Loading mechanism and test method for simulation test of shield tunnel and stratum complex

Abstract

This invention relates to a simulation test device for shield tunnels and geological complexes, and discloses a horizontal loading mechanism for simulating shield tunnels and geological complexes. The loading mechanism for simulating shield tunnels and geological complexes disclosed in this invention includes a base, a soil chamber, and a tunnel model. The tunnel model is placed inside the soil chamber. A pressurization mechanism is installed on the base corresponding to the soil inside the soil chamber. The loading mechanism also includes an expansion simulation system and a pressure monitoring system. The expansion simulation system includes an expansive soil bag, a water supply pipe, and a water supply device. At least one expansive soil bag is placed inside the soil chamber. One end of the water supply pipe is connected to the inside of the expansive soil bag, and the other end is connected to the water supply device. The pressure monitoring system includes a pressure sensor and a data acquisition instrument. A pressure sensor is installed outside the tunnel model, and the pressure sensor is connected to the data acquisition instrument. This loading mechanism can simulate the pressure exerted on a tunnel by a composite geological formation containing expansive materials such as expansive rock.

Description

Technical Field

[0001] The invention relates to a shield tunnel and stratum complex simulation test equipment, in particular to a horizontal loading mechanism for a shield tunnel and stratum complex simulation test. Background Art

[0002] The shield method occupies an important position in today's tunnel construction methods, especially in projects such as urban subways, integrated pipeline corridors and large underwater tunnels. During the shield tunneling process, if the stratum contains swelling rock layers, it will produce obvious deviatoric pressure on the shield tunnel, and the swelling and shrinkage of the swelling rock will affect the internal force and deformation of the shield segment. Swelling rock is a highly water-sensitive material. Under the action of precipitation infiltration, it produces obvious volume changes due to humidity changes. When the deformation is constrained, it produces large internal stress and exerts force on the adjacent structures that constrain its deformation. This will have a significant negative impact on the engineering mechanical properties of the shield tunnel and surrounding rock passing through it. For example, a certain section of tunnel in China passes through a relatively complex stratum, including both highly permeable gravel strata with a high quartz content and soft carbonaceous mudstone strata. It may also be affected by the expansion pressure of mudstone, soil-rock interaction, and a large tunnel burial depth (the maximum burial depth of the top plate is about 47m). Its design and construction are difficult and risky. Before formal construction, a simulation test of the shield tunnel and stratum complex is required to ensure smooth construction and avoid unnecessary safety accidents.

[0003] The traditional loading device used for shield tunnel simulation test generally includes a base, a soil box and a tunnel model. A transverse reaction beam is installed on the top of the base. The soil box is arranged in the base. The soil box is filled with soil and a vertical tunnel model is arranged in the middle of the soil. Transverse jacks are respectively installed between the box plates in the front, back, left and right directions of the soil box and the corresponding bases. A pressure plate is installed on the top of the soil box, and a vertical jack is installed between the pressure plate and the reaction beam. Different pressures are applied to the tunnel model in the five directions of up, front, back, left and right through the transverse jacks and the vertical jacks to simulate the situation where the tunnel is subjected to different pressures in various directions in the stratum.

[0004] Although the traditional loading device for the above-mentioned shield tunnel and stratum composite simulation test can simulate the soil pressure of uniform strata, it has the following defects: (1) The surrounding simulated strata can only be considered as uniform strata, and it is impossible to use multiple materials to form composite stratum conditions, and it is impossible to simulate the pressure of composite strata mixed with swelling materials such as swelling rocks on the tunnel. (2) It is impossible to simulate the bias pressure of different sizes and directions generated by the swelling materials on the tunnel, and the quantitative swelling force generated by the swelling materials. (3) The original model soil cannot change its properties as the test progresses after configuration, and it is impossible to simulate the dynamic impact of the swelling rock absorbing water to complete expansion on the tunnel.

[0005] Patent applications with publication numbers CN104931414A and CN104990659 A both disclose simulations of the effects of expansive materials on tunnel-related structures. The methods generally involve pressurizing the expansive soil, pumping water into the expansive soil, causing the expansive soil to swell, measuring the pressure parameters at the corresponding positions, and providing the expansive performance parameters of the expansive soil in the slurry shield tunnel. Although this patent application can simulate the effects of expansive soil on tunnel-related structures well, there are still two problems: first, the expansion of the expansive soil is difficult to control by directly injecting water into the expansive soil through a pipeline, and only a rough simulation can be achieved, and a targeted and accurate simulation cannot be performed; second, the structure only simulates the situation in which the tunnel is in the overall expansive material, and cannot simulate the pressure exerted on the tunnel by the composite stratum doped with expansive materials such as expansive rock, which is a more common situation encountered in current tunnel construction. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a loading mechanism and a test method for a shield tunnel and stratum complex simulation test, which can simulate the situation where a composite stratum doped with swelling materials such as swelling rocks exerts pressure on a tunnel.

[0007] The present invention discloses a loading mechanism for a simulation test of a shield tunnel and a stratum complex, comprising a base, a soil box and a tunnel model, wherein the soil box is arranged inside the base, soil is arranged inside the soil box, and the tunnel model is arranged inside the soil. A pressurizing mechanism is arranged on the base corresponding to the soil in the soil box, and the loading mechanism also comprises an expansion simulation system and a pressure monitoring system, wherein the expansion simulation system comprises an expansion soil bag, a water pipe and a water supply device, wherein at least one expansion soil bag is arranged inside the soil, wherein one end of the water pipe is connected to the inside of the expansion soil bag, and the other end is connected to the water supply device, wherein the pressure monitoring system comprises a pressure sensor and a data acquisition instrument, wherein the pressure sensor is arranged outside the tunnel model, and wherein the pressure sensor is connected to the data acquisition instrument.

[0008] Preferably, the expansive soil bag comprises a first elastic membrane and a second elastic membrane, the first elastic membrane is provided with a plurality of water-permeable holes, the second elastic membrane is a water-proof structure, the first elastic membrane is wrapped in the second elastic membrane, the expansive soil is filled in the first elastic membrane, and the port of the water pipe is arranged between the first elastic membrane and the second elastic membrane.

[0009] Preferably, the first elastic film and the second elastic film are both elastic PE films.

[0010] Preferably, the pressurizing mechanism includes a reaction beam, a transverse jack and a vertical jack. The transverse jack is arranged around the soil box. The box plates around the soil box are movably matched with the base. The transverse jack is connected between the box plates around and the base. The reaction beam is arranged above the soil box and connected to the base. A pressure plate is arranged on the top of the soil box, and the vertical jack is arranged between the pressure plate and the reaction beam.

[0011] Preferably, the tunnel model is arranged vertically, the pressure plate is provided with a central through hole corresponding to the top port of the tunnel model, and the aperture of the central through hole is larger than the outer diameter of the tunnel model.

[0012] Preferably, the water pipe extends from between the central through hole of the pressure plate and the tunnel model into the soil box.

[0013] Preferably, a flow detection device and a flow control device are provided on the water delivery pipe, and both the flow detection device and the flow control device are connected to a control device.

[0014] Preferably, a pressure sensor connected to a data acquisition instrument is provided on the outer surface of the expansion soil bag.

[0015] The test method disclosed in the present application using the loading mechanism for the shield tunnel and stratum complex simulation test comprises the following steps:

[0016] Determine the number and location of expansion bags according to the distribution of expansion materials in the shield tunnel area, and set up corresponding expansion bags;

[0017] Pressurizing the soil box through a pressurizing mechanism to maintain a preset pressure in the soil box;

[0018] Inject water into the expansion soil bag through the water pipe to make the expansion soil in the expansion soil bag expand;

[0019] The data from the pressure sensor outside the tunnel model is detected by the data acquisition instrument.

[0020] Preferably, a pressure sensor connected to a data acquisition instrument is provided on the outer surface of the expansion bag, and a flow detection device and a flow control device are provided on the water delivery pipe, and the flow detection device and the flow control device are both connected to a control device;

[0021] When water is injected into the expansive soil bag, the expansion force is measured by a pressure sensor on the outer surface of the expansive soil bag, and the amount of water injected is monitored and controlled by a flow detection device and a flow control device on the water pipe, so that the currently measured expansion force of the expansive soil bag is equal to the preset expansion force.

[0022] The beneficial effects of the present invention are as follows: the loading mechanism of the present application can simulate the bias pressures of different sizes and directions generated by the expansion material on the tunnel when the expansion material expands by setting an independent expansion bag in the soil box and setting the corresponding expansion bag according to the distribution of the expansion material in the area where the shield tunnel is located. Compared with the existing simulation method of the whole expansion soil, it can more accurately simulate the composite stratum doped with expansion materials such as expansion rock. For the pressure situation of the tunnel, the expansion bag gradually expands with the water injection, and can accurately reflect the process of simulating the expansion rock to absorb water until it is fully expanded. The present invention can not only simulate water and soil pressure, but also simulate the expansion force in all directions or locally, and can be widely used in various simulation tests of shield tunnels and stratum complexes. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the main structure of the horizontal loading mechanism for the simulation test of the shield tunnel and the stratum complex according to the present invention;

[0024] Figure 2 It is a schematic diagram of the top view of the structure of the horizontal loading mechanism for the simulation test of the shield tunnel and the stratum complex according to the present invention;

[0025] Figure 3 It is a schematic structural diagram of the expansion soil bag of the horizontal loading mechanism for the shield tunnel and stratum complex simulation test of the present invention before being formed;

[0026] Figure 4 It is a schematic structural diagram of the expansion soil bag after being formed of the horizontal loading mechanism for the shield tunnel and stratum complex simulation test according to the present invention.

[0027] Figure numerals: base 1, horizontal jack 2, reaction beam 3, pressure plate 4, vertical jack 5, expansion soil bag 6, first elastic membrane 61, second elastic membrane 62, expansion soil 63, sealing member 64, pressure sensor 65, tunnel model 7, soil box 8, box plate 81, angle iron 82, soil 9, water pipe 10, flow velocity detection and flow control integrated machine 11, flow control device 12, flow detection device 13, control device 14, water supply equipment 15, data acquisition instrument 16. DETAILED DESCRIPTION

[0028] The present invention is further described below.

[0029] like Figure 1 and Figure 2As shown, the loading mechanism for the simulation test of the shield tunnel and stratum complex disclosed in the present invention includes a base 1, a soil box 8 and a tunnel model 7. The soil box 8 is arranged in the base 1, and soil 9 is arranged in the soil box 8. The tunnel model 7 is arranged in the soil 9. A pressurizing mechanism is arranged on the base 1 corresponding to the soil 9 in the soil box 8. The loading mechanism also includes an expansion simulation system and a pressure monitoring system. The expansion simulation system includes an expansion soil bag 6, a water pipe 10 and a water supply device 15. At least one expansion soil bag 6 is arranged in the soil 9. One end of the water pipe 10 is connected to the inside of the expansion soil bag 6, and the other end is connected to the water supply device 15. The pressure monitoring system includes a pressure sensor 65 and a data acquisition instrument 16. The pressure sensor 65 is arranged outside the tunnel model 7, and the pressure sensor 65 is connected to the data acquisition instrument 16.

[0030] Among them, the arrangement of the base 1, the soil box 8, the tunnel model 7 and the pressurizing mechanism can all be implemented with reference to the prior art. The expansion soil bag 6 is used to hold the expansion soil 63. Its specific size and quantity are determined according to the actual simulation object. It can be one or more. The water pipe 10 can be a hose or a hose connected with a hard pipe. The water supply equipment 15 can be a water tank, tap water, pool, etc. The pressure sensor 65 can be a surface-mounted soil pressure sensor 65. The data acquisition instrument 16 can be a computer, a mobile device or a dedicated measurement and display instrument.

[0031] The test method using the loading mechanism for the shield tunnel and stratum complex simulation test comprises the following steps:

[0032] Determine the number and position of the expansion bags 6 according to the distribution of the expansion materials in the area where the shield tunnel is located, and set the corresponding expansion bags 6;

[0033] Pressurizing the soil box 8 by a pressurizing mechanism so that the soil box 8 maintains a preset pressure;

[0034] Inject water into the expansion soil bag 6 through the water pipe 10 to expand the expansion soil 63 in the expansion soil bag 6;

[0035] The data of the pressure sensor 65 outside the tunnel model 7 is detected by the data acquisition device 16 .

[0036] Before the test, the shield tunnel area must be surveyed on site to measure the location and size of the expansion material that affects the tunnel, and to measure or calculate the initial pressure of the tunnel. The corresponding expansion bags are arranged according to the actual measurement data. Figure 2In the embodiment shown, five expansive soil bags 6 are used for simulation to accurately simulate the composite stratum mixed with expansive materials such as expansive rocks, and the preset pressure in the soil box 8 is determined according to the initial pressure of the tunnel. After the expansive soil 63 in the expansive soil bag 6 is filled with water and expanded, the pressure sensor 65 outside the tunnel model 7 can sense the pressure change in this process, thereby measuring the pressure of the composite stratum on the tunnel. The specific distribution of the pressure sensor 65 outside the tunnel model 7 is set according to the simulation requirements, for example, corresponding pressure sensors 65 can be set at key positions of the corresponding tunnel.

[0037] The expansion soil bag 6 can adopt a water-permeable or water-proof structure. Generally, the water-proof structure can reduce the impact of water injection on the soil 9 in the soil box 8 and reduce the interference conditions of the simulation. However, the conventional bag-shaped water-proof structure is easy to cause uneven water absorption of the expansion soil 63 during water injection. Figure 3 and 4 As shown, in order to improve the water absorption uniformity of the expansive soil 63, the expansive soil bag 6 includes a first elastic membrane 61 and a second elastic membrane 62, the first elastic membrane 61 is provided with a plurality of water-permeable holes, the second elastic membrane 62 is a water-proof structure, the first elastic membrane 61 is wrapped in the second elastic membrane 62, the expansive soil 63 is filled in the first elastic membrane 61, and the port of the water pipe 10 is arranged between the first elastic membrane 61 and the second elastic membrane 62. The injected water will first reach between the first elastic membrane 61 and the second elastic membrane 62, and with the more uniform diffusion of the first elastic membrane 61, combined with the relatively slow water injection speed, the uniformity can be greatly improved. The first elastic membrane 61 and the second elastic membrane 62 can both be made of plastic materials such as elastic PE film, and the first elastic membrane 61 can also be made of a plastic net bag structure. In the embodiment shown in the figure, after the first elastic membrane 61 and the second elastic membrane 62 wrap the expansive soil 63, a sealing member 64 such as a sealing tape can be used for quick sealing.

[0038] The pressurizing mechanism can refer to the existing test mechanism. Specifically, in the present application, the pressurizing mechanism can simulate the soil pressure application process under a single soil body. In order to improve the uniformity of pressurization as much as possible, in the preferred embodiment of the present application, the pressurizing mechanism includes a reaction beam 3, a transverse jack 2 and a vertical jack 5. The transverse jack 2 is arranged around the soil box 8. The box plates 81 around the soil box 8 are movably matched with the base 1. The transverse jack 2 is connected between the box plates 81 around the soil box 8 and the base 1. The reaction beam 3 is arranged above the soil box 8 and connected to the base 1. A pressure plate 4 is arranged on the top of the soil box 8. The vertical jack 5 is arranged between the pressure plate 4 and the reaction beam 3. The vertical jack 5 and the transverse jack 2 can provide pressure in the vertical direction and the horizontal direction respectively. Through three-dimensional pressurization, the uniformity of pressurization is ensured, which is more in line with the actual stress conditions of the tunnel. In order to enable the box plate 81 to move stably and prevent the soil 9 from leaking out of the soil box 8, angle irons 82 may be provided at the four corners of the soil box 8, and the box plate 81 and the angle irons 82 may slide relative to each other.

[0039] In a preferred embodiment of the present application, the tunnel model 7 is arranged vertically, and the pressure plate 4 is provided with a central through hole corresponding to the top port of the tunnel model 7, and the aperture of the central through hole is larger than the outer diameter of the tunnel model 7. The vertical arrangement of the tunnel does not consider the gravity of the tunnel itself, and the test will simulate the maximum bearing capacity of the structure under the action of soil pressure. The vertical placement of the tunnel can clearly record the tunnel destruction process and the final state, and will not cause the collapse of the tunnel structure due to gravity to affect the test analysis. In order to prevent the pressure from directly acting on the port of the tunnel, a central through hole is provided in the pressure plate 4. Regardless of whether the tunnel model 7 can pass through the central through hole, the pressure of the pressure plate 4 will not directly act on the port of the tunnel model 7. The water pipe 10 can pass through the pressure plate 4 or the box plate 81 of the soil box 8 to enter the soil box 8, but this method is relatively troublesome. In the preferred embodiment of the present application, the water pipe 10 passes through the central through hole of the pressure plate 4 and the tunnel model 7 and extends into the soil box 8.

[0040] In order to better control the amount of water injected and thus the degree of expansion, a flow detection device 13 and a flow control device 12 are provided on the water delivery pipe 10, and both the flow detection device 13 and the flow control device 12 are connected to a control device 14. The flow detection device 13 can be an ordinary flow meter, but it should be noted that a high-precision flow meter should be selected, and the flow control device 12 uses a solenoid valve or other valve that can accurately control the flow. The control device 14 can be an electric control cabinet, a computer, or multiple solenoid valves and flow rate sensors can be integrated and installed in one body to form a flow rate detection and flow control all-in-one machine 11 for easy management.

[0041] Since the expansion of the expansive material in each part of the tunnel is different, in order to better simulate the actual situation, in the preferred embodiment of the present application, the outer surface of the expansive soil bag 6 is provided with a pressure sensor 65 connected to the data acquisition instrument 16. When water is injected into the expansive soil bag 6, the magnitude of the expansion force is measured by the pressure sensor 65 on the outer surface of the expansive soil bag 6, and the amount of water injection is monitored and controlled by the flow detection device 13 and the flow control device 12 on the water pipe 10, so as to achieve the quantitative expansion force, so that the current measured expansion force of the expansive soil bag 6 is equal to the preset expansion force. In this way, the expansion force of each expansive soil bag 6 can be accurately controlled respectively, and the expansion of the expansive material around the actual tunnel can be simulated, and finally the accurate simulation of the dynamic influence of the process of expansive rock and other expansive materials absorbing water to full expansion on the tunnel is achieved, so that it meets the actual engineering application.

Claims

1. A loading mechanism for a shield tunnel and stratum complex simulation test, comprising a base (1), a soil box (8) and a tunnel model (7), wherein the soil box (8) is arranged in the base (1), soil (9) is arranged in the soil box (8), the tunnel model (7) is arranged in the soil (9), and a pressurizing mechanism is arranged on the base (1) corresponding to the soil (9) in the soil box (8), characterized in that: It also includes an expansion simulation system and a pressure monitoring system, wherein the expansion simulation system includes an expansion soil bag (6), a water pipe (10) and a water supply device (15), wherein at least one expansion soil bag (6) is arranged in the soil body (9), one end of the water pipe (10) is connected to the inside of the expansion soil bag (6), and the other end is connected to the water supply device (15), and the pressure monitoring system includes a pressure sensor (65) and a data acquisition instrument (16), wherein the pressure sensor (65) is arranged outside the tunnel model (7), and the pressure sensor (65) is connected to the data acquisition instrument (16); The expansive soil bag (6) comprises a first elastic membrane (61) and a second elastic membrane (62); the first elastic membrane (61) is provided with a plurality of water-permeable holes; the second elastic membrane (62) is a water-proof structure; the first elastic membrane (61) is wrapped in the second elastic membrane (62); the expansive soil (63) is filled in the first elastic membrane (61); and the port of the water pipe (10) is arranged between the first elastic membrane (61) and the second elastic membrane (62).

2. The loading mechanism for the simulation test of the shield tunnel and stratum complex according to claim 1, characterized in that: The first elastic film (61) and the second elastic film (62) are both elastic PE films.

3. The loading mechanism for the shield tunnel and stratum composite simulation test according to claim 1, characterized in that: The pressurizing mechanism comprises a reaction beam (3), a transverse jack (2) and a vertical jack (5); the transverse jack (2) is arranged around a soil box (8); the box plates (81) around the soil box (8) are movably matched with the base (1); the transverse jack (2) is connected between the box plates (81) around the soil box (8) and the base (1); the reaction beam (3) is arranged above the soil box (8) and connected to the base (1); a pressure plate (4) is arranged on the top of the soil box (8); and the vertical jack (5) is arranged between the pressure plate (4) and the reaction beam (3).

4. The loading mechanism for the shield tunnel and stratum composite simulation test according to claim 3, characterized in that: The tunnel model (7) is arranged vertically, and the pressure plate (4) is provided with a central through hole corresponding to the top port of the tunnel model (7), and the aperture of the central through hole is larger than the outer diameter of the tunnel model (7).

5. The loading mechanism for the simulation test of the shield tunnel and stratum complex according to claim 4, characterized in that: The water delivery pipe (10) passes through between the central through hole of the pressing plate (4) and the tunnel model (7) and extends into the soil box (8).

6. The loading mechanism for the shield tunnel and stratum composite simulation test according to claim 1, characterized in that: The water delivery pipe (10) is provided with a flow detection device (13) and a flow control device (12), and the flow detection device (13) and the flow control device (12) are both connected to a control device (14).

7. The loading mechanism for the shield tunnel and stratum composite simulation test according to claim 1, characterized in that: The outer surface of the expansion soil bag (6) is provided with a pressure sensor (65) connected to a data acquisition instrument (16).

8. A test method using the loading mechanism for simulation test of shield tunnel and stratum complex according to any one of claims 1 to 7, characterized in that: The steps include: Determining the number and position of the expansion bags (6) according to the distribution of the expansion material in the area where the shield tunnel is located, and setting the corresponding expansion bags (6); Pressurizing the soil box (8) by means of a pressurizing mechanism so that a preset pressure is maintained in the soil box (8); injecting water into the expansion soil bag (6) through the water pipe (10) to cause the expansion soil (63) in the expansion soil bag (6) to expand; The data of the pressure sensor (65) outside the tunnel model (7) is detected by a data acquisition instrument (16).

9. The test method according to claim 8, characterized in that The outer surface of the expansion bag (6) is provided with a pressure sensor (65) connected to a data acquisition instrument (16); the water pipe (10) is provided with a flow detection device (13) and a flow control device (12); and the flow detection device (13) and the flow control device (12) are both connected to a control device (14); When water is injected into the expansion bag (6), the expansion force is measured by a pressure sensor (65) on the outer surface of the expansion bag (6), and the injection amount is monitored and controlled by a flow detection device (13) and a flow control device (12) on the water pipe (10), so that the currently measured expansion force of the expansion bag (6) is equal to the preset expansion force.

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