A model box for simulating shallow-buried bias tunnel test

Abstract

The present application belongs to the technical field of tunnel engineering, and particularly relates to a model box for simulating shallow-buried bias tunnel test; the model box comprises a test box body, the bottom surface of a test cavity in the test box body is a plane, excavation windows adapted to the contour of a tunnel are opened on the front and rear sidewalls of the test cavity, the left and right sidewalls of the test cavity are air bags capable of adjusting pressure, used for applying adjustable side pressure, the top surface of the test cavity is capable of adjusting the slope in the left and right directions, used for applying asymmetric overburden load; the model box for simulating shallow-buried bias tunnel test provided by the present application changes the internal space shape of the pressure box by the top plate with changeable inclination angle, and fills the model soil box with heavy objects to achieve the purpose of applying asymmetric overburden load to the model soil box, thereby solving the problem of inaccurate overburden load application in shallow-buried bias tunnel test.

Description

Technical Field

[0001] This invention belongs to the field of tunnel engineering technology, specifically relating to a model box for simulating shallow buried biased tunnel tests. Background Technology

[0002] High-speed railway tunnels require greater clearance during design and construction, leading to a significant increase in long-span tunnels. During the excavation of these long-span tunnels, the increased excavation area results in problems such as greater relaxation range and increased deformation, especially in soft rock tunnels with abundant shallow-buried, weak surrounding rock. The surrounding rock's self-stabilizing properties are even worse, and its bearing capacity is lower, further increasing the difficulty of tunnel construction, leading to severely low construction efficiency and significant material waste. Corresponding model box tests are needed to provide technical support for on-site construction, reduce resource waste caused by construction method defects, and achieve the goals of safe and environmentally friendly construction. However, existing model boxes have significant technical compatibility issues: firstly, existing model boxes cannot apply precise overburden loads and cannot meet the requirements of eccentric loads; secondly, existing model boxes apply lateral pressure unevenly, making it difficult to simulate the actual stress conditions of the surrounding rock on site. These technical contradictions seriously affect the accuracy of tunnel model box test results, making it difficult to provide more accurate data references for on-site construction. There is an urgent need to develop tunnel excavation model boxes with more convenient testing processes and more accurate test results. Summary of the Invention

[0003] This invention aims to solve the problems of inaccurate bias loading, uneven application of lateral pressure, and inconsistent excavation progress in existing bias tunnel test model boxes.

[0004] The present invention provides the following technical solution: a model box for simulating shallow buried biased tunnel tests, comprising a test box body, the bottom surface of the test chamber inside the test box body is a plane, the front and rear side walls of the test chamber body have excavation windows adapted to the tunnel contour, the left and right side walls of the test chamber body are pressure-adjustable airbags for applying adjustable lateral pressure, and the top surface of the test chamber body can be inclined in the left and right directions for applying asymmetric overburden loads.

[0005] Furthermore, the test chamber includes a model soil box, a pressure chamber, and an airbag chamber; the pressure chamber is located on top of the model soil box, and the top surface of the model soil box is connected to the bottom surface of the pressure chamber; the airbag chamber is located on the left and right sides of the model soil box, and the sides of the airbag chamber connected to the model soil box are connected; the airbag is located inside the airbag chamber, and the top plate of the pressure chamber can be adjusted in the left and right directions.

[0006] Furthermore, the top plate of the pressure box includes a first top plate and a second top plate that are movably inserted together, and a locking nut is connected between the first top plate and the second top plate. The locking nut is used to lock the insertion length of the first top plate and the second top plate; a feed port is opened on the first top plate. The left and right side plates of the pressure chamber are provided with protruding ribs arranged at intervals along the height direction. The top plate is placed on the protruding ribs at different heights on the left and right sides to change the tilt angle of the top plate.

[0007] Furthermore, the front panel of the pressure chamber is fixed to the left and right side panels with screws.

[0008] Furthermore, the airbag inside the airbag box is divided into several sections from top to bottom, and each section can independently control the air pressure.

[0009] Furthermore, a movable support is installed at the bottom of the model soil box.

[0010] Furthermore, it also includes auxiliary excavation tools, which include hand-held supports and excavation molds adapted to the tunnel contour. The excavation molds are divided into upper molds and lower molds. Both the upper and lower molds are constructed with interfaces that can be combined with the hand-held supports. The upper and lower molds are alternately combined with the hand-held supports for auxiliary excavation.

[0011] Furthermore, it also includes a steel arch monitoring component, which consists of a steel arch adapted to the tunnel profile, on which monitoring modules are distributed.

[0012] Furthermore, a covered discharge port is provided below the front panel of the pressure chamber.

[0013] Furthermore, each section of the airbag is connected to a pressure gauge.

[0014] Compared with the prior art, the advantages of the present invention are: This invention provides a model box for simulating shallow-buried biased tunnel tests. The internal spatial shape of the pressure box is changed by a top plate with an adjustable tilt angle. By filling the inside with heavy objects, an asymmetric overburden load is applied to the model soil box, solving the problem of inaccurate overburden load application in shallow-buried biased tunnel tests. By adding an inlet and outlet to the pressure box, the entry and exit of materials inside the pressure box are facilitated, improving the convenience of the test process.

[0015] The airbag makes full contact with the soil on both sides of the model soil box, which can provide uniform lateral pressure to improve the accuracy of the test. The pressure gauge connected to the airbag can display the lateral pressure in real time during the test, making it easy to adjust the lateral pressure during the test.

[0016] Using auxiliary excavation tools can effectively ensure the consistency of excavation advance in the model test and effectively prevent soil collapse during excavation; at the same time, it ensures the consistency of the spacing of the steel arch frame, which is more in line with the simulated on-site construction conditions and improves the accuracy of the model test. The monitoring module on the steel arch frame facilitates the monitoring of the stress and strain on the steel arch frame during the test. Attached Figure Description

[0017] Figure 1 A schematic diagram of a model box used to simulate a shallow-buried biased tunnel test; Figure 2 This is a schematic diagram of a pressure chamber; Figure 3 A schematic diagram of tools used for excavation; Figure 4 This is a schematic diagram of the steel arch frame monitoring component.

[0018] In the diagram: 1-Pressure box; 1.1-First top plate; 1.2-Second top plate; 1.3-Locking nut; 1.4-Inlet; 1.5-Protruding ridge; 1.6-Front side plate; 1.7-Outlet; 2-Model soil box; 3-Airbag box; 4-Moving support; 5-Auxiliary excavation tool; 5.1-Handheld support; 5.2-Upper mold; 5.3-Lower mold; 6-Steel arch frame; 7-Monitoring module. Detailed Implementation

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] like Figure 1 As shown: A model box for simulating shallow buried biased tunnel tests includes a test box body, the bottom surface of the test chamber inside the test box body is a plane, the front and rear side walls of the test chamber body have excavation windows adapted to the tunnel contour, the left and right side walls of the test chamber body are pressure-adjustable airbags for applying adjustable lateral pressure, and the top surface of the test chamber body can be adjusted in the left and right directions for applying asymmetric overburden loads.

[0021] The test chamber includes a model soil box 2, a pressure chamber 1, and an airbag chamber 3. The pressure chamber 1 is located on top of the model soil box 2, and the top surface of the model soil box 2 is connected to the bottom surface of the pressure chamber 1. The weight inside the pressure chamber 1 is in direct contact with the soil above the model soil box 2 to apply pressure to the soil below. The airbag chamber 3 is located on the left and right sides of the model soil box 2, and the sides of the airbag chamber 3 that are connected to the model soil box 2 are connected. The airbag is located inside the airbag chamber 3, and the top plate of the pressure chamber 1 can be adjusted in the left and right directions.

[0022] like Figure 2As shown: The top plate of the pressure box 1 includes a first top plate 1.1 and a second top plate 1.2 that are movably connected. A locking nut 1.3 is connected between the first top plate 1.1 and the second top plate 1.2. The locking nut 1.3 is used to lock the connection length of the first top plate 1.1 and the second top plate 1.2. The first top plate 1.1 has a feed port 1.4 for easy filling with heavy objects such as fine sand. The left and right side plates of the pressure box 1 are provided with protruding ribs 1.5 arranged at intervals along the height direction. The top plate is placed on the protruding ribs 1.5 at different heights on the left and right sides to change the tilt angle of the top plate.

[0023] The front panel 1.6 of the pressure chamber 1 is fixed to the left and right side panels with screws and can be disassembled to facilitate the placement of the top panel into the pressure chamber 1.

[0024] A covered discharge port 1.7 is provided below the front side plate 1.6 of the pressure box 1 to facilitate the discharge of heavy objects such as fine sand from the pressure box 1.

[0025] The airbag inside the airbag box 3 is divided into several sections from top to bottom. Each section can independently control the air pressure to apply tiered lateral pressure. Each section of the airbag is connected to an air compressor via pipeline to control the airbag pressure. Each section of the airbag is also connected to a pressure gauge to display the lateral pressure on both sides of the model soil box 2.

[0026] The bottom of the model soil box 2 is equipped with a movable support 4. The movable support 4 is welded together with a horizontal beam, three vertical beams and three diagonal beams. The vertical beams are located at both ends and the middle of the horizontal beam, and the diagonal beams are located above the vertical beams. One end of the diagonal beam is welded to the outside of the model soil box 2, and the other end is welded to the horizontal beam. The two ends and the middle of the horizontal beam are connected to load-bearing wheels. The load-bearing wheels can be moved up and down by a lever device, and can be in a fixed or movable state.

[0027] The movable support 4 can effectively ensure the stability of the model soil box 2, prevent it from overturning, and ensure the safety of the test personnel. The connected load-bearing wheels can facilitate the movement of the model box device within the test site to meet the scheduling needs of the test personnel.

[0028] like Figure 3 As shown: It also includes an auxiliary excavation tool 5, which includes a hand-held support 5.1 and an excavation mold adapted to the tunnel contour. The excavation mold is divided into an upper mold 5.2 and a lower mold 5.3. Both the upper mold 5.2 and the lower mold 5.3 are constructed with interfaces that can be combined with the hand-held support 5.1. The upper mold 5.2 and the lower mold 5.3 are alternately combined with the hand-held support 5.1 for auxiliary excavation.

[0029] like Figure 4As shown: It also includes a steel arch frame monitoring component, which includes a steel arch frame 6 adapted to the tunnel profile. Monitoring modules 7 are distributed on the steel arch frame 6. One monitoring module 7 is arranged at the arch top, arch shoulder, arch waist and invert arch positions of the steel arch frame 6. The monitoring module 7 includes a miniature earth pressure cell and strain gauge.

[0030] Insert the handheld support 5.1 into the interface of the upper mold 5.2, and fully insert the upper mold 5.2 horizontally into the soil of the model soil box 2. Remove the soil inside the upper mold 5.2. Then insert the handheld support 5.1 into the interface of the lower mold 5.3, remove the soil inside the lower mold 5.3, and then fix the steel arch 6 to the end of the excavated soil. Repeat the process of removing the soil inside the upper mold 5.2, removing the soil inside the lower mold 5.3, and setting up the steel arch 6 in sequence to complete the entire test excavation process.

[0031] Using the auxiliary excavation tool 5 for excavation can effectively ensure the consistency of the excavation advance in the model test and effectively prevent the collapse of the soil during excavation; at the same time, it can ensure the consistency of the spacing of the steel arch frame 6, which is more in line with the simulated on-site construction conditions and improves the accuracy of the model test. The monitoring module 7 on the steel arch frame 6 facilitates the monitoring of the stress and strain on the steel arch frame during the test.

[0032] The test procedure for using a model box to simulate shallow-buried biased tunnel tests is as follows: Step 1: According to the model soil mix ratio, mix all materials evenly to form model soft soil, and pour it into the model soil box 2 in layers for compaction. Step 2: Place the pressure box 1, which can apply asymmetric overburden load, on top of the model soil box 2. Unscrew the fixing screws to open the front side plate 1.6. Adjust the length of the top plate according to the overburden load requirements of the test design and place it on the protruding ridge 1.5. Fix the length of the top plate by tightening the locking nut 1.3. Then fix the front side plate 1.6 back in place. Step 3: Fill the pressure box 1 with fine sand and other heavy materials through the feed inlet 1.4 to fill the space under the top plate; Step 4: Apply the required lateral pressure for the test using an airbag; Step 5: Conduct an excavation test using the auxiliary excavation tool 5 with controllable excavation advance. First, fully insert the upper mold 5.2 horizontally into the upper part of the excavation area to carry out upper bench excavation. Then, fully insert the lower mold 5.3 horizontally into the lower part of the excavation area to carry out lower bench excavation. Subsequently, install the steel arch frame 6 on the excavation section. Then, perform the above operations in sequence until the tunnel excavation is completely completed. Step 6: Discharge the heavy objects from the pressure chamber 1 through the discharge port 1.7, relieve the pressure of the air bladder, clean the materials in the model soil box 2, process the test data, and end the test.

[0033] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A model box for simulating shallow-buried biased tunnel tests, characterized in that: The test chamber includes a test chamber with a flat bottom surface. The front and rear side walls of the test chamber have excavation windows that are adapted to the tunnel contour. The left and right side walls of the test chamber are pressure-adjustable airbags for applying adjustable lateral pressure. The top surface of the test chamber can be tilted in the left and right directions for applying asymmetric overburden loads. The test chamber includes a model soil box (2), a pressure chamber (1), and an airbag box (3); the pressure chamber (1) is located on top of the model soil box (2), and the top surface of the model soil box (2) is connected to the bottom surface of the pressure chamber (1); the airbag box (3) is located on the left and right sides of the model soil box (2), and the side of the airbag box (3) connected to the model soil box (2) is connected; the airbag is located inside the airbag box (3), and the top plate of the pressure chamber (1) can be adjusted in the left and right directions; The pressure box (1) has a top plate consisting of a first top plate (1.1) and a second top plate (1.2) that are movably connected. A locking nut (1.3) is connected between the first top plate (1.1) and the second top plate (1.2). The locking nut (1.3) is used to lock the connection length of the first top plate (1.1) and the second top plate (1.2). The first top plate (1.1) has a feed inlet (1.4). The left and right side plates of the pressure box (1) are provided with protruding ribs (1.5) arranged at intervals along the height direction. The top plate is placed on the protruding ribs (1.5) at different heights on the left and right sides to change the tilt angle of the top plate. It also includes an auxiliary excavation tool (5), which includes a hand-held support (5.1) and an excavation mold adapted to the tunnel profile. The excavation mold is divided into an upper mold (5.2) and a lower mold (5.3). Both the upper mold (5.2) and the lower mold (5.3) are equipped with interfaces that can be combined with the hand-held support (5.1). The upper mold (5.2) and the lower mold (5.3) are alternately combined with the hand-held support (5.1) for auxiliary excavation.

2. The model box for simulating shallow-buried biased tunnel tests according to claim 1, characterized in that: The front panel (1.6) of the pressurization box (1) is fixed to the left and right side panels by screws.

3. The model box for simulating shallow-buried biased tunnel tests according to claim 2, characterized in that: The airbag inside the airbag box (3) is divided into several blocks from top to bottom, and the air pressure of each block can be controlled independently.

4. A model box for simulating shallow-buried biased tunnel tests according to claim 2, characterized in that: The bottom of the model soil box (2) is provided with a movable support (4).

5. A model box for simulating shallow-buried biased tunnel tests according to claim 1, characterized in that: It also includes a steel arch monitoring component, which includes a steel arch (6) adapted to the tunnel profile, on which monitoring modules (7) are distributed.

6. A model box for simulating shallow-buried biased tunnel tests according to claim 2, characterized in that: The pressure chamber (1) has a covered discharge port (1.7) located below the front side plate (1.6).

7. A model box for simulating shallow-buried biased tunnel tests according to claim 3, characterized in that: Each section of the airbag is connected to a pressure gauge.

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