Visual soil freeze-thawing process test apparatus

[0037] With reference to the drawings, the present invention will be further detailed through actual measurement examples:

[0038] Such as Figure 1-8 As shown, a visualized soil freezing and thawing process test device, including 1. Mariott bottle 2. Bracket 3. Displacement sensor 4. Handle 5. Temperature control top plate 6. Probe hole 7. Temperature sensor 8. Sealing ring 9. Water level adjustment tube 10. Water pipe 11. Temperature control bottom plate 12. Filter paper 13. Semi-cylindrical sample tank 14. Soil sample 15. High resolution camera 16. Temperature control box 17. Adjustable light source 18. Data acquisition instrument 19. Electronic computer 20. Circulation slot. The temperature control box 16 is connected with an external compressor, and the temperature in the temperature control box 16 is controlled by the compressor, so that the temperature of the box body reaches the ambient temperature required by the test and remains stable; in the temperature control box 16, a semi-cylindrical sample tank 13 is placed on the temperature control bottom plate 11, the temperature control bottom plate 11 is engraved with a groove, and a sealing ring 8 is arranged on the groove to contact the bottom surface of the semi-cylindrical sample tank 13, so as to ensure the tightness of the tank body during the test; There are two small holes on the warm bottom plate 11, one of which is connected to the Mariot bottle 1 through the water pipe 10, and the other hole is connected to the water head adjusting pipe 9. During the test, the water head adjusting pipe 9 is used to make the Mariote bottle The air pressure, water pressure, external atmospheric pressure in 1 and the bottom surface pressure of soil sample 14 are in equilibrium, so as to realize the control of the test water supply conditions; filter paper 12 and soil sample 14 are placed on the temperature control bottom plate 11 in sequence, and the top of soil sample 14 is with temperature control The top plate 5 contacts, the temperature control top plate 5 has a circulation groove 20, and the top plate is equipped with a handle 4, so that the temperature control top plate 5 can be easily moved; the temperature control top plate 5 and the temperature control bottom plate 11 are composed of upper and lower cover plates (such as image 3 (Shown), a circulation groove 20 is engraved on the cover plate, and the circulation groove 20 is connected with an external cold bath to realize the control of the end surface temperature of the soil sample 14; the temperature control top plate 5, the sample tank 13 and the temperature control bottom plate 11 pass through the bracket 2 The displacement sensor 3 is fixed on the bracket 2 and is in contact with the top surface of the temperature control top plate 5; the temperature sensor 7 is inserted into the soil sample 14 through the probe hole 6 on the wall of the sample tank 13. During the test, the temperature sensor 7 and The displacement sensor 3 is connected to the data acquisition instrument 18 through a lead wire, so that the dynamic change process of the axial temperature and displacement of the soil sample 14 over time during the test can be obtained; the adjustable light source 17 is placed on both sides of the high-resolution camera 15, which can be adjusted The dimming light source 17 can ensure the quality of the images collected by the high-resolution camera 15 on the one hand, and on the other hand can also enhance the comparability between different experiments; the high-resolution camera 15 is placed on the front of the semi-cylindrical sample tank 13, with the lens perpendicular to On the wall surface of the semi-cylindrical sample tank 13, the high-resolution camera 15 is connected to the electronic computer 19 through a lead wire. The electronic computer 19 can control the format and sampling interval of the image collected by the high-resolution camera 15 during the test.

[0039] A one-way freezing test under open system conditions was performed on clay with a water content of 20% indoors, and the test time was 120h. Before the test, adjust the temperature of the temperature control box, the temperature control ceiling, and the bottom plate to 1℃ and keep it at a constant temperature for 6h-8h. After the internal temperature of the soil sample is evenly distributed, keep the temperature of the temperature control box and the temperature control bottom plate unchanged, and quickly lower the temperature control top plate The temperature reaches -15°C for one-way freezing test. The freezing process pictures collected during the test are as follows Figure 9-12 Shown. Figure 9-12 It shows that with the continuation of the one-way freezing time, the freezing front of the soil gradually moves down, the ice-containing area gradually expands, and the redistribution of water in the soil is more obvious. Figure 9-12 It can be seen the whole process of the development of the ice layer inside the soil during the one-way freezing of the soil. Picture 9 Is the initial state of the sample; Picture 10 After the negative temperature is applied to the cold end of the sample, the freezing front moves down rapidly at the initial stage of soil freezing, and part of the water inside the soil turns into ice; Picture 11 with Picture 12 As the freezing duration increases, the downward speed of the freezing front of the soil decreases, and more water inside the soil becomes ice, which produces a clear ice layer inside the soil, which in turn causes the volume of the soil to expand. Frost heave.

[0040] The present invention combines the temperature change process of the sample at different levels and the total deformation of the soil obtained by the test, and can be processed by digital processing such as format conversion, gray conversion, geometric distortion correction, reflection removal, and image segmentation selection threshold. Obtain the soil freezing rate, water migration rate, ice crystal growth rate, ice thickness, frost heave rate and other parameters.