Hydraulic tunnel rock lining structure based on supergravity centrifugal test platform and implementation method thereof

Abstract

The invention discloses a hydraulic tunnel rock lining structure based on a supergravity centrifugal test platform and an implementation method of the hydraulic tunnel rock lining structure, and belongs to the technical field of hydraulic underground engineering. A hydraulic tunnel rock lining structure based on a supergravity centrifugal test platform comprises a model box, a shell of the model box is rigid, a surrounding rock similar material is arranged in the model box, a cylindrical hole is formed in the middle of the surrounding rock similar material, a lining similar material is further arranged in the model box, and the lining similar material is cylindrical. The cylindrical holes are distributed in the cylindrical holes and are attached to the surrounding rock similar material; the top of the model box is fixedly connected with the centrifuge system hanging basket, and the bottom is connected with the vibration table. The supergravity centrifugal test platform can be used for reducing the scale of a test model, so that the test cost is greatly reduced; and the interaction relation of surrounding rock linings under the earthquake working condition can be simulated.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic underground engineering, and particularly relates to a hydraulic tunnel rock lining structure based on a supergravity centrifuge test platform and an implementation method thereof. Background Art

[0002] The interaction mechanism of the rock lining structure of the diversion tunnel is complex. The change process of the lining structure from excavation → lining → first water filling → emptying, etc. only reflects part of the stress characteristics of the diversion tunnel structure by relying on numerical analysis methods. It is urgent to conduct experimental verification to meet the design requirements of future large-scale groundwater tunnels. Summary of the Invention

[0003] To overcome the technical problem that the interaction of the existing hydraulic tunnel rock lining structure lacks quick and effective experimental verification, the present invention provides a hydraulic tunnel rock lining structure based on a supergravity centrifuge test platform and an implementation method thereof.

[0004] The technical solution adopted by the present invention to solve its technical problems is as follows: A hydraulic tunnel rock lining structure based on a supergravity centrifuge test platform includes a model box. The outer shell of the model box is rigid. A surrounding rock similar material is arranged inside the model box. A cylindrical hole is provided in the middle of the surrounding rock similar material. A lining similar material is also arranged inside the model box. The lining similar material is in a cylindrical shape and is distributed in the cylindrical hole and is in contact with the surrounding rock similar material. The top of the model box is fixedly connected to the hanging basket of the centrifuge system, and the bottom of the model box is connected to the vibration table.

[0005] Combined with the development of the support structure theory of tunnel engineering and engineering construction experience, the design calculation considers the combined bearing of the surrounding rock and the lining, and adopts crack control design. A large amount of monitoring data shows that the steel bar stress after the tunnel is filled with water and operated is much smaller than its design strength, and due to the fact that the development of cracks is affected by various factors, it is very difficult to accurately predict the specific location of crack development. Therefore, there is basically no measured data on the maximum crack width. The characteristic of a pressurized diversion tunnel is that the structure mainly generates circumferential tensile stress under the action of internal water pressure, and then cracks and fails. However, after the concrete cracks, its seepage field will change accordingly, which in turn affects the stress of the concrete structure. Therefore, under the coupling action of the stress field and the seepage field, the stress conditions of the structure are complex. According to preliminary analysis, it may mainly occur in the short time period of the first water filling of the tunnel. At present, the existing numerical analysis results reflect this characteristic of the stress of the diversion tunnel structure, but there is no experimental data to further confirm it. Therefore, the interaction mechanism of the rock lining structure of the diversion tunnel is complex and further research is urgently needed. The excavation size of large-scale hydraulic tunnels is large, and the cost of in-situ tests on site can reach tens of millions. Using a supergravity centrifuge test platform can scale down the test model, greatly reducing the test cost.

[0006] In this application, a supergravity centrifugal test platform can be used to scale down the test model, greatly reducing the test cost; and it can simulate the interaction relationship between the surrounding rock and the lining under seismic conditions.

[0007] In some embodiments, monitoring sensors are arranged in the model box, including at least one of the following: a. At least two monitoring sections are arranged in the direction perpendicular to the axial direction of the cylindrical hole, and fiber optic crack gauges are arranged at the positions corresponding to each monitoring section inside the lining similar material. b. Longitudinal distributed strain optical fibers are arranged both longitudinally up and down and left and right at the interface between the lining similar material and the surrounding rock similar material. c. At least two monitoring sections are arranged in the direction perpendicular to the axial direction of the cylindrical hole, and circumferential distributed strain optical fibers are arranged at the positions corresponding to each monitoring section in the area outside the interface between the lining similar material and the surrounding rock similar material. d. At least two monitoring sections are arranged in the direction perpendicular to the axial direction of the cylindrical hole, and fiber optic pressure gauges are arranged at the positions corresponding to each monitoring section at the interface between the lining similar material and the surrounding rock similar material.

[0008] In some embodiments, a water delivery pipe is further included, and the water delivery pipe communicates with the inside of the lining similar material and the outside of the model box.

[0009] In some embodiments, a sealing layer is arranged between the surrounding rock similar material and the model box.

[0010] The present invention also provides an implementation method for the hydraulic tunnel rock lining structure based on the supergravity centrifugal test platform described in any one of the above embodiments, including the following steps: S1. Prepare the surrounding rock similar material and the lining similar material. S2. Arrange the surrounding rock similar material and the lining similar material in the model box. S3. Seal the model box and conduct a simulation experiment on the model box.

[0011] In some embodiments, the target sizes of the lining and the surrounding rock are obtained according to the prototype size and the Buckingham π theorem.

[0012] In some embodiments, it includes the following steps: S1. Prepare the surrounding rock similar material and the lining similar material, and prefabricate the lining similar material into a cylindrical structure. S2. Paste a sealing layer on the inner wall of the model box, place the surrounding rock similar material into the model box to a certain height, then place the prefabricated lining similar material in the form of a cylindrical structure, and then continue to place the surrounding rock similar material. S3. Seal the model box and conduct a simulation experiment on the model box.

[0013] In some embodiments, the following steps are included: S1. Prepare surrounding rock similar materials and lining similar materials. The lining similar materials are prefabricated into a cylindrical structure. S2. Paste a sealing layer on the inner wall of the model box. Place the surrounding rock similar materials in the model box to a certain height, then place the prefabricated lining similar materials in the shape of a cylinder, and then continue to place the surrounding rock similar materials. S21. Inject viscous fluid into the surrounding rock similar materials to simulate the action of external water pressure. S3. Seal the model box and conduct a simulation experiment on the model box.

[0014] In some embodiments, the simulation experiment on the model box in S3 includes one or more of the following steps: S31. Start the centrifuge to simulate the self-weight consolidation of the formation and record the monitoring data. S32. Inject water into the lining similar materials through the water delivery pipeline to simulate the internal pressure action and record the monitoring data. S33. Start the shaking table to simulate the interaction between the surrounding rock and the lining under seismic action and record the monitoring data. S34. Pump and drain the lining similar materials through the water delivery pipeline to simulate the emptying condition and record the monitoring data.

[0015] The beneficial effects of the present invention are as follows: The present invention can scale the test model by using the hypergravity centrifuge test platform, greatly reducing the test cost. It can simulate the interaction relationship between the surrounding rock and the lining under seismic conditions. It can simulate the change process of the lining → water filling → emptying and other processes to analyze the interaction between the surrounding rock and the lining. Description of the Drawings

[0016] Figure 1 It is an overall schematic diagram of the hydraulic tunnel rock lining structure based on the hypergravity centrifuge test platform provided by the present invention. Figure 2 It is Figure 1 The sectional view of Figure 3 It is Figure 1 The schematic diagram of the monitoring section and instrument installation in

[0017] In the figure, the labels are: 1 - surrounding rock similar materials, 2 - lining similar materials, 3 - rigid bottom plate, 4 - rigid side wall, 5 - side wall reinforcement, 6 - top rigid cover plate, 7 - top reinforcement, 9 - monitoring data pipeline, 10 - water delivery pipeline, 11 - water pump, 12 - sealing layer, 13 - monitoring data monitoring and analysis system, 31 - fiber optic crack gauge, 32 - longitudinal distributed strain optical fiber, 33 - circumferential distributed strain optical fiber, 34 - fiber optic pressure gauge. Detailed implementation manners

[0018] The present invention will be further described below with reference to the accompanying drawings.

[0019] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] Combined with Figures 1-3 As shown, the present invention provides a hydraulic tunnel rock lining structure based on a hypergravity centrifuge test platform and an implementation method thereof.

[0021] The hydraulic tunnel rock lining structure based on the hypergravity centrifuge test platform includes a model box. The outer shell of the model box is rigid. As Figure 1 shown, the model box includes a rigid bottom plate 3, rigid side walls 4 and a top rigid cover plate 6. Side wall stiffeners 5 are provided on the rigid side walls 4, and top stiffeners 7 are provided on the top rigid cover plate 6.

[0022] A surrounding rock similar material 1 is arranged in the model box. A cylindrical hole is provided in the middle of the surrounding rock similar material 1. A lining similar material 2 is also arranged in the model box. The lining similar material 2 is in a cylindrical shape and is distributed in the cylindrical hole and is in contact with the surrounding rock similar material 1. The surrounding rock similar material 1 is used to simulate the formation of the surrounding rock, and the lining similar material 2 is used to simulate the formation of the lining. An internal water loading cavity is formed inside the cylindrical lining similar material 2 here.

[0023] The top of the model box is fixedly connected to the hanging basket of the centrifuge system, and the bottom of the model box is connected to the vibration table. In this embodiment, the top stiffener 7 is fixedly connected to the hanging basket of the centrifuge system.

[0024] Combined with the development of the support structure theory for tunnel engineering and engineering construction experience, the design calculation considers the combined load-bearing of the surrounding rock and the lining, and adopts crack control design. A large amount of monitoring data shows that the steel bar stress is much smaller than its design strength after the tunnel is filled with water. Moreover, due to the influence of various factors on the development of cracks, it is very difficult to accurately predict the specific location of crack development. Therefore, there is basically no measured data on the maximum development width of cracks. The characteristic of a pressurized water conveyance tunnel is that the structure mainly generates circumferential tensile stress under the action of internal water pressure, and then undergoes cracking failure. However, after the concrete cracks, its seepage field will change accordingly, which in turn affects the stress of the concrete structure. Therefore, under the coupled action of the stress field and the seepage field, the stress conditions of the structure are complex. According to preliminary analysis, it may mainly occur in the short time period when the tunnel is first filled with water. At present, the existing numerical analysis results reflect this characteristic of the stress of the water conveyance tunnel structure, but there is no experimental data to further confirm it. Therefore, the interaction mechanism between the rock lining structure of the water conveyance tunnel is complex and further research is urgently needed. The excavation size of large hydraulic tunnels is large, and the cost of in-situ tests on site can reach tens of millions. By using the supergravity centrifuge test platform, the test model can be scaled down, greatly reducing the test cost.

[0025] In this application, the supergravity centrifuge test platform can be used to scale down the test model, greatly reducing the test cost; it can simulate the interaction relationship between the surrounding rock and the lining under seismic conditions.

[0026] In this embodiment, monitoring sensors are arranged in the model box, combined with Figure 2 and Figure 3 , specifically: Two monitoring sections are arranged in the direction perpendicular to the axial direction of the cylindrical hole, and fiber optic crack gauges 31 are arranged at the positions corresponding to each monitoring section inside the lining similar material 2. To avoid end effects, preferably the two monitoring sections are arranged in the middle of the axis direction of the model box.

[0027] In this embodiment, a set of fiber optic crack gauges 31 is arranged at each monitoring section, and the two sets of fiber optic crack gauges 31 are arranged staggeredly, which are used to monitor the crack development position and width of the lining after the chamber is filled with water.

[0028] Longitudinal distributed strain optical fibers 32 are arranged both longitudinally up and down and left and right at the interface between the lining similar material 2 and the surrounding rock similar material 1. The longitudinal distributed strain optical fibers 32 are used to monitor the relative deformation between the surrounding rock and the lining under long-term operation conditions.

[0029] Two monitoring sections are arranged in the direction perpendicular to the axial direction of the cylindrical hole, and circumferential distributed strain optical fibers 33 are arranged at the positions corresponding to each monitoring section in the area outside the interface between the lining similar material 2 and the surrounding rock similar material 1. The circumferentially distributed strain optical fiber 33 is used to monitor the deformation of the broken zone that may occur in the surrounding rock under the action of internal water pressure, so as to reflect the influence on the depth of the damaged zone of the surrounding rock under different internal water pressures.

[0030] At least two monitoring sections are provided in the direction perpendicular to the axial direction of the cylindrical hole, and fiber optic pressure gauges 34 are arranged at the positions corresponding to each monitoring section on the interface between the lining similar material 2 and the surrounding rock similar material 1.

[0031] The foregoing monitoring sensors are connected to the monitoring data monitoring and analysis system 13 through the monitoring data pipelines 9, so as to analyze the monitoring data.

[0032] Refer to Figure 2 In this embodiment, it also includes a water conveyance pipeline 10, and the water conveyance pipeline 10 communicates with the inside of the lining similar material 2 and the outside of the model box. In this embodiment, a water pump 11 is connected to the outside of the water conveyance pipeline 10, and the water conveyance pipeline 10 is used to fill and drain the internal water loading cavity, so as to simulate the working conditions of the rock lining structure of the hydraulic tunnel.

[0033] In this embodiment, a sealing layer 12 is provided between the surrounding rock similar material 1 and the model box.

[0034] The present invention also provides an implementation method for the rock lining structure of a hydraulic tunnel based on the ultra-gravity centrifuge test platform described in the above embodiment, which at least includes the following steps: S1. Prepare the surrounding rock similar material 1 and the lining similar material 2; S2. Arrange the surrounding rock similar material 1 and the lining similar material 2 into the model box; S3. Seal the model box and conduct a simulation experiment on the model box.

[0035] In this embodiment, the target dimensions of the lining and the surrounding rock are obtained according to the prototype dimensions and the Buckingham π theorem.

[0036] According to the Buckingham π theorem, assuming that the centripetal acceleration is ng, the centrifuge model similarity relationship is shown in Table 1 below: Table 1

[0037] Assume that the inner diameter of the prototype tunnel is , then the inner diameter of the model is , the lining thickness of the prototype tunnel is r, then the lining thickness of the model is , the size of the model box is about 3 times the inner diameter of the model, meeting the boundary conditions; Using 3D printing technology, print the surrounding rock similar material 1 and the lining similar material 2, with densities of and .

[0038] In this embodiment, a high-gravity centrifugal test platform is used for the test. In order to reduce the model size and test cost, an acceleration of 100g is adopted, that is, the similarity ratio n = 100.

[0039] In this embodiment, the diameter of the prototype tunnel is 15m and the lining thickness is 1m. It can be obtained that the diameter of the model tunnel is 0.15m and the precast lining thickness is 0.01m. The size of the model box is 1.0m × 0.7m × 0.7m, which meets the boundary conditions.

[0040] The annular distributed strain optical fiber is preferably arranged outside the surrounding rock at R = In this embodiment, it is arranged outside the surrounding rock at R = 15cm.

[0041] In this embodiment, the surrounding rock of the prototype tunnel is kaolinized altered rock. Using the powder layer spray head 3D printing technology, an altered rock similar material is developed with a density of , E = 0.08GPa. The concrete similar material has a density of , E = 28GPa.

[0042] Furthermore, in this embodiment, the following steps are included. S1. Prepare the surrounding rock similar material 1 and the lining similar material 2. The lining similar material 2 is precast into a cylindrical structure with a thickness of . Combined with the foregoing parameters, the lining thickness in this embodiment is 1cm.

[0043] S2. Paste the sealing layer 12 on the inner wall of the model box. Place the surrounding rock similar material 1 into the model box to a certain height (>= 1.5 * ), then put the precast lining similar material 2 in the shape of a cylindrical structure, and then continue to place the surrounding rock similar material 1; Combined with the foregoing parameters, the certain height here means ≥ 22.5cm. Implementing in this way can avoid the influence of chamber excavation on the surrounding rock mass.

[0044] S21. In order to ensure the similarity of the permeability coefficient of the surrounding rock material, inject viscous fluid into the surrounding rock similar material 1 to simulate the action of external water pressure; According to the similarity principle, the external water pressure is determined to be 0.1MPa in this embodiment.

[0045] S3. Seal the model box and conduct a simulation experiment on the model box.

[0046] The sealed model box in this embodiment refers to the closed area formed by enclosing the aforementioned rigid bottom plate 3, rigid side walls 4, and top rigid cover plate 6.

[0047] In this embodiment, the simulation experiment on the model box in S3 includes the following steps. S31. Start the centrifuge to simulate the self-weight consolidation of the formation, record the monitoring data, and analyze the initial deformation of the rock lining structure under the action of the initial ground stress; S32. Inject water into the lining similar material 2 through the water conveyance pipeline 10 to simulate the internal pressure effect. Adopt the step-by-step pressurization method. According to the similarity principle, the internal water pressures are 0.5 MPa, 0.8 MPa, and 1.0 MPa respectively. Record the monitoring data, analyze the development of lining cracks under different internal pressure states, and the influence of different internal pressures on the range of the surrounding rock broken zone. At the same time, according to the monitoring data of the pressure cells, summarize the bearing ratios of the surrounding rock and the lining for the internal pressure; S33. Start the shaking table to simulate the interaction between the surrounding rock and the lining under the earthquake action, and record the monitoring data; S34. Turn off the shaking table, pump and drain the lining similar material 2 through the water conveyance pipeline 10 to simulate the emptying condition, and record the monitoring data; According to the monitoring data analysis, study the interaction law between the surrounding rock and the lining of large hydraulic tunnels under long-term water-rich conditions (earthquakes) under the altered rock conditions.

[0048] Apply a fixed force to the model using a centrifuge, and apply seismic loads to the hydraulic tunnel model in the model box using a shaking table. Obtain data such as deformation stress through monitoring sensors. The invention conducts a scaled simulation test on large underground caverns, and can obtain the deformation and failure laws of the surrounding rock lining during the operation of large hydraulic tunnels in complex geological environments, so as to guide the design work of future large underground caverns.

[0049] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. The hydraulic tunnel rock lining structure based on the hypergravity centrifugal test platform is characterized in that: It includes a model box with a rigid outer shell. Inside the model box, there is a surrounding rock similar material (1). In the middle of the surrounding rock similar material (1), there is a cylindrical hole. Inside the model box, there is also a lining similar material (2). The lining similar material (2) is in a cylindrical shape, distributed inside the cylindrical hole and in contact with the surrounding rock similar material (1). The top of the model box is fixedly connected to the hanging basket of the centrifuge system, and the bottom of the model box is connected to the shaking table.

2. The hydraulic tunnel rock lining structure based on the hypergravity centrifugal test platform according to claim 1, characterized in that: at Monitoring sensors are arranged inside the model, including at least one of the following: a. At least two monitoring sections are arranged in the direction perpendicular to the axial direction of the cylindrical hole. Fiber optic crack gauges (31) are arranged at the positions corresponding to each monitoring section inside the lining similar material (2). b. Longitudinal distributed strain optical fibers (32) are arranged both longitudinally up and down and left and right at the interface between the lining similar material (2) and the surrounding rock similar material (1). c. At least two monitoring sections are arranged in the direction perpendicular to the axial direction of the cylindrical hole. Circumferential distributed strain optical fibers (33) are arranged at the positions corresponding to each monitoring section in the area outside the interface between the lining similar material (2) and the surrounding rock similar material (1). d. At least two monitoring sections are arranged in the direction perpendicular to the axial direction of the cylindrical hole. Fiber optic pressure gauges (34) are arranged at the positions corresponding to each monitoring section at the interface between the lining similar material (2) and the surrounding rock similar material (1).

3. The hydraulic tunnel rock lining structure based on the hypergravity centrifugal test platform according to claim 1, characterized in that: It also includes a water delivery pipe (10). The water delivery pipe (10) connects the inside of the lining similar material (2) and the outside of the model box.

4. The hydraulic tunnel rock lining structure based on the supergravity centrifugal test platform according to any one of claims 1 to 3, characterized in that: A sealing layer (12) is arranged between the surrounding rock similar material (1) and the model box.

5. Method for implementing a hydraulic tunnel rock lining structure based on a supergravity centrifugal test platform as described in any one of claims 1-4, characterized in that: It includes the following steps, S1. Prepare the surrounding rock similar material (1) and the lining similar material (2); S2. Place the surrounding rock similar material (1) and the lining similar material (2) into the model box; S3. Seal the model box and conduct a simulation experiment on the model box.

6. The implementation method of the hydraulic tunnel rock lining structure for the hypergravity centrifugal test platform according to claim 5, characterized in that: Obtain the target dimensions of the lining and the surrounding rock according to the prototype dimensions and the Buckingham π theorem.

7. The implementation method of the hydraulic tunnel rock lining structure for the hypergravity centrifugal test platform according to claim 5, characterized in that: It includes the following steps, S1. Prepare the surrounding rock similar material (1) and the lining similar material (2). The lining similar material (2) is prefabricated into a cylindrical structure; S2. Paste the sealing layer (12) on the inner wall of the model box. Place the surrounding rock similar material (1) into the model box to a certain height, then put the prefabricated lining similar material (2) in a cylindrical structure, and then continue to place the surrounding rock similar material (1); S3. Seal the model box and conduct a simulation experiment on the model box.

8. The implementation method of the hydraulic tunnel rock lining structure for the hypergravity centrifugal test platform according to claim 7, characterized in that: It includes the following steps, S1. Prepare the surrounding rock similar material (1) and the lining similar material (2). The lining similar material (2) is prefabricated into a cylindrical structure; S2. Paste the sealing layer (12) on the inner wall of the model box. Place the surrounding rock similar material (1) into the model box to a certain height, then put the prefabricated lining similar material (2) in a cylindrical structure, and then continue to place the surrounding rock similar material (1); S21. Inject viscous fluid into the surrounding rock similar material (1) to simulate the action of external water pressure; S3. Seal the model box and conduct a simulation experiment on the model box.

9. The implementation method of the hydraulic tunnel rock lining structure for the hypergravity centrifuge test platform according to any one of claims 5-8, characterized in that: the simulation experiment on the model box in S3 includes one or more of the following steps, S31. Start the centrifuge to simulate the self-weight consolidation of the formation and record the monitoring data; S32. Inject water into the lining similar material (2) through the water delivery pipe (10) to simulate the internal pressure effect and record the monitoring data; S33. Start the shaking table to simulate the interaction between the surrounding rock and the lining under the action of earthquake and record the monitoring data; S34. Drain the lining similar material (2) through the water delivery pipe (10) to simulate the emptying condition and record the monitoring data.

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