Tunnel model test loading device

Abstract

The invention relates to a tunnel model test loading device, comprising: a model box, the interior of which is configured to be used for loading model soil and duct pieces; the vertical hydraulic loading system is configured to be used for applying vertical step-by-step loading soil pressure to the pipe piece; the lateral hydraulic loading system is configured to be used for applying lateral step-by-step loading soil pressure to the pipe piece; the water pressure loading system is configured to be used for injecting water into a preset position in the model box so as to apply pore water pressure which is loaded step by step to the duct piece; the sensing assembly is at least used for sensing soil pressure and water pressure. According to the invention, the continuous loading simulation of the segment can be realized, so that the actual engineering stress state can be simulated more truly.

Description

Technical Field

[0001] This invention relates to the field of tunnel segment loading tests, and in particular to a loading device for tunnel model tests. Background Technology

[0002] Segment construction is the main load-bearing component of tunnel lining, and its mechanical properties need to be verified through loading tests. Model tests are widely used due to their low cost and ease of implementation, and are of great significance for ensuring the safety of tunnel construction in complex geological formations.

[0003] However, existing segment loading systems have significant shortcomings. First, the loading methods are crude, often using jacks or steel strands for point or line loading, which cannot simulate the continuous distribution of water and soil pressure in actual engineering, affecting the accuracy of the tests. Second, most devices only test single-ring, horizontally placed segments, ignoring the effects of inter-ring interactions, assembly methods, and the segment's own weight, resulting in significant differences from actual working conditions. Although a few studies have attempted to load standing multi-ring segments, these methods suffer from cumbersome assembly and high costs. Furthermore, existing systems have poor compatibility, low reusability, and rely on large steel reaction frames, leading to high costs and difficult maintenance. Therefore, existing technologies cannot accurately simulate the true stress state of segment structures in complex geological environments. Summary of the Invention

[0004] Therefore, it is necessary to provide a tunnel model test loading device to address at least one of the above problems, which can simulate continuous load loading on tunnel segments, thereby more realistically simulating the stress state of actual engineering projects.

[0005] The present invention provides a loading device for a tunnel model test, comprising: a model box configured to load model soil and tunnel segments; a vertical hydraulic loading system configured to apply vertically progressively increasing earth pressure to the tunnel segments; a lateral hydraulic loading system configured to apply laterally progressively increasing earth pressure to the tunnel segments; a water pressure loading system configured to inject water into predetermined locations inside the model box to apply progressively increasing pore water pressure to the tunnel segments; and a sensing component configured to sense at least the earth pressure and water pressure.

[0006] Preferably, the lateral hydraulic loading system includes: a first hydraulic cylinder; a first hydraulic tank connected to the first hydraulic cylinder; a plurality of first hydraulic rods, each with a first end connected to the first hydraulic tank and horizontally arranged, and capable of extending or retracting; a side plate fixedly connected to the second ends of the plurality of first hydraulic rods; a first control rod capable of controlling the flow rate of oil supplied from the first hydraulic cylinder to the first hydraulic tank to control the horizontal movement of the side plate; and a plurality of first push rods horizontally arranged, the first push rods passing through the side wall of the model box, the first end of the first push rod located inside the model box, and the second end of the first push rod located outside the model box and fixedly connected to the side plate.

[0007] Preferably, the model box includes: a model box body having side walls and an upward-facing receiving cavity; a cover rotatably mounted from the opening of the receiving cavity, and the vertical hydraulic loading system is disposed on the cover.

[0008] Preferably, the vertical hydraulic loading system includes: a second hydraulic cylinder fixedly connected to the cover; a second hydraulic tank connected to the second hydraulic cylinder and fixedly connected to the cover; a plurality of second hydraulic rods, the first end of which is connected to the second hydraulic tank and arranged vertically, and capable of extending or shortening; a horizontal plate fixedly connected to the second ends of the plurality of second hydraulic rods; a second control rod capable of controlling the flow rate of oil supplied from the second hydraulic cylinder to the second hydraulic tank to control the up and down movement of the horizontal plate; and a plurality of second push rods arranged vertically, the first end of which is fixedly connected to the horizontal plate, and the second end of which can extend into the receiving cavity of the model box body when the cover is closed.

[0009] Preferably, the sensing component includes a resistive pressure cell for measuring earth pressure.

[0010] Preferably, the sensing component includes a steel wire earth pressure cell for measuring earth pressure.

[0011] Preferably, the sensing component further includes a piezometer for measuring water pressure.

[0012] Preferably, the sensing component further includes a resistance strain gauge for measuring the deformation of the tunnel structure.

[0013] Preferably, the sensing component further includes: an internal displacement gauge for measuring the overall convergent deformation of the tunnel structure cross-section.

[0014] Preferably, the sensing component further includes an acoustic emission sensor for real-time sensing and monitoring of the damage state inside the tunnel structure.

[0015] The aforementioned tunnel model test loading device overcomes the limitations of traditional point or line loading, enabling the application of continuous, distributed loads to the circumference of the tunnel segment ring. This more realistically simulates the continuous action of soil and water pressure on the tunnel segment in actual engineering. Simultaneously, the independently controllable vertical and lateral hydraulic loading, combined with individually adjustable water pressure loading, allows researchers to flexibly construct complex initial stress and seepage fields. This enables systematic research on the mechanical behavior of the tunnel segment structure, joint stress-deformation patterns, and overall stability under different stress paths and soil-water coupling conditions, providing high-precision experimental data support for tunnel engineering design and safety assessment. Attached Figure Description

[0016] Figure 1 This is a schematic diagram showing the positional relationship between the model box, the first push rod, and the vertical hydraulic loading system.

[0017] Figure 2 This is a schematic diagram of a lateral hydraulic loading system.

[0018] Figure 3 This is a schematic diagram of the lateral hydraulic loading system from another perspective.

[0019] Figure 4 This is a schematic diagram of a vertical hydraulic loading system.

[0020] Explanation of reference numerals in the attached figures:

[0021] 100. Model box;

[0022] 110. Model box body; 111. Side wall; 112. Receiving cavity;

[0023] 120. Cover; 130. Connecting shaft;

[0024] 200. Lateral hydraulic loading system; 201. First hydraulic cylinder; 202. First hydraulic tank; 203. First hydraulic rod; 204. Side plate; 205. First control rod; 206. First push rod; 207. First hydraulic pipeline;

[0025] 300. Vertical hydraulic loading system; 301. Second oil cylinder; 302. Second hydraulic tank; 303. Second hydraulic rod; 304. Horizontal plate; 305. Second control rod; 306. Second push rod; 307. Second hydraulic pipeline. Detailed Implementation

[0026] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] The following is combined Figures 1 to 4 The loading device for tunnel model testing according to an embodiment of the present invention will be described.

[0028] like Figures 1 to 4 As shown, the tunnel model test loading device of the present invention includes: a model box 100, a lateral hydraulic loading system 200, a vertical hydraulic loading system 300, a water pressure loading system, and a sensing component.

[0029] The interior of the model box 100 is configured to hold model soil and tunnel segments. Specifically, the model box 100 is filled with pre-prepared model soil in layers and compacted to the bottom of the tunnel segment structure to accurately simulate the underlying and surrounding strata of the tunnel. To accommodate different test requirements, one or more side panels of the model box can be designed to be detachable or equipped with high-strength transparent observation windows, facilitating visual observation and recording of the tunnel segment assembly and soil filling process. In specific test operations, the model soil is first filled into the box in layers and compacted to a predetermined height to form a stable underlying layer for the tunnel segment structure. Subsequently, pre-customized, scaled-down model tunnel segments (which can be one or more rings, and can be assembled using staggered or continuous joints) are precisely lowered to the designed position using hoisting equipment. To isolate the influence of the water pressure loading system, flexible sealant is used to reliably seal the end joints of the model tunnel segments to achieve structural waterproofing.

[0030] The vertical hydraulic loading system 300 is configured to apply vertically progressively increasing earth pressure to the tunnel segments, simulating the self-weight stress and additional stress of the overlying soil layer. The vertical hydraulic loading system 300 is located on top of the model box or integrated into the top of the model box 100.

[0031] The lateral hydraulic loading system 200 is configured to apply progressively increasing lateral earth pressure to the tunnel segments to simulate horizontal stress. Vertical and lateral earth pressures are used to simulate total stress.

[0032] A hydraulic loading system (not shown) is configured to inject water into predetermined locations inside the model box 100 to apply progressively increasing pore water pressure to the tunnel segments. This pore water pressure is used to simulate seepage pressure, thereby studying the impact of changes in the surrounding rock seepage field on the stress field. The hydraulic loading system is used to simulate the groundwater environment. Progressive loading refers to a step-by-step increase in load over time, used to achieve a specified stress path and monitor the response. Progressive loading means that the load is not applied all at once, but rather increases in stages and steps over time according to a preset stress path. This loading method allows researchers to monitor the stress and deformation response of the tunnel segment structure and surrounding soil after each load level stabilizes, thereby systematically studying its stress characteristics and failure mechanisms, and accurately simulating the dynamic changes in the surrounding rock stress field during tunnel construction.

[0033] The sensing components are configured to sense at least earth pressure and water pressure.

[0034] This invention provides a tunnel model test loading device that can simulate continuous load loading on tunnel segments, thereby more realistically simulating the stress state of actual engineering projects.

[0035] Through the integrated design described above, this invention overcomes the limitations of traditional point or line loading, enabling the application of continuous, distributed loads to the circumference of tunnel segments (especially multi-ring assemblies), thus more realistically simulating the continuous action of soil and water pressure on tunnel segments in actual engineering. Simultaneously, the independently controllable vertical and lateral hydraulic loading, combined with individually adjustable water pressure loading, allows researchers to flexibly construct complex initial stress and seepage fields, systematically studying the mechanical behavior of tunnel segments, joint stress-deformation patterns, and overall stability under different stress paths and soil-water coupling conditions, providing high-precision experimental data support for tunnel engineering design and safety assessment.

[0036] Furthermore, the lateral hydraulic loading system 200, the vertical hydraulic loading system 300, and the water pressure loading system are all connected to a controller (not shown in the figure). These three loading systems can be independently or collaboratively controlled according to the experimental design, thereby accurately constructing various complex stress paths and water-soil coupling environments within the model box 100 to conduct in-depth research on the mechanical properties and evolution laws of tunnel segment structures under different initial and dynamic stress fields.

[0037] Specific control modes include:

[0038] Independent control mode:

[0039] Each system can be operated independently to study the effects of a single load factor. For example, the vertical bearing capacity of the tunnel segments under deep burial conditions can be studied by gradually increasing the overlying soil pressure using only the vertical hydraulic loading system; or the impact of seepage on the waterproofing performance of the tunnel segment joints can be investigated by increasing the pore water pressure using only the water pressure loading system.

[0040] Linkage and coordination control mode:

[0041] The controller can synchronize multiple loading systems according to a specific ratio and timing based on a preset mathematical model or real monitoring data. For example:

[0042] Simulate "K0 static earth pressure state": Link control of vertical and lateral hydraulic systems to maintain a fixed proportional coefficient (i.e., lateral pressure coefficient) between lateral and vertical pressure, simulating the initial stress field of natural strata under conditions of no lateral deformation.

[0043] Simulating the "tunnel excavation and unloading" process: First, establish the initial geostress field (σ) in conjunction with the process. v , σ h Then, the lateral hydraulic loading system 200 is controlled to "unload" in the area corresponding to the tunnel axis direction to simulate the stress release of the surrounding rock caused by excavation. At the same time, the water pressure can be maintained or changed to study the unloading-seepage coupling effect.

[0044] Simulating "sudden drop in water level" or "rain infiltration": Under the condition of keeping the total stress (hydraulic pressure) constant, the water pressure loading system is controlled to rapidly reduce or increase the pore water pressure, thereby effectively simulating the change in effective soil stress caused by water level changes and its dynamic impact on the stress of the tunnel segments.

[0045] Through the aforementioned refined control capabilities of both independent and interconnected systems, this invention overcomes the shortcomings of traditional loading tests, which suffer from a single load mode and an inability to reflect changes in stress paths. It can systematically study the full-cycle mechanical response of tunnel segment structures under different geological conditions (such as strata with different lateral pressure coefficients), different construction stages (such as excavation, support, and later operation), and different hydrological events, providing more scientific and comprehensive experimental data support for segment design, assembly method selection, and engineering risk early warning.

[0046] In an exemplary embodiment, the lateral hydraulic loading system 200 includes: a first hydraulic cylinder 201, a first hydraulic tank 202, a plurality of first hydraulic rods 203, a side plate 204, a first control rod 205, and a plurality of first push rods 206.

[0047] The first hydraulic tank 202 is connected to the first hydraulic cylinder 201. The first hydraulic cylinder 201 serves as the power source of the system and is connected to the first hydraulic tank 202 via the first hydraulic pipeline 207. The first hydraulic tank 202 serves as a pressure distribution and buffer container, stabilizing and distributing the hydraulic oil supplied by the first hydraulic cylinder 201.

[0048] The first ends of multiple first hydraulic rods 203 are connected to the first hydraulic tank 202 and are horizontally arranged, and can be extended or retracted. Specifically, by supplying oil to the first hydraulic tank 202 through the first cylinder 201, the piston rods of all the first hydraulic rods 203 can be synchronously controlled to extend or retract horizontally, thereby driving the side plate 204 to move horizontally.

[0049] The side plate 204 is fixed to the second end of a plurality of first hydraulic rods 203.

[0050] The first control lever 205 controls the flow rate of oil supplied from the first cylinder 201 to the first hydraulic tank 202, thereby controlling the horizontal movement of the side plate 204. Specifically, the first control lever 205 is connected to a flow control valve (e.g., a proportional valve or a servo valve) of the first cylinder 201, which can precisely adjust the flow rate and volume of oil supplied from the first cylinder 201 to the first hydraulic tank 202. By controlling the oil supply rate, the extension and retraction speed of the first hydraulic rod 203 can be precisely controlled, thereby controlling the horizontal movement speed of the side plate 204 and the magnitude of the applied pressure, achieving step-by-step loading or dynamic loading.

[0051] Multiple first push rods 206 are horizontally arranged, passing through the side wall 111 of the model box 100. The first end of the first push rod 206 is located inside the model box 100, and the second end of the first push rod 206 is located outside the model box 100 and fixed to the side plate 204.

[0052] Working principle and beneficial effects:

[0053] When the first control lever 205 controls the first hydraulic cylinder 201 to extend the first hydraulic rod 203, the side plate 204 moves horizontally inward, thereby synchronously pushing all the first push rods 206 to move horizontally inward. The inner ends of these evenly arranged first push rods 206 work together on the model soil to form a large-area, high-density loading surface. This design optimizes traditional point loading into near-surface continuous loading, which can more uniformly simulate the horizontal ground stress on the tunnel segment sidewalls of the actual strata. Through the precise adjustment of the hydraulic pressure by the first control lever 205, independent, stable, and graded control of lateral pressure can be achieved, accurately reproducing complex in-situ stress states.

[0054] In an exemplary embodiment, the model box 100 includes a model box body 110 and a cover 120.

[0055] The model box body 110 has side walls 111 and an upward-opening receiving cavity 112, which is used for layering model soil and placing model segments. The side walls 111 need to have sufficient rigidity and strength to withstand the reaction force from the lateral loading system and the pressure of the internal soil and water.

[0056] The cover 120 is rotatably mounted on the opening of the receiving cavity, and the vertical hydraulic loading system 300 is mounted on the cover. When the cover 120 is closed and locked, the vertical hydraulic loading system 300 integrated thereon is precisely positioned directly above the test area, applying vertical loads to the model soil and segment structure below. This integrated design of the loading system and the openable cover not only optimizes the spatial layout but also ensures the accuracy and repeatability of the vertical loading direction and position in each test.

[0057] Specifically, a connecting shaft 130 is provided at the connection between the model box body 110 and the cover 120, and the cover 120 can rotate around the connecting shaft 130.

[0058] In an exemplary embodiment, the vertical hydraulic loading system includes: a second cylinder 301, a second hydraulic tank 302, a second hydraulic rod 303, a horizontal plate 304, a second control rod 305, and a second push rod 306.

[0059] The second hydraulic cylinder 301 is fixedly connected to the cover 120.

[0060] The second hydraulic tank 302 is connected to the second hydraulic cylinder 301 and fixed to the cover. The second hydraulic cylinder 301 is connected to the second hydraulic tank 302 through the second hydraulic pipeline 307.

[0061] Multiple second hydraulic rods 303 have their first ends connected to the second hydraulic tank and are arranged in a vertical direction, and are capable of being extended or shortened.

[0062] The horizontal plate 304 is fixed to the second end of a plurality of second hydraulic rods 303.

[0063] The second control lever 305 can control the flow rate of oil supplied from the second oil cylinder to the second hydraulic tank, so as to control the up and down movement of the horizontal plate.

[0064] Multiple second push rods 306 are arranged vertically. The first end of each second push rod is fixed to a horizontal plate, and the second end of each second push rod can extend into the receiving cavity of the model box body when the cover is closed. The structure and working principle of the vertical hydraulic loading system 300 are similar and will not be described in detail, except that the direction of its push rods is different.

[0065] In an exemplary embodiment, the sensing component includes a resistive pressure cell for measuring soil pressure.

[0066] Multiple resistance pressure cells are pre-embedded in the model soil, specifically including: 1) Contact interface measurement points: directly arranged on the contact interface between the outer surface of the model segment and the surrounding model soil, used to directly measure the normal earth pressure on the segment structure; 2) Soil internal measurement points: arranged in layers in the model soil around the segment, used to monitor the distribution and transmission law of the stress field inside the soil during loading.

[0067] The sensing component further includes a data acquisition unit (not shown in the figure), which is connected to the resistive pressure cell via wires and is able to acquire the pressure analog signals of each measuring point in real time and synchronously at a high frequency, and convert them into digital data records.

[0068] System Integration and Functionality: The measurement data from the sensing components are deeply integrated with the loading system. Data measured by the sensing components is fed back to the controller in real time. Operators or control algorithms can dynamically adjust the output forces of the lateral hydraulic loading system 200 and the vertical hydraulic loading system 300 based on the real-time earth pressure distribution, achieving precise closed-loop control of the load. Simultaneously, this time-series earth pressure data, combined with the pore water pressure data applied by the hydraulic loading system, provides a direct basis for subsequent analysis of the effective stress principle in the segment-soil system, research on the mechanical response of segments under different stress paths, and verification of the loading simulation effect.

[0069] In an exemplary embodiment, the sensing component includes a wire-type earth pressure cell for measuring earth pressure within the model soil. The wire-type earth pressure cell is specifically designed for accurately measuring static and dynamic earth pressure within the model soil and at the soil-structure interface.

[0070] Multiple steel wire earth pressure cells are pre-embedded in the following locations: 1) on the outer surface of the tunnel segment to directly sense the surrounding rock pressure borne by the segment; 2) in the model soil around the segment in layers and regions to draw the spatial distribution map of the stress field inside the soil during loading and to monitor the stress transmission path.

[0071] Steel-string earth pressure cells are suitable for electromagnetic interference environments that may exist in model tests and for working conditions that require long-term monitoring.

[0072] The steel wire earth pressure cell is electrically connected to the data acquisition instrument. The measured data (frequency signal after conversion) is synchronously acquired and recorded, forming redundancy and complementarity with the data from the resistive pressure cell. Based on this real-time, high-precision earth pressure feedback, the operator or central control system can perform more precise closed-loop control of the lateral hydraulic loading system 200 and the vertical hydraulic loading system 300, ensuring that the distribution and magnitude of the simulated load conform to the preset stress field conditions.

[0073] Furthermore, both steel wire earth pressure cells and resistive earth pressure cells are used simultaneously. The steel wire earth pressure cell is stable in the long term and has good anti-interference, while the resistive earth pressure cell has a fast response and is suitable for dynamic situations (such as rapid loading and transient peaks). The two complement each other and improve the reliability of the results.

[0074] In an exemplary embodiment, the sensing component further includes a piezometer for directly and in real-time measuring the pore water pressure in the model soil.

[0075] Multiple piezometers are installed in the following locations within the model box 100: 1) Pore water pressure monitoring points inside the soil: These are buried in layers in the model soil at different depths and horizontal distances around the tunnel segments to plot the spatial distribution of the pore water pressure field and monitor the dynamic propagation and dissipation of pore water pressure under the action of the water pressure loading system or in conjunction with the hydraulic loading system; 2) Structure-soil interface monitoring points: These are located near the outer wall of the tunnel segments, especially at key waterproofing locations such as joints and grouting holes, to assess the water pressure load behind the tunnel segments and the effectiveness of the waterproofing system.

[0076] In an exemplary embodiment, the sensing component further includes a resistance strain gauge for measuring the deformation of the tunnel structure, thereby indirectly and accurately analyzing its deformation and stress state.

[0077] Resistance strain gauges are installed in the following locations in the model box 100: 1) Strain rosettes or uniaxial strain gauges are pasted on the inner and outer arc surfaces of the segments along the circumferential, longitudinal, and principal stress prediction directions to measure the tensile, compressive, and shear strains of the segment concrete under load, in order to analyze its overall bending moment, axial force distribution, and possible stress concentration areas; 2) They are densely arranged in areas with complex stress, such as near the joints of the segment's circumferential and longitudinal seams and around bolt holes, to study the local deformation, stiffness changes, and force transmission mechanisms at the joints.

[0078] In an exemplary embodiment, the sensing component further includes an internal displacement gauge for measuring the overall convergent deformation of the tunnel structure cross-section. The internal displacement gauge is electrically connected to a data acquisition unit.

[0079] Internal displacement gauges are typically multi-point radial displacement gauges or measuring rings composed of multiple high-precision linear variable differential transformers (LVDTs). The installation method is as follows: after the model tunnel segments are assembled, a slightly deformable measuring ring is concentrically fixed to the inner side of the tunnel segment lining using lightweight supports. Displacement probes are arranged on this measuring ring along multiple radial directions (e.g., key points such as the arch crown, arch waist, arch bottom, and left and right 45-degree directions). The inner end of each displacement probe is hinged to the measuring ring, and the outer end of each displacement probe gently abuts against the inner surface of the tunnel segment via a low-friction contact head.

[0080] When the tunnel segment structure undergoes cross-sectional deformation (e.g., from a circular shape to an elliptical shape) under external water and soil pressure, the position of the contact point between the inner wall of the segment and the displacement measuring rod will change, thereby pushing or pulling the displacement measuring rod. This minute radial displacement is captured in real time and converted into an electrical signal by a high-precision displacement sensor (such as the LVDT core) connected to each displacement measuring rod. The data acquisition instrument synchronously records the displacement values ​​of all radial measuring points.

[0081] In an exemplary embodiment, the sensing component further includes an acoustic emission sensor for real-time sensing and monitoring of damage conditions inside the tunnel structure.

[0082] Multiple high-frequency acoustic emission sensors are arranged in an array on key surfaces of the model segment (such as the inner arc surface, near the joint between the segment's circumferential and longitudinal seams) to ensure that acoustic emission signals from any area of ​​the segment body and joint are effectively captured, and the acoustic emission source (i.e. the point of damage) is located in three-dimensional space by using the time difference of arrival principle.

[0083] In summary, compared to current model test loading devices that directly core sample tunnels, most of which can only simulate a single stress field, this invention can simulate the mechanical properties of tunnel segment structures under different stress fields. Compared to existing model test equipment, this invention simulates a wider range of geological conditions and is easier to produce and promote. For tunnel projects with various stress fields, this equipment can be used to study the stress and deformation development patterns of segment structures and joints under different stress fields.

[0084] The operation of the tunnel model test loading device of the present invention is as follows:

[0085] (1) Experimental preparation

[0086] Through reasonable design, while ensuring the effective connection of sensor lines, the pressure-holding and sealing performance of the platform sensor interfaces is guaranteed. A sufficient number of adapters are procured and installed according to the sensor requirements of the test deployment. Customized processing of the tunnel segment structure involves designing and customizing the model tunnel segment type, reinforcement, and components based on the prototype tunnel segment design and similarity ratio.

[0087] Based on the experimental requirements and the dimensions of the model segments, segment molds were fabricated; the internal reinforcement of the segments was laid out, and the overall structure was poured, followed by water curing; after the segments were cured, when using grooved ring segments for simulation, the groove positions and depths should be reasonably designed according to the actual segment structure to simulate the weakening of the structural bending stiffness at the joints. Based on the experimental objectives, combined with the tunnel engineering geological conditions and the stress state of the segment structure, experimental model soil was prepared. Orthogonal experiments were used to prepare model soils with different gradations, and after testing the physical and mechanical parameters of the model soils, model soils meeting the similarity scale were selected.

[0088] (2) Model soil layer ramming and structural installation

[0089] Pre-mixed model soil is filled into the model box in layers and compacted to the bottom of the tunnel segment structure as the underlying layer. The pre-made model tunnel segments are lowered using a crane, and both ends of the segments are sealed with sealant for waterproofing. The model soil is then filled and compacted layer by layer, with a small hammer used to compact the soil around the model tunnel segments until the design elevation is reached.

[0090] According to the deployment location and orientation of various sensors, the installation of each group of sensors is coordinated with the model soil ramming and structural installation, and the sensor wiring is led to the interface of the structural loading platform.

[0091] (3) Conduct the experiment

[0092] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A loading device for tunnel model testing, characterized in that, include: The model box, whose interior is configured to hold model soil and segments; A vertical hydraulic loading system configured to apply vertically progressively increasing earth pressure to the segments; A lateral hydraulic loading system is configured to apply lateral, progressively increasing earth pressure to the segments. A hydraulic loading system is configured to inject water into predetermined locations inside the model box to apply progressively increasing pore water pressure to the segments. The sensing component is configured to sense at least earth pressure and water pressure.

2. The tunnel model test loading device according to claim 1, characterized in that, The lateral hydraulic loading system includes: First oil cylinder; A first hydraulic tank is connected to the first hydraulic cylinder; Multiple first hydraulic rods, each having its first end connected to the first hydraulic tank, are horizontally positioned and capable of extending or retracting; Side plate, which is fixedly connected to the second end of a plurality of the first hydraulic rods; The first control lever controls the flow rate of oil supplied from the first cylinder to the first hydraulic tank, thereby controlling the horizontal movement of the side plate; Multiple first push rods are arranged horizontally, each push rod passing through the side wall of the model box. The first end of each push rod is located inside the model box, and the second end of each push rod is located outside the model box and fixed to the side plate.

3. The tunnel model test loading device according to claim 1, characterized in that, The model box includes: The model box body has side walls and an upward-opening receiving cavity; A cover, which is rotatably mounted on the opening of the receiving cavity, is provided with a vertical hydraulic loading system on the cover.

4. The tunnel model test loading device according to claim 3, characterized in that, The vertical hydraulic loading system includes: The second hydraulic cylinder is fixedly connected to the cover. The second hydraulic tank is connected to the second oil cylinder and fixed to the cover; Multiple second hydraulic rods, each having its first end connected to the second hydraulic tank and arranged vertically, are capable of extending or retracting. A horizontal plate, which is fixed to the second end of a plurality of second hydraulic rods; The second control lever controls the flow rate of oil supplied from the second cylinder to the second hydraulic tank, thereby controlling the up-and-down movement of the horizontal plate. Multiple second push rods are arranged vertically, with the first end of each push rod fixed to a horizontal plate and the second end of each push rod capable of extending into the receiving cavity of the model box body when the cover is closed.

5. The tunnel model test loading device according to claim 1, characterized in that, The sensing component includes: A resistance pressure cell, used to measure earth pressure.

6. The tunnel model test loading device according to claim 1, characterized in that, The sensing component includes: A steel wire earth pressure cell is used to measure earth pressure.

7. The tunnel model test loading device according to claim 1, characterized in that, The sensing component further includes: A piezometer is used to measure water pressure.

8. The tunnel model test loading device according to claim 1, characterized in that, The sensing component further includes: Resistance strain gauges are used to measure the deformation of tunnel structures.

9. The tunnel model test loading device according to claim 1, characterized in that, The sensing component further includes: Internal displacement gauges are used to measure the overall convergent deformation of the cross-section of tunnel structures.

10. The tunnel model test loading device according to claim 1, characterized in that, The sensing component further includes: Acoustic emission sensors are used for real-time sensing and monitoring of damage conditions inside tunnel structures.

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