Test equipment for aeolian sand highway subgrade reduced scale model

Abstract

The utility model belongs to the technical field of civil engineering test equipment, and particularly discloses test equipment for an aeolian sand highway subgrade reduced scale model, which comprises a model box and a subgrade reduced scale model, the subgrade reduced scale model is arranged in the model box, a loading device is arranged above the subgrade reduced scale model, a displacement meter is arranged on the upper surface of the subgrade reduced scale model, and a displacement sensor is arranged on the upper surface of the displacement meter. A miniature settlement rod is embedded in the roadbed reduced scale model, soil pressure sensors are laid in the roadbed reduced scale model in a layered mode, a plurality of fiber bragg grating strain gauges are embedded in the roadbed reduced scale model below the loading device, the soil pressure sensors are connected with a soil pressure cell collector, and the fiber bragg grating strain gauges are connected with a fiber bragg grating demodulator. The soil pressure cell acquisition instrument and the fiber grating demodulation instrument are connected with the PC through wires; a displacement meter, a miniature settlement rod, a soil pressure sensor, a fiber bragg grating strain gauge and the like are laid and installed on the roadbed reduced scale model to detect various performance indexes of the roadbed reduced scale model after pressure is applied, and guidance is provided for actual engineering.

Description

Technical Field

[0001] The utility model belongs to the technical field of civil engineering test equipment, and in particular relates to a test equipment for a scaled model of a roadbed of aeolian sand highway. Background Art

[0002] Traditionally, highway construction relies on road-building materials such as sand and gravel, but in the desert areas of Xinjiang, other road-building materials are very scarce except for the abundant wind-blown sand, and the transportation cost is high. In view of the safety and stability requirements of automobiles running on the road, the engineering attaches great importance to the bearing characteristics and deformation characteristics of the highway subgrade.

[0003] The experimental research on highway subgrade is divided into field test and indoor test. Field test is expensive, technically demanding and inconvenient to carry out, so indoor test becomes the main research method. Indoor test includes full-scale model test and scaled model test. However, the workload of full-scale model test and the required manpower and material resources are close to field test, and the cost of conducting comprehensive research is extremely high. At the same time, there is a lack of good methods for stress and deformation testing inside the subgrade soil. In the process of studying the bearing characteristics and deformation characteristics of highway subgrade, these two issues become the main focus. It is urgent to develop a scaled model test equipment for highway subgrade that is close to actual working conditions, which can better carry out the research on the bearing characteristics and deformation characteristics of highway subgrade, provide guidance for actual engineering, and save manpower, financial resources and material resources. Utility Model Content

[0004] The utility model aims to provide a test device for a scaled model of a wind-blown sand highway embankment, so as to solve the problem of conducting indoor tests on the pressure and deformation of the wind-blown sand highway embankment under the action of automobile loads, so as to better measure the stress and deformation inside the wind-blown sand highway embankment.

[0005] In order to meet the above objectives, the technical solution adopted by the utility model is:

[0006] A test device for a scaled model of a roadbed of aeolian sand highway comprises a model box and a scaled model of the roadbed, wherein the scaled model of the roadbed is arranged in the model box, a loading device is arranged directly above the scaled model of the roadbed, a plurality of displacement meters are arranged on the upper surface of the scaled model of the roadbed, a plurality of miniature settlement rods are buried on the scaled model of the roadbed, a plurality of soil pressure sensors are laid in layers inside the scaled model of the roadbed, a plurality of fiber grating strain gauges are buried in the scaled model of the roadbed directly below the loading device, the soil pressure sensors are connected to a soil pressure box collector via a wire, the fiber grating strain gauges are connected to a fiber grating demodulator via a wire, and the soil pressure box collector and the fiber grating demodulator are connected to a PC via a wire.

[0007] Preferably, the loading device includes a ground anchor reaction frame, on which an electro-hydraulic pulsation fatigue testing machine is provided, the electro-hydraulic pulsation fatigue testing machine is connected to a testing machine control system via a wire, a bearing plate is provided at the lower end of the electro-hydraulic pulsation fatigue testing machine, and the bearing plate acts on a scaled model of the roadbed in the model box.

[0008] Preferably, a three-dimensional full-field strain testing system is provided on one side of the model box, and the three-dimensional full-field strain testing system includes two high-speed cameras, and the high-speed cameras are installed on one side of the model box through a support frame, and the high-speed cameras are connected to a control box through wires, and the control box is connected to a display through wires.

[0009] The beneficial effects of the utility model are:

[0010] The utility model places a scaled model of the roadbed in a model box to provide boundary conditions, and then applies pressure to the scaled model of the roadbed through a loading device to detect the bearing characteristics and deformation characteristics of the roadbed, and detects various performance indicators of the scaled model of the roadbed after the pressure is applied by laying and installing displacement meters, micro settlement rods, soil pressure sensors and fiber grating strain meters on the scaled model of the roadbed. The test can better carry out indoor research on the bearing characteristics and deformation characteristics of highway roadbeds, and provide guidance for practical projects. The utility model has the advantages of simple structure, convenient operation, high precision, short test time, and can more comprehensively monitor the strain, displacement, speed, acceleration and the like of the side of the roadbed model, and can simulate a variety of different working conditions, solving the problem that the existing model test device is difficult to monitor the strain of the entire section of the roadbed. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural schematic diagram of the utility model;

[0012] In the figure: 1. displacement meter, 2. micro settlement rod, 3. soil pressure sensor, 4. fiber grating strain gauge, 501. high-speed camera, 502. support frame, 503. control box, 504. display, 6. roadbed scale model, 7. fiber grating demodulator, 8. soil pressure box collector, 901. anchor reaction frame, 902. electro-hydraulic pulsation fatigue testing machine, 903. testing machine control system, 904. bearing plate, 10. model box, 11. PC. DETAILED DESCRIPTION

[0013] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments:

[0014] like Figure 1The test equipment for the scaled model of the roadbed of aeolian sand highway shown in the figure comprises a model box 10 and a scaled model of the roadbed 6. The scaled model of the roadbed 6 is contained in the model box 10 for testing. A loading device is arranged directly above the scaled model of the roadbed 6. The loading device comprises a ground anchor reaction frame 901. The ground anchor reaction frame 901 is provided with an electro-hydraulic pulsating fatigue testing machine 902 (the electro-hydraulic pulsating fatigue testing machine model used is PAM800-1000). The electro-hydraulic pulsating fatigue testing machine 902 is connected to the ground anchor reaction frame 901. The electro-hydraulic pulsating fatigue testing machine 902 is connected to the testing machine control system 903 through a conducting wire. A bearing plate 904 is provided at the lower end of the electro-hydraulic pulsating fatigue testing machine 902. The bearing plate 904 acts on the subgrade scale model 6 in the model box 10. When loading, the electro-hydraulic pulsating fatigue testing machine 902 is lifted by the anchor reaction frame 901. The testing machine control system 903 controls the electro-hydraulic pulsating fatigue testing machine 902 to apply force to the bearing plate 904, and the bearing plate 904 then transmits force to the subgrade scale model 6 to generate pressure on it. A number of displacement meters 1 (the displacement meter model used is KTC-100) are provided on the upper surface of the subgrade scale model 6 to detect the position of the road surface moving downward after the subgrade scale model 6 is loaded with pressure; a number of miniature settlement rods 2 are buried on the subgrade scale model 6 to detect and monitor the subgrade settlement; a number of soil pressure sensors 3 (the soil pressure sensor model used is BW27R) are laid in layers inside the subgrade scale model 6 to detect the pressure borne by the subgrade scale model 6; the subgrade scale model 6 directly below the loading device is provided with a plurality of displacement meters 1 (the displacement meter model used is KTC-100) ... 6 is embedded with a plurality of fiber grating strain gauges 4 (the fiber grating strain gauge model used is ZX-FBG-S01D) for measuring the strain of the scaled roadbed model 6; the soil pressure sensor 3 is connected to the soil pressure box collector 8 (the model used is JM5951 collector) through a wire, the fiber grating strain gauge 4 is connected to the fiber grating demodulator 7 (the fiber grating demodulator model used is ZX-FP-C04-1) through a wire, the soil pressure box collector 8 and the fiber grating demodulator 7 are connected to the PC 11 through a wire, and the data detected by the soil pressure sensor 3 and the fiber grating strain gauge 4 are collected through the fiber grating demodulator 7 and the soil pressure box collector 8, and then displayed on the PC 11.

[0015] A three-dimensional full-field strain testing system is provided on one side of the model box 10. The three-dimensional full-field strain testing system includes two high-speed cameras 501. The high-speed cameras 501 are installed on one side of the model box 10 through a support frame 502. The high-speed cameras 501 are connected to a control box 503 through wires, and the control box 503 is connected to a display 504 through wires.

[0016] The material of the model box 10 is angle steel, organic glass and high-transmittance and high-strength ordinary glass. One side of the model box 10 is used as an observation surface, and is surrounded by high-transmittance and high-strength glass. The observation surface of the roadbed scale model 6 placed in the model box 10 is sprayed black with matte black paint. After the paint is dried, a matte white paint pen is used to make white scattered spots on the observation surface (the requirements for scattered spots are: the produced speckles must ensure randomness, and the determination of the speckle size needs to be identified by computer, and it is best to control it within 3-5 pixels). It is used in the three-dimensional full-field strain test system as a sign for monitoring the deformation of the roadbed scale model, and is used to monitor the cumulative plastic deformation of the roadbed soil.

[0017] Example

[0018] When conducting highway subgrade bearing and cumulative plastic deformation model tests, the specific steps are as follows:

[0019] (1) After the aeolian sand filler is dried and cooled, mix it to the optimal moisture content and let it sit overnight to make the moisture content fully uniform for later use.

[0020] (2) Calculate the volume of each layer according to the actual requirements of the thickness and compaction of the aeolian sand roadbed scale model. , calculate the wet density at the optimal moisture content , calculate the filler mass required for each layer .

[0021] (3) Weigh the fillers required for each layer and put them into the model box and spread them evenly. Use a vibrating compactor to compact each layer of fillers before filling the next layer.

[0022] (4) When the filling reaches the place where the monitoring equipment (soil pressure sensor 3 and fiber Bragg grating strain gauge 4, etc.) needs to be buried, first chisel out a groove the size of the monitoring equipment in the layer of aeolian sand filler, install the monitoring equipment in the groove of the aeolian sand roadbed, and use a small bubble level to calibrate the instrument to ensure that it is installed horizontally.

[0023] (5) After filling to the top, a black-bottomed white speckle observation surface is made on the observation surface of the aeolian sand roadbed scale model 6, and a displacement meter 1 is installed on the surface and a micro settlement rod 2 is buried. The three-dimensional full-field strain test system is installed and debugged. The specific steps of the test are as follows:

[0024] Step 1: Spray the observation surface of the completed wind-blown sand roadbed scale model 6 with matte black paint evenly. The thickness is required to be uniform and should not be too thick or too thin. Too thick will cause the produced speckle to be not completely consistent with the deformation of the wind-blown sand filler, while too thin will make it difficult to produce speckle and the speckle imaging effect will be poor.

[0025] Step 2: Use a matte white paint pen to create speckles on the observation surface after black spraying. Randomness must be guaranteed, and the size of the speckles needs to be determined by computer recognition. It is best to control it within 3-5 pixels.

[0026] Step 3. Select a fixed-focus lens with an appropriate focal length based on the scope of the site and the size of the observation surface.

[0027] Step 4: After installing the two high-speed cameras 501 and the support frame 502, adjust the lenses to the best imaging effect, that is, the imaging effect is the clearest, the brightness is uniform, and there is no exposure.

[0028] Step 5. Open the test analysis software and calibrate the lens with a calibration ruler to eliminate the distortion caused by the lens.

[0029] Step 6. Enter the acquisition mode, try to collect a few photos, then enter the analysis mode, perform calculations and analysis on the trial photos, and after checking that the imaging effect is good, return to the acquisition mode and wait for loading to start acquisition.

[0030] (6) Complete the debugging of each monitoring instrument and read the initial value of each sensor.

[0031] (7) Load the scaled model of the roadbed and collect the corresponding data obtained by each monitoring device at regular intervals. The applied load is divided into static load and dynamic load:

[0032] Case 1: When performing static loading, you only need to use the bearing area and applied stress to calculate the required pressure.

[0033] Case 2: When dynamic loading is performed, the vibration frequency needs to be determined. Considering that this is a scaled model test of aeolian sand roadbed, the vibration frequency under the action of the vehicle load is calculated. A sinusoidal wave load is used to apply vibration load to the scaled model of aeolian sand roadbed. The expression of the proposed sinusoidal wave load is:

[0034] Where: P is the dynamic load size, P0 is the load mean, simulating the static load of the car; P d is the dynamic load amplitude, simulating the additional load caused by vehicle vibration; f is the load frequency, and t is the time.

[0035] The determination of frequency f is related to the car. , where v is the driving speed and L is the length of the simulated vehicle. The specific vibration frequency f needs to be determined according to actual requirements.

[0036] The examples of the utility model are described in detail above in conjunction with the embodiments, but the utility model is not limited to the above examples. Various changes can be made within the knowledge scope of ordinary technicians in the field without departing from the purpose of the utility model, and should also be regarded as the protection scope of the utility model.

Claims

1. A test device for a scaled model of a roadbed of aeolian sand, comprising a model box (10) and a scaled model of the roadbed (6), wherein the scaled model of the roadbed (6) is arranged in the model box (10), and characterized in that: A loading device is provided directly above the scaled-down model of the roadbed (6); a plurality of displacement meters (1) are provided on the upper surface of the scaled-down model of the roadbed (6); a plurality of miniature settlement rods (2) are buried on the scaled-down model of the roadbed (6); a plurality of soil pressure sensors (3) are laid in layers inside the scaled-down model of the roadbed (6); a plurality of fiber grating strain gauges (4) are buried in the scaled-down model of the roadbed (6) directly below the loading device; the soil pressure sensors (3) are connected to a soil pressure box acquisition instrument (8) via a wire; the fiber grating strain gauges (4) are connected to a fiber grating demodulator (7) via a wire; and the soil pressure box acquisition instrument (8) and the fiber grating demodulator (7) are connected to a PC (11) via a wire.

2. The test equipment for the scaled model of aeolian sand highway embankment according to claim 1, characterized in that: The loading device comprises a ground anchor reaction frame (901), an electro-hydraulic pulsation fatigue testing machine (902) is arranged on the ground anchor reaction frame (901), the electro-hydraulic pulsation fatigue testing machine (902) is connected to a testing machine control system (903) via a wire, a bearing plate (904) is arranged at the lower end of the electro-hydraulic pulsation fatigue testing machine (902), and the bearing plate (904) acts on a roadbed scale model (6) in the model box (10).

3. The test equipment for the scaled model of aeolian sand highway embankment according to claim 1, characterized in that: A three-dimensional full-field strain test system is provided on one side of the model box (10), and the three-dimensional full-field strain test system comprises two high-speed cameras (501). The high-speed cameras (501) are installed on one side of the model box (10) via a support frame (502), and the high-speed cameras (501) are connected to a control box (503) via a wire, and the control box (503) is connected to a display (504) via a wire.

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