Sleeve-shaped tunnel model loading test device and test method

Abstract

The invention discloses a cuff-shaped tunnel model loading test device and a test method, solves the problem that a loading unit cannot be tightly attached to a tunnel model in the prior art, and has the beneficial effects that the accuracy of a test result is ensured, and the same or different loads are applied to each side of the tunnel model. According to the specific scheme, the cuff-shaped tunnel model loading test device comprises a model box, and one side of the model box is made of a transparent material; the device comprises a tunnel model, a cuff loading unit is arranged on the tunnel model in an annular fit mode, a plurality of pressure cavities are formed in the cuff loading unit in the annular direction of the tunnel model, and a gas transmission assembly provides gas sources for the pressure cavities so as to apply the same or different loads to the top, the bottom and the side portions of the tunnel model. The two sides of the cuff loading unit are detachably connected, the tunnel model with the cuff loading unit is placed in the model box, and the model box is filled with a filling material.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel model loading, in particular to a cuff-shaped tunnel model loading test device and a test method. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] In earth tunnels where the high groundwater level changes greatly with the seasons, the tunnel structure will inevitably be subjected to repeated effects of the surrounding variable pressure during service, resulting in fatigue effects. At the same time, the changes in temperature and humidity caused by the change of seasons will cause cracks and deformations in the tunnel lining structure. Therefore, it is extremely important to study the fatigue failure of tunnel structures under such hydrogeological conditions. Compared with other research methods, model tests have the characteristics of repeatability and flexibility. They can intuitively and in real time monitor the changes in mechanical parameters of tunnel structures when they are subjected to different loads. At the same time, the simulation of materials and complex working conditions based on similarity theory is closer to reality, making it the preferred solution for studying the characteristics of tunnel structures.

[0004] For earth tunnels with high groundwater levels, the tunnels are subjected to the dynamic effects of overburden pressure, lateral water pressure and lower buoyancy, which causes different parts of the tunnel structure to be subjected to loads that change irregularly over time and space. Therefore, in order to reveal the temporal and spatial variation of the stress on the tunnel structure in the soil layer under high groundwater levels, accurately simulating the complex load characteristics of the tunnel during operation is the key to accurately predicting its service life. At present, research is being conducted on loading devices for tunnel models: Chinese invention patent with publication number CN118533523A discloses a radial confining pressure loading device for circular arc tunnel lining, which uses a pressurizing component to be installed around the tunnel lining along the axial direction, and applies radial pressure to the tunnel lining through a distribution beam, but there are still spacing bands between the components, which cannot achieve uniform surface-to-surface contact loading, so that the local loading force is different from that of other parts and the stress state of different parts cannot be simulated; Chinese invention patent with publication number CN118566005A discloses an airbag tunnel model test loading device, which uses an airbag loading method to apply the generated force vertically and horizontally to the soil through the top plate and the side plate, but the uneven or loose contact between the airbag and the pressure plate may cause excessive or too small local pressure, and the boundary of the test soil box may produce a boundary effect on the model test, and it is still impossible to achieve direct loading of the tunnel structure, affecting the accuracy of the test results. At the same time, it is difficult for the existing technology to accurately simulate the dynamic loading of the water pressure. It can be seen that there are still deficiencies in the application of pressure loading around the tunnel model structure.

[0005] In addition, because the pressure on the top, bottom and sides of existing tunnels may be different in actual working conditions, the existing loading device cannot apply different loads to the top, sides and bottom of the tunnel respectively. If the same load is applied to all of them, it cannot effectively conform to reality and affects the accuracy of the test results. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a cuff-shaped tunnel model loading test device to restore the effects of different surrounding pressures on the tunnel structure. A cuff loading unit is used, which is simple to operate, easy to carry, and can achieve uniform loading of confining pressure.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions: A cuff-shaped tunnel model loading test device, comprising: A model box, one side of the model box is made of transparent material; A tunnel model, wherein a cuff loading unit is arranged in a circumferential direction of the tunnel model, a plurality of pressure chambers are arranged inside the cuff loading unit along the circumferential direction of the tunnel model, a gas supply assembly provides gas sources to each pressure chamber respectively to apply the same or different loads to the top, bottom and side of the tunnel model, two sides of the cuff loading unit are detachably connected, and the tunnel model with the cuff loading unit is placed in a model box, and the model box is filled with filling materials; A monitoring unit, which is located outside the model box and monitors the tunnel model through the transparent side of the model box; The stress acquisition unit includes a stress sensor, and the stress sensor is arranged at the tunnel model.

[0008] A cuff-shaped tunnel model loading test device as described above, wherein the cuff loading unit includes a cuff body, the interior of the cuff body is hollow, the pressure chamber is located in the hollow part inside the cuff body, the cuff body has a set width, the circumference of the cuff body is smaller than the outer circumference of the tunnel model, and the two sides of the cuff body are connected by a buckle assembly.

[0009] A cuff-shaped tunnel model loading test device as described above, wherein four air bags are arranged in the cuff body, and the pressure chambers are formed inside the air bags, and two adjacent pressure chambers are in contact with each other, and the pressure chambers are sequentially arranged on the top, side, bottom and side of the tunnel model to simulate different pressures on the top, bottom and side of the tunnel; The inner surface of the cuff body is provided with anti-slip patterns.

[0010] A cuff-shaped tunnel model loading test device as described above, wherein a limiter is arranged on the outside of the cuff body, a channel is formed between the limiter and the cuff body, the buckle assembly comprises a fixing belt, the fixing belt is arranged through the channel, the length of the fixing belt is adjustable, a female buckle is arranged at one end of the fixing belt, and a male buckle matching with the female buckle is arranged at the other end; An environmental control unit is arranged on the outside of the cuff body, and the environmental control unit includes a heating element and a humidity control element, and the heating element and the humidity control element are respectively connected to the control controller. A temperature sensor and a humidity sensor are arranged on the cuff body, and the temperature sensor and the humidity sensor are respectively connected to the control controller.

[0011] A cuff-shaped tunnel model loading test device as described above, wherein the pressure chamber is respectively provided with a built-in gas supply port and a built-in exhaust port, a pressure regulating valve is provided at the built-in gas supply port, and a pressure control valve is provided at the built-in exhaust port, the pressure regulating valve and the pressure control valve are respectively connected to the pressure controller, and the built-in gas supply port is connected to the gas supply component; A pressure sensor is provided in each pressure chamber, and the pressure sensor is connected to a pressure controller to change the load size to achieve the application of dynamic load.

[0012] The pressure value of the pressure chamber acting on the top of the tunnel is obtained according to the natural weight of the overlying soil, the thickness of the overlying soil layer, the weight of the ground water, the height of the ground water, the effective weight of the soil within the groundwater level, the height from the groundwater level to the tunnel vault, the weight of the groundwater and the correction parameters; The pressure value of the pressure chamber acting on the side of the tunnel model is determined according to the weight of water, the depth of the calculation point from the groundwater surface, the static earth pressure and the correction parameters; The pressure value of the pressure chamber acting on the bottom of the tunnel model is determined according to the water density, gravity acceleration, the volume of the displaced water and the correction parameters.

[0013] In the cuff-shaped tunnel model loading test device as described above, the gas supply assembly includes gas supply pipes respectively connected to the pressure chambers, each gas supply pipe is respectively connected to the pressure controller, and the pressure controller is connected to the air compressor.

[0014] In a cuff-shaped tunnel model loading test device as described above, the monitoring unit includes a displacement monitoring component, which includes fluorescent tracer particles, a laser light source, a camera and a controller. The fluorescent tracer particles are evenly spread on the surface of the tunnel model according to the position of the tunnel displacement to be monitored, and the laser light source and the camera are respectively placed on the outside of the transparent side of the model box, and the laser light source and the camera are respectively connected to the controller.

[0015] In the cuff-shaped tunnel model loading test device as described above, the stress sensor is connected to a data acquisition instrument, and the data acquisition instrument and the controller are both connected to a computer.

[0016] As described above, a cuff-shaped tunnel model loading test device, the model box includes a bottom plate, the bottom plate supports a front plate, a side plate and a rear plate, the front plate and the rear plate are arranged opposite to each other, the front plate forms the transparent side of the model box, the side plate has a channel for the line to pass through, and the channel is equipped with a hole plug.

[0017] In a second aspect, the present invention further discloses a test method of a cuff-shaped tunnel model loading test device, including the following contents: A tunnel model is made, a cuff loading unit is arranged on the peripheral side of the tunnel model, and a stress sensor is arranged at the tunnel model; Assembling a model box, one side of the model box is a transparent side, and the distance between the opposite sides of the model box is adapted to the length of the tunnel model; Fill the model box with filling materials, place the tunnel model with the cuff loading unit in the model box, fit one end of the tunnel model with the transparent side of the model box, and continue to fill the filling materials; The gas delivery component provides gas sources to each pressure chamber to apply the same or different loads to the top, bottom and sides of the tunnel model, gradually increase the load, and maintain it after reaching the set pressure. During the process of load increase and maintenance, the stress sensor obtains the stress change of the tunnel model, and the monitoring unit obtains the deformation of the tunnel model.

[0018] The beneficial effects of the present invention are as follows: 1) In the present invention, a cuff loading unit is arranged in a ring-shaped fit on the tunnel model, and a plurality of pressure chambers are arranged in the cuff body. The cuff body can be in direct and close contact with the tunnel model. During the inflation of the pressure chamber, the cuff body is in close contact with the tunnel model, and the local pressure will not be too large or too small, thereby realizing direct loading on the tunnel model, without boundary effect, and will not affect the accuracy of the test results. Moreover, by setting up a plurality of pressure chambers, the same or different loads can be applied to the top, side and bottom of the tunnel model, respectively, which is more in line with the actual working conditions of the tunnel.

[0019] 2) In the present invention, four airbags are arranged in the cuff body, and four independent pressure chambers are formed by the four airbags. The airbags are in contact with each other, so that the cuff body is wrapped around the tunnel model. By setting a plurality of independent pressure chambers, uniform loading of different parts of the surface of the tunnel model is achieved, which more realistically and accurately simulates the stress conditions of the tunnel under the actual soil pressure, water pressure and buoyancy force, thereby improving the accuracy and reliability of the test results.

[0020] 3) The present invention is provided with a heating element and a humidity regulating element, and a test environment for multi-physical field coupling simulation is constructed, which realizes the simulation test of the tunnel model under the multi-physical field coupling of temperature, humidity and pressure as a whole, truly and accurately simulates the engineering conditions of the tunnel in the actual environment, and makes the test results more accurate.

[0021] 4) The setting of the pressure controller in the present invention can control each pressure chamber separately, and the synchronous and gradual increase of pressure can simulate the dynamic loading of water pressure, thereby simulating the change of water pressure at any time; the operation process is simple and convenient, reducing the influence of human factors on the experimental results; during the test, the displacement change and stress change of the tunnel model can be simulated, and the monitoring is efficient and convenient, which provides strong support for subsequent data analysis.

[0022] 5) The length of the fixing belt in the cuff body of the present invention is adjustable, which can realize loading tests of different tunnel models within a set range, further broadening the test range. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 It is a schematic diagram of a cuff-shaped tunnel model loading test device according to one or more embodiments of the present invention.

[0025] Figure 2 It is an external schematic diagram of a cuff body in a cuff-shaped tunnel model loading test device according to one or more embodiments of the present invention.

[0026] Figure 3 It is a schematic diagram of the end surface of a cuff body in a cuff-shaped tunnel model loading test device according to one or more embodiments of the present invention.

[0027] Figure 4 It is a schematic diagram of a model box in a cuff-shaped tunnel model loading test device according to one or more embodiments of the present invention.

[0028] In the figure: the distances or sizes between parts are exaggerated to show the positions of various parts, and the schematic diagram is for reference only.

[0029] Wherein: 1. Tunnel model, 2. Cuff body, 3. Built-in air supply port, 4. Pressure regulating valve, 5. Pressure sensor, 6. Built-in exhaust port, 7. Pressure control valve, 8. Buckle, 9. Male buckle, 10. Female buckle, 11. Air supply port, 12. Air supply pipe, 13. Exhaust port, 14. Exhaust pipe, 15. Multi-channel pressure controller, 16. Air compressor, 17. Fluorescent tracer particles, 18. Laser light source, 19. High-speed camera, 20. Synchronous controller, 21. Bracket, 22. Stress sensor, 23. Data acquisition instrument, 24. Computer, 25. Model box, 26. Bottom plate, 27. Side plate, 28. Front plate, 29. Back plate, 30. Channel, 31. Hole plug, 32. Limiting piece, 33. Fixing belt, 34. Heating element, 35. Humidity regulating element. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise explicitly stated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof; As introduced in the background technology, in the prior art, there is a problem that the loading unit and the tunnel model cannot fit tightly together. In order to solve the above technical problem, the present invention proposes a cuff-shaped tunnel model loading test device.

[0032] Embodiment 1 In a typical embodiment of the present invention, reference is made to Figure 1 As shown, a cuff-shaped tunnel model loading test device includes a model box 25, one side of the model box 25 is made of transparent material; a cuff loading unit is arranged in the circumferential direction of the tunnel model 1, a plurality of pressure chambers are arranged inside the cuff loading unit along the circumferential direction of the tunnel model 1, a gas supply assembly provides a gas source to the pressure chamber to apply a load to the tunnel model 1, the two sides of the cuff loading unit are detachably connected, the tunnel model 1 with the cuff loading unit is placed in the model box 25, the model box 25 is filled with filling material, and the filling material is specifically soil; a monitoring unit, the monitoring unit is located outside the model box 25, and the monitoring unit monitors the tunnel model 1 through the transparent side of the model box; a stress acquisition unit, including a stress sensor 22, and the stress sensor 22 is arranged in the tunnel model 1.

[0033] The cuff loading unit includes a cuff body 2, an air delivery assembly, and an exhaust assembly. The cuff body 2 is hollow inside, and the pressure chamber is located in the hollow inside the cuff body 2. The cuff body 2 has a set width, and the circumference of the cuff body 2 is less than the outer circumference of the tunnel model 1. The two sides of the cuff body 2 are connected by a buckle assembly. A limiter 32 is set on the outside of the cuff body 2, and a channel is formed between the limiter 32 and the cuff body 2. Figure 2 As shown, the buckle assembly includes a fixing belt 33, which is set through the channel. The length of the fixing belt 33 is adjustable and can be adjusted according to the girth of the tunnel model 1. A female buckle 10 is set at one end of the fixing belt 33, and a male buckle 9 matching the female buckle is set at the other end. The male buckle 9 and the female buckle 10 are fixed on the outer surface of the cuff body 2, so that the fixing belt 33 can be an existing safety belt structure.

[0034] In this embodiment, the cuff body 2 is made of a high-strength, wear-resistant and flexible material, and can fit tightly on the outer surface of the tunnel model 1. Four airbags are arranged inside the cuff body 2, and a pressure chamber is formed inside the airbags; anti-slip grooves are arranged on the inner surface of the cuff body 2 to increase the friction between the cuff body 2 and the tunnel model 1 to prevent the cuff body 2 from sliding relative to the tunnel model 1 during loading; a wear-resistant coating is arranged on the outer surface of the cuff body 2 to extend the service life. During the test, one airbag is located at the top and one airbag is located at the bottom as much as possible, and the other two airbags are located on both sides of the tunnel model 1.

[0035] The multiple pressure chambers are independent of each other, and each pressure chamber is respectively provided with a built-in gas supply port 3, a built-in exhaust port 6 and a pressure sensor 5. A pressure regulating valve 4 is provided at the built-in gas supply port 3, and a pressure control valve 7 is provided at the built-in exhaust port 6. The pressure regulating valve 4 and the pressure control valve 7 are both connected to a pressure controller, and the pressure controller is an existing multi-channel pressure controller 15.

[0036] It needs to be explained that the gas supply component includes multiple gas supply pipes 12, the cuff body 2 is provided with a gas supply port 11, the gas supply pipes 12 are provided through the gas supply port 11, one end of the multiple gas supply pipes 12 are respectively connected to the built-in gas supply ports 3 of each different pressure chamber, and the other end are respectively connected to different channels of the multi-channel pressure controller 15, and the pressure sensors 5 provided at different pressure chambers are connected to different channels of the multi-channel pressure controller 15; the exhaust component includes multiple exhaust pipes 14 and exhaust ports 13, the multiple exhaust pipes 14 are connected to the cuff body 2 through the built-in exhaust ports 6, and the multiple exhaust pipes 14 are connected and finally merged into one exhaust pipe to exhaust through the exhaust port 13.

[0037] It is easy to understand that each air pipe 12 is connected to a pressure controller respectively, the pressure controller is connected to an air compressor 16, the output port of the air compressor 16 is connected to a multi-channel pressure controller 15, the multi-channel pressure controller 15 is connected to multiple air pipes 12, and the pressure sensor 5 on each pressure chamber is connected to the multi-channel pressure controller 15. The pressure sensor 5 monitors the pressure in each pressure chamber in real time to obtain the actual monitoring pressure, and transmits the data to the multi-channel pressure controller 15. The multi-channel pressure controller 15 automatically adjusts the opening of the pressure regulating valve 4 provided on each pressure chamber according to the difference between the preset pressure and the actual monitoring pressure to ensure that the pressure of each pressure chamber in the cuff body 2 is always stable within the set range.

[0038] In this embodiment, four airbags are specifically arranged in the cuff body 2 so that the pressure chambers are respectively placed at the top, bottom and both sides of the tunnel model 1, and pressure sensors 5 are respectively arranged on the outside of each airbag.

[0039] Considering the elastic properties of the cuff body 2, elastic deformation will occur when pressurized, so the elastic modulus and Poisson's ratio are introduced to correct the pressure formula. It is assumed that the deformation of the airbag conforms to Hooke's law, the deformation of the airbag under pressure is uniform, and the nonlinear characteristics of the material are not considered.

[0040] Considering the deformation of the airbag, the pressure will generate stress inside the airbag According to Hooke's law,

[0041] And strain and volume deformation and the original volume The relationship is as follows:

[0042] Since the volume change caused by pressure change will affect the pressure transmission, the corrected pressure for

[0043] For an isotropic elastic material, in a three-dimensional stress state, the generalized Hooke's law has the following general form:

[0044]

[0045]

[0046] In the formula, is the elastic modulus, is the Poisson's ratio, are the principal stresses in the x, y, and z directions, are the principal strains in the x, y, and z directions. In the case of isotropic compression, all principal stresses are equal, that is, , so the principal strains can be written in a unified form:

[0047] Substituting the above formula into the volume strain formula, we have

[0048] in, is the bulk modulus.

[0049] Then we get the correction factor

[0050]

[0051] Pressure value of the pressure chamber acting on the top of the tunnel model 1 (that is, the maximum setting value of the tunnel top pressure sensor stored in the pressure controller) can be determined according to the following formula:

[0052] In the formula, - overburden pressure, ——Natural density of overlying soil; ——thickness of overlying soil layer; - the gravity of ground water; - height of water on the ground; ——Effective weight of soil within the groundwater level; - the height from the groundwater level to the tunnel crown; - gravity of groundwater; The pressure value of the pressure chamber acting on the side of the tunnel model 1 (that is, the maximum setting value of the tunnel side pressure sensor stored in the pressure controller) is determined according to the following formula:

[0053] - hydrostatic pressure, - the weight of water, ——the depth of the calculation point from the groundwater surface, - static earth pressure, , ——coefficient of earth pressure at rest, for normally consolidated soil, , ——internal friction angle of soil, - the weight of the soil, ——The depth of the calculation point from the ground; Pressure value of the pressure chamber acting on the side of the tunnel model 1 :

[0054] ——is the height of the tunnel side wall.

[0055] The buoyancy force on the bottom of the tunnel model 1 is calculated according to the Archimedean principle, that is, the buoyancy force on an object in a liquid is equal to the gravity of the liquid it displaces, that is, the pressure value of the pressure chamber acting on the bottom of the tunnel model 1 (That is, the maximum setting value of the tunnel bottom pressure sensor 5 stored in the pressure controller):

[0056] in, - the density of water, - the acceleration due to gravity, ——The volume of the water displaced. Assuming that the arch bottom of the tunnel model is arc-shaped, the radius of the tunnel model is r, and the groundwater level is at 1 / 2 of the arch bottom of the tunnel model, the volume of the water displaced is πr 2 .

[0057] In addition, the inner wall of the cuff body 2 is circular, and the outer side of the cuff body 2 is an arc surface in the inflated state. An environment control unit is arranged on the outer side of the cuff body 2, and the environment control unit includes a heating element 34 and a humidity adjustment element 35. The heating element 34 and the humidity adjustment element 35 are respectively connected to the control controller. The heating element 34 is used for heating, and the humidity adjustment element 35 is used for adjusting the humidity environment of the tunnel model 1. The heating element 34 can adopt a flexible heating sheet, refer to Figure 3 As shown, the heating element 34 is attached to the outer wall of the cuff body 2, and the heating element is connected to an external power supply and a controller. The humidity regulating element 35 can be an ultrasonic atomizer fixed in the groove of the cuff body 2, and the ultrasonic atomizer is detachably connected to an external water source through a pipeline. A plurality of humidity regulating elements 35 are provided to ensure the uniformity of humidity regulation and ensure that the tunnel model 1 is always in the set multi-physical field environment during the test.

[0058] Among them, the control controller can specifically be a PLC controller or other types of controllers. A temperature sensor and a humidity sensor are set at the cuff body 2. The temperature sensor and the humidity sensor are respectively connected to the control controller. The heating element and the humidity adjustment element are controlled to be turned on or off according to the information fed back by the two, so as to adjust the temperature and humidity.

[0059] In this embodiment, the monitoring unit includes a displacement monitoring component, specifically a PIV (high-precision particle) displacement monitoring component, the PIV displacement monitoring component includes fluorescent tracer particles 17, a laser light source 18, a camera and a controller, the camera adopts a high-speed camera 19, the controller is a synchronous controller 20, the fluorescent tracer particles 17 are evenly spread on the surface of the tunnel model 1 according to the position of the tunnel displacement to be monitored, the laser light source 18 and the high-speed camera 19 are placed in front of the front plate 28 of the model box 25, the angle and position of the laser light source 18 and the high-speed camera 19 are adjusted so that the laser illuminates the fluorescent tracer particles 17 at the tunnel model, so that the high-speed camera 19 can obtain the particle motion image, the laser light source 18 and the high-speed camera 19 are respectively fixed on a stable bracket 21, and the laser light source 18 and the high-speed camera 19 are respectively connected to the synchronous controller 20; Regarding the stress sensor 22, multiple stress sensors 22 are pasted on the tunnel model 1 according to the tunnel stress parts to be monitored. Some stress sensors are arranged on the inner side of the airbag, and some stress sensors are arranged at the position between two adjacent airbags. The data acquisition instrument 23 is connected to the stress sensor 22, which is used to receive the data transmitted by the stress sensor 22 and monitor the stress changes of the tunnel model during the loading process in real time. The synchronous controller 20 and the data acquisition instrument 23 are both connected to the computer 24, which is used to process data. The computer 24 obtains the image information captured by the high-speed camera 19 and displays it on the display screen. The computer 24 obtains the stress value obtained by the stress sensor and displays it on the display screen; the computer 24 is connected to the multi-channel pressure controller 15, which is used to control the opening of the multi-channel pressure controller 15.

[0060] The synchronous controller may be a PLC controller or other types of controllers.

[0061] It can be understood that the bracket 21 is specifically an existing tripod bracket, the height of the bracket 21 is adjustable, and the angles of the laser light source 18 and the high-speed camera 19 relative to the bracket 21 are adjustable.

[0062] refer to Figure 4 As shown, the model box includes a bottom plate 26, a side plate 27, a front plate 28 and a rear plate 29. The front plate 28, the side plate 27 and the rear plate 29 of the model box are detachably connected. In this embodiment, the front plate 28 includes a frame, a transparent material is arranged in the middle of the frame, and the transparent material is specifically an acrylic plate or a glass plate. The two side plates 27 are arranged opposite to each other, one side of the side plate 27 is connected to the front plate 28 by bolts, and the other side of the side plate 27 is also connected to the rear plate 29 by bolts.

[0063] It is easy to understand that a plurality of holes 30 are provided on the side plate 27 for the entry and exit of the gas pipe, the exhaust pipe and the data line. Each hole 30 is equipped with a hole plug 31. The holes without pipelines passing through are blocked by the hole plug 31. The hole plug 31 prevents the soil material from leaking out. The tunnel model 1 equipped with the cuff body 2 is placed in the model box 25, and the model box 25 is filled with soil material.

[0064] This embodiment also discloses a test method of a cuff-shaped tunnel model loading test device, including the following contents: According to the outer circumference of the tunnel model 1, adjust the length of the rope behind the male buckle 9 on the cuff body 2 so that the length surrounded by the buckle 8 and the cuff body 2 meets the circumference of the tunnel model; at the same time, adjust the position of the side plate 27 on the bottom plate 26 to support the tunnel model 1; wrap the cuff with the adjusted length around the tunnel model 1 and fix it with the buckle 8, and connect the gas pipe, exhaust pipe and data cable; Evenly spread fluorescent tracer particles 17 at the cross section of the tunnel model 1, and stick stress sensors 22 on the tunnel model 1 according to the stress position of the tunnel to be monitored; Assemble the model box, and adjust the distance between the front plate 28 and the rear plate 29 according to the length of the tunnel model 1, so that there is no gap between the tunnel model 1 and the front plate 28 and the rear plate 29, and no soil material infiltrates; Fill the model box with soil material. When the soil material is filled to the position of the tunnel model, the assembled tunnel model 1 of the cuff loading unit is stably placed in the model box so that the tunnel model is close to the front plate 28 of the model box. The air supply pipe 12, the exhaust pipe 14, the pressure sensor 5 and the data lines of the stress sensor 22 on the cuff body 2 are neatly arranged in sequence on the filling material and extend out of the model box 25 through a plurality of holes 30 on the model box. A hole plug 31 is provided at the hole 30, and the line passes through the hole plug 31. The air delivery pipe 12 extending out of the model box 25 is connected to each channel of the multi-channel pressure controller 15 to deliver air pressure to each pressure chamber, the pressure sensor 5 is connected to the multi-channel pressure controller 15 to monitor the pressure of each pressure chamber in real time, the multi-channel pressure controller 15 is connected to the air compressor 16, the stress sensor 22 is connected to the data acquisition instrument 23 to monitor the change of stress of the tunnel model during the loading process in real time, and the exhaust pipe 14 is connected to the atmosphere to allow the cuff body 2 to be naturally exhausted under atmospheric pressure conditions; After the cuff loading unit is assembled, it is debugged and calibrated to check whether the multi-channel pressure controller 15, the air compressor 16 and the gas transmission components are working properly to ensure that the loading device can accurately apply the load. Before formal loading, a pre-load test is carried out to check the stability of the loading device and the tunnel model. The pre-loaded load is generally 10% - 20% of the formal load, and the loading time is 5-10 minutes; Place the laser light source 18 and the high-speed camera 19 in front of the front plate 28 in the model box, adjust the position and angle of the laser light source 18 so that the light illuminates the spread fluorescent tracer particles 17, adjust the position and angle of the high-speed camera 19 so that it can clearly capture the area illuminated by the laser light source, connect the laser light source 18 with the high-speed camera 19 and the synchronous controller 20 to accurately control the pulse emission time of the laser light source 18 and the exposure time of the camera, ensure that the high-speed camera 19 can capture the moment when the particles are illuminated by the laser, and record the displacement curve and deformation photos of the tunnel model 1 during the loading process; According to the test plan, the parameters of the multi-channel pressure controller are set, the air compressor 16 and the pressure regulating valve 4 are turned on, and the load of the cuff loading unit is gradually increased until the predetermined loading value is reached, and the air compressor 16 and the pressure regulating valve 4 are turned off. During the loading process, the stress sensor 22 obtains the stress change of the tunnel model 1, and the high-speed camera 19 takes pictures of the displacement change of the fluorescent tracer particles, so as to know the deformation of the tunnel model 1, and the computer records the loading time, load size, stress change and other data; The computer has built-in interface program and Abaqus numerical simulation software. The program can read the stress and displacement data collected by the stress sensor and displacement monitoring component in the model test, and parse and convert them into a data packet in a form compatible with the Abaqus numerical simulation software. The Abaqus numerical simulation software is opened to establish a finite element model corresponding to the model loading test, and the analyzed stress data is applied to the corresponding area of ​​the tunnel model 1 as the initial stress state. The displacement data is applied to the corresponding nodes of the finite element model to simulate the deformation, and relevant parameters are set for calculation.

[0065] The stress and displacement data obtained from the numerical simulation are compared and analyzed with the measured data in the model test, the difference between the two is calculated, and the corresponding error is obtained.

[0066] The error is within 10%, which shows that the model established by Abaqus software can well reflect the actual model test situation, accurately simulate the changes of physical quantities such as stress, strain, pore pressure in the actual test, and directly replace the relevant data package to carry out numerical simulation test; If the error is outside 10%, the computer automatically calculates the required pressure adjustment amount based on the comparison results, and controls the pressure controller to adjust the pressure regulating valve of each pressure chamber to achieve dynamic adjustment of the loading pressure in the model test. After adjustment, the above steps are repeated until the error between the simulation results and the test results is within an acceptable range.

[0067] After the test, the pressure control valve 7 of each chamber is controlled by the multi-channel pressure controller 15 to gradually reduce the load of the cuff loading unit until the load is zero. The unloading process should be slow and smooth to avoid secondary damage to the tunnel model. According to the above installation steps, all components are removed, and the tunnel model 1 is inspected and evaluated, and the damage and deformation degree of the tunnel model 1 are recorded. If the tunnel model 1 needs to be preserved, it can be properly packaged and stored. Finally, the cuff loading unit is cleaned and maintained, and the debris and dirt on the device are removed. The wear of each component is checked, and if necessary, it is replaced or repaired.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A cuff-shaped tunnel model loading test device, characterized in that: include: A model box, one side of the model box is made of transparent material; A tunnel model, wherein a cuff loading unit is arranged in a circumferential direction of the tunnel model, a plurality of pressure chambers are arranged inside the cuff loading unit along the circumferential direction of the tunnel model, a gas supply assembly provides gas sources to each pressure chamber respectively to apply the same or different loads to the top, bottom and side of the tunnel model, two sides of the cuff loading unit are detachably connected, and the tunnel model with the cuff loading unit is placed in a model box, and the model box is filled with filling materials; A monitoring unit, which is located outside the model box and monitors the tunnel model through the transparent side of the model box; The stress acquisition unit includes a stress sensor, and the stress sensor is arranged at the tunnel model.

2. A cuff-shaped tunnel model loading test device according to claim 1, characterized in that: The cuff loading unit includes a cuff body, which is hollow inside. The pressure chamber is located in the hollow part inside the cuff body. The cuff body has a set width. The circumference of the cuff body is smaller than the outer circumference of the tunnel model. The two sides of the cuff body are connected by a buckle assembly.

3. A cuff-shaped tunnel model loading test device according to claim 2, characterized in that: Four airbags are arranged in the cuff body, and the pressure chambers are formed inside the airbags. Adjacent pressure chambers are in contact with each other, and the pressure chambers are arranged in sequence at the top, side, bottom and side of the tunnel model.

4. The cuff-shaped tunnel model loading test device according to claim 2, characterized in that: A limiter is arranged on the outside of the cuff body, a channel is formed between the limiter and the cuff body, the buckle assembly comprises a fixing belt, the fixing belt is arranged through the channel, the length of the fixing belt is adjustable, a female buckle is arranged at one end of the fixing belt, and a male buckle matching with the female buckle is arranged at the other end; An environmental control unit is arranged on the outside of the cuff body, and the environmental control unit includes a heating element and a humidity control element, and the heating element and the humidity control element are respectively connected to the control controller. A temperature sensor and a humidity sensor are arranged on the cuff body, and the temperature sensor and the humidity sensor are respectively connected to the control controller.

5. The cuff-shaped tunnel model loading test device according to claim 1, characterized in that: The pressure chamber is respectively provided with a built-in gas delivery port and a built-in exhaust port, a pressure regulating valve is provided at the built-in gas delivery port, and a pressure control valve is provided at the built-in exhaust port, the pressure regulating valve and the pressure control valve are respectively connected to the pressure controller, and the built-in gas delivery port is connected to the gas delivery component; A pressure sensor is respectively arranged in each pressure chamber, and the pressure sensor is connected to the pressure controller.

6. A cuff-shaped tunnel model loading test device according to claim 5, characterized in that: The gas delivery assembly includes gas delivery pipes respectively connected to the pressure chambers, each gas delivery pipe is respectively connected to the pressure controller, and the pressure controller is connected to the air compressor.

7. The cuff-shaped tunnel model loading test device according to claim 3, characterized in that: The pressure value of the pressure chamber acting on the top of the tunnel is obtained according to the natural weight of the overlying soil, the thickness of the overlying soil layer, the weight of the ground water, the height of the ground water, the effective weight of the soil within the groundwater level, the height from the groundwater level to the tunnel vault, the weight of the groundwater and the correction parameters; The pressure value of the pressure chamber acting on the side of the tunnel model is determined according to the weight of water, the depth of the calculation point from the groundwater surface, the static earth pressure and the correction parameters; The pressure value of the pressure chamber acting on the bottom of the tunnel model is determined according to the water density, gravity acceleration, the volume of the displaced water and the correction parameters.

8. The cuff-shaped tunnel model loading test device according to claim 1, characterized in that: The monitoring unit includes a displacement monitoring component, which includes fluorescent tracer particles, a laser light source, a camera and a controller. The fluorescent tracer particles are evenly spread on the surface of the tunnel model according to the position of the tunnel displacement to be monitored. The laser light source and the camera are respectively placed on the outside of the transparent side of the model box, and the laser light source and the camera are respectively connected to the controller; The stress sensor is connected to a data acquisition instrument, and the data acquisition instrument and the controller are both connected to a computer.

9. The cuff-shaped tunnel model loading test device according to claim 1, characterized in that: The model box includes a bottom plate, which supports a front plate, a side plate and a rear plate. The front plate and the rear plate are arranged opposite to each other. The front plate forms the transparent side of the model box. The side plates are provided with holes for the circuits to pass through, and the holes are provided with plugs.

10. A test method for a cuff-shaped tunnel model loading test device according to any one of claims 1 to 9, characterized in that: It includes the following: A tunnel model is made, a cuff loading unit is arranged around the tunnel model, and a stress sensor is arranged at the tunnel model; Assembling a model box, one side of the model box is a transparent side, and the distance between the opposite sides of the model box is adapted to the length of the tunnel model; Fill the model box with filling materials, place the tunnel model with the cuff loading unit in the model box, fit one end of the tunnel model with the transparent side of the model box, and continue to fill the filling materials; The gas delivery component provides gas sources to each pressure chamber to apply the same or different loads to the top, bottom and sides of the tunnel model, gradually increase the load, and maintain it after reaching the set pressure. During the process of load increase and maintenance, the stress sensor obtains the stress change of the tunnel model, and the monitoring unit obtains the deformation of the tunnel model.

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