Model device for simulating and detecting yielding support performance of buffer layer of soft rock tunnel

Abstract

The utility model discloses a model device for simulating and detecting the yielding support performance of a buffer layer of a soft rock tunnel. The model device comprises a tunnel buffer layer preparation unit and a pressurization detection unit, the preparation unit comprises a detachable mold box body, a first bottom plate and a plurality of groups of steel barrels with different diameters, the steel barrels are in threaded connection with the first bottom plate, and a plurality of groups of symmetrical first through holes are uniformly distributed in the side walls of the steel barrels; the pressurization detection unit comprises a detection box body, pressurization plates and jacks, the pressurization plates are arranged on the four inner sides of the detection box respectively and arranged in a staggered mode relative to the pressurization plates, and each pressurization plate is connected with the output ends of the multiple jacks. The preparation unit can prefabricate a simulation tunnel containing a surrounding rock layer, a buffer layer and a secondary lining layer, a detection hole is reserved and matched with the deformation detection unit, the simulation tunnel is transferred to the pressurization detection unit after prefabrication is completed, a pressurization plate is driven by a jack to achieve three-dimensional uniform pressurization, and the yielding supporting performance detection of the buffer layer is completed. According to the device, preparation and detection are separated, the detection efficiency is improved, a simulation structure is attached to an actual tunnel, and the detection result is more accurate.

Description

Technical Field

[0001] This utility model relates to the field of geotechnical engineering technology, specifically to a model device for simulating and testing the pressure relief support performance of the buffer layer in soft rock tunnels. Background Technology

[0002] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this utility model and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] The essence of tunnel engineering is to excavate a space in the strata below the ground to meet various functional requirements. This process causes the strata, which have long been in equilibrium, to undergo stress adjustment and deformation due to the disturbance of excavation, attempting to quickly form a new equilibrium state. However, due to differences in strata conditions, the surrounding rock will exhibit different stability states. Some surrounding rock cannot achieve self-equilibrium during the stress adjustment process, and as deformation develops, it will become damaged and unstable, thereby endangering the safety of the project.

[0004] Deeply buried tunnels often contain weak rock masses with significant rheological properties and time-dependent weakening effects. After excavation, the surrounding rock parameters gradually decrease over time, leading to increased rheological deformation and increasing the risk of cracking in the initial support and secondary lining. This severely impacts tunnel safety during construction and operation. To control the rapid development of soft rock deformation under high ground stress and ensure the self-supporting capacity of the surrounding rock, a multi-layer lining structure of "double-layer initial support + secondary lining" is commonly used during tunnel construction. Although multi-layer lining has achieved many successes in managing large deformation tunnels, this strong support measure often fails in practice when faced with intense compression and large deformation of the surrounding rock. During tunnel operation, frequent large deformation problems such as secondary lining cracking, spalling, and even localized collapses occur.

[0005] To ensure tunnel safety, a buffer layer is set between the secondary lining and the surrounding rock to absorb the rheological deformation of the surrounding rock. Its special mechanical properties enable it to coordinate with the deformation of the surrounding rock, absorb the long-term deformation energy of the surrounding rock, and achieve long-term stability of the weak tunnel surrounding rock.

[0006] To scientifically evaluate the impact of different buffer layer parameters (thickness, elastic modulus) on the support effect, determine the optimal yield pressure (deformation threshold) and support timing, and avoid excessive deformation leading to collapse or wasted support, simulation through similar model tests can be used. However, existing model equipment has the following problems: When testing various buffer materials, assembling the simulated tunnel buffer layer inside the pressure testing model equipment requires waiting for the simulated tunnel buffer layer to assemble, and disassembling the original simulated tunnel buffer layer for the next experiment, resulting in low overall efficiency; the tunnel buffer layer model setup is simple and differs significantly from the actual tunnel buffer layer, failing to accurately simulate yield support performance; the pressure application method is simple and differs greatly from the actual three-dimensional stress state of the surrounding rock in the tunnel; the pressure is uneven throughout the pressure application process; and the placement of various sensors cannot be precisely determined, leading to inaccurate test results, etc. Utility Model Content

[0007] To address the aforementioned problems, this invention provides a model device for simulating and testing the pressure relief support performance of the buffer layer in soft rock tunnels.

[0008] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0009] A model device for simulating and testing the pressure relief support performance of a buffer layer in a soft rock tunnel includes a tunnel buffer layer preparation unit and a pressure testing unit.

[0010] The tunnel buffer layer preparation unit includes: a mold box body and multiple steel barrels of different diameters; the mold box body is detachably connected as a whole, a first base plate is provided at the bottom of the mold box body, and the steel barrels are detachably connected to the first base plate; multiple sets of first through holes are evenly distributed on the side wall of the steel barrels, and the multiple sets of first through holes are symmetrically arranged in pairs.

[0011] The pressurization detection unit includes: a detection box body, a pressure plate, and a jack;

[0012] Pressure plates are installed inside the four side walls of the test chamber body. The pressure plates are staggered and opposite to each other. The output end of the jack passes through the side wall of the test chamber body and is connected to the pressure plate. Each pressure plate is connected to the output end of multiple jacks.

[0013] In one or more embodiments, the sidewalls connected to the mold box body are detachably connected by an "L"-shaped angle iron and a first bolt.

[0014] In one or more embodiments, each side wall of the mold box body is provided with a handle to facilitate the removal of the side wall.

[0015] In one or more embodiments, a suspension rod is provided at each of the four top corners of the first base plate, the top of the suspension rod is provided with a lifting ring, and the bottom of the suspension rod is screwed to the first base plate.

[0016] In one or more embodiments, the tunnel buffer layer preparation unit includes three steel barrels with different diameters, namely a first steel barrel, a second steel barrel, and a third steel barrel; and the diameter of the first steel barrel is larger than that of the second steel barrel, and the diameter of the second steel barrel is larger than that of the third steel barrel.

[0017] In one or more embodiments, a first circular hole is provided at the center of the first base plate, and first screw holes are evenly distributed around the first circular hole.

[0018] Preferably, a second circular hole is provided at the bottom of the steel drum. The structure of the second circular hole is the same as that of the first circular hole, and the position of the second circular hole is opposite to that of the first circular hole.

[0019] More preferably, the second circular hole is surrounded by second screw holes, the structure of which is the same as that of the first screw hole, and the position of the second screw hole is opposite to that of the first screw hole; the second bolt cooperates with the second screw hole and the first screw hole to detachably connect the steel barrel to the first base plate.

[0020] In one or more embodiments, each group of first through holes includes multiple through holes arranged side by side in a vertical arrangement.

[0021] In one or more embodiments, the tunnel buffer layer preparation unit further includes a deformation detection unit, which includes a digital dial gauge and a strain gauge, the strain gauge being electrically connected to a static strain gauge.

[0022] In one or more embodiments, a second base plate is provided at the bottom of the detection box body, and the distance between the upper surface of the second base plate and the lower surface of the bottom of the pressure plate is slightly greater than the thickness of the first base plate.

[0023] In one or more embodiments, a cross-shaped top plate is provided on the top of the detection box body, and the cross-shaped top plate is detachably connected to the side wall of the detection box body.

[0024] The beneficial effects of this utility model are as follows:

[0025] (1) In this utility model, the model device is divided into a tunnel buffer layer preparation unit and a pressure testing unit. The tunnel buffer layer preparation unit can prepare various simulated tunnels. The prepared simulated tunnel is transferred to the pressure testing unit to test the pressure-bearing support performance of the buffer layer. Compared with preparing the simulated tunnel buffer layer in the pressure testing model device and then performing pressure testing, in this utility model, it is only necessary to directly replace the prepared simulated tunnel to realize the pressure-bearing support performance testing of various tunnel buffer layers, which improves the overall testing efficiency. Moreover, it is not necessary to wait for the original simulated tunnel buffer layer to be disassembled. It is only necessary to move the original simulated tunnel out and move the new simulated tunnel in, which greatly saves time and improves the overall testing efficiency.

[0026] (2) In the process of preparing the simulated tunnel buffer layer in this utility model, the adjacent sidewalls of the mold box body are first connected and fixed to the first base plate. Then, the first steel barrel is fixed to the first base plate with bolts. Plaster is used to simulate the surrounding rock of the tunnel. Plaster is poured between the outer wall of the first steel barrel and the inner wall of the sidewall of the mold box body. After the pouring is completed, the first steel barrel is removed. The second steel barrel is fixed to the first base plate with bolts. The buffer layer material to be tested is poured between the outer wall of the second steel barrel and the plaster. After the pouring is completed, the second steel barrel is removed. The third steel barrel is fixed to the first base plate with bolts. Secondary lining concrete material is poured between the outer wall of the third steel barrel and the buffer layer material. After the pouring is completed, the third steel barrel is removed. In order to achieve demolding of each steel barrel, a certain amount of release agent is applied to each steel barrel before each pouring. Reference Figure 4 In the tunnel buffer layer preparation unit, three steel cylinders, in conjunction with the first base plate, form a simulated tunnel consisting of, from the outside in, the surrounding rock layer, the buffer layer, the secondary lining concrete layer, and the hollow layer. Similar to the actual tunnel structure, this simulates the pressure-bearing support performance of the buffer layer during the rheological deformation of weak rock mass. Simultaneously, during each steel cylinder pouring process, positioning rods are inserted into two sets of first through holes symmetrically arranged along the cylinder axis. This creates first detection holes at the interface between the inner wall of the surrounding rock and the outer wall of the buffer layer, and second detection holes at the interface between the inner wall of the buffer layer and the outer wall of the secondary lining concrete layer. Dial gauges placed in these two detection holes allow for the detection of buffer layer deformation. Additionally, strain gauges are attached to the inner wall of the secondary lining concrete layer and connected to a static strain gauge to obtain minute deformations of the secondary lining. The setting of the detection holes is similar to the setting of convergence measurement points in an actual tunnel, allowing for more precise detection of buffer layer deformation.

[0027] (3) In this utility model, each pressure plate is connected to the output end of multiple jacks, which can provide stable and uniform pressure.

[0028] (4) In this utility model, pressure plates are respectively installed inside the four side walls of the detection box body. The pressure plates are staggered, which can achieve the application of large deformation displacement without affecting the application of pressure in other directions, and at the same time ensure that more uniform pressure is provided during the pressurization process. Attached Figure Description

[0029] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.

[0030] Figure 1 Left view of the tunnel buffer layer fabrication unit;

[0031] Figure 2 A top view of the tunnel buffer layer fabrication unit;

[0032] Figure 3 This is a structural diagram of a steel drum;

[0033] Figure 4 A schematic diagram of the tunnel structure fabricated by the tunnel buffer layer fabrication unit;

[0034] Figure 5 A schematic diagram of the pressure detection unit with the top plate removed;

[0035] Figure 6 This is a schematic diagram of the top plate of the pressure detection unit;

[0036] Among them, 1 is the first base plate, 2 is the mold box body, 3 is the lifting rod, 4 is the handle, 5 is the first circular hole, 6 is the first screw hole, 7 is the second screw hole, 8 is the first through hole, 9 is the second circular hole, 10 is the tunnel surrounding rock layer, 11 is the buffer layer, 12 is the secondary lining concrete layer, 13 is the hollow layer, 14 is the first inspection hole, 15 is the second inspection hole, 16 is the pressure plate, 17 is the second base plate, 18 is the jack, 19 is the lifting ring, 20 is the steel barrel, 21 is the inspection box body, and 22 is the cross-shaped top plate. Detailed Implementation

[0037] It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0038] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this utility model. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0039] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations.

[0040] Example 1

[0041] refer to Figure 1 , 2 3 and 5, a model device for simulating and testing the pressure-bearing support performance of a buffer layer in a soft rock tunnel, comprising a tunnel buffer layer preparation unit and a pressure testing unit.

[0042] The tunnel buffer layer preparation unit includes: a mold box body 2 and multiple steel barrels 20 of different diameters; the mold box body 2 is detachably connected as a whole, and a first base plate 1 is set at the bottom of the mold box body 2, and the steel barrels 20 are detachably connected to the first base plate 1; multiple sets of first through holes 8 are evenly distributed on the side wall of the steel barrels 20, and the multiple sets of first through holes 8 are symmetrically arranged in pairs.

[0043] The pressure testing unit includes: a testing box body 21, a pressure plate 16, and a jack 18;

[0044] Pressure plates 16 are respectively installed inside the four side walls of the test box body 21. The pressure plates 16 are staggered. The output end of the jack 18 passes through the side wall of the test box body 21 and is connected to the pressure plate 16. Each pressure plate 16 is connected to the output end of multiple jacks 18.

[0045] The side walls of the mold box body 2 are detachably connected by an "L"-shaped angle iron and a first bolt. The "L"-shaped angle iron can firmly connect the side walls of the mold box body 2 together, preventing the simulated tunnel material from overflowing during the pouring of various simulated tunnel materials.

[0046] refer to Figure 1 Each side wall of the mold box body 2 is provided with a handle 4. Since the side walls, the first base plate 1 and the side walls connected to the mold box body 2 are all detachably connected, the presence of the handle 4 makes it easy to remove the heavy side walls.

[0047] refer to Figure 1A lifting rod 3 is installed at each of the four top corners of the first base plate 1. The top of the lifting rod 3 is equipped with a lifting ring 19, and the bottom of the lifting rod 3 is screwed to the first base plate 1. A small crane is used to lift the entire mold box body and place it into the position defined in the pressure testing unit.

[0048] In this embodiment, the tunnel buffer layer preparation unit includes three steel barrels 20 with different diameters, namely the first steel barrel, the second steel barrel, and the third steel barrel; and the diameter of the first steel barrel is larger than that of the second steel barrel, and the diameter of the second steel barrel is larger than that of the third steel barrel.

[0049] refer to Figure 2 and 3 To enable a detachable connection between the steel drum 20 and the first base plate 1, a first circular hole 5 is provided in the center of the first base plate 1, and first screw holes 6 are evenly distributed around the first circular hole 5. Second circular holes 9 are provided at the bottom of the first, second, and third steel drums. The structure of the second circular holes 9 is the same as that of the first circular holes 5, and their positions are opposite to those of the first circular holes 5. Second screw holes 7 are evenly distributed around the second circular holes 9. The structure of the second screw holes 7 is the same as that of the first screw holes 6, and their positions are opposite to those of the first screw holes 6. A second bolt engages with the second screw holes 7 and 6 to detachably connect the steel drum to the first base plate. The engagement of the first circular hole 5 and the second circular hole 9, and the engagement of the second bolt with the second screw holes 7 and 6, allows for the determination of the position of each steel drum and enables a detachable connection between the steel drum and the first base plate.

[0050] refer to Figure 3 Each group of first through holes 8 includes multiple through holes arranged side by side, one above the other. The arrangement of multiple through holes allows for the detection of deformation of the buffer layer at different height positions.

[0051] The tunnel buffer layer fabrication unit also includes a deformation detection unit, which comprises a digital dial gauge and strain gauges, with the strain gauges electrically connected to a static strain gauge. After the simulated tunnel is fabricated, the deformation of the buffer layer and the minute deformation of the secondary lining can be detected by placing the dial gauge and strain gauges at designated locations.

[0052] refer to Figure 5 The bottom of the detection chamber body 21 is provided with a second base plate 17. The distance between the upper surface of the second base plate 17 and the lower surface of the bottom of the pressure plate 16 is slightly greater than the thickness of the first base plate 1. This distance is set so that the prepared simulated tunnel can be placed into the detection chamber body 21.

[0053] refer to Figure 6The top of the test chamber body 21 is provided with a cross-shaped top plate, which is detachably connected to the side wall of the test chamber body. The cross-shaped top plate is provided with a position that allows observation of the internal pressure plate 16 of the test chamber body 21, and also allows observation of the pressurization process of the pressure plate 16.

[0054] The testing process of the model device for simulating and testing the pressure relief support performance of the buffer layer in soft rock tunnels is as follows:

[0055] In this invention, the tunnel buffer layer preparation unit first connects and fixes the adjacent sidewalls of the mold box body 2 to the first base plate 1 during the preparation of the simulated tunnel buffer layer. Then, the first steel barrel is bolted to the first base plate 1. Plaster is used to simulate the surrounding rock of the tunnel. Plaster is poured between the outer wall of the first steel barrel and the inner wall of the sidewall of the mold box body 2. After pouring, the first steel barrel is removed. The second steel barrel is bolted to the first base plate 1, and the buffer layer material to be tested is poured between the outer wall of the second steel barrel and the plaster. After pouring, the second steel barrel is removed. The third steel barrel is bolted to the first base plate 1, and secondary lining concrete material is poured between the outer wall of the third steel barrel and the buffer layer material. After pouring, the third steel barrel is removed. To facilitate demolding of each steel barrel, a fixed amount of release agent is applied to each steel barrel before each pour. (Reference) Figure 4 In the tunnel buffer layer preparation unit, the combination of three steel barrels and the first bottom plate forms a simulated tunnel consisting of a tunnel surrounding rock layer 10, a buffer layer 11, a secondary lining concrete layer 12, and a hollow layer 13 from the outside to the inside. It is similar to the actual tunnel structure and can realistically simulate the pressure relief support performance of the buffer layer during the rheological deformation of weak rock mass.

[0056] refer to Figure 4 During each pouring of the steel drum 20, positioning rods are inserted into two sets of first through holes 8 symmetrically arranged along the axis of the steel drum 20. This creates a first detection hole 14 at the interface between the inner wall of the tunnel surrounding rock layer 10 and the outer wall of the buffer layer 11, and a second detection hole 15 at the interface between the inner wall of the buffer layer 11 and the outer wall of the secondary lining concrete layer 12. Since detecting the deformation of the buffer layer requires observing the deformation of its outer and inner walls, dial gauges are placed in these two detection holes to detect the buffer layer's deformation. Simultaneously, strain gauges are attached to the inner wall of the secondary lining concrete layer 12 and connected to a static strain gauge to obtain minute deformations of the secondary lining layer 12. The setting of the detection holes is similar to the setting of convergence measurement points in actual tunnels, allowing for more accurate detection of the buffer layer's deformation.

[0057] After the simulated tunnel is poured, the side walls of the mold box body 2 are disassembled and removed from the first base plate 1 by hand 4. The cross-shaped top plate 22 of the pressure testing unit is removed, and the entire mold box body is lifted and placed on the second base plate of the pressure testing unit using a small crane.

[0058] After placing the digital dial gauge and strain gauge in their designated positions, the pressure plate 16 is adjusted using jack 18 to ensure it is in contact with the outer wall of the tunnel surrounding rock layer 10. The cross-shaped top plate 22 of the pressure testing unit is then installed, and a pressure test is conducted using jack 18. During the pressure test, the deformation data of the buffer layer and secondary lining are recorded, thus enabling the testing of the buffer layer's pressure-bearing support performance. During the test, each pressure plate 16 is connected to the output ends of multiple jacks 18, providing stable and uniform pressure. Pressure plates 16 are respectively installed inside the four side walls of the testing box body 21. The staggered arrangement of the pressure plates 16 allows for the application of large deformation displacements without affecting the application of pressure in other directions, while also ensuring more uniform pressure during the pressure test.

[0059] In this invention, the model device is divided into a tunnel buffer layer preparation unit and a pressure testing unit. The tunnel buffer layer preparation unit can prepare various simulated tunnels. The prepared simulated tunnel is then transferred to the pressure testing unit to test the pressure-bearing support performance of the buffer layer. Compared with preparing the simulated tunnel buffer layer in the pressure testing model device and then performing pressure testing, this invention only requires directly replacing the prepared simulated tunnel to test the pressure-bearing support performance of various tunnel buffer layers, thus improving the overall testing efficiency. Furthermore, it eliminates the need to wait for the original simulated tunnel buffer layer to be disassembled; the original simulated tunnel can simply be moved out and replaced with a new one, greatly saving time and improving the overall testing efficiency.

[0060] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit this utility model. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of them. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A model device for simulating and testing the pressure-bearing support performance of a buffer layer in a soft rock tunnel, characterized in that, Includes a tunnel buffer layer preparation unit and a pressure testing unit; The tunnel buffer layer preparation unit includes: a mold box body and multiple steel barrels of different diameters; the mold box body is detachably connected as a whole, a first base plate is provided at the bottom of the mold box body, and the steel barrels are detachably connected to the first base plate; multiple sets of first through holes are evenly distributed on the side wall of the steel barrels, and the multiple sets of first through holes are symmetrically arranged in pairs. The pressurization detection unit includes: a detection box body, a pressure plate, and a jack; Pressure plates are installed inside the four side walls of the test chamber body. The pressure plates are staggered and opposite to each other. The output end of the jack passes through the side wall of the test chamber body and is connected to the pressure plate. Each pressure plate is connected to the output end of multiple jacks.

2. The model apparatus as described in claim 1, characterized in that, Each side wall of the mold box body is provided with a handle to facilitate the removal of the side wall.

3. The model apparatus as described in claim 1, characterized in that, Hanging rods are installed at the four top corners of the first base plate. The top of each hanging rod is equipped with a lifting ring, and the bottom of the hanging rod is screwed to the first base plate.

4. The model apparatus as described in claim 1, characterized in that, The tunnel buffer layer preparation unit includes three steel barrels with different diameters, namely the first steel barrel, the second steel barrel, and the third steel barrel; and the diameter of the first steel barrel is larger than that of the second steel barrel, and the diameter of the second steel barrel is larger than that of the third steel barrel.

5. The model apparatus as described in claim 4, characterized in that, The first base plate has a first circular hole at its center, and first screw holes are evenly distributed around the first circular hole; The bottom of the steel drum is provided with a second circular hole, the structure of which is the same as that of the first circular hole, and the position of the second circular hole is opposite to that of the first circular hole.

6. The model apparatus as described in claim 5, characterized in that, The second circular hole is surrounded by second screw holes, the structure of which is the same as that of the first screw hole, and the position of the second screw hole is opposite to that of the first screw hole; the second bolt cooperates with the second screw hole and the first screw hole to detachably connect the steel barrel to the first base plate.

7. The model apparatus as described in claim 1, characterized in that, Each group of first through holes includes multiple through holes, which are arranged side by side, one above the other.

8. The model apparatus as described in claim 1, characterized in that, The tunnel buffer layer preparation unit also includes a deformation detection unit, which includes a digital dial gauge and a strain gauge, and the strain gauge is electrically connected to a static strain gauge.

9. The model apparatus as claimed in claim 1, characterized in that, The bottom of the testing box body is provided with a second base plate, and the distance between the upper surface of the second base plate and the lower surface of the bottom of the pressure plate is slightly greater than the thickness of the first base plate.

10. The model apparatus as claimed in claim 1, characterized in that, The top of the testing box body is equipped with a cross-shaped top plate, which is detachably connected to the side wall of the testing box body.

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