A test system and test method for simulating tunnel excavation under seepage conditions

Abstract

The present invention relates to a test system and test method for simulating tunnel excavation under seepage conditions, wherein the test system comprises a water injection device, a model box, a tunnel structure and a detection device, wherein the model box has an opening at the top, a drainage hole at the bottom, and a tunnel simulation port on the end face, the water injection device comprises a water tank and a diversion assembly, a branch conduit of the diversion assembly has a water seepage hole, the branch conduit is arranged in the model box and one end extends along the tunnel simulation port direction, and the other end of the branch conduit is connected to the water tank, the tunnel structure comprises a tunnel shape and a lining assembly, the tunnel shape is arranged in a rock and soil area around the simulated tunnel excavation, the lining assembly is embedded in the tunnel shape, and the detection device is used to collect soil layer pressure change data when the tunnel structure is gradually pushed into the rock and soil area around the simulated tunnel excavation under the seepage condition. The present invention can more realistically reproduce the deformation and damage mechanism of the soil body around the tunnel under natural disaster conditions, and has good experimental effects and reliable test data.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel excavation engineering under seepage conditions, and in particular relates to a test system and a test method for simulating tunnel excavation under seepage conditions. Background Art

[0002] Tunnel construction is an indispensable part of modern transportation infrastructure. In addition to being affected by the surrounding rock and soil layers, tunnels are also affected by seepage during excavation. Under seepage conditions, when the surrounding rock around the tunnel is poor, it is very easy to cause risks such as water inrush, mud inrush, and collapse in the tunnel. Dealing with this problem is also one of the key technical difficulties encountered during tunnel excavation.

[0003] The tunnel simulation box test is an effective means to study the pressure changes of the soil around the tunnel during tunnel excavation under indoor simulated seepage conditions. Therefore, correctly evaluating and observing the pressure changes of the soil around the tunnel in the model box under seepage conditions has important scientific significance and reference value for actual tunnel excavation construction.

[0004] At present, there are a lot of tunnel simulation box tests under simulated disaster conditions, but the simulated disaster conditions are more concentrated on earthquake effects, different soil effects or moisture content conditions, and there are fewer tunnel simulation box tests under seepage conditions. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a test system and test method for simulating tunnel excavation under seepage conditions. The present invention can truly reproduce the damage and deformation of the soil around the tunnel under natural disaster conditions by simulating the pressure changes of the soil around the tunnel under seepage conditions. The experimental effect is good and the data is reliable.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A test system for simulating tunneling under seepage conditions, comprising:

[0008] The model box is used to place the rock and soil area around the simulated tunnel excavation, and is a cavity with an open top, a drainage hole is provided at the bottom of the cavity, and a plurality of tunnel simulation ports are provided on one end surface of the cavity;

[0009] A water injection device, used for forming a seepage state in the rock and soil area around the simulated tunnel excavation, comprising a water tank and a diversion assembly, wherein the diversion assembly comprises at least two branch conduits arranged side by side, and the branch conduits are provided with seepage holes in an axial array, the branch conduits are arranged in the rock and soil area around the simulated tunnel excavation and one end of the branch conduits extends toward the simulated tunnel opening, and the other end of the branch conduits is connected to the water tank;

[0010] A tunnel structure, comprising a tunnel shape and a lining assembly, wherein the tunnel shape is arranged in a rock and soil area around the simulated tunnel excavation and is coaxially opposite to the simulated tunnel opening, and the lining assembly is embedded in the tunnel shape;

[0011] The detection device includes a data collector, which is arranged in the rock and soil area around the simulated tunnel excavation on the periphery of the lining assembly and is used to collect soil layer pressure change data when the lining assembly is gradually pushed into the tunnel shape under seepage conditions.

[0012] Furthermore, the model box includes a bottom plate, transparent side plates and a supporting frame, the supporting frame is arranged on the bottom plate, the transparent side plates are arranged around the supporting frame, the drainage holes are arranged on the bottom plate, and the tunnel simulation port is arranged on one of the transparent side plates.

[0013] Furthermore, the diversion assembly also includes a diverter and a main conduit, one end of the main conduit is connected to the water tank, the other end of the main conduit is connected to the diverter, and the other end of the diverter is connected to the other end of each of the branch conduits.

[0014] Furthermore, the lining assembly is composed of a plurality of linings axially stacked and connected, the outer diameter of the lining assembly is the same as the inner diameter of the tunnel simulation opening, and the length of the lining assembly is consistent with the distance between the two end faces of the cavity axially opposite to it.

[0015] Furthermore, the data collector includes an earth pressure box group and a collection line. The earth pressure box group is arranged in the rock and soil area around the simulated tunnel excavation outside the lining assembly. One end of the collection line is connected to the earth pressure box group and the other end extends out of the model box.

[0016] Furthermore, the rock and soil area around the simulated tunnel excavation includes a sand layer, a loess layer and a miscellaneous fill layer, and the sand layer, loess layer and miscellaneous fill layer are stacked in sequence from bottom to top.

[0017] Furthermore, the lining assembly is arranged in the loess layer, the soil pressure box group is arranged in the loess layer outside the lining assembly, and the soil pressure box group is used to collect soil pressure change data when the lining assembly is gradually pushed into the loess layer under the seepage state.

[0018] The present invention also provides a test method for simulating tunnel excavation under seepage conditions, comprising the following steps:

[0019] Step S1, making a model box;

[0020] Step S2, making a lining assembly;

[0021] Step S3, making a simulated rock and soil area around the tunnel excavation in the model box;

[0022] Step S4, setting a data collector of a detection device and a branch conduit of a water injection device in the rock and soil area around the simulated tunnel excavation;

[0023] Step S5, erecting a water tank of the water injection device higher than the model box, and releasing water from the water tank into the model box according to the simulated seepage state, the water flows out through the branch conduit to penetrate the rock and soil area around the simulated tunnel excavation and then seeps out from the bottom of the model box, and stopping the water release after reaching the seepage state;

[0024] Step S6, after the tunnel shape is excavated in the rock and soil area around the simulated tunnel excavation along the tunnel simulation opening direction of the model box, the lining assembly is pushed into the tunnel shape;

[0025] Step S7, the data collector collects test data to complete the test.

[0026] Further, in step S2, the manufacturing method of the lining assembly is:

[0027] First, gypsum and water are uniformly mixed in a ratio of 0.6:1, and then poured into a test mold and cured for 24 hours to obtain a lining;

[0028] The axial surface of the lining is bonded and fixed with glue to form the lining assembly;

[0029] In step S3, the method for preparing the rock and soil area around the simulated tunnel excavation is:

[0030] The inside of the model box is filled with a sandy soil layer, a loess layer and a miscellaneous fill soil layer from bottom to top, wherein the loess layer is prepared by mixing quartz sand, on-site loess, slaked lime and kaolin;

[0031] In the step S4, the data collector is arranged in the loess layer, and the branch guide tube is arranged on the upper surface of the loess layer;

[0032] In the step S6, the tunnel shape is located within the loess layer.

[0033] Furthermore, the mass ratio of the quartz sand, on-site loess, slaked lime and kaolin is 0.9:0.06:0.02:0.02.

[0034] The present invention adopts the above technical solution, which has the following advantages and effects:

[0035] The present invention provides a test system and test method for simulating tunnel excavation under seepage conditions, which can simulate the pressure changes of the soil around the tunnel during tunnel excavation under seepage conditions, and can more realistically reproduce the deformation and failure mechanism of the soil around the tunnel under natural disaster conditions, obtain reliable test data, and provide more reasonable technical support for actual tunnel construction technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention is a schematic structural diagram of a test system for simulating tunnel excavation under seepage conditions.

[0037] Figure 2 This is an enlarged structural diagram of the model box.

[0038] Figure 3 This is a schematic diagram of the enlarged structure of the base plate.

[0039] Figure 4 Schematic diagram of the shunt connection enlargement structure.

[0040] Figure 5 Schematic diagram of the connection structure of the branch duct and the diverter.

[0041] Figure 6 This is an enlarged structural diagram of the first lining component.

[0042] Figure 7 This is an enlarged structural diagram of the second lining component.

[0043] Figure 8 This is a schematic diagram of the bonding structure of the first lining component.

[0044] Fig. 9 Schematic diagram of the plane structure simulating the tunnel excavation direction.

[0045] Fig.10 Schematic diagram of the cross-section structure in the simulated tunnel excavation direction.

[0046] Fig.11 This is a schematic diagram of the placement structure of the outer soil pressure box group of the first lining component.

[0047] Fig.12 for Fig.11 Schematic diagram of the cross-sectional structure.

[0048] Fig.13 The present invention is a flow chart of a test method for simulating tunnel excavation under seepage conditions.

[0049] Fig.14 This is a schematic diagram of the locations of the first tunnel simulation entrance and the second tunnel simulation entrance.

[0050] Fig.15It is a curve diagram of soil pressure variation of the loess layer around the first lining assembly of the present invention.

[0051] Fig.16 It is a curve diagram of soil pressure variation of the loess layer around the second lining assembly of the present invention.

[0052] The reference numerals are as follows: 1-box, 2-water inlet, 3-water outlet, 4-main conduit, 5-diverter, 501-first diverter joint, 502-second diverter joint, 503-third diverter joint, 504-fourth diverter joint, 505-fifth diverter joint, 6-first branch conduit, 7-second branch conduit, 8-third branch conduit, 9-fourth branch conduit, 10-seepage hole, 11-epoxy resin, 12-bottom plate, 13-transparent side plate, 1301-first transparent side plate, 1302-second transparent side plate, 1303-third transparent side plate, 1304-fourth transparent side plate, 14-support frame, 15-first bolt, 16-drain hole, 17-tunnel simulation port, 1701-first tunnel simulation port, 1702-second tunnel simulation port, 18-bracket, 19-second bolt, 20-sand layer, 21-loess layer, 22-miscellaneous Fill layer, 23-first lining assembly, 2301-first group one lining, 2302-first group two lining, 2303-first group three lining, 2304-first group four lining, 24-second lining assembly, 2401-second group one lining, 2402-second group two lining, 2403-second group three lining, 2404-second group four lining, 25-glue, 26-tunnel shape, 2601-first tunnel shape, 2 602- shape of the second tunnel, 27- earth pressure box group, 2711- earth pressure box on the upper part of the first lining, 2712- earth pressure box on the right side of the first lining, 2713- earth pressure box on the lower part of the first lining, 2714- earth pressure box on the left side of the first lining, 2721- earth pressure box on the upper part of the second lining, 2722- earth pressure box on the right side of the second lining, 2723- earth pressure box on the lower part of the second lining, 2724- earth pressure box on the left side of the second lining. DETAILED DESCRIPTION

[0053] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, so as to more clearly understand the purpose, characteristics and advantages of the present invention. It should be understood that the embodiments shown in the accompanying drawings are not intended to limit the scope of the present invention, but are only intended to illustrate the essential spirit of the technical solution of the present invention.

[0054] like Figure 1-Figure 10As shown. The present invention provides a test system for simulating tunnel excavation under seepage conditions, comprising a model box, a water injection device, a tunnel structure and a detection device. The model box is used to place the rock and soil area around the simulated tunnel excavation. The model box is a cavity with an open top, at least the four sides of the cavity are transparent, a plurality of drainage holes 16 are arranged at the bottom of the cavity, and a plurality of parallel and spaced tunnel simulation ports 17 are arranged on one end surface of the cavity. The water injection device is used to simulate the formation of a seepage state in the rock and soil area around the tunnel excavation. The water injection device comprises a water tank and a diversion assembly. The diversion assembly comprises at least two parallel branch conduits, and the branch conduits are provided with a plurality of seepage holes 10 in an axial array. The branch conduits are arranged in the rock and soil area around the simulated tunnel excavation and one end extends in the direction of the tunnel simulation port 17, and the other end of the branch conduit is connected to the water tank. The tunnel structure is used to simulate the tunnel. The tunnel structure comprises a tunnel shape 26 and a lining assembly. The tunnel shape 26 has an outer diameter matching the tunnel simulation port 17. The tunnel shape 26 is arranged in the rock and soil area around the simulated tunnel excavation and is opposite to the tunnel simulation port 17. The lining assembly is embedded in the tunnel shape 26. The detection device is used to collect experimental data. The detection device includes a data collector. The data collector is set in the rock and soil area around the simulated tunnel excavation on the periphery of the lining assembly. The data collector is used to collect soil pressure change data when the lining assembly is gradually pushed into the tunnel shape 26 under seepage state.

[0055] Specifically, the water tank includes a box body 1, a water inlet 2 and a water outlet 3. The box body 1 is used to hold water, the water inlet 2 is used to inject water into the box body 1, and the water outlet 3 is used to divert the water in the box body 1 to the diversion component and to switch the water. The water outlet 3 is connected to a PVC water tank joint with a valve, and the PVC water tank joint can also be selected according to the test needs. The water tank is set on the bracket 18 higher than the model box, so that the water in the water tank can be injected into the model box by gravity.

[0056] In the present invention, the tunnel shape 26 includes a first tunnel shape 2601 and a second tunnel shape 2602 , and the lining assembly includes a first lining assembly 23 and a second lining assembly 24 . Each lining assembly is axially embedded in the corresponding tunnel shape 26 and coaxially opposite to the corresponding tunnel simulation opening 17 .

[0057] Furthermore, the model box includes a bottom plate 12, a transparent side plate 13 and a supporting frame 14, the supporting frame 14 is arranged on the bottom plate 12, transparent side plates 13 are arranged around the supporting frame 14, the transparent side plates 13 are fully transparent plates, drainage holes 16 are arranged in an array at intervals on the bottom plate 12, a tunnel simulation port 17 is arranged on one of the transparent side plates 13, and the bottom plate 12, the transparent side plates 13 and the supporting frame 14 enclose a cavity.

[0058] Specifically, the model box is a rectangular parallelepiped structure with an open top. The model box is composed of a bottom plate 12 and a support frame 14 arranged around the bottom plate 12. Transparent side panels 13 are installed around the support frame 14 to seal the entire support frame 14. The bottom plate 12 is used to bear the weight of the rock and soil area around the simulated tunnel excavation in the model box. The bottom plate 12 is connected to the support frame 14 through a first bolt 15. The drainage holes 16 opened on the bottom plate 12 are used for drainage.

[0059] In the present invention, the bottom plate 12 is preferably made of a steel plate with a thickness of 20 mm to 30 mm, and the transparent side plate 13 is preferably made of a transparent acrylic plate with a thickness of 4 mm to 9 mm. The support frame 14 is welded into a rectangular parallelepiped frame using L-shaped angle steel, and the transparent side plates 13 are arranged around the support frame 14 for observing the tunnel excavation process and seepage state.

[0060] The transparent side panel 13 includes a first transparent side panel 1301, a second transparent side panel 1302, a third transparent side panel 1303 and a fourth transparent side panel 1304. The first transparent side panel 1301, the second transparent side panel 1302, the third transparent side panel 1303 and the fourth transparent side panel 1304 are connected to the support frame 14 by second bolts 19, respectively.

[0061] The first transparent side plate 1301 is provided with a tunnel simulation opening 17 for pushing the lining assembly in. The tunnel simulation opening 17 includes a first tunnel simulation opening 1701 and a second tunnel simulation opening 1702. The first tunnel simulation opening 1701 and the second tunnel simulation opening 1702 have the same size and are spaced apart.

[0062] Furthermore, the rock and soil area around the simulated tunnel excavation includes a sand layer 20, a loess layer 21 and a miscellaneous fill layer 22, and the sand layer 20, the loess layer 21 and the miscellaneous fill layer 22 are stacked in sequence from bottom to top.

[0063] Specifically, a sand layer 20, a loess layer 21 and a miscellaneous fill layer 22 are filled in the model box from bottom to top in sequence. The sand layer 20, the loess layer 21 and the miscellaneous fill layer 22 can be calculated according to the geological environment and parameters to be simulated. Those skilled in the art can achieve this through existing technology, and the present invention will not reiterate its preparation process here.

[0064] Furthermore, the flow guide assembly also includes a diverter 5 and a main conduit 4, one end of the main conduit 4 is connected to the water tank, the other end of the main conduit 4 is connected to the diverter 5, and the other end of the diverter 5 is connected to the other end of each branch conduit.

[0065] Specifically, there are multiple branch conduits, including a first branch conduit 6, a second branch conduit 7, a third branch conduit 8 and a fourth branch conduit 9. One end of the main conduit 4 is connected to the water outlet 3, and the other end is connected to the input end of the diverter 5 through the first diverter joint 501. The main conduit 4, the first branch conduit 6, the second branch conduit 7, the third branch conduit 8 and the fourth branch conduit 9 are preferably rubber transparent hoses with good toughness, and can also be selected according to test needs.

[0066] The diverter 5 is pasted on the fourth transparent side panel 1304 , and the diverter 5 is arranged opposite to the tunnel simulation port 17 . The first branch conduit 6 , the second branch conduit 7 , the third branch conduit 8 and the fourth branch conduit 9 are all laid on the loess layer 21 at intervals, and the first branch conduit 6 , the second branch conduit 7 , the third branch conduit 8 and the fourth branch conduit 9 are laid along the direction of the diverter 5 and the tunnel simulation port 17 .

[0067] The first branch conduit 6 is connected to the output end of the diverter 5 through the second diverter joint 502, the second branch conduit 7 is connected to the output end of the diverter 5 through the third diverter joint 503, the third branch conduit 8 is connected to the output end of the diverter 5 through the fourth diverter joint 504, and the fourth branch conduit 9 is connected to the output end of the diverter 5 through the fifth diverter joint 505, so that the first branch conduit 6, the second branch conduit 7, the third branch conduit 8 and the fourth branch conduit 9 are connected in parallel through the diverter 5.

[0068] Each branch conduit has water seepage holes 10 arranged in an axially equidistant array on the pipe body. The water seepage holes 10 are used to allow water to flow out and seep into the loess layer 21 .

[0069] In the present invention, the main conduit 4 is preferably connected to the water outlet 3 by clamping the main conduit 4 to the PVC water tank joint with a valve at the water outlet 3 through a stainless steel clamp.

[0070] The preferred connection method between the main conduit 4 and the first diverter joint 501 is: one end of the main conduit 4 is rotated to connect to the first diverter joint 501 , and epoxy resin 11 is applied to the connection area between the main conduit 4 and the first diverter joint 501 .

[0071] The preferred connection mode of the first branch conduit 6 and the diverter 5 is: one end of the first branch conduit 6 is connected to the second diverter joint 502, and the other end is not connected. The connection end of the first branch conduit 6 is rotated to connect to the second diverter joint 502, and epoxy resin 11 is applied to the connection area between the first branch conduit 6 and the second diverter joint 502. The connection mode of the second branch conduit 7, the third branch conduit 8 and the fourth branch conduit 9 and the diverter 5 is the same as the connection mode of the first branch conduit 6 and the diverter 5. The epoxy resin 11 plays a bonding and waterproofing role.

[0072] Furthermore, the lining assembly is composed of a plurality of linings axially stacked and connected, the outer diameter of the lining assembly is the same as the inner diameter of the tunnel simulation opening 17, and the length of the lining assembly is consistent with the distance between the two end faces of the cavity axially opposite to it.

[0073] Specifically, in the present invention, the first lining assembly 23 includes a first group of one lining 2301, a first group of two linings 2302, a first group of three linings 2303 and a first group of four linings 2304, and the second lining assembly 24 includes a second group of one lining 2401, a second group of two linings 2402, a second group of three linings 2403 and a second group of four linings 2404. The first group of one lining 2301, the first group of two linings 2302, the first group of three linings 2303, the first group of four linings 2304, the second group of one lining 2401, the second group of two linings 2402, the second group of three linings 2403 and the second group of four linings 2404 are all made of the same experimental mold and have the same shape properties.

[0074] The outer diameter of the first lining assembly 23 is the same as the inner diameter of the first tunnel simulation opening 1701, the outer diameter of the second lining assembly 24 is the same as the inner diameter of the second tunnel simulation opening 1702, and the overall length of the first lining assembly 23 and the second lining assembly 24 is equal to the length of the model box. Each lining assembly is formed by bonding a plurality of linings axially by glue 25.

[0075] Again Figure 8 In the present invention, taking the bonding of the first group one lining 2301 and the first group two lining 2302 as an example, the first group one lining 2301 and the first group two lining 2302 are bonded with glue 25, and the bonding methods of the other linings are the same.

[0076] Furthermore, the data collector includes an earth pressure box group 27 and a collection line. The earth pressure box group 27 is arranged in the rock and soil area around the simulated tunnel excavation outside the lining assembly. One end of the collection line is connected to the earth pressure box group 27, and the other end extends out of the model box. The data collector has built-in data acquisition and transmission software. The earth pressure box group 27 is connected to the collection line, and data acquisition can be completed through the data acquisition and transmission software. The data acquisition and data transmission software is a well-known technology for those skilled in the art, and the present invention will not be described in detail again.

[0077] Furthermore, the lining assembly is arranged in the loess layer 21, and the soil pressure box group 27 is arranged in the loess layer 21 around the lining assembly. The soil pressure box group 27 is used to collect soil pressure change data of the surrounding loess layer 21 during the process of the lining assembly being gradually pushed into the loess layer 21 under the seepage state.

[0078] like Fig.11 , Fig.12As shown. Specifically, in the present invention, the earth pressure box group 27 includes a first lining earth pressure box group and a second lining earth pressure box group. The first lining earth pressure box group consists of a first lining upper earth pressure box 2711, a first lining right earth pressure box 2712, a first lining lower earth pressure box 2713 and a first lining left earth pressure box 2714. The second lining earth pressure box group consists of a second lining upper earth pressure box 2721, a second lining right earth pressure box 2722, a second lining lower earth pressure box 2723 and a second lining left earth pressure box 2724. The first lining upper earth pressure box 2711, the first lining right earth pressure box 2712, the first lining lower earth pressure box 2713 and the first lining left earth pressure box 2714 are respectively located around the middle of the first lining assembly 23. The first lining soil pressure box group is used to monitor the soil pressure change data of the upper, right, lower and left sides of the loess layer 21 around the first lining component 23. The second lining upper soil pressure box 2721, the second lining right soil pressure box 2722, the second lining lower soil pressure box 2723 and the second lining left soil pressure box 2724 are respectively located around the middle of the second lining component 24, and the second lining soil pressure box group is used to monitor the soil pressure change data of the upper, right, lower and left sides of the loess layer 21 around the second lining component 24.

[0079] During the measurement, the soil pressure box group 27 has been installed in the loess layer 21 around the lining assembly, so that the soil pressure change data of the surrounding loess layer 21 can be obtained when the lining assembly is gradually pushed into the loess layer 21 under the seepage state, providing a reliable data source for the test.

[0080] The model box and tunnel structure of the present invention are calculated based on the dimensions and parameters actually required to be simulated, and those skilled in the art can implement them through existing methods, and the present invention will not go into details about the specific production process.

[0081] like Fig.13 The present invention also provides a test method for simulating tunnel excavation under seepage conditions, using a test system for simulating tunnel excavation under seepage conditions of the present invention, and the specific steps are as follows:

[0082] Step S1, making a model box.

[0083] Specifically, in the present invention, the length, width and height of the model box are all 1.25 m, the diameters of the first tunnel simulation opening 1701 and the second tunnel simulation opening 1702 on the first transparent side plate 1301 of the model box are both 13 cm, and the positions of the first tunnel simulation opening 1701 and the second tunnel simulation opening 1702 are as follows: Fig.14 shown.

[0084] Step S2, making a lining assembly.

[0085] Specifically, in the present invention, the lining assembly includes a pair, namely, a first lining assembly 23 and a second lining assembly 24, and the outer diameters of the first lining assembly 23 and the second lining assembly 24 are the same as the diameters of the first tunnel simulation opening 1701 and the second tunnel simulation opening 1702. The thickness of each lining of the first lining assembly 23 and the second lining assembly 24 is 0.07m and the length is 0.30m.

[0086] When each lining component is made, gypsum and water are uniformly mixed in a ratio of 0.6:1, and then poured into a test mold for curing for 24 hours to obtain a lining, and then the axial surface of the lining is bonded and fixed with glue 25 to form a lining component.

[0087] Step S3, creating a simulated rock and soil area around the tunnel excavation in the model box.

[0088] Specifically, in the present invention, when simulating the rock and soil area around the tunnel excavation, the sand layer 20, loess layer 21 and miscellaneous fill layer 22 are first filled in the model box from bottom to top, and the filling thicknesses of the sand layer 20, loess layer 21 and miscellaneous fill layer 22 are 0.44m, 0.48m and 0.32m respectively.

[0089] The miscellaneous fill soil layer 22 is prepared from on-site miscellaneous fill soil, and the sand soil layer 20 is prepared from on-site sand soil. Since the loess particles in the loess layer 21 have the disadvantages of porous structure and poor water permeability, the loess particles in the construction site cannot be directly used for the test, and the soil samples need to be re-proportioned according to the physical parameters such as cohesion and friction angle of the loess layer. The loess layer 21 of the present invention is prepared by uniformly mixing quartz sand, on-site loess, slaked lime and kaolin in a mass ratio of 0.9:0.06:0.02:0.02.

[0090] Step S4, a data collector of the detection device and a branch conduit of the water injection device are installed in the rock and soil area around the simulated tunnel excavation. The data collector is installed in the loess layer 21 of the rock and soil area around the simulated tunnel excavation, and the branch conduit is installed on the upper surface of the loess layer 21.

[0091] Step S5, erect the water tank of the water injection device higher than the model box, and discharge water from the water tank to the model box according to the seepage state to be simulated, and the water flows out through the branch pipe to penetrate the rock and soil area around the simulated tunnel excavation and then seep out from the bottom of the model box, and stop draining water after reaching the seepage state. The water tank is erected higher than the model box to ensure that the water in the water tank flows by gravity into the bottom of the model box, and it needs to be left to stand for 24 hours after stopping draining water.

[0092] Step S6, simulating the tunnel excavation process, excavating the tunnel shape 26 in the loess layer 21 of the rock and soil area around the simulated tunnel excavation along the direction of the tunnel simulation port 17 of the model box, and then pushing the lining components into the corresponding tunnel shapes 26 respectively.

[0093] Specifically, in the present invention, the first lining assembly 23 is pushed into the first tunnel shape 2601 along the first tunnel simulation opening 1701, and the second lining assembly 24 is pushed into the second tunnel shape 2602 along the second tunnel simulation opening 1702.

[0094] Step S7, collecting test data through the data collector of the detection device to complete the experiment.

[0095] Take the following experiment as an example. Fig.15 , Fig.16 The soil pressure values ​​of the loess layer 21 measured by the first lining component 23 and the second lining component 24 are basically the same. Fig.15 It can be seen that the soil pressure value at the upper soil pressure box 2711 of the first lining is smaller than the soil pressure box 2712 on the right side of the first lining, and the soil pressure value at the lower soil pressure box 2713 of the first lining is smaller than the soil pressure value at the left side of the first lining. This is because the loess layer 21 of the tunnel excavation is a water-rich sand layer, and the seepage effect of the pore water in the soil of the loess layer 21 is saturated seepage. During the extraction of the lining components, effective stress is generated in the soil skeleton and excess pore water pressure is generated in the fluid. During the actual test, part of the pore water will be discharged with the disturbance of tunnel excavation, and the effective stress in the soil will gradually increase. Therefore, the soil pressure values ​​at the soil pressure box 2712 on the right side of the first lining and the soil pressure box 2714 on the left side of the first lining will also be larger.

[0096] At the same time, since the tunnel shape 26 in the test adopts an arch structure, under the action of the deadweight of the soil layer and the excavation disturbance, the pore water pressure in the loess layer 21 flows in the soil layer, and the arch structure transfers more stress to the earth pressure box 2712 on the right side of the first lining and the earth pressure box 2714 on the left side of the first lining. At the same time, the stress field formed by the pore water pressure around the tunnel structure tends to act in the spatial direction of the tunnel structure, which leads to the earth pressure values ​​of the earth pressure box 2712 on the right side of the first lining and the earth pressure box 2714 on the left side of the first lining being more significant, while the earth pressure box 2711 on the upper part of the first lining is less affected by the pore water pressure. Therefore, the stress value at the earth pressure box 2711 on the upper part of the first lining is smaller than the earth pressure values ​​at the earth pressure box 2712 on the right side of the first lining, the earth pressure box 2713 on the lower part of the first lining and the earth pressure box 2714 on the left side of the first lining.

Claims

1. A test system for simulating tunneling under seepage conditions, characterized in that: include: The model box is used to place the rock and soil area around the simulated tunnel excavation, and is a cavity with an open top, a drainage hole (16) is arranged at the bottom of the cavity, and a plurality of tunnel simulation openings (17) are arranged on one end surface of the cavity; A water injection device, used for forming a seepage state in the rock and soil area around the simulated tunnel excavation, comprising a water tank and a diversion assembly, wherein the diversion assembly comprises at least two branch conduits arranged side by side, wherein the branch conduits are provided with seepage holes (10) in an array, wherein the branch conduits are arranged in the rock and soil area around the simulated tunnel excavation and one end of the branch conduits extends in the direction of the tunnel simulation opening (17), and the other end of the branch conduits is connected to the water tank; A tunnel structure, comprising a tunnel shape (26) and a lining assembly, wherein the tunnel shape (26) is arranged in a rock and soil area around the simulated tunnel excavation and is coaxially opposite to the tunnel simulation opening (17), and the lining assembly is embedded in the tunnel shape (26); The detection device comprises a data collector, the data collector being arranged in a rock and soil area around the simulated tunnel excavation on the periphery of the lining assembly and used to collect soil pressure change data when the lining assembly is gradually pushed into the tunnel shape (26) under a seepage state; The rock and soil area around the simulated tunnel excavation comprises a sand layer (20), a loess layer (21) and a miscellaneous fill layer (22), wherein the sand layer (20), the loess layer (21) and the miscellaneous fill layer (22) are stacked in sequence from bottom to top; The flow guide assembly further comprises a flow diverter (5) and a main conduit (4); one end of the main conduit (4) is connected to the water tank, the other end of the main conduit (4) is connected to the flow diverter (5), and the other end of the flow diverter (5) is connected to the other end of each branch conduit; the branch conduits are laid on the upper surface of the loess layer (21) at intervals, and the branch conduits are connected in parallel through the flow diverter (5); each branch conduit has seepage holes (10) arranged in an axially equidistant array for water discharge, and the seepage holes (10) are used to allow water to flow out and seep into the loess layer (21); The data collector comprises an earth pressure box group (27) and a collection line, the earth pressure box group (27) being arranged in a rock and soil area around the simulated tunnel excavation outside the lining assembly, one end of the collection line being connected to the earth pressure box group (27) and the other end extending out of the model box; The data collector is arranged in the loess layer (21), the lining assembly is arranged in the loess layer (21), and the soil pressure box group (27) is arranged in the loess layer (21) outside the lining assembly, and is used to collect soil pressure change data when the lining assembly is gradually pushed into the loess layer (21) under a seepage state.

2. A test system for simulating tunnel excavation under seepage conditions according to claim 1, characterized in that: The model box comprises a bottom plate (12), transparent side plates (13) and a support frame (14); the support frame (14) is arranged on the bottom plate (12); the transparent side plates (13) are arranged around the support frame (14); the drainage hole (16) is arranged on the bottom plate (12); and the tunnel simulation port (17) is arranged on one of the transparent side plates (13).

3. A test system for simulating tunneling under seepage conditions according to claim 2, characterized in that: The lining assembly is composed of a plurality of linings which are axially stacked and connected. The outer diameter of the lining assembly is the same as the inner diameter of the tunnel simulation opening (17). The length of the lining assembly is consistent with the distance between the two end surfaces of the cavity which are axially opposite to each other.

4. A test method for simulating tunnel excavation under seepage conditions, using a test system for simulating tunnel excavation under seepage conditions as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: Step S1, making a model box; Step S2, manufacturing a lining assembly; the manufacturing method of the lining assembly is: First, gypsum and water are uniformly mixed in a ratio of 0.6:1, and then poured into a test mold and cured for 24 hours to obtain a lining; The axial surface of the lining is bonded and fixed with glue (25) to form the lining assembly; The method for preparing the rock and soil area around the simulated tunnel excavation is as follows: Step S3, making a simulated rock and soil area around the tunnel excavation in the model box; The method for preparing the rock and soil area around the simulated tunnel excavation is as follows: A sand layer (20), a loess layer (21) and a miscellaneous fill layer (22) are sequentially filled into the model box from bottom to top, wherein the loess layer (21) is prepared by mixing quartz sand, on-site loess, slaked lime and kaolin; the mass ratio of the quartz sand, on-site loess, slaked lime and kaolin is 0.9:0.06:0.02:0.02; Step S4, setting a data collector of a detection device and a branch conduit of a water injection device in the rock and soil area around the simulated tunnel excavation; Step S5, erecting a water tank of the water injection device higher than the model box, and releasing water from the water tank into the model box according to the simulated seepage state, the water flows out through the branch conduit to penetrate the rock and soil area around the simulated tunnel excavation and then seeps out from the bottom of the model box, and stopping the water release after reaching the seepage state; Step S6, after excavating a tunnel shape (26) in the rock and soil area surrounding the simulated tunnel excavation along the direction of the tunnel simulation opening (17) of the model box, the lining assembly is pushed into the tunnel shape (26); Step S7, the data collector collects test data to complete the test.

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