A tunnel lining cushion permeation characteristic test device and method

Abstract

The application provides a tunnel lining cushion permeation characteristic test device and method, which comprises a constant pressure water supply system, a tunnel lining cushion simulation system, an outflow monitoring system and a mechanical water stop system. The constant pressure water supply system is located above the tunnel lining cushion simulation system, and pure water flows to the tunnel lining cushion under constant pressure through the constant pressure water supply system. The outflow monitoring system is located below the tunnel lining cushion simulation system, and the pressure outside the tunnel lining cushion is monitored in real time under the condition that the water flow is free to overflow. The mechanical water stop system realizes water stop of the contact positions of the above three different systems through a simple and effective mechanical structure. The test device can simulate the cushion seepage process under the influence of single factor or multiple factors such as different lining crack sizes, lining gap sizes and cushion blockage degrees. The application has a clever structure design and a simple method, and provides technical support for the test research of the tunnel lining cushion permeation characteristics.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel test in high groundwater area, and particularly relates to a tunnel lining cushion permeation characteristic test device and method. BACKGROUND

[0002] Building national water network is a key foundation for guaranteeing national water security, and is an effective way to solve the problem of the incompatibility between the temporal and spatial distribution of water resources and the water demand of economic and social development, and to meet the demand of the broad masses of the people and economic and social development for certain water quantity and water quality. With the rapid advancement of the construction of national water network, underground tunnel projects are increasing. The lining structure of the tunnel includes single lining and double lining. The tunnel with single lining is mainly controlled by the displacement of the surrounding strata, and is prone to local deformation and damage or permeation damage. The tunnel with double lining can increase the safety reserve of the tunnel structure to a certain extent and improve the long-term use capacity of the tunnel. Therefore, the research and application of the double lining structure are of great significance to the construction of national water network and the long-term safe and stable operation.

[0003] The double lining of the tunnel includes inner lining and outer lining, and the inner and outer lining are separated by a drainage cushion, so that the inner and outer lining work independently. That is, the outer lining mainly bears the surrounding soil pressure, external water pressure and other additional loads, while the inner lining mainly bears the internal water pressure. In addition, when the inner lining of the tunnel is damaged and causes internal water seepage, the drainage cushion can collect and discharge the seepage water, reducing the risk of tunnel instability and damage caused by internal water seepage. Under the condition of long-term operation of the water conveying tunnel, the construction of cast-in-place concrete, concrete precipitates, air and fine particles in water and other factors may cause the drainage cushion to be blocked and fail, which threatens the safety and stability of the tunnel. When the inner lining and the outer lining deform unevenly and locally extrude or the inner lining produces large-scale cracks, the permeation characteristics of the drainage cushion will also be seriously affected. Therefore, the evolution mechanism and influencing factors of the permeation characteristics of the tunnel lining cushion are crucial to the seepage safety of the tunnel. However, the research on the permeation characteristics of the tunnel lining cushion is still relatively scarce and needs to be promoted.

[0004] Experimental research is one of the important means of basic research, and it is necessary to specially develop a set of tunnel lining cushion permeation characteristic test device and propose a corresponding test method to provide technical support for the mechanism research of the tunnel lining cushion permeation characteristics and theoretical support for the safe and stable operation of the national water network. SUMMARY

[0005] The main purpose of the present application is to provide a tunnel lining cushion permeability test device and method, which can simulate the seepage process of the cushion under the influence of different single factors or multiple factors such as the size of the lining crack, the size of the gap between the inner and outer linings, and the degree of cushion blockage.

[0006] The present application provides the following technical solutions to achieve the above-mentioned purposes:

[0007] A tunnel lining cushion permeability test device comprises a constant-pressure water supply system, a tunnel lining cushion simulation system, an outflow monitoring system arranged in sequence from top to bottom, and a mechanical water stop system surrounding the constant-pressure water supply system, the tunnel lining cushion simulation system and the outflow monitoring system.

[0008] The constant-pressure water supply system comprises:

[0009] A constant-pressure pump, a water supply pipe and a water supply tank, wherein the constant-pressure pump is connected with the water supply tank through the water supply pipe;

[0010] The tunnel lining cushion simulation system comprises:

[0011] An inner lining plate and an outer lining plate coaxially sleeved, and an annular cavity is formed between the two;

[0012] A drainage cushion and a gap control sheet are sequentially filled in the annular cavity from top to bottom, and the inner lining plate is used to guide the water in the water supply tank into the drainage cushion;

[0013] The outflow monitoring system comprises:

[0014] An overflow tank surrounding the tunnel lining cushion simulation system, and a circle of outflow ports is arranged at the position where the top of the overflow tank is connected with the drainage cushion;

[0015] A seepage pressure pipe and an overflow pipe are arranged around the overflow tank, and a seepage pressure gauge is arranged on the seepage pressure pipe;

[0016] The mechanical water stop system comprises:

[0017] An upper annular water stop groove and a lower annular water stop groove arranged at the bottom of the water supply tank and the top of the overflow tank, respectively;

[0018] An upper rubber ring and a lower rubber ring correspondingly embedded in the upper annular water stop groove and the lower annular water stop groove;

[0019] An upper pressing plate, a middle pressing plate and a lower pressing plate distributed in the axial direction, and three-way sealing and pressing are realized through the pressing rods and nuts arranged in penetration;

[0020] The upper pressing plate, the middle pressing plate and the lower pressing plate are arranged around the outer peripheral contact surface of the water supply tank, the tunnel lining cushion simulation system and the overflow tank.

[0021] Further, the constant pressure pump inputs the pure water into the water supply warehouse through the water supply pipe, and the water supply warehouse is connected with the inner lining plate to realize large-range constant water head test conditions of the tunnel lining and cushion simulation system.

[0022] Further, the gap size between the inner lining plate and the outer lining plate is fixed, and the pressure degree of the drainage cushion is controlled by changing the thickness of the gap control piece.

[0023] Further, the inner lining plate has a crack at the center position, and the crack size is controlled to carry out cushion permeability test under different tunnel lining crack sizes.

[0024] Further, the water in the water supply warehouse enters the center position of the drainage cushion through the crack at the center position of the inner lining plate, and then the water flow seeps from the center to the periphery of the drainage cushion, realizing the real simulation of the circumferential seepage of the tunnel lining cushion.

[0025] Further, the water flowing out of the drainage cushion flows into the overflow warehouse through the outflow port, realizing the collection of the water flowing out of the drainage cushion in all directions.

[0026] Further, the seepage pressure pipe and the overflow pipe are arranged in pairs in parallel, and the position of the seepage pressure pipe is lower than that of the overflow pipe, so as to ensure that the water flowing out of the drainage cushion flows freely from the overflow pipe, and the seepage pressure gauge installed at the end of the seepage pressure pipe is used to monitor the pressure at the outlet position of the drainage cushion.

[0027] Further, the upper annular water stop groove is arranged between the middle pressure plate and the inner lining plate, and the upper rubber ring is arranged in the upper annular water stop groove, and the mechanical water stop between the constant pressure water supply system and the tunnel lining cushion simulation system is realized by mutual extrusion of the upper pressure plate and the middle pressure plate; the lower annular water stop groove is arranged at the top of the overflow warehouse, the lower rubber ring is arranged in the lower annular water stop groove, and the mechanical water stop between the tunnel lining cushion simulation system and the outflow monitoring system is realized by mutual extrusion of the middle pressure plate and the lower pressure plate.

[0028] Further, the upper pressure plate, the middle pressure plate and the lower pressure plate are provided with a plurality of circular holes around the circumference, the pressure rod passes through the circular holes of the upper pressure plate, the middle pressure plate and the lower pressure plate, nuts are installed on both sides of the circular holes, and the uniform extrusion between the upper pressure plate, the middle pressure plate and the lower pressure plate is realized by tightening the nuts.

[0029] A tunnel lining cushion permeability test method is provided, which is carried out by using the above device, and the method comprises the following steps:

[0030] Step 1: select an inner lining plate with a specified crack size, install the pressure rod after arranging the upper rubber ring in the upper annular water stop groove, and tighten the nuts to make the gap between the upper pressure plate and the middle pressure plate reach a closed state;

[0031] Step 2: Gap control piece and drainage cushion are arranged on the outer lining plate in sequence, and the pressurizing rod is installed after the lower rubber ring is arranged in the lower annular water stop groove, and the nut is screwed, so that the gap between the middle pressurizing plate and the overflow bin is closed;

[0032] Step 3: Start the constant pressure pump, set the pressure to slowly fill the water supply pipe, water supply bin, inner lining plate crack, drainage cushion, overflow bin, osmotic pressure pipe and overflow pipe with pure water, so that the whole test system reaches a saturated state;

[0033] Step 4: Install the osmotic pressure meter on the osmotic pressure pipe, and start the osmotic pressure meter to monitor the pressure at the outlet position of the drainage cushion;

[0034] Step 5: Adjust the pressure of the constant pressure pump to the required pressure value, and when the flow of the overflow pipe or the pressure monitored by the osmotic pressure meter reaches a stable state, the drainage cushion permeability test at this pressure value is completed, and then the pressure of the constant pressure pump is adjusted again to start the next pressure test.

[0035] Compared with the prior art, the present application has the following beneficial effects:

[0036] 1. With the rapid advancement of national water network construction, underground tunnel projects are increasing. However, the mechanism research on the permeability characteristics of tunnel lining cushion is still relatively scarce, and the present application provides a test means for the research on the permeability characteristics of tunnel lining cushion.

[0037] 2. The present application can realize the research on the permeability characteristics of the cushion under different tunnel lining crack scales by changing the size of the crack at the center position of the inner lining plate.

[0038] 3. The present application can realize the real simulation of the circumferential seepage of the tunnel lining cushion by supplying water to the center position of the drainage cushion through the crack at the center position of the inner lining plate.

[0039] 4. The present application can simulate the cushion permeability test under the condition that the drainage cushion is locally extruded due to uneven deformation of the inner and outer linings of the tunnel by changing the thickness of the gap control piece.

[0040] 5. The present application can simulate the permeability test under different degrees or ranges of tunnel lining cushion blockage by simply adjusting the local structure of the drainage cushion.

[0041] 6. The present application realizes the monitoring of the pressure at the outlet position of the annular drainage cushion and the collection of the drainage cushion outflow through ingenious structure design; in addition, the problem of water stop between the constant pressure water supply system, the tunnel lining cushion simulation system and the outflow monitoring system is solved. DETAILED DESCRIPTION

[0042] Figure 1is a structural schematic view of a tunnel lining cushion permeability test device according to an embodiment of the present application;

[0043] Figure 2 is Figure 1 a disassembled schematic view;

[0044] Figure 3 in (a) is Figure 2 a structural schematic view of an inner lining plate in (b) is a disassembled schematic view of the inner lining plate; Figure 3

[0045] Figure 4 in (a) is Figure 2 a structural schematic view of an overflow bin in (b) is a disassembled schematic view of the overflow bin. Figure 4

[0046] In the figure: 1 - constant pressure pump; 2 - water supply pipe; 3 - water supply bin; 4 - upper pressurizing plate; 5 - middle pressurizing plate; 6 - lower pressurizing plate; 7 - seepage pressure pipe; 8 - seepage pressure gauge; 9 - overflow pipe; 10 - pressurizing rod; 11 - nut; 12 - overflow bin; 13 - upper rubber ring; 14 - lower rubber ring; 15 - inner lining plate; 16 - crack; 17 - outflow port; 18 - drainage cushion; 19 - upper annular water stop groove; 20 - lower annular water stop groove; 21 - outer lining plate; 22 - gap control piece. DETAILED DESCRIPTION

[0047] In order to make the technical problems to be solved by the present application, technical solutions and beneficial effects more clearly understood, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0048] ​​It should be noted that in the present application: the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices; the terms "up", "down", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "transverse", "longitudinal" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and these terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation; the terms "mounting", "setting", "provided with", "connected", "connected", "sleeved" and the like should be interpreted broadly; for example, it can be fixedly connected, detachably connected, or integrally constructed; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be internal communication between two devices, elements or components. In addition, in addition to being used to indicate the orientation or positional relationship, some terms can also be used to indicate other meanings, for example, the term "up" can also be used to indicate a certain dependent relationship or connection relationship in some cases. For those skilled in the art, the specific meaning of these terms in the present application can be understood according to the specific circumstances.

[0049] Embodiment:

[0050] The present application provides a kind of tunnel lining cushion permeability test device, please refer to Figures 1-4 As shown, it includes constant pressure water supply system, tunnel lining cushion simulation system, outflow monitoring system and mechanical water stop system.

[0051] Wherein, constant pressure water supply system includes constant pressure pump 1, water supply pipe 2 and water supply warehouse 3, is located in tunnel lining and cushion simulation system top;The tunnel lining cushion simulation system includes inner lining plate 15 and outer lining plate 21 and the drainage cushion 18 and gap control sheet 22 between them;The outflow monitoring system includes outflow port 17, overflow warehouse 12, overflow pipe 9, osmotic pressure pipe 7 and osmotic pressure gauge 8, is located in tunnel lining cushion simulation system around;The mechanical water stop system includes upper annular water stop groove 19, lower annular water stop groove 20, upper rubber ring 13, lower rubber ring 14, upper pressing plate 4, middle pressing plate 5, lower pressing plate 6, pressing rod 10 and nut 11, is located in constant pressure water supply system, tunnel lining and cushion simulation system and outflow monitoring system three systems around and its contact position.

[0052] The constant pressure pump 1 is connected with the water supply tank 3 through the water supply pipe 2, the constant pressure pump 1 inputs pure water into the water supply tank 3 through the water supply pipe 2, the water supply tank 3 is connected with the inner lining plate 15, and the large-range constant water head test condition of the tunnel lining and cushion simulation system is realized.

[0053] The gap size between the inner lining plate 15 and the outer lining plate 21 is fixed, the drainage cushion 18 and the gap control piece 22 are sequentially arranged between the inner lining plate 15 and the outer lining plate 21 from top to bottom, and the pressure receiving degree of the drainage cushion 18 is controlled by changing the thickness of the gap control piece 22.

[0054] The inner lining plate 15 has a crack 16 at the center position, and the crack 16 can be controlled to carry out the cushion permeation characteristic test under different tunnel lining crack scales.

[0055] The water in the water supply tank 3 enters the center position of the drainage cushion 18 through the crack 16 at the center position of the inner lining plate 15, and then the water flow seeps from the center to the periphery of the drainage cushion 18, so that the real simulation of the circumferential seepage of the tunnel lining cushion is realized.

[0056] A circle of outflow ports 17 are arranged at the position where the top of the overflow tank 12 is connected with the drainage cushion 18, the water flowing out of the drainage cushion 18 flows into the overflow tank 12 through the outflow ports 17, and the water flowing out of the drainage cushion 18 in all directions is collected.

[0057] Four seepage pressure pipes 7 and four overflow pipes 9 are arranged around the overflow tank 12, the seepage pressure pipes 7 and the overflow pipes 9 are arranged in pairs in parallel, the position of the seepage pressure pipe 7 is lower than that of the overflow pipe 9, the water flowing out of the drainage cushion 18 is ensured to flow out of the overflow pipe 9 freely, and the seepage pressure meter 8 installed at the end of the seepage pressure pipe 7 monitors the pressure at the outlet position of the drainage cushion 18.

[0058] The upper annular water stop groove 19 is arranged between the middle pressure plate 5 and the inner lining plate 15, the upper rubber ring 13 is arranged in the upper annular water stop groove 19, the mechanical water stop between the constant pressure water supply system and the tunnel lining cushion simulation system is realized through the mutual extrusion of the upper pressure plate 4 and the middle pressure plate 5, the lower annular water stop groove 20 is arranged at the top of the overflow tank 12, the lower rubber ring 14 is arranged in the lower annular water stop groove 20, and the mechanical water stop between the tunnel lining cushion simulation system and the outflow monitoring system is realized through the mutual extrusion of the middle pressure plate 5 and the lower pressure plate 6.

[0059] Eight circular holes are arranged around the upper pressure plate 4, the middle pressure plate 5 and the lower pressure plate 6, eight pressure rods 10 pass through the circular holes of the three pressure plates (4, 5, 6), nuts 11 are arranged on both sides of the circular holes, and the uniform extrusion between the pressure plates is realized by tightening the nuts 11.

[0060] When the above-mentioned technology is implemented, the water supply pipe 2, the water supply bin 3, the upper pressing plate 4, the middle pressing plate 5, the lower pressing plate 6, the seepage pipe 7, the overflow pipe 9, the pressing rod 10, the nut 11, the overflow bin 12, the inner lining plate 15, the outer lining plate 21, and the gap control piece 22 are all made of stainless steel. Among them, the inner diameter of the water supply pipe 2 is 20 mm, and the wall thickness is 1 mm; the inner diameter of the water supply bin 3 is 190 mm, and the wall thickness is 5 mm; the thickness of the pressing plate (4, 5, 6) is 14 mm, and the diameter of the circular hole on the pressing plate (4, 5, 6) is 23 mm; the inner diameters of the seepage pipe 7 and the overflow pipe 9 are both 10 mm, and the wall thicknesses are both 2 mm; the depth of the overflow bin 12 is 50 mm, and the width is 5 mm; the diameter of the inner lining plate 15 is 190 mm, and the thickness is 14 mm; the diameter of the outer lining plate 21 is 182 mm, and the thickness is 50 mm; the thickness of the gap control piece 22 is 1, 2, or 3 mm, which is selected according to the test working condition; the size of the crack 16 is 10×10 mm (length×width); the diameter of the outflow port 17 is 3 mm; the depth of the upper water stop groove 19 is 1.75 mm; the depth of the lower water stop groove 20 is 2 mm; and the drainage cushion layer 18 is a composite geomembrane with a thickness of 7 mm.

[0061] With the above device, the embodiment of the present application further provides a test method for the seepage characteristics of a tunnel lining cushion layer, which comprises the following steps:

[0062] Step 1: select the inner lining plate 15 with a crack 16 of 10×10 mm (length×width), arrange the upper rubber ring 13 in the upper annular water stop groove 19, install the pressing rod 10 and tighten the nut 11, so that the gap between the upper pressing plate 4 and the middle pressing plate 5 reaches a closed state;

[0063] Step 2: arrange the gap control piece 22 with a thickness of 1 mm and the drainage cushion layer 18 on the outer lining plate 21 in sequence, arrange the lower rubber ring 14 in the lower annular water stop groove 20, install the pressing rod 10 and tighten the nut 11, so that the gap between the middle pressing plate 5 and the overflow bin 12 reaches a closed state;

[0064] Step 3: start the constant pressure pump 1, set a small pressure, and make pure water slowly fill the water supply pipe 2, the water supply bin 3, the inner lining plate crack 16, the drainage cushion layer 18, the overflow bin 12, the seepage pipe 7, and the overflow pipe 9, that is, the entire test system reaches a saturated state;

[0065] Step 4: install the four seepage meters 8 on the four seepage pipes 7 respectively, and start the seepage meter 8 to monitor the pressure at the outlet position of the drainage cushion layer 18;

[0066] Step 5: adjust the pressure of the constant pressure pump 1, set its pressure value to 0.5Mpa, after the flow of the overflow pipe 9 or the pressure monitored by the osmometer 8 reaches a steady state, end the drainage cushion layer permeation characteristic test under this pressure value, then adjust the pressure value of the constant pressure pump 1 to 1Mpa, start the next pressure test.

[0067] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical scope disclosed by the present application, which can be easily thought by any person skilled in the art, should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A device for testing the permeability characteristics of a tunnel lining blanket, characterized in that: The tunnel lining cushion simulation system comprises: The constant pressure water supply system comprises: The constant pressure pump (1), the water supply pipe (2) and the water supply warehouse (3), the constant pressure pump (1) is connected with the water supply warehouse (3) through the water supply pipe (2); The tunnel lining cushion simulation system comprises: The inner lining plate (15) and the outer lining plate (21) are coaxially sleeved, and an annular cavity is formed between the two; The drainage cushion (18) and the gap control sheet (22) are sequentially filled in the annular cavity from top to bottom, and the inner lining plate (15) is used for guiding the water in the water supply warehouse (3) into the drainage cushion (18); The outflow monitoring system comprises: The overflow warehouse (12) surrounds the tunnel lining cushion simulation system, and a circle of outflow ports (17) is arranged at the position where the top of the overflow warehouse (12) is connected with the drainage cushion (18); The seepage pressure pipe (7) and the overflow pipe (9) are arranged around the overflow warehouse (12), and the seepage pressure gauge (8) is arranged on the seepage pressure pipe (7); The mechanical water stop system comprises: The upper and lower annular water stop grooves (19, 20) are arranged at the bottom of the water supply warehouse (3) and the top of the overflow warehouse (12) respectively; The upper and lower rubber rings (13, 14) are correspondingly embedded in the upper and lower annular water stop grooves (19, 20); The upper, middle and lower pressurizing plates (4, 5, 6) are distributed in the axial direction, and three-way sealing and compression are realized through the pressurizing rods (10) and the nuts (11) penetratingly arranged; The upper, middle and lower pressurizing plates (4, 5, 6) surround the outer peripheral contact surfaces of the water supply warehouse (3), the tunnel lining cushion simulation system and the overflow warehouse (12); The inner lining plate (15) has a crack (16) at the center position, and the crack (16) is used for carrying out cushion permeation characteristic test under different tunnel lining crack scales by controlling the size of the crack (16).

2. The test device for permeability characteristics of tunnel lining bedding course according to claim 1, characterized in that: The constant pressure pump (1) inputs pure water into the water supply warehouse (3) through the water supply pipe (2), the water supply warehouse (3) is connected with the inner lining plate (15), and a large-scale constant water head test condition of the tunnel lining and the cushion simulation system is realized.

3. The test device for permeability characteristics of tunnel lining bedding course according to claim 1, characterized in that: The gap size between the inner lining plate (15) and the outer lining plate (21) is fixed, and the pressure degree of the drainage cushion (18) is controlled by changing the thickness of the gap control sheet (22).

4. The test device for permeability characteristics of tunnel lining bedding course according to claim 1, characterized in that: The water in the water supply warehouse (3) enters the center position of the drainage cushion (18) through the crack (16) at the center position of the inner lining plate (15), and then the water flow seeps from the center to the periphery of the drainage cushion (18), so that the real simulation of the circumferential seepage of the tunnel lining cushion is realized.

5. The test device for permeability characteristics of tunnel lining bedding course according to claim 4, characterized in that: The water flowing out of the drainage cushion (18) flows into the overflow warehouse (12) through the outflow port (17), so that the water flowing out of the drainage cushion (18) is collected in all directions.

6. The test device for permeability characteristics of tunnel lining bedding course according to claim 1, characterized in that: The osmotic pressure pipe (7) and the overflow pipe (9) are arranged in pairs in parallel, and the position of the osmotic pressure pipe (7) is lower than that of the overflow pipe (9), so that the water flowing out of the drainage cushion layer (18) can overflow freely from the overflow pipe (9), and the osmotic pressure gauge (8) installed at the end of the osmotic pressure pipe (7) is used to monitor the pressure at the outlet position of the drainage cushion layer (18).

7. The test device for permeability characteristics of tunnel lining bedding course according to claim 1, characterized in that: The upper annular water stop groove (19) is arranged between the middle pressurizing plate (5) and the inner lining plate (15), the upper rubber ring (13) is arranged in the upper annular water stop groove (19), the mechanical water stop between the constant pressure water supply system and the tunnel lining cushion simulation system is realized through the mutual extrusion of the upper pressurizing plate (4) and the middle pressurizing plate (5), and the lower annular water stop groove (20) is arranged at the top of the overflow bin (12), the lower rubber ring (14) is arranged in the lower annular water stop groove (20), and the mechanical water stop between the tunnel lining cushion simulation system and the outflow monitoring system is realized through the mutual extrusion of the middle pressurizing plate (5) and the lower pressurizing plate (6).

8. The test device for permeability characteristics of tunnel lining bedding course according to claim 1, characterized in that: The upper pressurizing plate (4), the middle pressurizing plate (5) and the lower pressurizing plate (6) are all provided with a plurality of circular holes, the pressurizing rod (10) passes through the circular holes of the upper pressurizing plate (4), the middle pressurizing plate (5) and the lower pressurizing plate (6), the nuts (11) are arranged on both sides of the circular holes, and the uniform extrusion between the upper pressurizing plate (4), the middle pressurizing plate (5) and the lower pressurizing plate (6) is realized by rotating the nuts (11).

9. A method of testing the permeability characteristics of a tunnel lining blanket, characterized in that, The device of any one of claims 1-8 is used, and the method comprises the following steps: Step 1: select the inner lining plate (15) with a specified crack size, install the pressurizing rod (10) after arranging the upper rubber ring (13) in the upper annular water stop groove (19) and tighten the nut (11), so that the gap between the upper pressurizing plate (4) and the middle pressurizing plate (5) reaches a closed state; Step 2: arrange the gap control piece (22) and the drainage cushion layer (18) on the outer lining plate (21) in sequence, install the pressurizing rod (10) after arranging the lower rubber ring (14) in the lower annular water stop groove (20) and tighten the nut (11), so that the gap between the middle pressurizing plate (5) and the overflow bin (12) reaches a closed state; Step 3: start the constant pressure pump (1), set the pressure so that the pure water slowly fills the water supply pipe (2), the water supply bin (3), the inner lining plate crack (16), the drainage cushion layer (18), the overflow bin (12), the osmotic pressure pipe (7) and the overflow pipe (9), so that the entire test system reaches a saturated state; Step 4: install the osmotic pressure gauge (8) on the osmotic pressure pipe (7) respectively, and start the osmotic pressure gauge (8) to monitor the pressure at the outlet position of the drainage cushion layer (18); Step 5: adjust the pressure of the constant pressure pump (1) to the required pressure value, and after the flow of the overflow pipe (9) or the pressure monitored by the osmotic pressure gauge (8) reaches a stable state, end the drainage cushion layer permeability test under the pressure value, and then adjust the pressure of the constant pressure pump (1) to start the next pressure test.

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