A load performance test system and test method for assembled reinforced earth retaining wall

Abstract

The present invention discloses a test system and method for load performance of assembled reinforced earth retaining wall, comprising a test model box, a load loading device and a data acquisition device for collecting deformation of the reinforced earth retaining wall after being loaded, wherein the test model box has an upper opening and at least one peripheral opening, and a reinforced earth retaining wall is arranged in the test model box, and the reinforced earth retaining wall is located at the peripheral opening; the load loading device can apply a vertical load to the reinforced earth retaining wall in the test model box from the upper opening. The test system can effectively simulate and measure the changes of the reinforced earth retaining wall structure under dynamic and static loads, and is easy to test; the test method is easy to operate, can simplify the measurement data of the entire dynamic and static load simulation, and can obtain accurate data of the load test.

Description

Technical Field

[0001] The present invention relates to the field of reinforced soil retaining walls, and particularly to an assembled reinforced soil retaining wall load performance test system and a test method. Background Art

[0002] At present, as an effective flexible reinforced subgrade retaining structure for highways, railways, bridge abutments and slopes, the reinforced soil retaining wall structure mainly needs to bear the actions of static load and dynamic load. The static load is mainly generated by the earth pressure of the backfill behind the retaining wall and the gravity of the overlying structure on the retaining wall structure, while the dynamic load mainly comes from the traffic load or seismic load on the ground surface layer, the dynamic load caused by natural factors, etc. acting on the retaining wall. The former is related to the structural form of the reinforced soil retaining wall, the properties of the filler and the overlying structure facilities, etc., while the latter is mainly related to factors such as the working service environment of the reinforced soil retaining wall and the load weight, vehicle speed, driving position of the vehicle, etc.

[0003] In recent years, many scholars at home and abroad often conduct research on the reinforced soil retaining wall structure through on-site or indoor model tests, theoretical analysis and numerical simulation, etc., so as to continuously promote the development of the reinforced soil technology. Among them, the indoor model test is an effective research method that replaces the prototype test according to a certain geometric ratio, and can monitor relatively reliable test results by controlling external conditions and natural conditions. At the same time, it can also verify the accuracy of the corresponding theoretical research and numerical simulation analysis, and is also an effective method to study or solve many difficult problems in the field of geotechnical engineering. Compared with the indoor model test, it is difficult to find a suitable actual project for on-site tests. And even if on-site tests can be carried out, there are many influencing factors and it is difficult to avoid them one by one, so the monitored data cannot be guaranteed to be completely reliable; while the numerical simulation and theoretical analysis research processes are very complex, and many parameters are difficult to be accurate and simplified, which has certain limitations. Therefore, it is necessary to develop an assembled reinforced soil retaining wall test platform and an effective test method to simulate and measure the changes of the assembled reinforced soil retaining wall structure under static and dynamic loads, so as to accurately obtain real values. Summary of the Invention

[0004] The present invention aims to solve at least one of the above-mentioned technical problems, and provides a reinforced soil retaining wall test system and a test method. This test system can effectively simulate and measure the changes of the reinforced soil retaining wall structure under static and dynamic loads, and is easy to test; this test method is convenient to operate, can simplify the measurement data of the entire static and dynamic load simulation and can obtain accurate data of the load test.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] An assembled reinforced soil retaining wall load performance test system, comprising:

[0007] A test model box having an upper opening and at least one circumferential opening, with a reinforced soil retaining wall disposed inside the test model box, and the reinforced soil retaining wall sealing the circumferential opening;

[0008] A load loading device capable of applying a vertical load to the reinforced soil retaining wall inside the test model box from the upper opening and measuring the settlement of the reinforced soil retaining wall in the vertical direction; and

[0009] A data acquisition device for acquiring the deformation of the reinforced soil retaining wall after being subjected to a load.

[0010] As an improvement to the above technical solution, the reinforced soil retaining wall includes a retaining wall panel sealing the circumferential opening, a reinforcement member having one end fixed to the inner side of the retaining wall panel, and a filler covering the reinforcement member, and at least one layer of the reinforcement member is provided.

[0011] As an improvement to the above technical solution, the data acquisition device includes

[0012] A flexible displacement gauge installed on the reinforcement member and used for measuring the deformation of the reinforcement member after being subjected to a load;

[0013] A displacement sensor installed on the circumferential opening, which can slide relative to the retaining wall panel and is used for measuring the horizontal displacement and the vertical settlement of the retaining wall panel after being subjected to a load;

[0014] An accelerometer installed in the filler and used for measuring the acceleration of the place where it is buried after being subjected to a load;

[0015] An earth pressure cell installed in the filler and used for measuring the earth pressure of the place where it is buried after being subjected to a load.

[0016] As an improvement to the above technical solution, an installation frame is provided on the outer side of the test model box on one side of the circumferential opening, the displacement sensor is installed on the installation frame, the installation frame does not contact the retaining wall panel, and the displacement sensor abuts against the retaining wall panel.

[0017] As an improvement to the above technical solution, the test model box includes a base and a frame, the frame is installed on the base, a rear steel plate is provided on the side of the frame opposite to the circumferential opening, and side steel plates and fiberglass panels are respectively provided corresponding to both sides of the circumferential opening.

[0018] As an improvement to the above technical solution, the load loading device includes a reaction frame, a hydraulic cylinder with its output end downwardly disposed on the reaction frame, and a loading plate disposed on the output end of the hydraulic cylinder, and the hydraulic cylinder can apply a vertical load to the reinforced soil retaining wall inside the test model box through the loading plate.

[0019] As an improvement of the above technical solution, it also includes a digital image testing system, which includes a digital camera and an image acquisition and analysis computer. The test model box is provided with a transparent fiberglass panel on one side of the peripheral opening; the digital camera and the image acquisition and analysis computer are both arranged on one side of the fiberglass panel. The digital camera can obtain the deformation displacement image information of the filler around different layers of reinforcement materials, and the image acquisition and analysis computer can receive the image information taken by the digital camera, and calculate and draw the displacement cloud map and strain field of the filler layer near the interface between any layer of reinforcement materials and the filler.

[0020] A method for testing the load performance of an assembled reinforced earth retaining wall, comprising:

[0021] Step 1: Test equipment preparation: prepare the test model box, load loading device and data acquisition equipment, and debug the load loading device and data acquisition equipment until they meet the preset requirements;

[0022] Step 2: Construct the test unit layer, fill and compact the filler and reinforcement in the test model box in layers, install a flexible displacement meter on the reinforcement, bury an accelerometer and an earth pressure box in the filler at a preset position, and build a retaining wall panel composed of assembled modules at the opening on the side, so that the reinforcement is connected to the retaining wall panel composed of assembled modules; install a displacement sensor that can be fixed relative to the test model box on the retaining wall panel composed of assembled modules;

[0023] Step 3: construct a reinforced earth retaining wall, and fill the test unit layer layer by layer according to the method of step 2 until the preset test height is reached and the reinforced earth retaining wall is formed;

[0024] Step 4: Install the loading plate. After the reinforced earth retaining wall is completed, use a level to level the top test unit layer of the reinforced earth retaining wall, and then place the loading plate on the preset test pressure point of the top test unit layer;

[0025] Step 5, loading test, debug the data acquisition equipment and unify the test time of each measurement. The load loading device adopts a sinusoidal loading method to load until the reinforced earth retaining wall is destroyed; during the test, various measurement data in the data acquisition equipment are recorded; the digital camera obtains the deformation displacement image information of the filler around different layers of reinforcement materials, and the image acquisition and analysis computer can receive the image information taken by the digital camera, and calculate and draw the displacement cloud map and strain field of the filler layer near the interface between any layer of reinforcement materials and filler; the expression of the applied sinusoidal excitation force is as follows:

[0026] P=P 0 +P A sin(2πft)

[0027] Where P 0is the fixed load value (kN);

[0028] P A is the dynamic load amplitude (kN);

[0029] f is the loading frequency (Hz);

[0030] t is the time (s);

[0031] Step 6, Test conclusion: After the reinforced soil retaining wall fails, use a high-definition digital camera to take pictures of the cumulative deformation of the top loading plate and the retaining wall panel of the reinforced soil retaining wall and record the number of cracks.

[0032] As an improvement of the above technical solution, the specific loading method in Step 5 is as follows: The load loading device first gradually applies static load from zero to the predetermined dynamic load center value P 0 , with each level of loading being n kN, where n is a natural integer; then successively apply dynamic load values of P 0 ±n kN, P 0 ±2n kN, P 0 ±3n kN, P 0 ±4n kN, P 0 ±5n kN, P 0 ±6n kN, with each level of loading lasting for 5 - 10 minutes until the retaining wall fails and the test ends.

[0033] As an improvement of the above technical solution, Step 2 includes the following steps:

[0034] Step 2.1, Layered filling and compaction of the filler in the test model box, and building the retaining wall panel composed of assembled modules at the opening on the peripheral side. The filling thickness of each test unit layer is 10 - 12 cm, and the height of the retaining wall is 110 - 144 cm; During the filling process, use an electric plate compactor to level and compact the filler 3 - 5 times, and then use a 15 - 30 kg weight to compact the filler per unit area, with the number of compaction times per unit area being 4 - 7 times; During the leveling process, gradually add filler until the compacted thickness of the test unit layer is 12 - 16 cm, and the compaction coefficient is above 95%;

[0035] Step 2.2, Lay the reinforcement on the compacted test unit layer according to the preset specifications, with one end of the reinforcement connected to the retaining wall panel composed of assembled modules; Install a flexible displacement meter on the reinforcement, and bury an accelerometer and an earth pressure cell in the test unit layer;

[0036] Step 2.3, Fix and install a displacement sensor on the mounting frame outside the peripheral opening, with the displacement sensor abutted against the outside of the retaining wall panel composed of assembled modules.

[0037] As an improvement of the above technical solution, the filler in step 2.1 is medium sand with good particle gradation.

[0038] Compared with the prior art, the beneficial effects of this application are as follows:

[0039] The load performance test system of the prefabricated reinforced soil retaining wall of the present invention has upper side openings and circumferential side openings on the test model box; and a load loading device is used to apply loads to the upper side openings to simulate the influence of the self-weight of the reinforced soil retaining wall itself, the external service environment, and factors such as the load weight, vehicle speed, and driving position of the vehicle on its structure in actual use; while at the circumferential side openings, precast panel modules are used to assemble a reinforced soil retaining wall, which can simulate the actual situation of the damaged side of the outdoor actual reinforced soil retaining wall, and the data acquisition device can convert the deformation amount of the reinforced soil retaining wall after being subjected to the load and convert this deformation amount into measurable data parameters, so as to facilitate the quantitative management of these simulation data. The load performance test system of this reinforced soil retaining wall has a simple structure, can effectively simulate the damaged conditions of the reinforced soil retaining wall after being subjected to the load, and digitalize these damaged conditions, which is more intuitive. In addition, this application also provides a load performance test method for the prefabricated reinforced soil retaining wall. This method is convenient to operate, easy to simulate and measure, can effectively simplify the data of conventional simulation measurements, and at the same time the measured data is more in line with the data when the actual reinforced soil retaining wall is damaged, and has a wide range of applicability. Description of the Drawings

[0040] The following further details the specific implementation manners of the present invention in conjunction with the drawings, where:

[0041] Figure 1 is the front view of the embodiment of the present invention;

[0042] Figure 2 is the top view of the embodiment of the present invention;

[0043] Figure 3 is the principle block diagram of the embodiment of the present invention;

[0044] Figure 4 is the structural schematic diagram of the inverted trapezoidal internal layout of the reinforcing bars in the embodiment of the present invention;

[0045] Figure 5 is the structural schematic diagram of the wrapped-back internal layout of the reinforcing bars in the embodiment of the present invention;

[0046] Figure 6 is the structural schematic diagram of the cooperation between the reinforcing bars and the retaining wall panel in the embodiment of the present invention;

[0047] Figure 7 is the particle size gradation curve diagram of the sand particles in the embodiment of the present invention. Specific Embodiments

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0049] It should be noted that when a component is referred to as being "fixed to" another component, it can be directly on the other component or there may also be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component at the same time. When a component is considered to be "disposed on" another component, it can be directly disposed on the other component or there may be an intermediate component at the same time. When a part is referred to as being "disposed in the middle", it is not only disposed at the exact middle position, but as long as it is not disposed at the two ends, it falls within the scope defined by the middle. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention in this specification are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0051] As Figures 1 to 7As shown in the figure, the present invention provides an assembled reinforced soil retaining wall load performance test system, which includes a test model box 1, a load loading device 3 and a data acquisition device 4. The test model box 1 has an upper opening 11 and at least one circumferential opening 12. A reinforced soil retaining wall 2 is arranged in the test model box 1, and the circumferential opening 12 is blocked by the reinforced soil retaining wall 2. The load loading device 3 can apply a vertical load to the reinforced soil retaining wall 2 in the test model box 1 from the upper opening 11 and measure the settlement of the reinforced soil retaining wall 2 in the vertical direction. The data acquisition device 4 is used to collect the deformation of the reinforced soil retaining wall 2 after being loaded. Among them, in the load performance test system of the reinforced soil retaining wall of the present invention, an upper opening 11 and a circumferential opening 12 are opened on the test model box 1; and the load loading device 3 is used to apply a load to the upper opening 11 to simulate the influence of factors such as the self-weight of the reinforced soil retaining wall 2 itself, the external service environment, the load weight, vehicle speed, and driving position of the vehicle on its structure in actual use; and the circumferential opening 12 can simulate the actual situation of the side where the outdoor actual reinforced soil retaining wall 2 is damaged, and the data acquisition device 4 can convert the deformation of the reinforced soil retaining wall 2 after being loaded and convert this deformation into data parameters that can be measured, so as to facilitate the quantitative management of these simulation data. The load performance test system of this reinforced soil retaining wall has a simple structure, can effectively simulate the damaged situation of the reinforced soil retaining wall 2 after being loaded, and digitalize these damaged situations, which is more intuitive.

[0052] In actual use, the reinforced soil retaining wall 2 tested and simulated by the present application includes a retaining wall panel 21 blocking the circumferential opening 12, a reinforcing material 22 with one end fixed inside the retaining wall panel 21, and a filler 23 covering the reinforcing material 22. At least one layer of the reinforcing material 22 is provided, and preferably more than five layers in the present application, so as to improve the measurement accuracy. The retaining wall panel 21 can be designed modularly, so that the actual structural process of building the actual reinforced soil retaining wall 2 can be simulated. In this embodiment, the retaining wall panel 21 can be made into a regular square type, which is convenient for the masonry work during the test process. Among them, refer to Figure 6 , in some embodiments, the retaining wall panel 21 can be directly prefabricated into a module. The retaining wall panel 21 is a hollow structural module, and a steel bar 24 is arranged in the hollow area. The retaining wall panel 21 has a groove at the upper part and a protruding connecting piece at the lower part, and can be assembled with the reinforcing material 22 to the circumferential opening 12 together. The connection between the reinforcing material 22 and the retaining wall panel 21 can be carried out by snap friction connection and wrapping friction connection, or mechanical connection, depending on the actual test conditions. The friction connection is mainly that the reinforcing material 22 is stuck between the modules of two adjacent retaining wall panels 21, and the connection between the retaining wall panel 21 and the reinforcing material 22 is realized by the friction force of the gap between the modules of the retaining wall panel 21. The mechanical connection is to directly pass the steel bar 24 in the retaining wall panel 21 through the reinforcing material 22 and limit the reinforcing material 22.

[0053] In this application, the reinforcing material 22 can be a biaxially oriented HDPE geogrid. The aperture specification of the biaxially oriented HDPE geogrid is 40mm×40mm, and the strength model is TGSG-3030. Among them, the biaxially oriented HDPE geogrid can be divided into M type, A type, and B type. The ultimate tensile strengths of the three types are approximately 32.7kN / m, 29.5kN / m, and 16.7kN / m in sequence, and the peak failure strains are approximately 10.8%, 10.3%, and 10.2% in sequence. The test M-type reinforcing material is the original biaxial geogrid without cutting the transverse ribs. The A-type reinforcing material is obtained by cutting off one transverse rib of the geogrid every other transverse rib. The B-type reinforcing material is obtained by cutting off two transverse ribs of the geogrid every other transverse rib. The A-type and B-type reinforcing materials are both processed on the basis of the M-type reinforcing material. These three types of biaxial geogrids can effectively analyze the influence of the reduction of grid strength on the working performance of the reinforced soil retaining wall. The following tests can be carried out based on these three types of geogrids, improving the accuracy of the tests.

[0054] See Figures 2 to 5 , the data acquisition device 4 includes a flexible displacement gauge 41, a displacement sensor 42, an accelerometer 43, and an earth pressure cell 44. Among them, the flexible displacement gauge 41 is installed on the reinforcing material 22 and is used to measure the deformation of the reinforcing material 22 after being subjected to a load and the earth pressure cell 44. The displacement sensor 42 is installed on the circumferential opening 12. The displacement sensor 42 can slide relative to the retaining wall panel 21 and is used to measure the horizontal displacement and the vertical settlement of the retaining wall panel 21 after being subjected to a load. The accelerometer 43 is installed in the filler 23 and is used to measure the acceleration of the place where it is buried after being subjected to a load. The earth pressure cell 44 is installed in the filler 23 and is used to measure the earth pressure of the place where it is buried after being subjected to a load. It should be noted that the measured value of this displacement sensor 42 is the deformation of the retaining wall panel 21 itself. Therefore, it can be seen that the displacement sensor 42 needs to be fixed during the test. For this reason, in this application, an installation frame 13 is provided on the outer side of the test model box 1 on one side of the circumferential opening 12. The displacement sensor 42 is installed on the installation frame 13. The installation frame 13 does not contact the retaining wall panel 21, and the displacement sensor 42 abuts against the retaining wall panel 21. During the test, in order to improve the accuracy of the test data, in this application, lubricating oil needs to be applied to the displacement sensor 42, so as to improve the sensitivity of the entire displacement sensor 42.

[0055] See Figure 2 , Figure 4 and Figure 5, the test model box 1 includes a base 14 and a frame 15. The frame 15 is installed on the base 14. A rear steel plate 16 is provided on one side of the frame 15 opposite to the circumferential opening 12. Side steel plates 17 and a fiberglass panel 18 are respectively provided on both sides of the frame 15 corresponding to the circumferential opening 12. The setting of the fiberglass panel 18 is mainly to facilitate the test personnel to observe the deformation condition of the reinforced soil retaining wall 2 inside the entire test model box 1 during the test process. In another embodiment of the present application for easy observation, corresponding scales are provided on the fiberglass panel 18. According to the working condition design requirements, the laying positions of each layer of earth pressure cells 44, accelerometers 43, and reinforcement materials 22, as well as the positions of the layered filling and compaction of the filler 23 are marked to guide the smooth progress of the filling process. For the accuracy of the test, the test structure composed of the base 14, the frame 15, the rear steel plate 16, the fiberglass panel 18, and the side steel plates 17 in the present application can be considered as non-deformable, so as to reduce the error caused by the deformation of the test model box 1 during the test process and affect the accuracy of the measurement data.

[0056] In an improved embodiment, in order to better record the deformation condition of each soil layer, the test system further includes a digital image test system 36. The digital image test system 36 includes a digital camera 34 and an image acquisition and analysis computer 35. Both the digital camera 34 and the image acquisition and analysis computer 35 are provided on one side of the fiberglass panel 18. The digital camera 34 can obtain the deformation displacement picture information of the filler 23 around different layers of reinforcement materials 22. The image acquisition and analysis computer 35 can receive the image information captured by the digital camera 34 and calculate and draw the displacement nephogram and strain field of the filler 23 layer near the interface between any layer of reinforcement material 22 and the filler 23. The technology of using a digital camera to obtain images and using a computer to analyze the image information is a conventional technical means. The applicant does not elaborate on the principle of how the computer analyzes the image information here. In addition, in this test system, the digital camera 34 and the image acquisition and analysis computer 35 are connected by a USB data cable. The digital image test system 36 is vertically arranged and faces the output end of the load loading device 3, and the distance is 500 mm to ensure that the images obtained by the digital image test system 36 are clear and distortion-free.

[0057] See Figures 1 to 3, To improve the convenience of loading, in this application, the load loading device 3 includes a reaction frame 31, a hydraulic cylinder 32 with its output end facing downwards and arranged on the reaction frame 31, and a loading plate 33 arranged on the output end of the hydraulic cylinder 32. The hydraulic cylinder 32 can apply a vertical load to the reinforced soil retaining wall 2 in the test model box 1 through the loading plate 33. Since the loading plate 33 directly acts on the reinforced soil retaining wall 2, to avoid the influence of its own force-induced deformation, in this application, the loading plate 33 is preferably a steel plate with high stiffness, and the specification can be 95 cm × 15 cm × 3 cm, which basically conforms to the actual acting area of the conventional load on the unit area of the reinforced soil retaining wall 2 in the actual process. In addition, regarding how to control the operation and loading process of the hydraulic cylinder 32, an MTS electro-hydraulic servo control system can be preferably used for control. This system can display the output load level value and loading frequency in real time, and can convert the load type by adjusting the relevant parameters of the system. Among them, for the specific structure and usage method of the MTS electro-hydraulic servo control system, reference can be made to: Xu Piyuan, Ge Yunhai, Liu Hong, & Yu Shuzhai. (0). Application of MTS electro-hydraulic servo loading system in building structure tests. Civil Engineering Construction Management: Proceedings of the Building Construction Professional Committee of Liaoning Civil Engineering Society.

[0058] See Figure 3 , In actual operation, this assembled reinforced soil retaining wall load performance test system further includes a data acquisition system. The data acquisition system can receive the data signals output by the flexible displacement gauge 41, displacement sensor 42, accelerometer 43, and earth pressure cell 44, and transmit the received data signals to an external upper computer. Among them, the data acquisition system is preferably the commonly used static strain gauge and dynamic strain gauge in the field. These two different types of strain gauges can measure the deformation data of the reinforced soil retaining wall 2 under static and dynamic load states respectively. Among them, the static strain gauge is preferably the JM3813 static strain gauge; and the dynamic strain gauge is preferably the JM3841 dynamic strain gauge. After the data acquisition system collects the data, it can transmit these data to the upper computer, facilitating the operator to observe and record the data in real time.

[0059] In addition, see Figure 4 and Figure 5 , The present invention also provides an assembled reinforced soil retaining wall load performance test method, including:

[0060] Step 1, Prepare test equipment, prepare the test model box 1, load loading device 3, and data acquisition equipment 4, and debug the load loading device 3 and data acquisition equipment 4 until they meet the preset requirements;

[0061] Step 2: construct the test unit layer, fill and compact the filler 23 and the reinforcement 22 in the test model box 1 in layers, install the flexible displacement meter 41 on the reinforcement 22, bury the accelerometer 43 and the earth pressure box 44 in the filler 23 at the preset position, and build the retaining wall panel 21 composed of assembled modules at the peripheral opening 12, so that the reinforcement 22 is connected to the retaining wall panel 21 composed of assembled modules; install the displacement sensor 42 that can be fixed relative to the test model box 1 on the retaining wall panel 21 composed of assembled modules;

[0062] Step 3, constructing a reinforced earth retaining wall 2, filling the test unit layer layer by layer according to the method of step 2, until the preset test height is reached and the reinforced earth retaining wall 2 is formed;

[0063] Step 4, installing the loading plate 33. After the reinforced earth retaining wall 2 is completed, use a level ruler to level the uppermost test unit layer of the reinforced earth retaining wall 2, and then place the loading plate 33 on the preset pressure test point of the uppermost test unit layer;

[0064] Step 5, loading test, debug the data acquisition device 4 and unify the test time of each measurement, the load loading device 3 adopts a sinusoidal loading method to load until the reinforced earth retaining wall 2 is destroyed; during the test, various measurement data in the data acquisition device 4 are recorded; the digital camera 34 obtains the deformation displacement image information of the filler 23 around different layers of reinforcement 22, and the image acquisition and analysis computer 35 can receive the image information taken by the digital camera 34, and calculate and draw the displacement cloud map and strain field of the filler 23 layer near the interface between any layer of reinforcement 22 and filler 23; the expression of the applied sinusoidal excitation force is as follows:

[0065] P=P 0 +P A sin(2πft)

[0066] Where P 0 is the load constant (kN);

[0067] P A is the dynamic load amplitude (kN);

[0068] f is the loading frequency (Hz);

[0069] t is time (s);

[0070] Step 6, end of the test, after the reinforced earth retaining wall 2 is destroyed, use a high-definition digital camera to photograph the cumulative deformation of the top loading plate 33 of the reinforced earth retaining wall and the retaining wall panel 21 and record the number of cracks.

[0071] ​In actual tests, factors such as the types of real traffic loads, driving speeds, load weights, and road surface conditions have a dynamic impact on the dynamic load levels and frequencies of the reinforced soil composite under traffic loads. Therefore, it is very difficult to accurately simulate traffic loads in reality. Thus, it is necessary to appropriately simplify the dynamic load waveform during research. The simplified waveform adopted in this application is a sine wave. Therefore, the above load loading device 3 is loaded in the manner as in the sine excitation force expression, which simplifies the entire simulation test and also facilitates obtaining more intuitively the impact of traffic loads on the reinforced soil retaining wall 2.

[0072] See Figure 4 and Figure 5 , in this application, the laying methods of the reinforcement 22 include inverted trapezoid, reverse wrapping, and strip grille layout. Model test analyses are carried out for two types of working conditions, namely static and dynamic loads and dynamic loads respectively: Vertical loads are applied in stages on the top of the reinforced soil retaining wall 2 until failure, 5 kN for each stage. The offset distance D of the loading plate 33 is changed respectively to analyze the working performance of the reinforced soil retaining wall 2. D = 0.3H, 0.45H, 0.6H, and the ratio of the foundation offset distance D to the retaining wall height H is defined as the strip foundation offset rate β. H is preferably 1265 mm to determine the optimal strip foundation offset rate β of the foundation from the inner side of the panel of the test unit layer. opt . To study the working performance of the reinforced soil retaining wall 2 with different grille types, namely M, A, and B type reinforcements and the length L of the reinforcement 22, the working performance of the reinforced soil retaining wall 2 with L = 1.0H, 0.7H, and 0.4H. The test working conditions are shown in Table 1 in detail. During the test, the vertical soil pressure at the vibration source position of the retaining wall, the horizontal displacement at different heights h of the panel of the test unit layer, and the strain of the reinforcement 22 are measured, and the dynamic load action effects under different working conditions are compared and analyzed. The test grouping scheme and parameters are shown in Table 1 in detail, where f is the frequency, P 0 is the amplitude, N is the number of reinforcement layers, u is the reinforcement layer spacing, B is the foundation width, L is the reinforcement length, and H is the retaining wall height.

[0073] Table 1 Test grouping list

[0074]

[0075]

[0076] Among them, the specific loading method in step 5 is as follows: The load loading device 3 first applies static loads step by step from zero to the predetermined dynamic load center value P 0 , and each stage is loaded with n kN, where n is a natural integer; then dynamic load values of P 0 ±n kN, P 0 ±2n kN, P 0 ±3n kN, P 0 ±4n kN, P 0 ±5n kN, P 0±6nkN, with a loading duration of 5 - 10 minutes for each level until the retaining wall fails to end the test. Among them, a specific measurement value is given in this application, that is, the above-mentioned P 0 When =30 and n=5, the load loading device 3 first applies static load step by step from zero to the predetermined dynamic load center value P 0 =30kN, with a loading of 5kN for each level; then dynamic load values of 30±5kN, 30±10kN, 30±15kN, 30±20kN, 30±25kN, and 30±30kN are applied in sequence, with a loading duration of 5 minutes for each level until the retaining wall fails to end the test.

[0077] In another embodiment of this application, step 2 includes the following steps:

[0078] Step 2.1: Fill and compact the filler 23 in layers in the test model box 1, and build the retaining wall panel 21 composed of assembled modules at the peripheral opening 12. The filling thickness of each test unit layer is 10 - 12 cm, and the height of the retaining wall is 110 - 144 cm; during the filling process, an electric plate compactor is used to level and compact the filler 23 3 - 5 times, and then a 15 - 30 kg weight is used to compact the filler 23 per unit area, with the number of compaction times per unit area being 4 - 7 times; during the flattening process, the filler 23 is gradually added until the compacted thickness of the test unit layer is 12 - 16 cm, and the compaction coefficient is above 95%;

[0079] Step 2.2: Lay the reinforcing material 22 on the compacted test unit layer according to the preset specifications, and one end of the reinforcing material 22 is connected to the retaining wall panel 21 composed of assembled modules; install a flexible displacement gauge 41 on the reinforcing material 22, and bury an accelerometer 43 and an earth pressure cell 44 in the test unit layer;

[0080] Step 2.3: Fix and install a displacement sensor 42 on the mounting frame 13 outside the peripheral opening 12, and the displacement sensor 42 abuts against the outside of the retaining wall panel 21 composed of assembled modules.

[0081] The purpose of such a setting can effectively make the simulated reinforced soil retaining wall 2 filled similar to the actual reinforced soil retaining wall 2 in structure, improving the accuracy of the actual simulation test data. Moreover, by arranging the above data acquisition devices 4 in a layered manner like this, the deformation conditions of each layer of the entire reinforced soil retaining wall 2 after receiving the load can be effectively measured.

[0082] Of course, in this application, in order to improve the accuracy of the test, the filler 23 in step 2.1 is medium sand with good particle gradation, and the medium sand parameters selected in this application are the coefficient of uniformity C u =8.80 - 9.02, and the coefficient of curvature C c= 1.30 to 1.35, the internal friction angle is 36 to 41°, the cohesion c is 1.28 to 1.32 kPa, and the dry density ρ dmax is 1.68 to 1.78 g / cm 3 . Among them, in this embodiment, the basic parameters of the sandy soil preferably obtained based on indoor geotechnical tests are: the density ρ is 1.81 g / cm 3 , the specific gravity of soil particles d s is 2.65, and the dry density ρ d is 1.69 g / cm 3 . The particle size distribution curve of the sandy soil particles is shown in detail in Figure 7 .

[0083] The present application provides a test method for the load performance of an assembled reinforced soil retaining wall. This method is easy to operate, easy to simulate and measure, can effectively simplify the data of conventional simulation and measurement, and at the same time, the measured data is more appropriate for the data when the actual reinforced soil retaining wall is damaged, with wide applicability.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the technical solutions of the present invention.

Claims

1. A method for testing the load performance of an assembled reinforced earth retaining wall, characterized in that: include: Step 1: The test method is based on a prefabricated reinforced earth retaining wall load performance test system. The prefabricated reinforced earth retaining wall load performance test system includes a test model box, a load loading device, a digital image testing system and a data acquisition device, wherein: The test model box has an upper opening and at least one peripheral opening, a reinforced earth retaining wall is arranged in the test model box, and the reinforced earth retaining wall is located at the peripheral opening; the test model box includes a base and a frame, the frame is installed on the base, a rear steel plate is arranged on the side of the frame opposite to the peripheral opening, and side steel plates and glass fiber reinforced plastic panels are arranged on both sides of the peripheral opening of the frame respectively; the reinforced earth retaining wall includes a retaining wall panel blocking the peripheral opening, a reinforcement material with one end fixed to the inner side of the retaining wall panel, and a filler coated on the outside of the reinforcement material, and the reinforcement material is provided with at least one layer; The load loading device can apply a vertical load to the reinforced earth retaining wall in the test model box from the upper opening and measure the vertical settlement of the reinforced earth retaining wall; the load loading device includes a reaction frame, a hydraulic cylinder with an output end downwardly arranged on the reaction frame, and a loading plate arranged on the output end of the hydraulic cylinder, and the hydraulic cylinder can apply a vertical load to the reinforced earth retaining wall in the test model box through the loading plate; The digital image testing system includes a digital camera and an image acquisition and analysis computer. A transparent glass fiber reinforced plastic panel is provided on one side of the test model box located at the peripheral opening. The digital camera and the image acquisition and analysis computer are both provided on one side of the glass fiber reinforced plastic panel. The digital camera can obtain deformation and displacement image information of the filler around different layers of reinforcement materials. The image acquisition and analysis computer can receive the image information captured by the digital camera, and calculate and draw the displacement cloud map and strain field of the filler layer near the interface between any layer of reinforcement materials and the filler. The data acquisition device is used to collect the deformation of the reinforced earth retaining wall after being loaded; the data acquisition device includes A flexible displacement meter is installed on the reinforcement and is used to measure the deformation of the reinforcement after being loaded; A displacement sensor is installed on the peripheral opening, the displacement sensor can slide relative to the retaining wall panel and is used to measure the horizontal displacement of the retaining wall panel after being loaded; a mounting frame is provided on the outer side of the test model box on one side of the peripheral opening, the displacement sensor is installed on the mounting frame, the mounting frame does not contact the retaining wall panel, and the displacement sensor abuts against the retaining wall panel; An accelerometer is installed in the filler and is used to measure the acceleration of the buried part after being loaded; Earth pressure cell, which is installed in the filler and is used to measure the amount of earth pressure after the load is applied to the buried area; At the beginning of the method, the above-mentioned prefabricated reinforced earth retaining wall load performance test system is prepared, and the load loading device and data acquisition equipment are debugged until they meet the preset requirements; Step 2: construct a test unit layer, fill and compact the filler and reinforcement in layers in the test model box, install a flexible displacement meter on the reinforcement, bury an accelerometer and an earth pressure box in the filler at a preset position, and build a retaining wall panel composed of assembled modules at the peripheral opening, so that the reinforcement is connected to the retaining wall panel composed of assembled modules; install a displacement sensor that can be fixed relative to the test model box on the retaining wall panel composed of assembled modules; Step 3: construct a reinforced earth retaining wall, and fill the test unit layer layer by layer according to the method of step 2 until the preset test height is reached and the reinforced earth retaining wall is formed; Step 4: Install the loading plate. After the reinforced earth retaining wall is completed, use a level ruler to level the uppermost test unit layer of the reinforced earth retaining wall, and then place the loading plate on the preset pressure test point of the uppermost test unit layer. Step 5: Loading test, debug the data acquisition equipment and unify the test time of each measurement. The load loading device adopts a sinusoidal loading method to load until the reinforced earth retaining wall is destroyed; during the test, various measurement data in the data acquisition equipment are recorded; the digital camera obtains the deformation and displacement image information of the filler around different layers of reinforcement materials, and the image acquisition and analysis computer can receive the image information taken by the digital camera, and calculate and draw the displacement cloud map and strain field of the filler layer near the interface between any layer of reinforcement materials and filler; the expression of the applied sinusoidal excitation force is as follows: , where P 0 is the load value (kN); P A is the dynamic load amplitude (kN); f is the loading frequency (Hz); t is time(s); Step 6: At the end of the test, after the reinforced earth retaining wall is destroyed, use a high-definition digital camera to photograph the cumulative deformation of the top loading plate and the retaining wall panel of the reinforced earth retaining wall and record the number of cracks.

2. A method for testing load performance of assembled reinforced earth retaining wall according to claim 1, characterized in that: The specific loading method in step 5 is: the load loading device first applies static load step by step from zero to a predetermined dynamic load center value. P 0, each level is loaded with nkN, n is a natural integer; then the dynamic load values ​​are applied in sequence P 0±nkN, P 0±2nkN, P 0±3nkN, P 0±4nkN, P 0±5nkN, P 0±6nkN, each level of loading lasts 5-10min, and the test ends when the retaining wall is destroyed.

3. The load performance test method of the assembled reinforced earth retaining wall according to claim 1 is characterized in that: Step 2 includes the following steps: Step 2.1, fill and compact the filler in layers in the test model box, and build a retaining wall panel composed of assembled modules at the openings on the side. The filling thickness of each test unit layer is 10-12 cm, and the height of the retaining wall is 110-144 cm. During the filling process, an electric flat plate compactor is used to level and compact the filler 3-5 times, and then a weight of 15-30 kg is used to compact the filler per unit area, and the number of compactions per unit area is 4-7 times. During the flattening process, filler is gradually added until the compacted thickness of the test unit layer is 12-16 cm, and the compaction coefficient is above 95%; Step 2.2, laying reinforcement materials on the compacted test unit layer according to preset specifications, one end of the reinforcement materials being connected to the retaining wall panel composed of the assembled modules; installing a flexible displacement meter on the reinforcement materials, and burying an accelerometer and an earth pressure cell in the test unit layer; Step 2.3: A displacement sensor is fixedly mounted on a mounting frame outside the peripheral opening, and the displacement sensor abuts against the outer side of the retaining wall panel formed by the assembled modules.

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