A model test device for accurately testing earth pressure on rigid retaining walls

Abstract

This invention belongs to the field of geotechnical engineering model testing technology, specifically relating to a model testing device for accurately testing earth pressure on a rigid retaining wall. The device includes a model box, a rigid retaining wall, earth pressure testing components, load sensors, a reaction wall, a soil storage chamber, and a retaining wall moving device. The rigid retaining wall is divided into 10 independent panels along its height. Each panel contains one earth pressure testing component, and two load sensors are installed behind each panel, significantly reducing the interference of the rigid retaining wall's own bending moment on the earth pressure measurement results. The reaction wall, a rigid structure, is located behind all panels and is synchronously connected to each panel via load sensors, ensuring synchronized displacement of the 10 independent panels during the test. This invention is applicable to the study and analysis of earth pressure under three displacement modes: translation, rotation around the base, and rotation around the top of the retaining wall. It has advantages such as high measurement accuracy, simple structure, and convenient manufacturing.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering model testing technology, specifically relating to a model testing device for accurately testing the earth pressure of a rigid retaining wall. Background Technology

[0002] Rigid retaining walls are widely used in civil engineering, and the accurate calculation of the soil pressure behind the wall is a key basis for the safe design of retaining walls.

[0003] The magnitude of earth pressure is closely related to the displacement of the retaining wall. When the retaining wall is stationary, the soil behind it is at rest, and the corresponding earth pressure is called the rest earth pressure. As the retaining wall displaces away from the fill, the earth pressure gradually decreases. If the soil reaches an active limit equilibrium state, it corresponds to the ultimate active earth pressure. However, in actual engineering, the displacement of the retaining wall often fails to reach the value required for the limit equilibrium state. In this case, the earth pressure behind the wall is between the rest earth pressure and the ultimate active earth pressure. Earth pressure under this condition is collectively referred to as non-ultimate active earth pressure.

[0004] Currently, classical theoretical calculation methods exist for at-rest earth pressure, ultimate active earth pressure, and passive earth pressure. However, despite extensive research, a widely accepted unified theory has yet to be established for earth pressure under non-ultimate states. Against this backdrop, indoor model tests have become an indispensable means of constructing and verifying theories of non-ultimate earth pressure. However, because non-ultimate earth pressure is highly sensitive to retaining wall displacement and the height of earth pressure testing components, achieving high-precision earth pressure measurement has become a core technical challenge that urgently needs to be addressed in conducting relevant model tests.

[0005] Traditional rigid retaining wall model tests typically employ earth pressure measuring elements arranged along the wall's height. However, due to the wall's significant height and stiffness along this direction, its own bending moment inevitably interferes with earth pressure measurements at different heights, thus affecting the distribution of earth pressure along the wall's height. Currently, there is no effective technique to completely eliminate the influence of the rigid retaining wall's own bending moment on earth pressure measurements, nor is there a reliable method to accurately assess this interference. Therefore, there is an urgent need in this field to develop a model testing device and method applicable to three displacement modes: translation, rotation around the base, and rotation around the top, capable of accurately testing the non-limit active earth pressure of rigid retaining walls. Summary of the Invention

[0006] To address the technical problems of traditional rigid retaining wall model tests, this invention provides a model test device for accurately testing earth pressure on rigid retaining walls.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A model test device for accurately testing earth pressure on a rigid retaining wall includes a model box, a rigid retaining wall, earth pressure testing components, load sensors, a reaction wall, a soil storage chamber, and a retaining wall moving device. The rigid retaining wall is divided into several independent panels along its height, with a gap between adjacent panels. Each panel contains one earth pressure testing component, and at least two load sensors are located behind each panel. The reaction wall is a rigid structure located behind all load sensors and synchronously connected to each load sensor. The soil storage chamber is located at the bottom of the space between the reaction wall and the rigid retaining wall. The retaining wall moving device is located behind the reaction wall and is used to control the displacement mode, displacement velocity, and displacement amount of the rigid retaining wall away from the soil. The model box is used for filling with soil and is adapted for the installation and testing of the rigid retaining wall.

[0009] The rigid retaining wall has a total height of 1m and is divided into 10 independent panels along its height. Each panel is 9cm high and there is a 1cm gap between adjacent panels.

[0010] Each panel has a pre-drilled circular hole inside. The circular hole is the same size and elevation as the earth pressure testing element, and the centroid of the circular hole coincides with the center of the panel. The earth pressure testing element is arranged in the circular hole, and the surface of the earth pressure testing element protrudes 1 mm from the surface of the panel.

[0011] There are a total of 20 load sensors, which are arranged in groups of 2 behind each panel, with the two load sensors in the same group arranged symmetrically along the vertical center line of the panel.

[0012] The retaining wall moving device includes two gear transmissions evenly arranged along the height direction. By coordinating the connection or disconnection of the gear transmissions with the reaction wall, three displacement modes of the rigid retaining wall are realized: translation, rotation around the bottom, and rotation around the top.

[0013] The model box consists of a steel frame, a transparent acrylic base plate, and three sides. The internal clear height of the model box is 1.2m, with a 10cm high foundation soil filling area reserved at the bottom for foundation soil filling, and a 10cm high operating space reserved at the top. The internal clear length of the model box perpendicular to the back of the rigid retaining wall is 1.2m, and the internal clear length parallel to the back of the rigid retaining wall is 0.5m. The area inside the model box located behind the rigid retaining wall is the backfill area for the retaining wall.

[0014] A method for conducting non-ultimate active earth pressure tests on rigid retaining walls using a model testing device for accurately measuring earth pressure on rigid retaining walls, characterized by comprising the following steps:

[0015] S1. Adjust the connection status of the retaining wall moving device according to the displacement mode of the rigid retaining wall to be studied.

[0016] S2. Fill the foundation soil evenly in the 10cm height reserved at the bottom of the model box, and compact the filled soil to form a foundation soil layer.

[0017] S3. In the backfill area behind the retaining wall in the model box, the soil is filled in multiple layers to ensure that each layer of soil is filled evenly; after the filling is completed, the soil pressure data collected by all soil pressure testing components is read and compared with the solution of classical static earth pressure theory.

[0018] S4. According to the displacement mode set in step S1, start the retaining wall moving device. The retaining wall moving device includes two gear transmission devices evenly arranged along the height direction. When the preset displacement is reached, the data collected by all soil pressure testing components and load sensors are read simultaneously.

[0019] S5. When the readings of all earth pressure testing components and load sensors are basically stable, it is determined that the fill in the model box has reached the limit equilibrium state; the test data obtained at this time are sorted out and compared with the Coulomb active earth pressure theoretical solution.

[0020] In step S1, the adjustment method of the retaining wall moving device corresponding to different displacement modes is as follows:

[0021] Translation mode test: There is no connection between the reaction wall and the model box, but both gear drives are connected to the reaction wall;

[0022] Bottom-rotation mode test: The reaction wall is connected to the model box at the bottom by a detachable hinge, the connection between the gear drive located at the bottom and the reaction wall is disconnected, and only the connection between the gear drive located at the top and the reaction wall is maintained;

[0023] Top-rotation mode test: The reaction wall is connected to the model box at the top by a detachable hinge, the connection between the upper gear drive and the reaction wall is disconnected, and only the connection between the lower gear drive and the reaction wall is maintained.

[0024] In step S2, the thickness of the foundation soil layer is 10cm; in step S3, the number of soil layers in the backfill area behind the retaining wall is 10.

[0025] Compared with the prior art, the beneficial effects of this invention are:

[0026] This invention divides a rigid retaining wall into several independent panels along its height and utilizes reaction walls to achieve synchronous displacement of each panel. This ensures accurate implementation of the displacement modes while effectively eliminating the interference of the rigid retaining wall's own bending moment on the earth pressure measurement results. The device of this invention requires only simple adjustments to achieve three typical displacement modes of the retaining wall: translation, rotation around the base, and rotation around the top, which is beneficial for systematically evaluating the impact of displacement modes on non-ultimate earth pressure. The device of this invention ensures the accuracy of earth pressure measurement results even under eccentric loading by deploying one earth pressure testing element on each panel and supplementing it with two load sensors arranged symmetrically at the same elevation for verification. Furthermore, the mutual verification of earth pressure measurement results by the load sensors enhances the reliability of the test results. The test method of this invention, through dual verification using classical at-rest earth pressure and Coulomb's active earth pressure theory, significantly improves the credibility and theoretical reference value of the test results. Attached Figure Description

[0027] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0028] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0029] Figure 1 This is a schematic diagram of the translation mode test of the present invention;

[0030] Figure 2 This is a schematic diagram of the panel and earth pressure testing components layout of the present invention;

[0031] Figure 3 This is a schematic diagram showing the layout of the reaction wall, load sensor, and soil storage chamber of the present invention.

[0032] Figure 4 A schematic diagram of the bottom-rotation mode test for the invention;

[0033] Figure 5 This is a schematic diagram of the hinge connection during the bottom rotation mode test of the present invention.

[0034] Figure 6This is a schematic diagram of the top-rotation mode test of the present invention.

[0035] Figure 7 This is a schematic diagram of the hinge connection during the top-rotation mode test of the present invention.

[0036] Figure 8 This is a comparison chart of the numerical model calculation results of this invention and the solution of the classical at-rest earth pressure theory;

[0037] Figure 9 This is a comparison chart of the numerical model calculation results of this invention and the solution of classical active earth pressure theory.

[0038] Among them: 1 is the earth pressure testing component; 2 is the load sensor; 3 is the reaction wall; 4 is the panel; 5 is the gear transmission device; 6 is the soil storage chamber; 7 is the foundation soil filling area; 8 is the backfill area behind the retaining wall; 9 is the operating space; 10 is the detachable hinge. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. These descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the claims of the present invention. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0041] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0042] Please see Figure 1This invention provides a model test device for accurately testing earth pressure on a rigid retaining wall. The model test device includes a model box, a rigid retaining wall, earth pressure testing components 1, a load sensor 2, a reaction wall 3, a soil storage chamber 6, and a retaining wall moving device. The rigid retaining wall has a total height of 1 m and is divided into 10 independent panels 4 along its height. Each panel 4 has a height of 9 cm, with a gap of approximately 1 cm between adjacent panels. Each panel 4 has a circular hole of the same size and elevation as the earth pressure testing components, with its centroid coinciding with the center of the panel. The retaining wall moving device is located behind the reaction wall and moves the retaining wall through two gear transmissions 5 evenly arranged along its height. The internal net height of the model box is 1.2 m. A 10 cm gap is reserved at the bottom for the foundation soil filling area 7, a 10 cm gap is reserved at the top for the operating space 9, and the remaining area is the backfill area 8 behind the retaining wall.

[0043] Please see Figure 2 There are a total of 10 earth pressure testing elements 1, which are arranged in the reserved round holes of the panel. The surface of the earth pressure testing elements protrudes about 1 mm from the surface of the panel.

[0044] Please see Figure 3 There are a total of 20 load sensors 2, which are set in groups of 2 behind each panel and symmetrically arranged along the vertical center line of the panel; the reaction wall 3 is a rigid structure, located behind all load sensors, and synchronously connected with each load sensor 2; the soil storage chamber 6 is set at the bottom of the space between the reaction wall and the rigid retaining wall.

[0045] Please see Figure 1 During the translation mode test, there is no connection between the reaction wall 3 and the model box, but the two gear transmission devices 5 are connected to the reaction wall 3.

[0046] Please see Figure 4 , Figure 5 During the bottom rotation mode test, the reaction wall 3 and the model box are connected at the bottom by two pre-reserved detachable hinges 10, while maintaining the connection between the upper gear transmission 5 and the reaction wall 3.

[0047] Please see Figure 6 , Figure 7 During the top rotation mode test, the reaction wall 3 and the model box are connected at the top by two pre-reserved detachable hinges 10, while maintaining the connection between the lower gear transmission 5 and the reaction wall 3.

[0048] This embodiment also provides a method for conducting non-ultimate active earth pressure tests on rigid retaining walls using the aforementioned model test apparatus for accurately testing earth pressure on rigid retaining walls, comprising the following steps:

[0049] Step 1: Adjust the retaining wall moving device according to the aforementioned implementation method based on the proposed retaining wall displacement mode.

[0050] Step 2: Evenly fill and compact the soil in the foundation soil filling area 7 of the model box to form a foundation soil layer with a thickness of 10 cm;

[0051] Step 3: In the backfilling area 8 behind the retaining wall of the model box, fill the soil in 10 layers, ensuring uniformity. After the filling is completed, read the earth pressure data and compare it with the solution of the classical static earth pressure theory to ensure that the two are basically consistent.

[0052] Step 4: Start the gear drive and simultaneously read the data from all soil pressure testing components and load sensors each time the preset displacement is reached.

[0053] Step 5: When the readings of the earth pressure testing components and load sensors are basically stable, it is determined that the backfill has reached the limit equilibrium state. The obtained data is sorted out and compared with the Coulomb active earth pressure theoretical solution to ensure that the two are basically consistent.

[0054] Based on the model test device for accurately testing earth pressure on rigid retaining walls proposed in this embodiment, numerical models of the rigid retaining wall consisting of 10 independent panels and a rigid retaining wall consisting of only one integral panel were established. Under identical conditions, the distributions of at-rest earth pressure and active earth pressure along the wall height of the two numerical models were obtained, and compared with the theoretical solutions of classical at-rest earth pressure and active earth pressure, respectively. Figure 8 , Figure 9 As shown. The results indicate that the method proposed in this embodiment, which divides the rigid retaining wall into 10 independent panels, is closer to the solutions of classical at-rest earth pressure and active earth pressure theories.

[0055] Therefore, the method proposed in this embodiment, which divides the rigid retaining wall into 10 independent panels along its height, can effectively eliminate the interference of the bending moment of the rigid retaining wall itself on the earth pressure measurement results.

[0056] The above description only illustrates the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention, and all such changes should be included within the protection scope of the present invention.

Claims

1. A model test device for accurately testing earth pressure on a rigid retaining wall, characterized in that: The system includes a model box, a rigid retaining wall, earth pressure testing components (1), load sensors (2), a reaction wall (3), a soil storage chamber (6), and a retaining wall moving device. The rigid retaining wall is divided into several independent panels (4) along its height, with a gap between adjacent panels (4). Each panel (4) contains one earth pressure testing component (1), and at least two load sensors (2) are installed behind each panel (4). The reaction wall (3) is a rigid structure located behind all load sensors (2) and is synchronously connected to each load sensor (2). The soil storage chamber (6) is located at the bottom of the space between the reaction wall (3) and the rigid retaining wall. The retaining wall moving device is located behind the reaction wall (3) and is used to control the displacement mode, displacement speed, and displacement amount of the rigid retaining wall away from the soil. The model box is used for filling soil and is adapted for the installation and testing of the rigid retaining wall. The adjustment methods for the retaining wall moving device corresponding to different displacement modes are as follows: Translation mode test: Make the reaction wall (3) unconnected to the model box, and keep both gear transmission devices (5) connected to the reaction wall (3); Rotation around the bottom test: The reaction wall (3) is connected to the model box at the bottom by a detachable hinge (10), the connection between the gear drive (5) located at the bottom and the reaction wall (3) is released, and only the connection between the gear drive (5) located at the top and the reaction wall (3) is maintained; Top rotation mode test: The reaction wall (3) is connected to the model box at the top by a detachable hinge (10), the connection between the upper gear drive (5) and the reaction wall (3) is released, and only the connection between the lower gear drive (5) and the reaction wall (3) is maintained.

2. The model test device for accurately testing earth pressure on a rigid retaining wall according to claim 1, characterized in that: The rigid retaining wall has a total height of 1m and is divided into 10 independent panels (4) along the height direction. Each panel (4) is 9cm high and the gap between two adjacent panels (4) is 1cm high.

3. The model test device for accurately testing earth pressure on a rigid retaining wall according to claim 1, characterized in that: Each panel (4) has a pre-drilled circular hole inside. The circular hole is the same size and elevation as the earth pressure testing element (1), and the centroid of the circular hole coincides with the center of the panel (4). The earth pressure testing element (1) is arranged in the circular hole, and the surface of the earth pressure testing element (1) protrudes 1 mm from the surface of the panel (4).

4. The model test device for accurately testing earth pressure on a rigid retaining wall according to claim 1, characterized in that: There are a total of 20 load sensors (2), which are arranged in groups of 2 behind each panel (4), and the two load sensors (2) in the same group are arranged symmetrically along the vertical center line of the panel (4).

5. The model test device for accurately testing earth pressure on a rigid retaining wall according to claim 1, characterized in that: The retaining wall moving device includes two gear transmissions (5) evenly arranged along the height direction. By coordinating the connection or disconnection between the gear transmissions (5) and the reaction wall (3), the rigid retaining wall can achieve three displacement modes: translation, rotation around the bottom, and rotation around the top.

6. The model test device for accurately testing earth pressure on a rigid retaining wall according to claim 1, characterized in that: The model box consists of a steel frame, a transparent acrylic base plate, and three sides; the internal net height of the model box is 1.2m, with a 10cm high foundation soil filling area (7) reserved at the bottom for filling the foundation soil, and a 10cm high operating space (9) reserved at the top; the internal net length of the model box perpendicular to the back of the rigid retaining wall is 1.2m, and the internal net length parallel to the back of the rigid retaining wall is 0.5m; the area inside the model box located behind the rigid retaining wall is the backfill area (8).

7. A method for conducting non-ultimate active earth pressure tests on rigid retaining walls using the apparatus described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Adjust the connection status of the retaining wall moving device according to the displacement mode of the rigid retaining wall to be studied. S2. Soil is uniformly filled in the 10cm height foundation soil filling area (7) reserved at the bottom of the model box, and the filled soil is compacted to form a foundation soil layer. S3. In the backfilling area (8) behind the retaining wall in the model box, the soil is filled in multiple layers to ensure that each layer of soil is filled evenly. After the filling is completed, the soil pressure data collected by all soil pressure testing components (1) is read and compared with the solution of classical static earth pressure theory. S4. According to the displacement mode set in step S1, start the retaining wall moving device. The retaining wall moving device includes two gear transmission devices (5) evenly arranged along the height direction. When the preset displacement is reached, the data collected by all soil pressure test components (1) and load sensors (2) are read simultaneously. S5. When the readings of all earth pressure testing components (1) and load sensors (2) are basically stable, it is determined that the soil in the model box has reached the limit equilibrium state; the test data obtained at this time are sorted out and compared with the Coulomb active earth pressure theoretical solution.

8. The method for conducting non-ultimate active earth pressure tests on rigid retaining walls according to claim 7, characterized in that, In step S2, the thickness of the foundation soil layer is 10cm; in step S3, the number of soil layers in the backfill area (8) behind the retaining wall is 10.

Images