A soil shearing simulation test system for serving earthquake engineering

Abstract

This invention discloses a soil shear simulation test system for earthquake engineering, relating to the technical field of earthquake engineering test devices. The invention includes a layered shear model box body and a model box connecting structure. The layered shear model box body comprises multiple single-layer model boxes stacked vertically, with adjacent single-layer model boxes forming an interlayer arrangement space through the model box connecting structure. A pressure-bearing lifting component and a limiting and guiding component are arranged within the interlayer arrangement space. The pressure-bearing lifting component is used to bear vertical loads and form interlayer gaps between adjacent single-layer model boxes, while also adjusting the height of the test system to allow adjacent single-layer model boxes to undergo shear in any direction within the plane. The limiting and guiding component guides the relative sliding between adjacent single-layer model boxes and limits their maximum shear displacement. The invention also includes a variable stiffness equivalent soil constraint device, which is disposed on the steel web of the single-layer model box to simulate the nonlinear constraint effect of soil on the test structure.

Description

Technical Field

[0001] This invention relates to the field of earthquake engineering testing equipment technology, specifically to a soil shear simulation testing system for earthquake engineering. Background Technology

[0002] In seismic model tests of underground structures, the layered shear model box is the core test device for simulating the shear deformation of soil under seismic loading. Its working principle involves stacking multiple rigid frames vertically and utilizing the relative sliding between layers to simulate the shear deformation mode of the soil, thereby studying the performance of underground structures under seismic loads.

[0003] A review of existing technologies reveals that existing layered shear model boxes, such as those described in CN114910232A, CN107476359A, or CN104406755A, employ rollers, rails, or elastic pads as interlayer connection components. While these structures can achieve a certain degree of relative sliding in the horizontal direction, their degrees of freedom are typically restricted to a single direction, making it difficult to realistically simulate the spatial shear constraint effect of soil on underground structures under multi-directional seismic wave input conditions. Furthermore, the point or line contact between the rollers and rails easily leads to stress concentration under vertical loads, and significant wear occurs under long-term reciprocating loading, affecting experimental accuracy and the lifespan of the device. Additionally, the shear model box method of directly filling the model box with solid soil presents problems such as difficulty in precisely controlling soil stiffness, the need to replace the soil after each test, time and labor costs, and low experimental efficiency.

[0004] Therefore, there is an urgent need for a layered shear model box that can reduce interlayer friction constraints while bearing vertical loads, allow multi-directional in-plane shear displacement, and reduce stress concentration and wear, so as to more realistically simulate the impact of soil shear deformation on the performance of underground structures under seismic loading. Summary of the Invention

[0005] The purpose of this invention is to provide a soil shear simulation testing system for earthquake engineering, thereby solving the problems mentioned in the background section. This objective is mainly achieved through the following technical solutions: A soil shear simulation test system for earthquake engineering includes a layered shear model box body and a model box connecting structure. The layered shear model box body includes multiple single-layer model boxes stacked vertically, and a model box connecting structure is provided between adjacent single-layer model boxes.

[0006] Furthermore, the single-layer model box includes a steel profile, an upper channel steel fixedly connected to the upper flange of the steel profile, a lower channel steel fixedly connected to the lower flange of the steel profile, and compartmentalized stiffening ribs in the upper and lower channel steels; Furthermore, in the adjacent single-layer model boxes, the lower channel steel of the upper model box is inverted onto the upper channel steel of the lower model box to enclose and form the interlayer arrangement space.

[0007] Furthermore, the upper and lower channel steels are provided with compartment stiffening ribs, which are arranged along the length and width of the channel steels to divide the interlayer arrangement space into an interlayer pressure-bearing cavity and an interlayer limiting and guiding area, which are alternately arranged in the interlayer arrangement space.

[0008] Furthermore, the model box connection structure includes a pressure-bearing lifting component and a limiting and guiding component; the pressure-bearing lifting component is located in the interlayer pressure-bearing receiving cavity, and the limiting and guiding component is located in the interlayer limiting and guiding area.

[0009] Furthermore, the pressure-bearing lifting component includes a liquid bladder and a liquid bladder sleeve; the liquid bladder is disposed inside the liquid bladder sleeve, and after the liquid bladder is filled with liquid, it expands the liquid bladder sleeve to bear the vertical load, so that gaps are formed between adjacent layers, ensuring that the upper and lower channel steels of adjacent layers do not contact each other during horizontal shearing, thereby realizing shearing in any direction in the plane. At the same time, the overall height of the soil shearing simulation test system serving earthquake engineering can be adjusted according to the size of the pressure-bearing lifting component and the amount of liquid filling.

[0010] Furthermore, the limiting guide assembly includes a limiting guide groove and an interlayer limiting post; the limiting guide groove is disposed in the interlayer limiting guide area of ​​the upper channel steel of the adjacent lower model box, and the interlayer limiting post is disposed in the lower channel steel limiting guide area of ​​the adjacent upper model box. The interlayer limiting post is correspondingly assembled in the limiting guide groove and can slide relative to each other in the limiting guide groove.

[0011] Furthermore, the limiting guide groove is provided with a limiting hole, and the interlayer limiting post is installed in the limiting hole accordingly; when the interlayer limiting post reaches the edge of the limiting hole, the interlayer limiting post abuts against the edge of the limiting hole to limit the maximum interlayer shear displacement.

[0012] Furthermore, a soil shear simulation test system for earthquake engineering also includes a variable stiffness equivalent soil constraint device, which is installed on the steel web of the single-layer model box to simulate the constraint effect of soil on the test structure.

[0013] Furthermore, the variable stiffness equivalent soil constraint device includes an elastic constraint member and an elastic constraint replacement assembly. The elastic constraint replacement assembly is connected to the elastic constraint member to realize the replacement of the elastic constraint member with different stiffnesses.

[0014] Furthermore, the variable stiffness equivalent soil constraint device also includes a guide sleeve and a guide screw. The guide screw is inserted into the guide sleeve and slidably engaged to guide the compression and elongation directions of the elastic constraint member. The guide screw is provided with a safety travel limit to limit the extraction displacement.

[0015] Furthermore, a soil shear simulation test system for earthquake engineering also includes a boundary fixing component, which includes a base plate and a frame; the base plate is used to fix it to the shaking table surface; the frame includes corner posts located at the four corners of the outer perimeter of the layered shear model box body, and the bottom ends of the corner posts are fixed to the bottom layer model box of the layered shear model box body on the base plate.

[0016] Furthermore, the frame also includes a central column disposed in the middle of the long side of the main body of the layered shear model box, and the corner columns and the central column are connected by angle iron to form an oblique truss; Furthermore, the frame is equipped with rubber buffer pads at corresponding positions on the top layer model box according to the total height of the shear model box. When the total shear displacement of the system formed by the accumulation of shear displacement between each layer reaches the preset maximum allowable total shear displacement, the buffer pads will contact the top layer model box and absorb the impact, thereby limiting the overall displacement of the test system from continuing to increase.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention constructs a single-layer model box by setting up a steel profile, an upper channel steel, a lower channel steel, and stiffening ribs in the upper and lower channel steels, and inverting the lower channel steel of the upper model box onto the upper channel steel of the lower model box to enclose and form an interlayer arrangement space. This structure solves the problems of complex interlayer connections and difficulty in forming pressure-bearing cavities in existing devices, provides stable structural support and a space for easy installation of pressure-bearing lifting components, and has the advantages of simple structure, convenient assembly, and reliable connection.

[0018] (2) This invention, by setting up a pressure-bearing lifting component composed of a liquid bladder and a liquid bladder sleeve, bears the vertical load in a surface contact manner and forms an interlayer gap between adjacent single-layer model boxes, so that adjacent model boxes do not contact each other during horizontal shearing. This structure solves the problem of local stress concentration and wear at the interlayer contact points of existing shear model boxes due to the connection methods of rollers, balls, etc., thus improving the stability and service life of the test system. At the same time, it solves the problem of the shearing direction of the shear model box being limited by the connection methods of rollers, balls, etc., realizing shearing in any direction in the plane.

[0019] (3) By setting up the limiting guide groove and the interlayer limiting column, when shearing occurs in any direction in the plane under the action of the vibration table, the interlayer limiting column can slide relative to the limiting guide groove. When the interlayer limiting column reaches the edge of the limiting hole, the interlayer limiting column abuts against the edge of the limiting hole. Through the abutting action between the interlayer limiting column and the limiting hole, the maximum interlayer shear displacement of the shear model box is further limited.

[0020] (4) This invention uses a variable stiffness equivalent soil constraint device set inside a single-layer model box to simulate the constraint effect of soil on the test structure, and the elastic constraint components with different stiffnesses can be replaced according to the test requirements. This structure solves the problem that the soil stiffness is difficult to control accurately when conventional solid soil is used to fill the existing shear model box during in-plane shearing, and also solves the problem of low efficiency and high cost caused by the need to replace the soil after the test. It realizes flexible equivalent simulation of the stiffness of soil of different types and depths, and the device can be reused, which significantly reduces the test cost. Attached Figure Description

[0021] Figure 1 This is an overall schematic diagram of the present invention; Figure 2 This is a front view of the present invention; Figure 3 This is a schematic diagram of the bottom model box of the present invention; Figure 4 This is a schematic diagram of the intermediate layer model box of the present invention; Figure 5 This is a cross-sectional view of the pressure-bearing lifting component of the present invention; Figure 6 This is a schematic diagram of the limiting and guiding component of the present invention; Figure 7 This is a schematic diagram of the variable stiffness equivalent soil restraint device of the present invention. Figure 8 This is a schematic diagram of the arrangement of the variable stiffness equivalent soil constraint device of the present invention.

[0022] In the diagram: 1. Base plate; 2. Frame; 3. Bottom layer model box; 4. Middle layer model box; 5. Top layer model box; 6. Structural steel; 7. Upper channel steel; 8. Compartmentalized stiffening rib; 9. Limiting guide groove; 10. Liquid bladder; 11. Liquid bladder sleeve; 12. Lower channel steel; 13. Interlayer limiting column; 14. Top plate of variable stiffness equivalent soil restraint device; 15. Elastic restraint replacement component; 16. Elastic restraint component; 17. Guide sleeve; 18. Partition plate; 19. Guide screw; 20. Limiting nut; 21. Bottom plate of variable stiffness equivalent soil restraint device; 22. Fixing screw. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 This embodiment provides a soil shear simulation test system for earthquake engineering, aiming to solve one of the problems of existing layered shear model boxes, which have strong restrictions on the shear direction and are prone to local stress concentration and wear at the interlayer contact points.

[0025] like Figure 1-6 As shown, the soil shear simulation test system includes a layered shear model box body and a model box connecting structure. The layered shear model box body consists of multiple single-layer model boxes stacked vertically, which are divided into bottom model box 3, middle model box 4 and top model box 5 according to their position.

[0026] The model box connection structure includes a pressure-bearing lifting component and a limiting and guiding component. In adjacent single-layer model boxes, the lower channel steel 12 of the upper model box is inverted onto the upper channel steel 7 of the lower model box, forming an interlayer arrangement space. Specifically, the interlayer arrangement space includes an interlayer pressure-bearing cavity and an interlayer limiting and guiding area, which are alternately arranged within the interlayer arrangement space.

[0027] The components of this embodiment are described in detail below: Specifically, such as Figures 1 to 4 As shown, the main body of the layered shearing model box in this embodiment includes multiple single-layer model boxes stacked vertically. The multiple single-layer model boxes are divided into bottom model box 3, middle model box 4 and top model box 5 according to their positions. Specifically, when stacked vertically, they are arranged from bottom to top as bottom model box 3, middle model box 4 and top model box 5.

[0028] The single-layer model box includes a steel section 6, an upper channel steel 7, a lower channel steel 12, and compartment stiffening ribs 8. The upper channel steel 7 is fixedly connected to the upper flange of the steel section 6. The lower channel steel 12 is fixedly connected to the lower flange of the steel section 6. The compartment stiffening ribs 8 are arranged along the length and width directions of the upper channel steel 7 and the lower channel steel 12. The compartment stiffening ribs 8 divide the interior of the upper channel steel 7 and the lower channel steel 12 into multiple segmented regions. The compartment stiffening ribs 8 are used to limit buckling of the groove openings of the upper channel steel 7 and the lower channel steel 12, improving the local stability of the model box's connection structure.

[0029] Preferably, the upper channel steel 7 / lower channel steel 12 is fixed to the section steel 6 by welding. The section steel 6 is preferably an I-beam, and the upper channel steel 7 and lower channel steel 12 have the same dimensions.

[0030] Specifically, such as Figure 5 and Figure 6 As shown, in this embodiment, when assembling adjacent layers of a single-layer model box, the lower channel steel 12 of the upper model box is inverted onto the upper channel steel 7 of the lower model box to form an interlayer arrangement space. The interlayer arrangement space includes an interlayer pressure-bearing cavity and an interlayer limiting and guiding area. The pressure-bearing lifting component is located in the interlayer pressure-bearing cavity, and the limiting and guiding component is located in the interlayer limiting and guiding area.

[0031] Preferably, the interlayer pressure-bearing cavity and the interlayer limiting and guiding area are arranged alternately in the interlayer arrangement space.

[0032] This invention comprises a single-layer model box consisting of shaped steel sections, an upper channel steel, a lower channel steel, and stiffening ribs inside the channel steel. The lower channel steel of the upper model box is inverted onto the upper channel steel of the lower model box to enclose and form an interlayer arrangement space. This structure solves the problems of complex interlayer connections and difficulty in forming pressure-bearing and accommodating cavities in existing devices, forming a stable model box connection structure with the advantages of simple structure, convenient assembly, and reliable connection.

[0033] Example 2 Based on Example 1, the present invention also proposes a specific structural configuration for the pressure-bearing lifting component and the limiting guide component.

[0034] Specifically, such as Figure 5 As shown, the pressure-bearing lifting assembly includes a liquid bladder 10 and a liquid bladder sleeve 11. The liquid bladder 10 and liquid bladder sleeve 11 are disposed within the pressure-bearing receiving cavity, with the liquid bladder sleeve 11 fitted over the outside of the liquid bladder 10. The height of the liquid bladder sleeve 11 is greater than the height of the interlayer arrangement space. Furthermore, the liquid bladder 10 is provided with an injection port and an exhaust port. Correspondingly, the upper channel steel 7 and the lower channel steel 12 have slots at corresponding positions of the injection port and exhaust port. These slots are used to arrange injection pipes and exhaust pipes for injecting liquid into and venting the liquid bladder 10. The injection port is connected to the injection pipe, and the exhaust port is connected to the exhaust pipe.

[0035] After the main body of the shearing model box is installed, liquid filling begins. During filling, the operator uses an injection device to inject liquid into the liquid bladder 10 through the injection port. At this time, the liquid bladder 10 expands the outer liquid bladder sleeve 11, lifting adjacent single-layer model boxes. Consequently, the overall height of the layered shearing model box body slowly increases with the amount of liquid filling until the liquid bladder 10 is completely filled, creating interlayer gaps between adjacent model boxes. Since the liquid bladder 10 is fitted with the liquid bladder sleeve 11, the liquid bladder sleeve 11 is used to prevent the liquid bladder 10 from bulging out of the pressure-bearing cavity.

[0036] Ultimately, after the liquid bladder 10 is filled with liquid, it forms a surface contact support interface. This surface contact support interface bears the vertical load of the shear model box. At the same time, the surface contact support interface ensures that the upper channel steel 7 and the lower channel steel 12 do not come into contact with each other during horizontal shearing, allowing adjacent model boxes to perform shearing in any direction within the plane.

[0037] This invention employs a pressure-bearing lifting assembly composed of a liquid bladder and a liquid bladder sleeve. This assembly bears vertical loads through surface contact and creates interlayer gaps between adjacent single-layer model boxes, preventing them from contacting each other during horizontal shearing. This structure solves the problems of localized stress concentration and wear that may occur under long-term reciprocating loads when using rollers, ball bearings, or other connection methods in existing technologies, thus improving the stability and service life of the testing device. It also addresses the limitation on the shearing direction of the model box caused by the directional constraints of rollers, ball bearings, etc., enabling shearing in any direction within a plane.

[0038] Specifically, such as Figure 6 As shown, the limiting and guiding assembly includes a limiting and guiding groove 9 and an interlayer limiting post 13. The limiting and guiding groove 9 is located within the compartmentalized stiffening rib 8 of the upper channel steel 7 of the adjacent lower model box. The interlayer limiting post 13 is located within the compartmentalized stiffening rib 8 of the lower channel steel 12 of the adjacent upper model box. The limiting and guiding groove 9 has limiting holes, and the interlayer limiting post 13 is correspondingly installed within these limiting holes. During the assembly of adjacent layers, the interlayer limiting post 13 engages with the limiting holes on the corresponding limiting and guiding groove 9.

[0039] More preferably, the limiting hole is a circular hole, and the size of the limiting hole is set according to the maximum interlayer displacement required for the test.

[0040] This invention utilizes a limiting and guiding assembly consisting of a limiting guide groove and interlayer limiting posts. When the shear model box undergoes shearing in any direction within a plane under the action of a vibration table, the interlayer limiting posts can slide relative to each other within the limiting guide groove. When the interlayer shear displacement reaches a preset maximum value, the interlayer limiting posts abut against the edge of the limiting holes. This abutment between the interlayer limiting posts and the edge of the limiting holes limits the maximum shear displacement of adjacent single-layer model boxes. This structure solves the problem of insufficient effective interlayer displacement control for layered shear model boxes during vibration table operation, improving the stability and safety of the shear model box during vibration table testing.

[0041] Example 3 Based on Embodiment 1 and / or Embodiment 2, to further improve the stability of the test system, the soil shear simulation test system for earthquake engineering in this embodiment also includes a boundary fixing component. Specifically, the boundary fixing component includes a base plate 1 and a frame 2. The base plate 1 is mounted on the shaking table surface. The base plate 1 is used to fix the entire test system. The frame 2 includes four corner columns and multiple central columns. The four corner columns are respectively placed at the four corners of the outer perimeter of the layered shear model box body. One or more central columns are located at the middle of the long side of the layered shear model box body.

[0042] Preferably, the bottom end of the corner post is fixed to the bottom plate 1 by bolts to the bottom model box 3.

[0043] Preferably, the corner posts and / or center posts are made of square steel tubing.

[0044] More preferably, the corner columns and the central columns are connected by angle iron to form a diagonal truss connection. This diagonal truss connection ensures the overall stability of frame 2 during vibration.

[0045] Furthermore, based on the total height of the shear model box, rubber buffer pads are installed at corresponding positions on frame 2 and the top-level model box 5. The thickness of the rubber buffer pads is determined according to the experimental requirements. It should be noted that when the shaking table applies horizontal seismic action, shear occurs in any direction within the plane between adjacent model boxes, and the shear amount is defined as inter-layer shear displacement.

[0046] This invention involves installing rubber buffer pads at corresponding positions on the frame and the top-level model box. During normal operation, the interlayer limiting posts restrict the maximum interlayer shear displacement between adjacent single-layer model boxes, and the top-level model box does not contact the rubber buffer pads. Only when the cumulative interlayer shear displacement reaches the maximum shear displacement of the soil shear simulation test system does the top-level model box contact the rubber buffer pads. At this point, the rubber buffer pads absorb the local vibration impact generated during model box collisions and limit the further increase of the shear displacement of the soil shear simulation test system.

[0047] Example 4 Based on Examples 1-3, the inventors discovered that if a model box filled with traditional solid soil is used, the soil may experience a large change in stiffness when shearing in any direction in the plane, making it difficult to accurately simulate the stiffness of the soil. Furthermore, the existing method of filling soil in layered shear model boxes requires replacing the soil after each test, resulting in low efficiency and high cost.

[0048] Therefore, to address the challenge of accurately simulating soil stiffness caused by shearing in any direction within a plane, the inventors have solved this problem using their previously proposed experimental device for simulating soil stiffness. Specifically, the soil shearing simulation test system also includes a variable stiffness equivalent soil constraint device.

[0049] like Figure 7 As shown, the variable stiffness equivalent soil constraint device includes a top plate 14, an elastic constraint replacement assembly 15, and an elastic constraint member 16. The top plate 14 is connected to the test structure and transmits the force of the variable stiffness equivalent soil constraint device to the test structure. The elastic constraint member 16 is disposed inside the variable stiffness equivalent soil constraint device and provides elastic constraint force. Preferably, the elastic constraint member 16 includes at least one spring unit, and multiple spring units can be connected in parallel to form different equivalent stiffnesses. The elastic constraint replacement assembly 15 is connected to the elastic constraint member 16 to replace the elastic constraint member 16.

[0050] The stiffness of the elastic constraint 16 is determined before the test based on the required stiffness of the equivalent soil under the test conditions. By using the elastic constraint replacement component 15, elastic constraint 16 with different stiffnesses can be replaced according to test requirements. The variable stiffness equivalent soil constraint device is used to simulate the nonlinear boundary conditions of the soil surrounding the underground structure during shear deformation.

[0051] The variable stiffness equivalent soil restraint device also includes a guide sleeve 17, a partition plate 18, a guide screw 19, and a limiting nut 20. The guide sleeve 17 is disposed inside the variable stiffness equivalent soil restraint device. The guide screw 19 is inserted into the guide sleeve 17, and the guide screw 19 and the guide sleeve 17 are slidably engaged to guide the compression and elongation directions of the elastic restraint member 16.

[0052] A partition 18 is mounted on a guide screw 19. A limiting nut 20 is mounted on the guide screw 19. The limiting nut 20 abuts against the partition 18. The limiting nut 20 is used to limit the stroke of the partition 18, thereby controlling the working state of the elastic constraint member 16.

[0053] The guide screw 19 is equipped with a safety travel limit. The safety travel limit is used to restrict the withdrawal displacement. During adjustment, it maintains the effective guide length between the guide screw 19 and the guide sleeve 17. It should be noted that the setting of the safety travel limit reduces the risk of the guide screw 19 being pulled out of the guide sleeve 17 during loading.

[0054] The variable stiffness equivalent soil restraint device also includes a base plate 21 and a fixing screw 22. Further, a row of mounting holes is provided on the web of the steel section 6. The mounting holes are spaced apart along the length of the model box. The fixing screw 22 passes through the mounting holes on the web of the steel section 6. The fixing screw 22 is connected to the web of the steel section 6 using a nut. Through the connection of the fixing screw 22, the variable stiffness equivalent soil restraint device is fixedly connected to the single-layer model box.

[0055] To ensure that this device is suitable for use with layered shear model boxes, specifically, as follows: Figure 8 As shown, the web of the steel section 6 in the model box connection structure is provided with mounting holes. The variable stiffness equivalent soil constraint device is connected to the steel section 6 through the mounting holes via the fixing screw 22, which is used to simulate the constraint effect of soil on the test structure.

[0056] This invention utilizes a variable stiffness equivalent soil constraint device installed inside a single-layer model box to simulate the constraint effect of soil on the test structure. The device allows for the replacement of elastic constraint components with different stiffnesses according to experimental requirements. This structure solves the problem of difficulty in accurately controlling soil stiffness during in-plane shearing when conventional shear model boxes are filled with solid soil. It also eliminates the inefficiency and high cost associated with replacing the soil after the test. This invention achieves flexible equivalent simulation of soil stiffness for different types and depths, and the device is reusable, significantly reducing experimental costs.

[0057] The working process of the test system according to the preferred embodiment of the present invention will be described in detail below: During assembly, first fix the base plate 1 to the vibrating table surface. Secure the four corner columns of the frame 2 to the base plate 1 with bolts, and complete the connection of the central column and diagonal truss. Place the bottom layer model box 3 at the designated position on the base plate 1 and fix it to the base plate 1 with bolts. Then, stack the intermediate layer model boxes 4 on top of the bottom layer model box 3, so that the lower channel steel 12 of the intermediate layer model box 4 is upside down onto the upper channel steel 7 of the bottom layer model box 3. Install the liquid bladder and liquid bladder sleeve in the interlayer pressure-bearing cavity, while ensuring that the interlayer limiting column 13 in the interlayer limiting guide area is assembled into the corresponding limiting guide groove 9. Install the remaining intermediate layer model boxes 4 and the top layer model box 5 in the same manner. After each layer of model boxes is installed, connect the variable stiffness equivalent soil restraint device of that layer to the web of the steel section 6 using fixing screws 22. Finally, liquid is injected into the liquid bladders 10 of each layer through the injection port, causing the liquid bladders 10 to expand the liquid bladder sleeves 11 and lift up the adjacent layer model boxes, thereby forming an interlayer gap between the upper channel steel 7 and the lower channel steel 12.

[0058] During the test, after the shaking table was started, the model boxes of each layer underwent relative motion under horizontal forces. The liquid bladder 10 and liquid bladder sleeve 11 bear the interlayer vertical load in surface contact, allowing adjacent model boxes to undergo shear in any direction within the plane. The upper channel steel 7 and lower channel steel 12 do not contact each other. The interlayer limiting column 13 slides within the limiting guide groove 9. When the interlayer limiting column 13 reaches the edge of the limiting hole, it limits the maximum interlayer shear displacement. Simultaneously, the variable stiffness equivalent soil constraint device connected to the test structure provides nonlinear constraints matching the stiffness of the equivalent soil, simulating the boundary action of soil on the underground structure.

[0059] In summary, this embodiment achieves interlayer surface contact support and in-plane shearing in any direction through the pressure-bearing lifting assembly composed of liquid bladder 10 and liquid bladder sleeve 11; the maximum interlayer shear displacement is effectively controlled through the cooperation of limiting guide groove 9 and interlayer limiting column 13; and the nonlinear constraint of different soils is simulated through the variable stiffness equivalent soil constraint device with replaceable stiffness, and the device can be reused.

Claims

1. A soil shear simulation test system for earthquake engineering, characterized in that, The system includes a layered shear model box body and a model box connecting structure. The layered shear model box body comprises multiple single-layer model boxes stacked vertically. Adjacent single-layer model boxes are connected by the model box connecting structure to form an interlayer arrangement space. A pressure-bearing lifting component and a limiting and guiding component are provided in the interlayer arrangement space. The pressure-bearing lifting component is used to bear vertical loads and form interlayer gaps between adjacent single-layer model boxes. The limiting and guiding component is used to allow adjacent single-layer model boxes to shear relative to each other in any direction in the plane and to limit the maximum shear displacement between adjacent single-layer model boxes.

2. The soil shear simulation test system according to claim 1, characterized in that, The single-layer model box includes a steel section (6), an upper channel steel (7) fixedly connected to the upper flange of the steel section (6), a lower channel steel (12) fixedly connected to the lower flange of the steel section (6), and compartment stiffening ribs (8) in the upper channel steel (7) and the lower channel steel (12).

3. The soil shear simulation test system according to claim 2, characterized in that, In the adjacent single-layer model boxes, the lower channel steel (12) of the upper model box is upside down on the upper channel steel (7) of the lower model box to enclose and form the interlayer arrangement space.

4. The soil shear simulation test system according to claim 3, characterized in that, The upper channel steel (7) and the lower channel steel (12) are provided with compartment stiffening ribs (8). The compartment stiffening ribs (8) are arranged along the length and width of the channel steel, dividing the interlayer arrangement space into an interlayer pressure-bearing cavity and an interlayer limiting guide area.

5. The soil shear simulation test system according to claim 4, characterized in that, Interlayer pressure-bearing cavities and interlayer limiting and guiding zones are arranged alternately in the interlayer arrangement space; pressure-bearing lifting components are installed in the interlayer pressure-bearing cavities, and limiting and guiding components are installed in the interlayer limiting and guiding zones.

6. The soil shear simulation test system according to claim 5, characterized in that, The pressure-bearing lifting assembly includes a liquid bladder (10) and a liquid bladder sleeve (11), with the liquid bladder (10) disposed inside the liquid bladder sleeve (11).

7. The soil shear simulation test system according to claim 5, characterized in that, The limiting guide assembly includes a limiting guide groove (9) and an interlayer limiting post (13); the limiting guide groove (9) is set in the upper channel steel (7) of the adjacent lower model box, and the interlayer limiting post (13) is set in the lower channel steel (12) of the adjacent upper model box. The interlayer limiting post (13) is installed in the limiting guide groove (9) and can slide relative to the limiting guide groove (9).

8. The soil shear simulation test system according to claim 7, characterized in that, The limiting guide groove (9) is provided with a limiting hole, and the interlayer limiting post (13) is installed in the limiting hole. The interlayer limiting post can slide relative to each other in any direction in the plane within the limiting hole. When the interlayer limiting post (13) reaches the edge of the limiting hole, the interlayer limiting post (13) abuts against the edge of the limiting hole to limit the maximum interlayer shear displacement.

9. The soil shear simulation test system according to claim 1, characterized in that, It also includes a variable stiffness equivalent soil constraint device, which is installed on the steel web of the single-layer model box to simulate the nonlinear constraint effect of soil on the test structure.

10. The soil shear simulation test system according to any one of claims 1-9, characterized in that, It also includes a boundary fixing component, which includes a base plate (1) and a frame (2); the base plate (1) is used to fix it to the vibration table surface; the frame (2) includes corner posts located at the four corners of the outer periphery of the layered shear model box body, and the bottom end of the corner posts is fixed to the bottom layer model box (3) of the layered shear model box body on the base plate (1).

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