Geogrid drawing model test device under freezing and thawing cycle effect

Abstract

The utility model provides a geogrid drawing model test device under the action of freeze-thaw cycle. The geogrid drawing model test device comprises a support base, and a constant-temperature water tank, a test box and a water circulating pipe connected between the constant-temperature water tank and the test box are arranged on the support base; a portal frame is arranged at the position close to the test box, a pressure loading structure is arranged on the portal frame, the test box is connected with a tension loading structure, and the pressure loading structure and the tension loading structure are connected with an upper computer. And a heater and a temperature controller are arranged on the constant-temperature water tank and are connected with each other. According to the geogrid drawing model test device under the action of the freeze-thaw cycle, the drawing characteristic of a material under the freeze-thaw cycle is researched under the laboratory condition, the frequency and time of the freeze-thaw cycle are controlled by utilizing the temperature change of the temperature box, data are acquired by utilizing the sensor in the process, and the test result is accurate. The influence on the interior of the geogrid under different conditions and different stages is analyzed.

Description

Technical Field

[0001] The utility model belongs to the technical field of engineering tests, and particularly relates to a geogrid pull-out model test device under freeze-thaw cycles. Background Technique

[0002] A geogrid is a geosynthetic material used for reinforcing soil masses, having good tensile strength and durability, and is commonly used in infrastructure construction such as highways, railways, and dams to enhance the stability and bearing capacity of soil masses. The impact of freeze-thaw cycles on geotechnical structures is a key issue, especially in infrastructure construction in cold regions (such as Xinjiang, Northeast China, etc.). In these regions, seasonal freeze-thaw processes can cause changes in soil volume, thereby having a negative impact on the performance and stability of geotechnical structures such as geogrids. Traditional geotechnical materials may become loose, deformed, or damaged in a freeze-thaw environment, which not only affects the safety and reliability of the project but also increases the maintenance cost and frequency. To address these challenges, the scientific and engineering communities have begun to focus on improving the freeze-thaw resistance of geogrids. Freeze-thaw cycles refer to the process in which water in the soil repeatedly freezes and thaws during temperature changes. The impact of this process on geogrids is mainly manifested as follows: physical damage, freeze-thaw cycles cause changes in soil structure, which may lead to volume expansion and contraction of the soil mass, thereby generating certain shear stress and tensile stress on the geogrid embedded in the soil mass; material aging, repeated freeze-thaw cycles will accelerate the aging of geogrid materials and reduce their tensile strength and durability.

[0003] The pull-out performance of a geogrid refers to the magnitude of the tensile force it can withstand in the soil mass and the interfacial friction with the surrounding soil mass, which is an important indicator for evaluating the reinforcement effect of geogrids. Under the action of freeze-thaw cycles, the pull-out performance of geogrids may change significantly. Therefore, special research and testing are required to ensure project safety. This solution proposes a geogrid pull-out model test device under freeze-thaw cycles to measure the pull-out performance of geogrids under freeze-thaw cycles under laboratory conditions and study the tensile strength and durability of the materials. Content of the Utility Model

[0004] The purpose of the utility model is to provide a geogrid pull-out model test device under freeze-thaw cycles, which solves the technical problem of how to study the pull-out characteristics of materials under freeze-thaw cycles under laboratory conditions. By changing the temperature of the temperature chamber, the number of freeze-thaw cycles and time are controlled. During the process, sensors are used to obtain data and analyze the influence on the inside of the geogrid under different conditions and at different stages.

[0005] A geogrid pull-out model test device under freeze-thaw cycles includes a support base, on which a constant temperature water tank, a test chamber, and a water circulation pipe connected between the constant temperature water tank and the test chamber are provided;

[0006] A gantry is arranged near the test chamber, a pressure loading structure is arranged on the gantry, the test chamber is connected to a tensile loading structure, and the pressure loading structure and the tensile loading structure are connected to a host computer.

[0007] A heater and a temperature controller are arranged on the constant temperature water tank, and the heater is connected to the temperature controller.

[0008] The test chamber includes a freeze-thaw box and a material box arranged inside the freeze-thaw box. The freeze-thaw box is closely attached to the material box to control the temperature change of the material, and the freeze-thaw box is connected to a refrigeration system.

[0009] The constant temperature water tank is connected to the freeze-thaw box through the water circulation pipe to control the temperature of the freeze-thaw box.

[0010] The pressure loading structure includes a second jack fixed at the top end of the gantry, a loading plate fixed at the free end of the second jack, and a second force sensor fixed at the bottom end of the loading plate. The loading plate movably closes the top opening of the freeze-thaw box.

[0011] The tensile loading structure includes a reaction frame fixed on the outer side of the freeze-thaw box, a first jack fixed on the reaction frame, a reaction pull-out rod connected to the first jack, the free end of the first jack is connected to a fixture, the fixture is connected to a displacement meter, and the reaction pull-out rod is connected to a first force sensor.

[0012] A fixture is arranged inside the freeze-thaw box. The fixture includes an inner clamping plate and an outer clamping plate connected in parallel to each other. A geogrid is arranged between the inner clamping plate and the outer clamping plate. A plurality of temperature sensors are arranged inside the geogrid, and the outer clamping plate is connected to a displacement meter.

[0013] Both the first force sensor and the second force sensor are connected to the host computer.

[0014] The positive effects of the present utility model are as follows:

[0015] (1) By changing the temperature and time of freeze-thaw through the refrigeration system, experiments on the geogrid are carried out using the pressure loading structure and the tensile loading structure. Through the data acquisition system, temperature data is continuously collected and analyzed to understand the specific influence mode of freeze-thaw cycles on the soil and the grid. Combining with the temperature sensors arranged around the geogrid, the temperature change of the soil is monitored in real time, especially the temperature fluctuation during the freeze-thaw cycle. After different freeze-thaw cycles, a pull-out experiment on the geogrid is carried out to evaluate its pull-out resistance performance, analyze the adjustment effect of the temperature controller on the soil temperature change, and finally evaluate its influence on the performance of the geogrid.

[0016] (2) This solution can more accurately simulate the interfacial mechanical properties of reinforced soil under freeze-thaw cycles. It adopts advanced sensing technologies and an automatic control system to collect parameters such as temperature and deformation coefficient, and adjusts the test conditions according to real-time data to improve the test accuracy and reliability. Compared with traditional test devices for the interfacial properties of reinforced soil, this device can conduct freeze-thaw cycle tests to study the interfacial mechanical properties of reinforced soil under special conditions. Description of the Drawings

[0017] Figure 1 This is the front view of the pull-out model test device in the present utility model.

[0018] Figure 2 This is the schematic three-dimensional structure diagram of the pull-out model test device in the present utility model.

[0019] Figure 3 This is the schematic connection structure diagram of the gantry and the jack in the present utility model.

[0020] Figure 4 This is the schematic connection structure diagram of the outer splint and the inner splint in the present utility model.

[0021] Among them, the reference numerals are: 1, constant temperature water tank; 2, support base; 3, water circulation pipe; 4, test box; 5, gantry; 6, tensile loading structure; 7, jack one; 101, freeze-thaw box; 102, material box; 103, loading plate; 104, jack two; 105, inner splint; 106, outer splint; 107, displacement gauge; 108, force sensor one; 109, reaction frame; 110, reaction pull-out rod. Detailed Embodiment

[0022] In order to more clearly illustrate the technical features of this solution, the following will elaborate on this solution through specific embodiments.

[0023] See Figures 1-3 , a pull-out model test device for geogrid under freeze-thaw cycles, including a support base 2, on which a constant temperature water tank 1, a test box 4, and a water circulation pipe 3 connecting the constant temperature water tank 1 and the test box 4 are arranged;

[0024] A gantry 5 is arranged near the test box 4, a pressure loading structure is arranged on the gantry 5, the test box 4 is connected to the tensile loading structure 6, and the pressure loading structure and the tensile loading structure 6 are connected to the host computer.

[0025] A heater and a temperature controller are arranged on the constant temperature water tank 1, and the heater and the temperature controller are connected.

[0026] The test chamber 4 includes a freeze-thaw chamber 101 and a material box 102 disposed inside the freeze-thaw chamber 101. The freeze-thaw chamber 101 is in close contact with the material box 102 to control the temperature change of the material, and the freeze-thaw chamber 101 is connected to the refrigeration system.

[0027] The constant temperature water tank 1 is connected to the freeze-thaw chamber through the water circulation pipe 3 to control the temperature of the freeze-thaw chamber.

[0028] The pressure loading structure includes a second jack 104 fixed at the top end of the gantry 5, a loading plate 103 fixed at the free end of the second jack 104, and a second force sensor fixed at the bottom end of the loading plate 103. The loading plate 103 movably closes the top opening of the freeze-thaw chamber 101.

[0029] The tension loading structure 6 includes a reaction frame 109 fixed outside the freeze-thaw chamber 101, a first jack 7 fixed on the reaction frame 109, a reaction pull rod 110 connected to the first jack 7. The free end of the first jack 7 is connected to a fixture, the fixture is connected to the displacement gauge 107, and the reaction pull rod 110 is connected to the first force sensor 108.

[0030] When the reaction pull rod 110 pulls outwards, due to the action and reaction forces, a reaction force will be applied to the test chamber 4, so a reaction frame 109 is added to withstand the test chamber 4 with the reaction force, and the displacement gauge 107 will be pulled out to measure the displacement.

[0031] A fixture is provided inside the freeze-thaw chamber. The fixture includes an inner clamping plate 105 and an outer clamping plate 106 connected in parallel. A geogrid is provided between the inner clamping plate 105 and the outer clamping plate 106. A plurality of temperature sensors are arranged inside the geogrid. The outer clamping plate 106 is connected to the free end of the first jack 7, and one end of the displacement gauge 107 is connected to the outer clamping plate 106. Under the action of the telescopic rod in the first jack 7, the outer clamping plate 106 is driven to move, and the outer clamping plate 106 drives the displacement gauge 107 to move to measure the displacement. The displacement gauge 107 is arranged inside the reaction frame 109 to achieve position limitation.

[0032] Both the first force sensor 108 and the second force sensor are connected to the host computer.

[0033] The specific working process of the present utility model:

[0034] The device of the present utility model includes a constant temperature water tank 1, a support base 2, a water circulation pipe 3, a test chamber 4, a gantry 5, and a tension loading structure 6.

[0035] Among them, the inside of the constant temperature water tank 1 is made of steel to build the water tank, and the outside is fitted with heat insulation materials to ensure accurate temperature; the support base 2 is made of high-strength materials to support the test device; the water circulation pipe 3 is connected to the constant temperature water tank 1 and the freeze-thaw chamber 101 of the test chamber 4 with a heat-insulated hose to control the temperature of the freeze-thaw chamber;

[0036] The test chamber 4 is composed of a freeze-thaw chamber 101 and a material box 102. The freeze-thaw chamber uses external thermal insulation materials and materials with a lower specific heat capacity inside to conduct heat. The material box 102 uses materials with a lower specific heat capacity to improve the temperature conduction efficiency. The loading plate 103 uses 1 cm thick steel to withstand the pressure of the jack.

[0037] The gantry 5 serves as a carrier for the jack 104 to apply a normal load. The fixture in the tensile loading structure 6 is composed of an inner clamping plate 105 and an outer clamping plate 106. A geocell is placed between the inner clamping plate 105 and the outer clamping plate 106. A displacement gauge 107 is used to measure the tensile length of the geocell, and a force sensor 108 is used to test the tensile force. The jack 7 provides the tensile force, and a reaction frame 109 is used to apply a reaction force to the pull-out rod 110.

[0038] The temperature control test method in this solution: Use the constant temperature water tank 1 to set the required test temperature, and transfer the constant temperature water to the tensile loading structure 6 through the water circulation pipe 3 to control the temperature of the specimen. The temperature sensor is installed inside the geogrid to monitor the temperature change of the specimen in real time to ensure the temperature stability during the test.

[0039] The pull-out test method in this solution includes the following:

[0040] (1) Soil sample preparation: Collect a sufficient amount of soil samples, process and screen them according to the experimental requirements, and use an electronic scale to weigh the soil samples to ensure that the mass of each test sample is uniform.

[0041] (2) Place the soil sample in the lower pull-out box, use a vibrator or manually compact it to the designed compaction degree, and then place the geocell. To ensure that the geocell plays its maximum role, it can be fixed with an iron rod first, and then fill the soil more than 10 cm above the geocell and compact the soil to wrap the geocell with the soil.

[0042] (3) Then pull out the iron rod, and finally fill and compact the soil in the upper pull-out box in the same way as the operation of the upper pull-out box. During the process, please ensure that the soil is filled evenly and solidly.

[0043] Among them, the upper pull-out box, the lower pull-out box, the iron rod and the vibrator are all prior arts in this field and will not be elaborated here.

[0044] (4) Remove the nuts on both sides of the fixture, place the geocell in the sandwich between the inner clamping plate 105 and the outer clamping plate 106, and then fix and clamp it with nuts to ensure that it will not come off during the pull-out process.

[0045] (5) Then turn on the constant temperature water tank 1, set the required water temperature, and turn on the water circulation pipe 3 to ensure that the temperature sensor is consistent with the water tank temperature.

[0046] (6) Install a displacement gauge 107 at the outer splint 106 to ensure that the value is 0 at the start of the test.

[0047] (7) Start the test process. First, provide the required normal pressure through the second jack 104 on the gantry 5 to ensure that it is applied at the exact center of the loading plate 103. Subsequently, use the first jack 7 to provide the pulling force required for the pulling rod. The value can be measured using the first force sensor 108. As the pulling progresses, the displacement starts to change. When the required displacement for the test is reached, the test ends.

[0048] (8) Data recording and monitoring: Use a computer data acquisition system to record various data during the test, including real-time acquisition and timed acquisition; regularly check the operating status of each sensor and instrument to ensure the accuracy and reliability of data recording; monitor the operation of the test device in real time and adjust the parameters in a timely manner to ensure the stable progress of the test.

[0049] (9) End of the test and data processing: When the test end point or the test purpose is reached, stop the operation of the test device; export the test data to the computer and perform data processing and analysis, including data cleaning, curve fitting, statistical analysis, etc.; write an experimental report, including the experimental design, method, results, and conclusions, etc. Cleaning and maintenance: Remove the soil sample from the shear box, clean the test device to ensure that the equipment is clean and tidy. Regularly check and maintain the test device, including sensor calibration, equipment debugging, part replacement, etc.

[0050] The technical features not described in this utility model can be achieved by or adopt the prior art and will not be elaborated here. Of course, the above description is not a limitation of this utility model, and this utility model is not limited to the above examples. Changes, modifications, additions, or substitutions made by those of ordinary skill in the art within the scope of the essence of this utility model should also fall within the protection scope of this utility model.

Claims

1. A direct shear test device for geogrid under freeze-thaw cycles, comprising a support base (2), characterized in that, A constant temperature water tank (1), a test chamber (4), and a water circulation pipe (3) connected between the constant temperature water tank (1) and the test chamber (4) are provided on the support base (2). A gantry (5) is provided near the test chamber (4). A pressure loading structure is provided at the top of the gantry (5). The outside of the test chamber (4) is connected to a tensile loading structure (6). The pressure loading structure and the tensile loading structure (6) are connected to a host computer.

2. The geogrid pull-out model test device under freeze-thaw cycles according to claim 1, characterized in that The test chamber (4) includes a freeze-thaw chamber (101) and a material box (102) provided inside the freeze-thaw chamber (101). The freeze-thaw chamber (101) is in close contact with the material box (102) to control the temperature change of the material. The freeze-thaw chamber (101) is connected to a refrigeration system.

3. The geogrid pull-out model test device under the action of freeze-thaw cycles according to claim 2, characterized in that A heater and a temperature controller are provided on the constant temperature water tank (1). The heater and the temperature controller are connected. The constant temperature water tank (1) is connected to the freeze-thaw chamber (101) through the water circulation pipe (3) to control the temperature of the freeze-thaw chamber (101).

4. The geogrid pull-out model test device under freeze-thaw cycles according to claim 3, wherein, The pressure loading structure includes a second jack (104) fixed at the top of the gantry (5), a loading plate (103) fixed at the free end of the second jack (104), and a second force sensor fixed at the bottom end of the loading plate (103). The loading plate (103) movably closes the top opening of the freeze-thaw chamber (101).

5. The direct shear test device for geogrid under freeze-thaw cycles according to claim 4, characterized in that The tensile loading structure (6) includes a reaction frame (109) fixed on the outside of the freeze-thaw chamber (101), a first jack (7) fixed on the reaction frame (109), a reaction pulling rod (110) connected to the first jack (7). The free end of the first jack (7) is connected to a clamp. The clamp is connected to a displacement gauge (107). The reaction pulling rod (110) is connected to a first force sensor (108).

6. The geogrid pull-out model test device under freeze-thaw cycles according to claim 5, characterized in that, A clamp is provided inside the freeze-thaw chamber (101). The clamp includes inner clamping plates (105) and outer clamping plates (106) connected in parallel to each other. A geocell is provided between the inner clamping plates (105) and the outer clamping plates (106). A plurality of temperature sensors are arranged inside the geocell. The outer clamping plates (106) are connected to the displacement gauge (107).

7. The pull-out model test device for geogrid under freeze-thaw cycles according to claim 6, characterized in that, Both the first force sensor (108) and the second force sensor are connected to the host computer.

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