Simulation Device and Usage Method for Wrapped Non-Load-Bearing Reinforced Earth Abutment Model Test

Abstract

The present invention relates to a simulation device for geotechnical engineering model tests, specifically a simulation device for lateral earth pressure, foundation, and horizontal restraint of the wall toe in model tests of geotechnical structures. It includes a foundation simulation component at the bottom of the model, a lateral earth pressure simulation component, a horizontal restraint simulation component for the wall toe, and a data acquisition component. The foundation simulation component is used to simulate the compressibility and vertical compression deformation of the foundation; the lateral earth pressure simulation component is used to simulate the horizontal earth pressure distribution behind the reinforced soil abutment; the horizontal restraint simulation component for the wall toe is used to simulate the horizontal restraint at the bottom of the abutment wall panel; and the data acquisition component is used to collect test data. The present invention has the characteristics of convenient operation, simple structure, and precise control.

Description

Technical Field

[0001] The present invention relates to a geotechnical engineering model test device, and in particular to a simulation device and a use method for a wrapped non-load-bearing reinforced soil abutment model test. Background Art

[0002] Since the French engineer Vidal officially proposed the theory of reinforced soil, the technology of reinforced soil has been widely applied in the construction of highway and railway projects, not only for strengthening the subgrade, but also for abutments. The world's first reinforced soil abutment was built in France in 1969; the first reinforced soil abutment in the United States was built in Nevada in 1974; currently, the application of reinforced soil abutments is very common internationally. In terms of technical principles, reinforced soil abutments can be divided into two types: load-bearing and non-load-bearing. The former directly supports the bridge load, and the latter does not bear the bridge load. In terms of form, both can be regarded as reinforced soil retaining walls. Generally speaking, reinforced soil abutments have the advantages of slope reduction, span reduction, cost saving, and rapid construction, and can effectively solve the problem of differential settlement at the bridge head.

[0003] For non-load-bearing reinforced soil abutments, the bridge is still borne by pile foundations, and the reinforced soil structure often wraps around the pile columns. This structural form is also called a wrapped non-load-bearing reinforced soil abutment. In this structure, due to factors such as the earth pressure behind the wall and the compression deformation of the foundation, there is an interaction between the reinforced soil mass and the pile columns. The magnitude and distribution characteristics of the force exerted by the reinforced soil mass on the pile columns have an obvious impact on the pile columns; the force exerted by the pile columns on the reinforced soil mass is also crucial for the stability and deformation analysis of the reinforced soil mass. In order to reveal the interaction mechanism, the distribution characteristics and magnitude of the interaction forces between the reinforced soil mass and the pile columns through indoor scaled model tests, a mechanism that can simulate the earth pressure behind the wall and the compression deformation of the foundation is needed. Summary of the Invention

[0004] The purpose of the present invention is to provide a simulation device for lateral earth pressure, foundation and toe horizontal restraint in a wrapped non-load-bearing reinforced soil abutment model test to solve the above problems.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A simulation device for a wrapped non-load-bearing reinforced soil abutment model test, comprising:

[0007] A foundation simulation component for simulating a reinforced soil abutment, including a foundation support frame, pile bodies, a bearing plate, and vertical compression springs. The vertical compression springs are arranged below the bearing plate, and the pile bodies are vertically arranged through the bearing plate at the center of the foundation support frame;

[0008] A lateral earth pressure simulation component for simulating the horizontal earth pressure of the backfill soil behind the model;

[0009] The toe horizontal restraint simulation component is used to simulate the horizontal restraint at the bottom of the model;

[0010] The data acquisition component is used to collect various test data.

[0011] Furthermore, the lateral earth pressure simulation component includes a plurality of loading plates and hydraulic cylinders connected to the loading plates. The hydraulic cylinders are installed on the lateral support frame, and the lateral support frame is installed on the foundation support frame through connecting rods. The loading plates are arranged in layers to simulate the change of lateral earth pressure with depth.

[0012] Furthermore, the hydraulic cylinders are connected to an external hydraulic mechanism. The hydraulic mechanism includes a manual pressure pump, a flow dividing block, and oil pipes. The manual pressure pump is connected to the hydraulic cylinders through oil pipes. The flow dividing block is arranged on the pipeline connected to the manual pressure pump to divide the oil circuit. An electric control valve is provided at the tail of the hydraulic cylinder to control the inlet and outlet of hydraulic oil in the hydraulic cylinder.

[0013] Furthermore, there are two manual pressure pumps, which apply pressure to the loading plates on both sides and in the middle respectively; a cushion layer is arranged between the loading plate and the model, and the cushion layer is fixed on the loading plate by wood screws.

[0014] Furthermore, the toe horizontal restraint simulation component includes a horizontal restraint support frame, fixing bolts, horizontal compression springs, and wooden strips;

[0015] The horizontal restraint support frame is welded to the foundation support frame. The fixing bolts are welded to the horizontal restraint support frame. The horizontal compression springs are sleeved on the fixing bolts, and the wooden strips are placed in front of the horizontal compression springs.

[0016] Furthermore, the data acquisition component includes:

[0017] Wire-pulling displacement gauges are arranged below the bearing plate and on the horizontal restraint support frame to measure the vertical displacement of the bearing plate and the horizontal displacement at the bottom of the model;

[0018] Pressure sensors are arranged between the front end of the hydraulic cylinder and the loading plate to obtain the thrust magnitude of each loading plate;

[0019] The vertical displacement numerical control box is connected to the wire-pulling displacement gauge for measuring the foundation settlement through a data acquisition line;

[0020] The horizontal displacement numerical control box is connected to the wire-pulling displacement gauge for measuring the horizontal displacement at the bottom of the model through a data acquisition line;

[0021] The pressure numerical control box is connected to the pressure sensor for real-time monitoring and feedback of the pressure change on the loading plate during the test;

[0022] A data recording computer is connected to the vertical displacement numerical control box, the horizontal displacement numerical control box and the pressure numerical control box through optical fibers to record the real-time collected data.

[0023] A method for using a simulation device of a wrapped non-load-bearing reinforced soil abutment model test includes the following steps:

[0024] (1) Assemble the foundation simulation component, the lateral earth pressure simulation component, the toe horizontal constraint simulation component and the data acquisition component, and place them in an existing rigid model box so that both sides of the model are supported;

[0025] (2) Turn on the lateral earth pressure simulation component and the data acquisition component;

[0026] (3) Fill the model, and layer by layer carry out the model filling work according to the process of stacking surface layer modules - backfilling fillers - compressing and vibrating - laying reinforcement materials;

[0027] (4) In the loading stage, use a manual pressure pump to load. Stop loading when the set value is reached and keep the pressure stable. During the loading process, record the horizontal displacement of the abutment every certain period of time;

[0028] (5) Observe whether the data is normal. When the data is normal, one group of tests ends. According to specific test requirements, change the model material parameters and constraint conditions to conduct multiple groups of tests.

[0029] Further, in step (1), seal the gaps between the bearing plates with sealant clay, cover a layer of Teflon film in front of the loading plate, and stick a layer of Teflon film on the pile body.

[0030] Further, in step (4), the force value on the loading plate is transmitted to the pressure numerical control box in real time through a pressure sensor. When loading, gently press the pressure rod until the force value displayed on the pressure numerical control box reaches the set value and then stop loading to keep the pressure stable.

[0031] Further, in step (4), when the difference between consecutive displacement readings is not greater than 0.01 mm, it is considered that the first-level loading platform is stable, and continue to pressurize to the next level. For each level of loading, it is necessary to stack a mass corresponding to the lateral earth pressure on the upper part of the abutment.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The foundation simulation component simulates the foundation modulus and the compression amount under additional stress by configuring springs with specific quantities and stiffnesses, and can better reflect the influence of foundation deformation on the working characteristics of the wrapped non-load-bearing reinforced soil abutment.

[0034] 2. The lateral earth pressure simulation component can simulate the lateral earth pressure of the abutment in a semi-infinite space by applying lateral earth pressure.

[0035] 3. The lateral soil pressure simulation component uses an electric control valve to control the oil in and out, which can continuously supplement the pressure of a loading plate that has not reached the set value, while not affecting the loading plate that has reached the preset pressure.

[0036] 4. Use two manual pressure pumps to apply pressure to the loading plates on both sides and in the middle respectively to avoid sudden pressure changes on adjacent loading plates caused by uncoordinated local soil deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the simulation device;

[0038] Figure 2 for Figure 1 A-A' structural cross-sectional view;

[0039] Figure 3 for Figure 2 Middle B-B' structural cross-sectional view;

[0040] Figure 4 for Figure 1 C-C' structural cross-sectional view;

[0041] Figure 5 for Figure 2 Middle D detail drawing;

[0042] Figure 6 for Figure 2 Middle E detail;

[0043] Numbers in the figure:

[0044] 0-model, 1-foundation simulation component, 2-bearing plate, 3-horizontal compression spring, 4-pile, 5-foundation support frame, 6-loading plate, 7-hydraulic cylinder, 8-electric control valve, 9-diverter block, 10-manual pressure pump, 11-cushion, 12-lateral support frame, 13-oil pipe, 14-pull-wire displacement meter, 15-pressure sensor, 16-vertical displacement CNC box, 17-horizontal displacement CNC box, 18-pressure CNC box, 19-data recording computer, 20-model box, 21-lateral soil pressure simulation component, 22-wooden strips, 23-connecting rods, 24-fixing bolts, 25-skirt board, 26-vertical compression spring, 27-wall toe horizontal constraint simulation component, 28-horizontal constraint support frame. DETAILED DESCRIPTION

[0045] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] Wrapped non-load-bearing reinforced soil bridge abutment model test device (refer toFigure 1 ) It consists of a foundation simulation component 1, a lateral earth pressure simulation component 21, a toe horizontal restraint simulation component 27, and a data acquisition component.

[0047] As Figure 1 shown, the upper part of the foundation simulation component 1 is a bearing plate 2 for supporting the abutment structure. A vertical compression spring 26 is arranged under each bearing plate to simulate the foundation deformation. During the test, the foundation modulus is a certain value. Since the areas of each bearing plate are different, the number of compression springs arranged below them is also different. The specific configuration is as Figure 3 shown. The vertical compression springs 26 used for the foundation are also fixed on the foundation support frame 5 and the bearing plate 2 respectively by cylindrical fixing bolts 24, as Figure 5 shown. The pile body 4 is used to simulate the load-bearing pile of the reinforced earth abutment in the model test. It is made of a hollow iron pipe and is directly welded to the foundation support frame 5 at the bottom. Skirt plates 25 are welded around the plane of the pile body 4 parallel to the bearing plate 2 to avoid the influence caused by sand leakage during the filling of the model test.

[0048] As Figure 2 , Figure 4 shown, the lateral pressure application component mainly generates thrust by a hydraulic cylinder 7. The hydraulic cylinder is fixed on the lateral support frame 12, and a wooden loading plate 6 is fixed at the front. In order to ensure that the load applied to the model is a flexible load, a cushion layer 11 made of rubber is fixed in front of the wooden loading plate 6. As Figure 6 shown, an electromagnetic control valve 8 is installed at the tail of the hydraulic cylinder 7 to control the inflow and outflow of hydraulic oil in the hydraulic cylinder 7. During the loading process, through the control of the manual pressure pump 10, the hydraulic oil enters from the rear of the hydraulic cylinder 7 and flows out from the front of the hydraulic cylinder 7; during the unloading process, the hydraulic oil enters from the front of the hydraulic cylinder 7 and flows out from the rear of the hydraulic cylinder 7. As Figure 2 shown, a flow dividing block 9 is arranged on the pipeline connected to the manual pressure pump 10 to divide the oil circuit. This device uses two manual pressure pumps 10 to control the hydraulic cylinders in the middle and on both sides respectively. The lateral support frame 12 is used to support the entire lateral pressure application component, and the oil pipe 13 is used for the transmission of hydraulic oil. In order to ensure that the lateral support frame 12 does not tip over during the loading process, the lateral support frame 12 is fixed to the foundation support frame 5 by a connecting rod 23, and the fixing method is bolt fixing.

[0049] As Figure 2 shown, on the left side of the toe horizontal restraint simulation component 27 is a horizontal restraint support frame 28. The horizontal restraint support frame 28 is welded to the foundation support frame 5. Cylindrical fixing bolts 24 are welded on the horizontal restraint support frame 28. The horizontal compression spring 3 can be sleeved on the fixing bolts 24, and a wooden strip 22 is placed on the right side to simulate the horizontal restraint at the bottom of the model 0, as Figure 5 shown.

[0050] The data acquisition component includes a wire-pulling displacement meter 14, a pressure sensor 15, a vertical displacement numerical control box 16, a horizontal displacement numerical control box 17, a pressure numerical control box 18, and a data recording computer 19. As Figure 3 shown, the wire-pulling displacement meters 14 are arranged diagonally under each bearing plate 2 to measure the vertical displacement of each plate, and are connected to the vertical displacement numerical control box 16 through data acquisition lines. As Figure 1 shown, there are 3 wire-pulling displacement meters 14 arranged on the horizontal restraint support frame 28 to measure the horizontal displacement at the bottom of the model, and are connected to the horizontal displacement numerical control box 17 through data acquisition lines. The pressure sensor 15 is arranged between the front end of the hydraulic cylinder 7 and the loading plate 6 to obtain the actual thrust magnitude of each loading plate 6, and is connected to the pressure numerical control box 18 using a data line for real-time monitoring and feedback of the pressure change received by each loading plate 6 during the test. The electromagnetic control valve 8 is also connected to the pressure numerical control box 18 through a relay. When the thrust magnitude measured by the pressure sensor 15 reaches the set value, the electromagnetic control valve 8 closes. The data recording computer 19 is connected to the vertical displacement numerical control box 16, the horizontal displacement numerical control box 17, and the pressure numerical control box 18 through optical fibers to record the real-time acquired data.

[0051] The specific operation process of conducting the test through the non-load-bearing reinforced soil abutment model test device is completed through the following steps:

[0052] First, assemble the foundation simulation component 1, the lateral earth pressure simulation component 21, the wall toe horizontal restraint simulation component 27, and the data acquisition component according to the drawing requirements, and place them in the existing rigid model box 20 so that both sides of the model can be supported. Seal the gaps between the bearing plates 2 with sealant clay to avoid sand leakage during the test. Cover a layer of Teflon film in front of the loading plate 6, which not only avoids lateral sand leakage but also reduces the frictional resistance. At the same time, to avoid the influence of the tension membrane effect, leave a certain margin between adjacent plates when applying the film. Also apply a layer of Teflon film to the pile body to simulate the situation of a smooth envelope in actual engineering.

[0053] Second, turn on the power supplies of the lateral earth pressure simulation component 21 and the data acquisition component.

[0054] Third, start filling the model, and layer by layer conduct the model filling work according to the process of stacking the surface layer modules - backfilling the filler - compressing and vibrating - laying the reinforcement. During the model filling process, pay attention to whether there is sand leakage and whether there are any abnormal readings in each numerical control box.

[0055] Fourth, enter the loading stage. The loading is carried out by manually pressing the pump 10. The force value on the loading plate 6 can be transmitted to the pressure numerical control box 18 in real time through the pressure sensor 15. When loading, the pressing rod should be gently pressed until the force value displayed on the pressure numerical control box 18 reaches the set value, and then stop loading to keep the pressure stable. Since the pressure on both sides of the model is much greater than that in the middle of the model during pressing, in order to maintain the pressure stability, two manual pressure pumps 10 are used to control the middle loading plate and the side loading plates respectively. During the loading process, the horizontal displacement of the abutment is recorded every 10 minutes. When the difference between the displacement readings for three consecutive times is not greater than 0.01 mm, it is considered that the first-level loading platform is stable and the pressure can be continuously increased to the next level. For each level of loading, the mass corresponding to the lateral earth pressure needs to be piled up on the upper part of the abutment.

[0056] Fifth, observe whether the data on the data recording computer 19 is normal. When the data is normal, a set of tests is completed, and multiple sets of tests can be carried out according to specific test requirements by changing the model material parameters, constraint conditions, etc.

[0057] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A method for using a simulation device of a wrapped non-load-bearing reinforced soil abutment model test, characterized in that, The simulation device includes: A foundation simulation component (1) for simulating a reinforced soil abutment, including a foundation support frame (5), piles (4), a bearing plate (2), and vertical compression springs (26). The vertical compression springs (26) are arranged below the bearing plate (2), and the piles (4) pass through the bearing plate (2) and are vertically arranged at the center of the foundation support frame (5); A lateral earth pressure simulation component (21) for simulating the horizontal earth pressure of the backfill soil behind the model; A toe horizontal constraint simulation component (27) for simulating the horizontal constraint at the bottom of the model; A data acquisition component for collecting various test data; The usage method of the simulation device includes the following steps: (1) Assemble the foundation simulation component, the lateral earth pressure simulation component, the toe horizontal constraint simulation component, and the data acquisition component, and place them in an existing rigid model box so that both sides of the model are supported; (2) Turn on the lateral earth pressure simulation component and the data acquisition component; (3) Fill the model, and layer by layer carry out the model filling work according to the process of stacking surface layer modules - backfilling fillers - compressing and vibrating - laying reinforcement; (4) In the loading stage, use a manual pressure pump to load the lateral earth pressure, stop loading when the set value is reached, and keep the pressure stable. During the loading process, record the horizontal displacement of the abutment every certain period of time; (5) Observe whether the data is normal. When the data is normal, one group of tests ends. According to specific test requirements, change the model material parameters and constraint conditions to conduct multiple groups of tests.

2. The method of using a simulation device for a wrapped non-load-bearing reinforced soil abutment model test according to claim 1, characterized in that, The lateral earth pressure simulation component (21) includes a plurality of loading plates (6) and hydraulic cylinders (7) connected to the loading plates (6). The hydraulic cylinders (7) are installed on a lateral support frame (12), and the lateral support frame (12) is installed on the foundation support frame (5) through a connecting rod. The loading plates (6) are arranged in layers to simulate the change of lateral earth pressure with depth.

3. The method of using a simulation device for a wrapped non-load-bearing reinforced soil abutment model test according to claim 2, characterized in that, The hydraulic cylinders (7) are connected to an external hydraulic mechanism. The hydraulic mechanism includes a manual pressure pump (10), a flow dividing block (9), and oil pipes (13). The manual pressure pump (10) is connected to the hydraulic cylinders (7) through the oil pipes (13). The flow dividing block (9) is arranged on the pipeline connected to the manual pressure pump (10) for dividing the oil circuit. An electric control valve (8) is provided at the tail of the hydraulic cylinders (7) for controlling the inflow and outflow of hydraulic oil in the hydraulic cylinders (7).

4. The method of using a simulation device for a wrapped non-load-bearing reinforced soil abutment model test according to claim 3, characterized in that, There are two manual pressure pumps (10), which respectively apply pressure to the loading plates on both sides and in the middle. A cushion layer (11) is arranged between the loading plates (6) and the model, and the cushion layer (11) is fixed on the loading plates with wood screws.

5. The method of using a simulation device for a wrapped non-load-bearing reinforced soil abutment model test according to claim 2, characterized in that The toe horizontal constraint simulation component (27) includes a horizontal constraint support frame (28), fixing bolts (24), horizontal compression springs (3), and wooden strips (22); The horizontal constraint support frame (28) is welded to the foundation support frame (5). The fixing bolts (24) are welded to the horizontal constraint support frame (28). The horizontal compression springs (3) are sleeved on the fixing bolts (24), and the wooden strips (22) are placed in front of the horizontal compression springs (3).

6. The method of using a simulation device for a wrapped non-load-bearing reinforced soil abutment model test according to claim 5, characterized in that, The data acquisition component includes: A wire-drawing displacement gauge (14) is arranged below the bearing plate (2) and on the horizontal restraint support frame (28) for measuring the vertical displacement of the bearing plate and the horizontal displacement at the bottom of the model; A pressure sensor (15) is arranged between the front end of the hydraulic cylinder (7) and the loading plate (6) for obtaining the thrust magnitude of each loading plate (6); A vertical displacement numerical control box (16) is connected to the wire-drawing displacement gauge (14) for measuring the foundation settlement through a data acquisition line; A horizontal displacement numerical control box (17) is connected to the wire-drawing displacement gauge (14) for measuring the horizontal displacement at the bottom of the model through a data acquisition line; A pressure numerical control box (18) is connected to the pressure sensor (15) for real-time monitoring and feedback of the pressure change received by the loading plate (6) during the test; A data recording computer (19) is connected to the vertical displacement numerical control box (16), the horizontal displacement numerical control box (17), and the pressure numerical control box (18) through optical fibers to record the real-time acquired data.

7. The method of using a simulation device for a wrapped non-load-bearing reinforced soil abutment model test according to claim 2, characterized in that In step (1), the gaps between the bearing plates are sealed with sealant clay, a layer of Teflon film is covered in front of the loading plate, and a layer of Teflon film is pasted on the pile body.

8. The method of using a simulation device for a wrapped non-load-bearing reinforced soil abutment model test according to claim 2, characterized in that, In step (4), the force value on the loading plate is transmitted to the pressure numerical control box in real time through the pressure sensor. When loading, the pressure rod needs to be slowly pressed until the force value displayed on the pressure numerical control box reaches the set value, then stop loading and keep the pressure stable.

9. The method of using a simulation device for a wrapped non-load-bearing reinforced soil abutment model test according to claim 1, characterized in that, In step (4), when the difference between consecutive displacement readings is not greater than 0.01 mm, it is considered that the first-level loading platform is stable, and continue to pressurize to the next level. For each level of loading, the mass corresponding to the lateral earth pressure needs to be piled up on the upper part of the abutment.

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