wires. The signal output terminal of the stress-strain data receiver 14 is connected to the signal input terminal of the stress-strain monitoring host 15. The wires connecting the earth pressure cells 8 and the strain gauges 3 are respectively led out through the corresponding small holes 17 on the transparent plate 2.

[0028] like Figures 1-3 As shown, the present invention also discloses the following more optimized specific structures:

[0029] To achieve reliable pressure loading, the pressurizing device also includes a reaction beam 4, a pressure plate 5, and a movable plate 10 (preferably an iron plate). The reaction beam 4 is installed on the corresponding opening side of the model box 1. Two electric jacks 6 are installed on the inner side of the reaction beam 4. The telescopic rods of the two electric jacks 6 are connected to the pressure plate 5. The movable plate 10 is placed inside the corresponding opening side of the model box 1 and inside the pressure plate 5. The pressure plate 5 and the movable plate 10 are connected by a force transmission rod 7.

[0030] To achieve reliable heating and melting, the melting ring 92 is a rosin ring made of rosin. To achieve good heat insulation, the heat insulation sheet 91 is made of asbestos cloth. To facilitate the installation of the electric heating melting device 9 and the lead wire, the two ends of the electric heating melting device 9 are respectively placed in the central through holes 18 of the two transparent plates 2. The central support pipe 94 is a steel pipe with through holes on its wall for the wire to pass through. To facilitate observation of the actual changes in the tunnel surrounding rock filling material in the model box 1, the transparent plate 2 is a glass plate with longitudinal and transverse scale lines.

[0031] The working principle of the present invention will be explained in detail below using a preferred simulation method:

[0032] like Figures 1-3 As shown, the simulation method employed by the deformation-controlled tunnel surrounding rock ultimate strain simulation device of the present invention includes the following steps:

[0033] Step 1: Fill the tunnel surrounding rock filler (not shown in the figure) into model box 1, and assemble model box 1, pressurization device, excavation simulation device and information acquisition device; the geometric similarity ratio of the tunnel surrounding rock filler to the real tunnel soil is 1:50, the similarity ratio of gravity acceleration is 1:1, and the similarity ratio of density is 1:1. The tunnel surrounding rock filler is prepared using barite powder, fly ash, cement and foam particles, and the porosity of the tunnel surrounding rock filler is changed by changing the volume ratio of foam particles; the specific process of filling and assembling each component is not described in detail here, and can be completed using conventional methods.

[0034] Step 2: Use three pressurizing devices to pressurize the tunnel surrounding rock filling material on the top, left and right sides of the model box 1 respectively, using the same pressure loading method on the three sides or different pressure loading methods on the three sides. Collect and record the pressure data of the three sides of the model box 1 after pressurization through the pressure data receiver 12 and the pressure monitoring host 13.

[0035] Step 3: Control the heating wire 93 to heat up through the electric heating controller 11, so that the melting ring 92 of the electric heating melting device 9 begins to melt. The melting method is one of the following: continuous melting from the outside to the inside, intermittent melting from the outside to the inside, continuous melting from the outside to the inside, and intermittent melting from the outside to the inside. Observe the changes of the tunnel surrounding rock filler and the electric heating melting device 9 through the transparent plate 2.

[0036] Step 4: Collect and record the stress and strain data of the tunnel surrounding rock filler during the melting process of the electrothermal melting device 9 using the information acquisition device;

[0037] Step 5: Extract the pressure data applied by the pressurizing device and the stress-strain data of the tunnel surrounding rock filler, and combine them with the deformation control data of the electrothermal melting device 9 corresponding to each stage of the excavation process simulated by the excavation simulation device to establish the surrounding rock stress-strain curve; the stress-strain data of the tunnel surrounding rock filler is used to compare with the deformation control data of the electrothermal melting device 9.

[0038] Step 6: Repeat steps 1-5, and use tunnel surrounding rock fillers with different porosities in step 1 and different pressures in step 2 to obtain stress-strain curves of surrounding rock under different confining pressures and porosities. Analyze the deformation and failure law and ultimate strain characteristics of surrounding rock under different confining pressures and porosities, and study the deformation evolution and failure law of surrounding rock during excavation unloading-stress release process.

[0039] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the technical solutions of the present invention. Any technical solution that can be implemented based on the above embodiments without creative effort should be considered to fall within the scope of protection of the patent of the present invention.

Claims

1. A tunnel surrounding rock ultimate strain simulation device based on deformation control, comprising a model box, a pressurizing device, an excavation simulation device, and an information acquisition device, wherein transparent plates are respectively installed on the front and rear sides of the model box, and a central through hole is provided at the center of the transparent plate, characterized in that: The front-to-back thickness of the model box is less than one-fifth of its left-to-right width. The top, left, and right sides of the model box are open, and the pressurizing device is installed on each of them. The pressurizing device includes electric jacks, a pressure data receiver, and a pressure monitoring host. The signal output terminals of multiple electric jacks are connected to the signal input terminals of the pressure data receiver via wires. The signal output terminal of the pressure data receiver is connected to the signal input terminal of the pressure monitoring host. The excavation simulation device includes an electrothermal melting device and an electrothermal controller. The electrothermal melting device includes a central support tube, melting rings, heat insulation sheets, and heating wires. Multiple melting rings of different diameters capable of melting at high temperatures are sequentially fitted around the central support tube. A heat insulation sheet is provided between every two adjacent melting rings. Multiple grooves are provided along the circumferential direction on the surface of each melting ring. The heating wires are all connected to the heating controller via wires. The electrothermal melting device is installed inside the model box at a position corresponding to the central through hole of the transparent plate. The information acquisition device includes earth pressure cells, strain gauges, stress-strain data receivers, and stress-strain monitoring hosts. Multiple earth pressure cells are respectively located inside the model box and on the outer periphery of the electrothermal melting device, evenly distributed along the circumference. Multiple strain gauges are placed inside the model box and located between the electrothermal melting device and the four sides of the model box. The signal output terminals of the multiple earth pressure cells and the multiple strain gauges are respectively connected to the signal input terminal of the stress-strain data receiver via wires. The signal output terminal of the stress-strain data receiver is connected to the signal input terminal of the stress-strain monitoring host.

2. The tunnel surrounding rock ultimate strain simulation device based on deformation control according to claim 1, characterized in that: The pressurizing device also includes a reaction beam, a pressure plate, and a movable plate. The reaction beam is installed on the corresponding opening side of the model box. Two electric jacks are installed on the inner side of the reaction beam. The telescopic rods of the two electric jacks are connected to the pressure plate. The movable plate is placed inside the corresponding opening side of the model box and inside the pressure plate. The pressure plate and the movable plate are connected by a force transmission rod.

3. The tunnel surrounding rock ultimate strain simulation device based on deformation control according to claim 1 or 2, characterized in that: The melting ring is a circular rosin ring made of rosin; the heat insulation sheet is asbestos cloth; the two ends of the electrothermal melting device are respectively placed in the central through holes of the two transparent plates; the central support tube is a steel pipe and its wall is provided with through holes for wires to pass through; the transparent plate is a glass plate with longitudinal and transverse scale lines.

4. A simulation method used in a tunnel surrounding rock ultimate strain simulation device based on deformation control as described in claim 1 or 2, characterized in that: Includes the following steps: Step 1: Fill the tunnel surrounding rock filler into the model box, and assemble the model box, pressurization device, excavation simulation device and information acquisition device; Step 2: Use three pressurizing devices to pressurize the tunnel surrounding rock filling material on the top, left and right sides of the model box respectively. The same pressure loading method or different pressure loading method on the three sides is adopted. The pressure data after pressurizing the three sides of the model box is collected and recorded by the pressure data receiver and the pressure monitoring host. Step 3: Control the heating wire to heat up through the electric heating controller, so that the melting ring of the electric heating melting device begins to melt. The melting method is one of the following: continuous melting from the outside to the inside, intermittent melting from the outside to the inside, continuous melting from the outside to the inside, or intermittent melting from the outside to the inside. Observe the changes in the tunnel surrounding rock filling and the electric heating melting device through the transparent plate. Step 4: Collect and record the stress and strain data of the tunnel surrounding rock filler during the melting process of the electrothermal melting device using an information acquisition device; Step 5: Extract the pressure data applied by the pressurizing device and the stress-strain data of the tunnel surrounding rock filler, and combine them with the deformation control data of the electrothermal melting device corresponding to each stage of the excavation process by the excavation simulation device to establish the stress-strain curve of the surrounding rock. Step 6: Repeat steps 1-5, and use tunnel surrounding rock fillers with different porosities in step 1 and different pressures in step 2 to obtain stress-strain curves of surrounding rock under different confining pressures and porosities. Analyze the deformation and failure law and ultimate strain characteristics of surrounding rock under different confining pressures and porosities, and study the deformation evolution and failure law of surrounding rock during excavation unloading-stress release process.

5. The simulation method according to claim 4, characterized in that: In step 1, the geometric similarity ratio of the tunnel surrounding rock filler to the actual tunnel soil is 1:50, the similarity ratio of gravity acceleration is 1:1, and the similarity ratio of density is 1:

1. The tunnel surrounding rock filler is prepared using barite powder, fly ash, cement, and foam particles, and the porosity of the tunnel surrounding rock filler is changed by changing the volume ratio of foam particles.

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