Adjustable wave impedance boundary model box for small vibration table

Abstract

The utility model relates to the field of geotechnical engineering dynamic model test simulation technology, concretely relates to a kind of adjustable wave impedance boundary model box for small shaking table, mounting hole is provided on bottom plate, bottom plate is connected to shaking table surface by mounting hole and fastening device cooperation, outer fixed frame is set in the four around of bottom plate, the inside boundary plate is set in the one side of outer fixed frame towards model soil, the rough interface layer is set on the upper surface of bottom plate, the wave impedance adjusting module is set between outer fixed frame and inside boundary plate, for adjusting the dynamic response of inside boundary plate in horizontal vibration or shear vibration process.The utility model sets up wave impedance adjusting module between outer fixed frame and inside boundary plate, makes that model box lateral boundary changes from traditional fixed rigid boundary or fixed flexible boundary into the boundary structure with adjustable dynamic response, to reduce the interference of sidewall boundary to model soil dynamic response.

Description

Technical Field

[0001] This utility model relates to the fields of dynamic model testing in geotechnical engineering, small shaking table testing, and model box boundary simulation technology, and in particular to an adjustable wave impedance boundary model box for a small shaking table. Background Technology

[0002] Small-scale shaking table tests are an important laboratory testing method for studying the dynamic response of foundation soil, slopes, retaining structures, underground structures, and foundation engineering under seismic loading. Due to the limited size of the shaking table, the model soil usually needs to be placed inside a model box for testing. The sidewalls and bottom boundary conditions of the model box directly affect the propagation, reflection, and superposition of seismic waves in the model soil, thereby affecting the test results such as acceleration amplification factor, pore pressure development, displacement response, and failure mode.

[0003] Traditional rigid model boxes offer advantages such as simple fabrication, high overall strength, and convenient installation. However, their rigid sidewalls generate strong wave reflections, causing the model soil to be constrained in a way that differs from actual semi-infinite ground conditions. To reduce boundary reflections, existing experiments often employ flexible boundary model boxes, layered shear boxes, or cushioning materials such as sponge or rubber on the sidewalls. However, the stiffness and damping of these flexible boundaries are often essentially fixed after fabrication, making it difficult to adjust them according to different soil types, input wave frequencies, model sizes, and experimental objectives.

[0004] In geotechnical dynamics, the degree of wave reflection at the interface between media is related to the difference in wave impedance between the two media. For small shaking table model boxes, if the equivalent dynamic stiffness, damping, and inertial characteristics of the sidewall boundaries cannot be adapted to the dynamic characteristics of the model soil, significant boundary effects will occur. Existing model boxes are usually improved only in terms of rigidity or flexibility, lacking wave impedance adjustment structures that can be partitioned, layered, and repeatedly set. Utility Model Content

[0005] The purpose of this invention is to provide an adjustable wave impedance boundary model box for a small shaking table. By setting a wave impedance adjustment module between the outer fixed frame and the inner boundary plate, the lateral boundary of the model box is transformed from a traditional fixed rigid boundary or a fixed flexible boundary into a boundary structure with adjustable dynamic response, thereby reducing the interference of the side wall boundary on the dynamic response of the model soil.

[0006] To address the problems of existing technologies, this utility model provides an adjustable wave impedance boundary model box for a small shaking table, comprising a base plate, an outer fixing frame, an inner boundary plate, a rough interface layer, a flexible sealing component, a corner flexible connection assembly, a wave impedance adjustment module, and a guide limiting assembly. The base plate has mounting holes, which are used to connect to the shaking table surface via fastening devices. The outer fixing frame is arranged around the base plate, and the inner boundary plate is located on the side of the outer fixing frame facing the model soil. The rough interface layer is located on the upper surface of the base plate. The wave impedance adjustment module is located between the outer fixing frame and the inner boundary plate, used to adjust the dynamic response of the inner boundary plate during horizontal vibration or shear wave action. The guide limiting assembly is located between the outer fixing frame and the inner boundary plate, used to guide and limit the displacement of the inner boundary plate. The flexible sealing component is located between adjacent inner boundary plates, and the corner flexible connection assembly is located at the corner of the model box.

[0007] Preferably, the wave impedance adjustment module includes a damping element, an elastic element, and a replaceable inertial element. The damping element is used to dissipate the motion energy of the inner boundary plate, the elastic element is used to provide a restoring force for the inner boundary plate, and the replaceable inertial element is used to change the equivalent mass of the inner boundary plate or the wave impedance adjustment module.

[0008] Preferably, the damping element is one of a damping rubber block, a friction damping sheet, a viscous damper, or a particle damping box.

[0009] Preferably, the elastic element is one of a compression spring, a leaf spring, a rubber elastic block, or a polyurethane elastic block.

[0010] Preferably, the replaceable inertial component is a counterweight, a counterweight plate, or an insert-type mass block, and is detachably disposed on the back side of the inner boundary plate or in the wave impedance adjustment module.

[0011] Preferably, the guide limiting assembly includes a guide rod, a guide groove, and a limiting block. The guide rod is used to guide the inner boundary plate to move in a predetermined direction, the guide groove is used to constrain the movement path of the inner boundary plate, and the limiting block is used to limit the maximum displacement of the inner boundary plate.

[0012] Preferably, the flexible sealing element is a rubber membrane, geotextile, flexible sheet, or elastic sealing strip, used to prevent model soil from leaking out from the gap between adjacent inner boundary plates and to allow relative displacement between adjacent inner boundary plates.

[0013] Preferably, the corner flexible connection component is a flexible corner mold, a corner elastic strip, or a bendable connection plate, used to reduce the impact of sudden changes in the stiffness of the model box corners on the dynamic response of the model soil.

[0014] Preferably, the rough interface layer is a sandpaper layer, a sand-adhesive layer, a toothed plate, or a replaceable bottom friction plate, used to provide interface friction conditions between the soil and the bottom plate of the simulation model.

[0015] Preferably, the wave impedance adjustment module is set at different heights and horizontal positions of the model box. The damping element, elastic element and replaceable inertial component at each position are all detachable and replaceable structures. The damping coefficient, elastic stiffness and added mass value are set to be compatible with the soil layer of the model, the test similarity ratio and the main frequency of the input seismic wave.

[0016] The advantages of this utility model compared to the prior art are:

[0017] 1. This utility model changes the equivalent stiffness, damping, and inertia of the lateral boundary by combining damping elements, elastic elements, and replaceable inertial elements, so that the boundary of the model box can adapt to different soils and different input wave conditions, thereby reducing the wave reflection effect of traditional rigid model boxes.

[0018] 2. The wave impedance adjustment module of this utility model can be arranged at different heights and horizontal positions of the model box, which makes it convenient to set the boundary dynamic response for layered foundations, different lateral positions or different test conditions, and improve the adaptability of shaking table model tests.

[0019] 3. By setting flexible sealing components and corner flexible connection components, this utility model can take into account both preventing soil leakage and making the boundary flexible deformation, thereby reducing the interference of sudden changes in stiffness of the plate joints and corners on the dynamic response of the model soil.

[0020] 4. The guide and limiting component of this utility model can constrain the movement path of the inner boundary plate and limit its maximum displacement, which is beneficial to improving the structural reliability of the model box under strong earthquake input or local impact.

[0021] 5. The damping element, elastic element and replaceable inertial element in the wave impedance adjustment module of this utility model can be selected and replaced according to the test requirements, which facilitates the reproduction of test parameters and the reuse of the model box. Attached Figure Description

[0022] Figure 1 This is a three-dimensional structural schematic diagram of an adjustable wave impedance boundary model box for a small vibration table according to this utility model.

[0023] Figure 2 This is a schematic diagram of the three-dimensional structure of the base plate of a small adjustable wave impedance boundary model box for a vibration table according to this utility model.

[0024] Figure 3 This is a schematic diagram of the box structure of a small adjustable wave impedance boundary model box for a vibration table according to this utility model.

[0025] Figure 4This is a schematic diagram of the wave impedance adjustment module of a small vibration table adjustable wave impedance boundary model box according to the present invention.

[0026] The following are the labels in the diagram: 1. Base plate; 2. Mounting hole; 3. Outer fixing frame; 4. Inner boundary plate; 5. Rough interface layer; 6. Flexible sealing component; 7. Corner flexible connection component; 8. Wave impedance adjustment module; 9. Guide limit component; 10. Damping element; 11. Elastic element; 12. Replaceable inertial component. Detailed Implementation

[0027] To further understand the features, technical means, and specific objectives and functions achieved by this utility model, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and specific embodiments.

[0028] Reference Figures 1 to 4 As shown, this utility model provides an adjustable wave impedance boundary model box for a small shaking table, including a base plate 1, an outer fixing frame 3, an inner boundary plate 4, a rough interface layer 5, a flexible sealing component 6, a corner flexible connection component 7, a wave impedance adjustment module 8, and a guide and limiting component 9. The base plate 1 is used to support the model soil and serves as the installation foundation between the model box and the shaking table surface. The base plate 1 is provided with mounting holes 2. The base plate 1 is connected to the shaking table surface by cooperating with fastening devices through the mounting holes 2. Specifically, the fastening devices include, but are not limited to, bolts and positioning pins. The mounting holes 2 are used to cooperate with bolts, positioning pins, or other connecting parts on the shaking table surface, so that the model box maintains a stable connection during vibration.

[0029] The outer fixing frame 3 is set around the base plate 1 to provide the overall load-bearing frame for the model box. The inner boundary plate 4 is set on the side of the outer fixing frame 3 facing the model soil and is in direct or indirect contact with the model soil to form the lateral boundary required for the test. The rough interface layer 5 is set on the upper surface of the base plate 1, which can be composed of a sandpaper layer, a sand-adhesive layer, a toothed plate, or a replaceable bottom friction plate to simulate the friction conditions between the soil and the substrate.

[0030] A flexible sealing element 6 is installed between adjacent inner boundary plates 4. The flexible sealing element 6 can be made of rubber membrane, geotextile, flexible sheet, or elastic sealing strip. The flexible sealing element 6 serves two purposes: firstly, to prevent model soil from leaking out through the gap between adjacent inner boundary plates 4; and secondly, to allow small relative displacement of adjacent inner boundary plates 4 under stress, thereby ensuring that the boundary remains continuously sealed while being adjustable.

[0031] The corner flexible connection components 7 are installed at the four corners of the model box. The corner flexible connection components 7 can be flexible corner molds, corner elastic strips, or bendable connection plates. Since the four corners of traditional rectangular model boxes usually have high stiffness, they are prone to forming obvious local boundary constraints. In this embodiment, the corner flexible connection components 7 reduce the abrupt change in corner stiffness, so that the model soil can also obtain smoother boundary conditions at the corners.

[0032] The wave impedance adjustment module 8 is disposed between the outer fixed frame 3 and the inner boundary plate 4, and is used to adjust the dynamic response of the inner boundary plate 4 during horizontal vibration or shear wave action. The wave impedance adjustment module 8 includes a damping element 10, an elastic element 11, and a replaceable inertial element 12. The damping element 10 can be a damping rubber block, a friction damping plate, a viscous damper, or a particle damping box; the elastic element 11 can be a compression spring, a leaf spring, a rubber elastic block, or a polyurethane elastic block; and the replaceable inertial element 12 can be a counterweight, a counterweight plate, or an insert-type mass block. In one embodiment, the elastic element 11 and the damping element 10 are arranged in parallel along the normal direction of the inner boundary plate 4 between the outer fixed frame 3 and the inner boundary plate 4. The two ends of the elastic element 11 abut against the back side of the outer fixed frame 3 and the inner boundary plate 4, respectively, to provide a restoring force along the normal direction. The damping element 10 is sandwiched between the outer fixed frame 3 and the inner boundary plate 4 to dissipate the vibration energy of the inner boundary plate 4 during reciprocating motion. The replaceable inertial element 12 is detachably installed on the back side of the inner boundary plate 4 by bolts to increase the equivalent mass of the inner boundary plate 4. By different combinations, quantities, and arrangements, the equivalent stiffness, damping, and inertia of the boundary can be changed.

[0033] The guide and limit assembly 9 is disposed between the outer fixed frame 3 and the inner boundary plate 4. The guide and limit assembly 9 may include a guide rod, a guide groove, and a limit block. The guide rod is used to guide the inner boundary plate 4 to move in a predetermined direction, the guide groove is used to constrain its movement path, and the limit block is used to limit the maximum displacement of the inner boundary plate 4 to avoid excessive deformation of the wave impedance adjustment module 8 caused by strong earthquake input or local soil impact.

[0034] In one specific implementation, the wave impedance adjustment module 8 can be set at different heights and positions within the model box to allow for independent adjustment of the soil boundary conditions at different layers. For a layered foundation model, the upper boundary can be set to lower stiffness and higher damping, while the lower boundary can be set to higher stiffness and lower damping. For experiments requiring simulation of free boundary characteristics, wave reflection can be reduced by decreasing stiffness and increasing energy dissipation capacity.

[0035] To facilitate the reproduction of test parameters, the specifications of each damping element 10, elastic element 11, and replaceable inertial element 12 in the wave impedance adjustment module 8 can be recorded before the test, and the same boundary conditions can be restored according to the records during multiple tests. During the test, the corresponding damping element 10, elastic element 11, and replaceable inertial element 12 are selected according to the model soil type, test similarity ratio, and input seismic wave dominant frequency. Specifically, the wave impedance of the model soil is first determined by the density and shear wave velocity of the model soil. Then, with the goal of matching the equivalent dynamic characteristics of the boundary with the wave impedance of the model soil, the elastic stiffness of the elastic element 11, the damping coefficient of the damping element 10, and the additional mass value of the replaceable inertial element 12 are determined according to the natural frequency and damping ratio relationship of the single degree of freedom system formed by the inner boundary plate 4 and the wave impedance adjustment module 8. Then, the parameters of each boundary position are adjusted through the wave impedance adjustment module 8. Subsequently, the model soil is filled in layers and the sensors are deployed. Finally, the model box is fixed on the shaking table surface, and the predetermined dynamic load is input.

[0036] In this embodiment, sensor mounting bases can also be provided on the inner boundary plate 4 or the outer fixed frame 3 to install accelerometers, displacement gauges, or earth pressure sensors for direct measurement of the boundary plate response. By measuring the boundary plate acceleration, displacement, and earth pressure, the influence of the model box boundary on the dynamic response of the model soil under different wave impedance settings can be further evaluated.

[0037] The above embodiments only illustrate one or more implementations of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this utility model. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model.

Claims

1. An adjustable wave impedance boundary model box for a small shaking table, characterized in that: The system includes a base plate (1), an outer fixing frame (3), an inner boundary plate (4), a rough interface layer (5), a flexible sealing component (6), a corner flexible connection component (7), a wave impedance adjustment module (8), and a guide limiting component (9). The base plate (1) is provided with mounting holes (2), and the base plate (1) is connected to the vibration table surface by cooperating with a fastening device through the mounting holes (2). The outer fixing frame (3) is arranged around the base plate (1), and the inner boundary plate (4) is arranged on the side of the outer fixing frame (3) facing the model soil. The rough interface layer... (5) Set on the upper surface of the base plate (1), the wave impedance adjustment module (8) is set between the outer fixed frame (3) and the inner boundary plate (4) to adjust the dynamic response of the inner boundary plate (4) during horizontal vibration or shear wave action, the guide limiting component (9) is set between the outer fixed frame (3) and the inner boundary plate (4) to guide and limit the displacement of the inner boundary plate (4), the flexible sealing component (6) is set between adjacent inner boundary plates (4), and the corner flexible connection component (7) is set at the corner of the model box.

2. The adjustable wave impedance boundary model box for a small vibration table according to claim 1, characterized in that: The wave impedance adjustment module (8) includes a damping element (10), an elastic element (11), and a replaceable inertial element (12). The damping element (10) is used to dissipate the motion energy of the inner boundary plate (4), the elastic element (11) is used to provide restoring force for the inner boundary plate (4), and the replaceable inertial element (12) is used to change the equivalent mass of the inner boundary plate (4) or the wave impedance adjustment module (8).

3. The adjustable wave impedance boundary model box for a small vibration table according to claim 2, characterized in that: The damping element (10) is one of the following: damping rubber block, friction damping sheet, viscous damper or particle damping box.

4. The adjustable wave impedance boundary model box for a small vibration table according to claim 2, characterized in that: The elastic element (11) is one of a compression spring, a leaf spring, a rubber elastic block, or a polyurethane elastic block.

5. The adjustable wave impedance boundary model box for a small vibration table according to claim 2, characterized in that: The replaceable inertial component (12) is a counterweight, counterweight plate or insert-type mass block, and is detachably installed on the back side of the inner boundary plate (4) or in the wave impedance adjustment module (8).

6. The adjustable wave impedance boundary model box for a small vibration table according to claim 1, characterized in that: The guide limiting assembly (9) includes a guide rod, a guide groove and a limiting block. The guide rod is used to guide the inner boundary plate (4) to move in a predetermined direction. The guide groove is used to constrain the movement path of the inner boundary plate (4). The limiting block is used to limit the maximum displacement of the inner boundary plate (4).

7. The adjustable wave impedance boundary model box for a small vibration table according to claim 1, characterized in that: The flexible sealing element (6) is a rubber membrane, geotextile, flexible sheet or elastic sealing strip, used to prevent the model soil from leaking out from the gap between adjacent inner boundary plates (4) and to allow relative displacement between adjacent inner boundary plates (4).

8. The adjustable wave impedance boundary model box for a small vibration table according to claim 1, characterized in that: The corner flexible connection component (7) is a flexible corner mold, a corner elastic strip, or a bendable connection plate, used to reduce the impact of sudden changes in the stiffness of the corner of the model box on the dynamic response of the model soil.

9. The adjustable wave impedance boundary model box for a small vibration table according to claim 1, characterized in that: The rough interface layer (5) is a sandpaper layer, a sand-adhesive layer, a toothed plate, or a replaceable bottom friction plate, used to provide interface friction conditions between the soil of the simulation model and the bottom plate (1).

10. A small adjustable wave impedance boundary model box for a shaking table according to any one of claims 2 to 9, characterized in that: The wave impedance adjustment module (8) is set at different heights and different horizontal positions of the model box. The damping element (10), elastic element (11) and replaceable inertial element (12) at each position are all detachable and replaceable structures. Their damping coefficient, elastic stiffness and additional mass value are configured according to the soil layer of the model, the test similarity ratio and the main frequency of the input seismic wave.

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