Cyclic test device suitable for soil moisture absorption, infiltration and evaporation

Abstract

The invention relates to the field of soil monitoring, and discloses a soil moisture absorption infiltration and evaporation cycle test device, which comprises a sample test mechanism, the sample test mechanism comprises a closed shade box, the bottom of the closed shade box is provided with a cement layer, the cement layer is internally provided with a buried heating component, the cement layer is provided with a weighing platform, and the weighing platform is provided with a weighing device. An acrylic bottom plate for bearing a sample and a water body is arranged on the weighing table, an enclosure frame is arranged at the top of the acrylic bottom plate, two concave shallow clamping grooves are formed in the acrylic bottom plate, and a hole is formed in the side, close to the water supply Markov bottle, of the enclosure frame and connected with a third valve. A bionic constraint system is constructed through an adjustable air pressure elastic film and a dip angle adjustable frosted water-permeable partition plate, dynamic association is formed between constraint stress fed back by a pressure sensor in real time and crack expansion captured by a high-definition camera, and the coupling rule of constraint strength-crack form-seepage velocity is quantitatively revealed for the first time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil monitoring, in particular to a soil water absorption and evaporation cycle test device. BACKGROUND

[0002] Soil cracking is a key scientific problem in the fields of ecological geotechnical engineering and water environment. In particular, in arid environments, soil dry shrinkage cracking not only causes rapid soil water loss, vegetation growth obstruction, and shallow soil block sliding instability of slopes, but also accelerates the migration and diffusion of pollutants through the cracking channels. When rainwater or surface runoff carrying pollutants (such as agricultural non-point source pollutants, industrial leakage pollutants, etc.) seeps into the soil, the preferential flow path formed by the cracking significantly improves the penetration efficiency of pollutants into deep soil and groundwater, posing a potential threat to water environment safety. Therefore, studying the evaporation and infiltration processes of water before and after soil cracking is not only an important theoretical basis for revealing soil hydrological processes, but also a key prerequisite for analyzing the migration and transformation rules of pollutants in the soil-water system.

[0003] Current soil column test research or test design mostly focuses on the evaporation and infiltration of soil in the vertical direction. Due to the small size and strong boundary effect of the circular column top opening, the cracking effect of soil in the vertical soil column after drying is not good. The existing device cannot fully simulate the evaporation and infiltration process of layered soil after drying and cracking, and it is difficult to accurately capture the influence mechanism of the cracking channel on pollutant migration. Moreover, there is a lack of related research on lateral infiltration and pollutant migration in the horizontal direction. Although a few scholars have attempted to study the horizontal infiltration process of soil by placing the soil column horizontally, this method cannot obtain the cracking damage effect of soil during the drying stage, nor can it simulate the migration path of pollutants under the coupling effect of cracking and water. In addition, the temperature field generated by the heat source (incandescent lamp) in the traditional way is unevenly distributed in space, which is quite different from the actual environment. The movement scale of the soil wetting front through manual reading has visual angle errors, which restricts the in-depth study of the collaborative migration mechanism of soil water and pollutants. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a soil water absorption and evaporation cycle test device, which solves the problems of current soil column test research being limited to vertical evaporation and infiltration processes, strong boundary effect, poor cracking simulation, lack of horizontal infiltration research, uneven heat field, and large manual observation errors.

[0005] To achieve the above purpose, the present application realizes the following technical scheme: a soil water absorption and evaporation cycle test device, comprising a liquid push water supply mechanism, a sample test mechanism, a wetting front scale test mechanism, and a numerical control output mechanism. The liquid water supply mechanism includes a water supply marshall bottle, the bottom of which is provided with an opening and a valve two, and the bottom of the water supply marshall bottle is provided with a scissor type lifting platform, the middle of the lifting platform support is provided with a long screw rod, and the water supply marshall bottle is connected with the sample testing mechanism through a rubber hose. The sample testing mechanism includes a sealed cover box, the bottom of which is provided with a cement layer, the inside of the cement layer is provided with a buried heating component, the cement layer is provided with a weighing platform, the weighing platform is provided with an acrylic bottom plate for carrying samples and water, the top of the acrylic bottom plate is provided with a surrounding frame, the acrylic bottom plate is provided with two concave shallow clamping grooves, the surrounding frame is provided with a valve three on the side close to the water supply marshall bottle, the valve three is connected with the valve two through a rubber hose, the top of the surrounding frame is provided with front and rear opposite sticky steel teeth, the concave shallow clamping grooves of the surrounding frame are respectively embedded with a frosted water permeable partition plate one and a frosted water permeable partition plate two, and the frosted water permeable partition plate one and the frosted water permeable partition plate two are movable along the concave shallow clamping grooves in the surrounding frame, the surfaces of the frosted water permeable partition plate one and the frosted water permeable partition plate two are etched with micron level grooves to simulate soil particle interface, and the outside is additionally provided with two elastic constraint films distributed on the side edges, the film is filled with an air bag with adjustable air pressure, and the inside is provided with a micro pressure sensor element, a predetermined water level scale is arranged on the side wall between the surrounding frame and the frosted water permeable partition plate one, a bearing cavity for bearing the test soil is arranged between the frosted water permeable partition plate one and the frosted water permeable partition plate two, a high-definition camera is arranged above the sealed cover box, and a temperature sensor is arranged on the inner wall of the sealed cover box. The wetting front scale testing mechanism includes a stainless steel guide rail, which is provided with a laser instrument that can slide linearly along the length direction; The numerical control output mechanism includes a control terminal for collecting images and data, the control terminal is connected with the weighing platform, the high-definition camera and the temperature sensor, and the control terminal is connected with a temperature controller.

[0006] Preferably, the inside of the water supply marshall bottle is fixed with a hollow pipe in communication with the atmosphere, and the top of the water supply marshall bottle is provided with an opening and a valve one.

[0007] Preferably, the middle of the sealed cover box is a glass-shaped light-transmitting structure.

[0008] Preferably, the buried heating component includes an electric heating wire, a three-dimensional heat conducting pipe network and an infrared heating plate on the top of the pipe network, and a temperature control liquid circulates in the pipe network.

[0009] Preferably, the bottom of the acrylic bottom plate is provided with a movable foot, and the corners of the acrylic bottom plate are provided with a horizontal calibration bubble level.

[0010] Preferably, the containment frame is opened on the side away from the valve three and is provided with two rows of fine adjustment screw rods, the lower row of fine adjustment screw rods is provided with two supports at three equal divisions, and the upper row of fine adjustment screw rods is provided with one support at the middle division.

[0011] Preferably, the side of the sealed mask box is provided with an exhaust fan and a light.

[0012] Preferably, the height of the stainless steel guide rail is flat with the weighing table surface, and the placement direction is parallel to the side wall of the containment frame.

[0013] Preferably, the vertical laser plane is perpendicular to the adhesive steel teeth.

[0014] Preferably, the temperature controller is connected to the buried heating component at the other end, for regulating the temperature of the experimental environment.

[0015] The application provides a device suitable for soil water absorption and evaporation cycle test. 1. The application has a composite heat field precise simulation technology: a three-dimensional gradient heating system (layered distribution of electric heating wires + heat pipe network + infrared heating plate) realizes independent control of soil internal conduction heat and surface radiation heat through temperature controller and computer feedback regulation, can precisely simulate the composite heat field effect of "solar radiation + ground temperature gradient" in natural environment, and improves heat field uniformity.

[0016] 2. The application has a boundary constraint dynamic regulation technology: an adjustable air pressure elastic membrane + an angle-adjustable frosted water-permeable partition plate constructs a bionic constraint system, the constraint stress in real time feedback of a pressure sensor and the crack expansion captured by a high-definition camera form a dynamic correlation, and the coupling law of constraint strength-crack morphology-seepage velocity is quantitatively revealed for the first time.

[0017] 3. The application has a modular expandable design: the quick replacement structure of the frosted water-permeable partition plate shortens the sample replacement time, and cooperates with the adjustable sample box, so that different texture soils such as clay and sand can be adapted. Engineering verification shows that the design makes the test dimension of a single device expand in multiple combinations.

[0018] 4. The application has a water and heat migration visualization technology: the combination of acrylic bottom plate and three-dimensional lighting system and high-definition camera realizes the whole process visualization observation of wetting front dynamic propagation, water redistribution and crack development. In the test, the preferential flow phenomenon that "finger flow preferentially passes through historical crack paths" is successfully captured, which provides direct evidence for studying the soil memory effect. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The figure shows the main structure of the test device of the application Figure 1 ; Figure 2The schematic diagram of the main structure of the test device of the present application Figure 2 ; Figure 3 The schematic diagram of the main structure of the test device of the present application Figure 3 ; Figure 4 The schematic diagram of the test sample testing mechanism of the present application Figure 5 The schematic diagram of the internal mechanism of the test sample testing of the present application Figure 1 ; Figure 6 The schematic diagram of the internal mechanism of the test sample testing of the present application Figure 2 ; Figure 7 The schematic diagram of the internal mechanism of the test sample testing of the present application Figure 3 ; Figure 8 The schematic diagram of the frosted water-permeable partition one and the frosted water-permeable partition two of the present application Figure 9 The physical diagram of the first time of the test soil absorption process of the present application Figure 10 The physical diagram of the completion of the first time of the test soil absorption of the present application Figure 11 The physical diagram of the first time of the test soil evaporation process of the present application Figure 12 The physical diagram of the second time of the test soil absorption process of the present application Figure 13 The schematic diagram of the wetting front moving process curve of the two times of the absorption process of the present application

[0020] Among them, 1, liquid water supply mechanism; 2, test sample testing mechanism; 3, wetting front scale testing mechanism; 4, numerical control output mechanism; 11, water supply malleable bottle; 12, hollow pipe; 13, valve one; 14, valve two; 15, rubber hose; 16, scissor lifting platform; 17, long screw rod; 21, closed cover box; 22, cement layer; 23, ground buried heating component; 24, weighing platform; 25, acrylic bottom plate; 26, movable foot; 27, horizontal calibration bubble gauge; 28, enclosure frame; 29, valve three; 210, fine adjustment screw rod; 211, viscous steel tines; 212, frosted water-permeable partition one; 213, frosted water-permeable partition two; 214, bearing cavity; 215, exhaust fan; 216, illuminating lamp; 217, high-definition video camera; 218, temperature sensor; 219, predetermined water level ruler; 31, stainless steel guide rail; 32, laser instrument; 33, vertical laser emitting surface; 41, control terminal; 42, temperature controller. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings of the specification of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0022] Please refer to the accompanying drawings of the specification of the present application Figure 1 -attached Figure 3 The embodiment of the present application provides a device suitable for soil water absorption and evaporation cycle test, which comprises a liquid water supply mechanism 1, a sample test mechanism 2, a wetting front scale test mechanism 3 and a numerical control output mechanism 4. The liquid water supply mechanism 1 comprises a water supply marshall bottle 11, the bottom end of which is provided with a valve 2 14. The bottom of the water supply marshall bottle 11 is provided with a scissor type lifting platform 16, the middle part of the support of which is provided with a long screw rod 17. The water supply marshall bottle 11 is connected with the sample test mechanism 2 through a rubber hose 15. A hollow pipe 12 communicating with the atmosphere is fixed in the water supply marshall bottle 11. The top end of the water supply marshall bottle 11 is provided with a valve 1 13. A sufficient amount of clean water is filled in the water supply marshall bottle 11, which is stably placed on the scissor type lifting platform 16. The valve 1 13 is opened, air is blown into the bottle through the hollow pipe 12 to remove the bubbles in the water. After the liquid level in the water supply marshall bottle 11 is stable, the valve 1 13 is closed. The long screw rod 17 is adjusted to realize the up and down movement of the lifting platform 6, so that the bottom end of the hollow pipe 12 is at the same level as the sample height. During the drying test, the front and rear lighting lamps 216 are first opened. The high-definition camera 217, the laser instrument 32 and the control terminal 41 are simultaneously opened. After the collection frequency is set, the data is collected smoothly. Then the valve 2 14 is opened to make the water in the water supply marshall bottle enter the water collecting tank through the rubber hose, and reach the preset water level 219. At this time, the liquid level scale in the water supply marshall bottle 11 and the wetting front scale indicated by the laser instrument 32 are recorded. Then, the liquid level scale in the water supply marshall bottle 11 is recorded every fixed time interval ts.

[0023] Please refer to the accompanying drawings of the specification of the present application Figure 1 -attached Figure 7The sample testing mechanism 2 comprises a sealed cover box 21, a cement layer 22 at the bottom of the sealed cover box 21, a buried heating component 23 arranged in the cement layer 22, the buried heating component 23 comprising an electric heating wire, a three-dimensional heat conduction pipe network and an infrared heating plate at the top of the buried heating component 23, a temperature-controlled liquid such as a glycol solution circulating in the pipe network, and the wavelength of the infrared heating plate at the top is adjustable at 2-15 μm, a weighing table 24 arranged on the cement layer 22, a bearing sample and water body acrylic bottom plate 25 arranged on the weighing table 24, a surrounding frame 28 arranged at the top of the acrylic bottom plate 25, two recessed shallow clamping grooves arranged on the acrylic bottom plate 25, a valve three 29 connected to the surrounding frame 28 and arranged on the side of the surrounding frame 28 close to the water supply marshall bottle 11, the valve three 29 connected to the valve two 14 through the rubber hose 15, the surrounding frame 28 arranged with front and rear opposite viscous steel teeth 211 at the top of the surrounding frame 28, the recessed shallow clamping grooves of the surrounding frame 28 embedded in the frosted water-permeable partition plate one 212 and the frosted water-permeable partition plate two 213, and the frosted water-permeable partition plate one 212 and the frosted water-permeable partition plate two 213 movable along the recessed shallow clamping grooves in the surrounding frame 28, the frosted water-permeable partition plate one 212 and the frosted water-permeable partition plate two 213 etched with micron-level grooves on the surface to simulate the soil particle interface, simulate the rough surface of the real soil particles, enhance the mechanical biting effect of the partition plate and the soil, make the experimental or engineering conditions closer to the physical interface characteristics of the natural soil, the groove structure can guide the directional arrangement of the soil particles, reduce the interface slip, and more truly reflect the shear behavior of the soil in the natural state, the frosted water-permeable partition plate one 212 and the frosted water-permeable partition plate two 213 arranged with an elastic constraint film outside, the film filled with an air bag with adjustable air pressure, the soil swelling / shrinking stress is fed back in real time through a pressure sensor, the constraint force of the elastic film is adjusted by inflation and deflation, the elastic constraint film is flexible and adaptable to the swelling / shrinking deformation of the soil caused by humidity, temperature and the like, the stress concentration or interface peeling caused by the rigid structure is avoided, the pressure sensor monitors the soil stress change, and data support is provided for research or engineering control (such as judging the soil consolidation degree and swelling potential), the flexible constraint film uniformly disperses the soil deformation stress, prevents local crushing or cracking, and is especially suitable for cohesive soil or swelling soil which is easy to be disturbed, the air pressure is adjusted according to different soil types to balance the demand of “fixing” and “allowing natural deformation”, a predetermined water level scale 219 arranged on the side wall between the surrounding frame 28 and the frosted water-permeable partition plate one 212, a bearing cavity 214 arranged between the frosted water-permeable partition plate one 212 and the frosted water-permeable partition plate two 213 for bearing the test soil, a high-definition camera 217 arranged directly above the sealed cover box 21, a temperature sensor 218 arranged at the bottom of the inner wall of the sealed cover box 21, a glass-shaped light-transmitting structure arranged in the middle of the sealed cover box 21, a movable foot 26 arranged at the bottom of the acrylic bottom plate 25, a horizontal calibration bubble gauge 27 arranged at the corners of the acrylic bottom plate 25, and upper and lower rows of micro-adjusting screw rods 210 arranged on the side of the surrounding frame 28 away from the valve three 29, two branches arranged at the three equal parts of the lower row of micro-adjusting screw rods 210, and one branch arranged at the middle of the upper row of micro-adjusting screw rods 210.An exhaust fan 215 and a light 216 are arranged on the side of the closed cover box 21. The closed cover box 21 is the outer shell of the soil moisture infiltration and evaporation cycle test device. Inside the closed cover box 21, there are a buried heating component 23, a weighing platform 24, an acrylic bottom plate 25 for supporting the test sample and water body, and a high-definition camera 217. The buried heating component 23 is embedded in the cement layer at the bottom of the closed cover box 21. The buried heating component 23 includes an electric heating wire, a three-dimensional heat conduction pipe network, and an infrared heating plate on the top of the three-dimensional heat conduction pipe network. The electric heating wire can be arranged in 2-4 layers. The wires in the same layer are S-shaped and coiled and fixed in the cement. The distance between each layer of wires should be greater than 2 cm. The electric heating wire needs to reserve at least 2 cm thick cement at the top and bottom. The three-dimensional heat conduction pipe network circulates a temperature-controlled liquid such as glycol solution. The infrared heating plate on the top has a wavelength of 2-15 μm which can be adjusted. The working temperature of the ground electric heating is adjusted by a temperature controller 42. The temperature controller 42 is connected to a computer system. When the ground electric heating system is made, the size of the bottom surface of the closed cover box 21 needs to be considered to ensure that the two can be embedded and closed. A temperature sensor 218 is arranged at a height of 10-20 cm above the top surface of the ground electric heating cement layer for monitoring the test environment temperature. The temperature sensor 218 is fixed on the side of the closed cover box 21 and connected to the computer system. The value of the temperature sensor 218 tc is compared with the expected value tr input to the computer. If the difference between tc and tr is large, the computer automatically controls the temperature controller 42 to adjust the working power until tc = tr ± 5%. The internal temperature gradient of the soil such as 0.5℃ / cm and the surface radiation intensity are independently controlled to simulate the composite heat field of "soil-atmosphere interface radiation + ground temperature conduction" in the natural environment. After the cement reaches the curing strength, the weighing platform 24 is placed on the cement layer 22. After the weighing platform 24 is placed, the weighing surface is adjusted to be horizontal by the spiral foot seat of the weighing platform 24. The weight storage module of the weighing platform is connected to the computer. The computer can realize real-time recording and storage of the weight. The test sample box structure composed of the acrylic bottom plate 25 and the surrounding frame 28 is placed on the horizontal weighing platform 24. The four movable feet at the bottom of the test sample box are adjusted. The test sample box structure is in a horizontal state by observing the central position of the horizontal calibration bubble gauge at the acrylic bottom plate 25. The ground glass water-permeable partition plate one 212 and the ground glass water-permeable partition plate two 213 are placed in the card slot at the bottom of the test sample box. The ground glass water-permeable partition plate one 212 and the ground glass water-permeable partition plate two 213 are provided with elastic constraint membranes outside. The membranes are filled with air bags with adjustable air pressure. The soil swelling / shrinking stress is fed back in real time by a pressure sensor to simulate the constraint effect of the surrounding rock mass on the crack expansion in the natural environment such as the restriction of the soil on both sides of the slope by the surrounding rock mass. The coupling process of stress-crack-seepage is monitored synchronously to find a new law that "the higher the boundary constraint strength is, the smaller the crack opening is, but the faster the lateral seepage is". The size of the ground glass water-permeable partition plate can be adjusted according to the size of the experimental test sample. The width of the ground glass water-permeable partition plate one 212 is slightly smaller than the width of the card slot by 0.5 mm to facilitate insertion and removal. The width of the ground glass water-permeable partition plate two 213 is smaller than the width of the card slot by 1 cm.The second sanding water-permeable baffle 213 is fixed by the fine adjustment screw rod 210, and when the test is completed, the second sanding water-permeable baffle 213 is removed by removing the fine adjustment screw rod 210, so that the sample can be easily removed. The second sanding water-permeable baffle 213 can adjust the inclination angle of the baffle to 0°-45° by rotating the screw rod. After the first sanding water-permeable baffle 212 and the second sanding water-permeable baffle 213 are fixed, the test sample is placed in the bearing cavity 214 between the two, the sample thickness is set in advance, and the sample height is marked on the corresponding position of the sample box. The prepared soil is placed in the middle of the sample box, and the soil is lightly tamped to the preset position according to the maximum dry density standard. After the sample is completed, the valve three 29 is opened, the four movable feet 26 are adjusted again for secondary leveling, the airtight cover box 21 is fixed, after the absorption test is completed, the ground heating component 23 switch is opened, the expected test temperature is set, the exhaust fan 215 is opened to help smoothly remove the moisture in the cover box, the high-definition camera 217 is opened, the image during drying is collected, and the terminal 41 controls the temperature of the cover box and records the weight. When the weight change rate of the test sample is less than 1g / hour, it is considered that the soil drying is completed, and the test is stopped. The next cycle of absorption test of dry soil repeats the above drying test process.

[0024] Please refer to the attached Figure 1 -attached Figure 7 The wetting front scale test mechanism 3 includes a stainless steel guide rail 31 provided with a laser instrument 32 capable of linear sliding along the length direction. The laser instrument 32 can emit a vertical laser plane 33. The height of the stainless steel guide rail 31 is flat with the table surface of the weighing table 24, and the placement direction is parallel to the side wall of the enclosure frame 28. The vertical laser plane 33 is perpendicular to the viscous steel teeth 211. The laser instrument 32 is slid on the stainless steel guide rail 31 to record the wetting front scale, until the wetting front reaches the position of the second sanding water-permeable baffle 213 and the clear water seeps out. It is considered that the sample absorption stage is completed, and the test is stopped by closing the valve two 14. The high-definition camera 217 and the laser instrument 32 are closed, and the evaporation experiment process is stopped.

[0025] Please refer to the attached Figure 1 -attached Figure 4 The numerical control output mechanism 4 includes a control terminal 41 for collecting images and data. The control terminal 41 is connected to the weighing table 24, the high-definition camera 217 and the temperature sensor 218. The control terminal 41 is connected to the temperature controller 42, and the temperature controller 42 is connected to the ground heating component 23 for adjusting the temperature of the experimental environment.

[0026] Working principle: refer to the attached Figures 1-13The soil water absorption and evaporation cycle test device has a closed cover box 21, an internal buried heating component 23, a weighing platform 24, an acrylic bottom plate 25 for supporting the sample and water body, and a high-definition camera 217. The buried heating component 23 is embedded in the cement layer at the bottom of the closed cover box 21, which includes an electric heating wire, a three-dimensional heat conduction pipe network, and an infrared heating plate at the top. The electric heating wire can be arranged in 2-4 layers, and the wires in the same layer are S-shaped and fixed in the cement. The distance between each layer of wires should be greater than 2 cm. The electric heating wire needs to reserve at least 2 cm thick cement at the top and bottom. The three-dimensional heat conduction pipe network circulates a temperature-controlled liquid such as glycol solution, and the top infrared heating plate has a wavelength of 2-15 μm which can be adjusted. The working temperature of the ground electric heating is adjusted by a temperature controller 42 connected to a computer system. When making the ground electric heating system, the size of the bottom surface of the closed cover box 21 should be considered to ensure that it can be embedded and closed. A temperature sensor 218 is installed at a height of 10-20 cm above the top surface of the cement layer of the ground electric heating, which is used to monitor the test environment temperature. The temperature sensor 218 is fixed to the side of the closed cover box 21 and connected to the computer system. The value of the temperature sensor 218 tc is compared with the expected value tr input to the computer. If the difference between tc and tr is large, the computer will automatically control the temperature controller 42 to adjust the working power until tc=tr±5%, realizing the independent control of the soil internal temperature gradient such as 0.5℃ / cm and the surface radiation intensity, simulating the composite heat field of "soil-atmosphere interface radiation + ground temperature conduction" in the natural environment. After the cement reaches the curing strength, the weighing platform 24 is placed on the cement layer 22. The weighing platform 24 is adjusted to be level by its own screw seat after being placed. The weight storage module of the weighing platform is connected to the computer, which can realize real-time recording and storage of weight. The sample box structure composed of the acrylic bottom plate 25 and the surrounding frame 28 is placed on the levelled weighing platform 24. The four movable feet at the bottom of the sample box are adjusted to make the sample box structure level by observing the centralization of the horizontal calibration bubble gauge at the acrylic bottom plate 25. The ground glass water-permeable partition plate one 212 and the ground glass water-permeable partition plate two 213 are placed in the bottom clamping groove of the sample box. The elastic restraint film is added outside the ground glass water-permeable partition plate one 212 and the ground glass water-permeable partition plate two 213. The film is filled with an air bag with adjustable air pressure. The soil swelling / shrinking stress is fed back in real time by the pressure sensor to simulate the restraining effect of the surrounding rock mass on the crack expansion in the natural environment, such as the restriction of the soil on both sides of the slope by the surrounding rock mass. The coupling process of stress-crack-seepage is monitored synchronously to discover the new law that "the higher the boundary constraint strength, the smaller the crack opening but the faster the lateral seepage". The size of the ground glass water-permeable partition plate can be adjusted according to the size of the experimental sample.5mm, so as to smoothly take out and insert, the width of the frosted water permeable baffle two 213 is less than the width of the card slot 1cm, the frosted water permeable baffle two 213 is fixed through the fine adjustment screw rod 210, when the test is finished, the frosted water permeable baffle two 213 is removed through the fine adjustment screw rod 210, then the frosted water permeable baffle two 213 is taken out, so as to achieve the purpose of smoothly disassembling the sample, the frosted water permeable baffle two 213 can adjust the baffle inclination 0°~45° through the rotating screw rod, after the frosted water permeable baffle one 212 and the frosted water permeable baffle two 213 are fixed, the test sample is placed in the bearing cavity 214 between the two, the thickness of the test sample is set in advance, and the test sample height is marked at the corresponding position of the test sample box, the prepared soil is weighed and placed in the middle of the test sample box, the soil is lightly tamped to the preset position according to the maximum dry density standard, after the test sample is completed, the valve three 29 is opened, the four movable feet 26 are adjusted again for secondary leveling, the airtight cover box 21 is fixed, enough water is filled in the water supply mason bottle 11, and the water supply mason bottle 11 is stably placed on the scissor type lifting platform 16, the valve one 13 is opened, air is blown into the bottle through the hollow pipe 12, and air bubbles in the water are removed, after the liquid level in the water supply mason bottle 11 is stable, the valve one 13 is closed, the long screw rod 17 is adjusted to realize the up and down movement of the lifting platform 6, so that the bottom end of the hollow pipe 12 is at the same level as the test sample height, during the drying test process, first, the front and rear lighting lamps 216 are turned on, the high-definition camera 217, the laser instrument 32 and the control terminal 41 are synchronously turned on, after the good collection frequency is set, the data is smoothly collected, then the valve two 14 is opened, the water in the water supply mason bottle is made to enter the water collecting tank through the rubber hose, and the preset water level height 219 is reached, at this time, the liquid level scale of the water supply mason bottle 11 is recorded, and the wetting front scale indicated by the laser instrument 32 is recorded, then, every fixed time ts, the liquid level scale of the water supply mason bottle 11 is recorded, the laser instrument 32 is slid on the stainless steel guide rail 31 to record the wetting front scale, until the wetting front reaches the position of the frosted water permeable baffle two 213 and clear water seeps out, it is considered that the test sample absorption and infiltration stage is completed, then the valve two 14 is closed to stop the test, the high-definition camera 217 and the laser instrument 32 are turned off, and the evaporation test process is stopped, after the absorption and infiltration test is completed, the ground heating component 23 switch is turned on, the expected test temperature is set, the exhaust fan 215 is turned on to help smoothly remove the moisture in the cover box, the high-definition camera 217 is turned on, the image in the drying process is collected, the control terminal 41 synchronously controls the cover box temperature and records the weight, when the test sample weight change rate is less than 1g / hour, it is considered that the soil drying is completed, then the test is stopped, and the next cycle absorption and infiltration experiment of the dry soil is carried out.

[0027] Although the embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A soil moisture absorption and evaporation cycle test device, comprising a liquid push water supply mechanism (1), a sample testing mechanism (2), a wetting front scale testing mechanism (3) and a numerical control output mechanism (4), characterized in that: The liquid-pushing water supply mechanism (1) includes a water supply Martens flask (11), a hole is opened at the bottom end of the water supply Martens flask (11) and is connected to a second valve (14), a scissor lift platform (16) is provided at the bottom of the water supply Martens flask (11), a long screw rod (17) is provided in the middle of the scissor lift platform (16) bracket, and the water supply Martens flask (11) is connected to the sample testing mechanism (2) through a rubber hose (15); The sample testing mechanism (2) includes a sealed shielding box (21), a cement layer (22) is provided at the bottom of the sealed shielding box (21), an underground heating component (23) is provided inside the cement layer (22), a weighing platform (24) is provided on the cement layer (22), an acrylic bottom plate (25) for carrying the sample and the water body is provided on the weighing platform (24), a protective frame (28) is provided on the top of the acrylic bottom plate (25), the acrylic bottom plate (25) is provided with two concave shallow grooves, the protective frame (28) is opened on one side close to the water supply Martens flask (11) and is connected to valve three (29), the valve three (29) is connected to valve two (14) through a rubber hose (15), and the top of the protective frame (28) is provided with front and rear opposite adhesive steel teeth (211), and the concave shallow grooves of the protective frame (28) are respectively embedded in the frosted permeable partition one (212) and A frosted water-permeable partition plate 2 (213), and the frosted water-permeable partition plate 1 (212) and the frosted water-permeable partition plate 2 (213) move along the concave shallow groove in the enclosure frame (28), the frosted water-permeable partition plate 1 (212) and the frosted water-permeable partition plate 2 (213) are etched with micron-level grooves on the surface to simulate the soil particle interface, and elastic constraint membranes distributed on both sides of the outer side are added, and an air bag with adjustable air pressure is filled in the membrane, and a micro pressure sensor element is provided inside. A predetermined water level gauge (219) is provided on the side wall between the enclosure frame (28) and the frosted water-permeable baffle plate 1 (212), a bearing cavity (214) for bearing the test soil is provided between the frosted water-permeable baffle plate 1 (212) and the frosted water-permeable baffle plate 2 (213), a high-definition camera (217) is provided just above the top of the sealed mask box (21), and a temperature sensor (218) is provided at the bottom of the inner wall of the sealed mask box (21); The wet front scale test mechanism (3) comprises a stainless steel guide rail (31), wherein the stainless steel guide rail (31) is provided with a laser instrument (32) that can slide linearly along the length direction, and the laser instrument (32) can emit a vertical laser beam (33); The numerical control output mechanism (4) includes a control terminal (41) for collecting images and data. The control terminal (41) is connected to a weighing platform (24), a high-definition camera (217) and a temperature sensor (218). The control terminal (41) is connected to a temperature controller (42).

2. A soil moisture absorption and evaporation cycle test device according to claim 1, characterized in that: A hollow tube (12) communicating with the atmosphere is fixed inside the water supply Martens flask (11), and a hole is opened at the top end of the water supply Martens flask (11) and is connected to a valve 1 (13).

3. The soil moisture absorption and evaporation cycle test device according to claim 1, characterized in that: The middle part of the sealed mask box (21) is a glass-shaped light-transmitting structure.

4. The device for testing soil moisture absorption, infiltration and evaporation cycles according to claim 1, characterized in that: The underground heating component (23) comprises an electric heating wire, a three-dimensional heat-conducting pipe network and an infrared heating plate on the top thereof, and a temperature-controlled liquid circulates in the pipe network.

5. The device for testing soil moisture absorption, infiltration and evaporation cycles according to claim 1, characterized in that: A movable foot (26) is provided at the bottom of the acrylic base plate (25), and a horizontal calibration bubble ruler (27) is provided at the corner of the acrylic base plate (25).

6. The device for testing soil moisture absorption, infiltration and evaporation cycles according to claim 1, characterized in that: The enclosure frame (28) has an opening on one side away from valve three (29) and is provided with upper and lower rows of fine-tuning screw rods (210), wherein two fine-tuning screw rods (210) are provided at three equal parts of the lower row, and one fine-tuning screw rod (210) is provided at a middle part of the upper row.

7. The device for testing soil moisture absorption, infiltration and evaporation cycles according to claim 1, characterized in that: An exhaust fan (215) and a lighting lamp (216) are provided on the side of the sealed shield box (21).

8. The device for testing soil moisture absorption, infiltration and evaporation cycles according to claim 1, characterized in that: The height of the stainless steel guide rail (31) is level with the surface of the weighing platform (24), and the placement direction is parallel to the side wall of the enclosure frame (28).

9. The device for testing soil moisture absorption, infiltration and evaporation cycles according to claim 1, characterized in that: The vertical laser irradiation surface (33) and the adhesive steel tooth (211) are perpendicular to each other.

10. The device for testing soil moisture absorption, infiltration and evaporation cycles according to claim 1, characterized in that: The other end of the temperature controller (42) is connected to the underground heating component (23) for regulating the temperature of the experimental environment.

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