Tester and method for testing permeability of soil body under dry-wet or freeze-thaw cycle effect

Abstract

The invention provides a soil permeability tester under a dry-wet or freeze-thaw cycle effect, which comprises a static pressure loading device part and a core test part which are connected and fixed through a bracket, the static pressure loading device part is composed of a hydraulic device, a hydraulic rod, a main body device, a bottom pedestal and a chute; the core testing part comprises a pressure rod, a pressure measuring pipe and a plastic top plate, the main body device comprises a reservoir and a sample cylinder, the reservoir comprises a first partition plate and a second partition plate, and the sample cylinder comprises a third partition plate and a fourth partition plate; the second partition plate and the third partition plate form a vertical guide drainage layer, and a water inlet is formed in the second partition plate; air holes are formed in the fourth partition plate; a bottom guide and discharge layer is arranged at the bottom of the sample cylinder, and resistance wires are arranged in the vertical guide and discharge layer and the bottom guide and discharge layer; a water outlet is formed; a ventilation opening and a humidifier are arranged on the second partition plate; the pressure rod comprises a first valve and a second valve; an extraction opening is formed in the plastic top plate; a barometer is installed on the fourth partition plate.

Description

Technical Field

[0001] The invention relates to the technical field of building material permeability testing equipment, and in particular to a permeability testing instrument and a testing method for soil under dry-wet or freeze-thaw cycle effects. Background Art

[0002] At present, most soil materials are used in practical engineering. The primary consideration is their performance in harsh environments. The dry-wet and freeze-thaw cycle effects in nature have a particularly prominent impact on soil. The dry-wet and freeze-thaw cycle effects caused by seasonal changes and rising or falling groundwater levels can have a significant impact on the permeability of soil.

[0003] At present, soil permeability testing requires different test devices. The main steps are to make a ring knife sample by compaction or static pressure, move it to a stacked saturation instrument to experience different dry-wet or freeze-thaw cycle effects, and finally take out the ring knife sample and put it into the permeability instrument for permeability testing. However, this method is cumbersome and the sample is easily disturbed during the experiment. The measurement operation is cumbersome and easily affects the measurement accuracy.

[0004] In view of this, it is necessary to design a soil permeability performance tester under the effects of dry-wet or freeze-thaw cycles, and to unify the permeability performance measurement equipment of the same specimen under dry-wet or freeze-thaw effects to simplify related work. Summary of the invention

[0005] In order to solve the technical problems described in the above background technology, the present invention provides a permeability performance tester and a testing method for soil under the effects of dry-wet or freeze-thaw cycles, which realizes the functions of a single device, a single sample, and continuous testing of permeability performance related parameters in a continuous sequence without taking out the sample, effectively simplifies the corresponding operating steps and equipment, and eliminates the influence of sample loss caused during the test on the test results.

[0006] In order to solve the above technical problems, the present invention provides a soil permeability tester under the effects of dry-wet or freeze-thaw cycles, comprising a static pressure loading device part and a core test part, both of which are connected and fixed by a bracket;

[0007] The static pressure loading device is composed of a hydraulic device, a hydraulic rod, a main device, a bottom pedestal and a slideway; the hydraulic rod drives the hydraulic device to move up and down; the hydraulic rod is fixed on the top of the bracket;

[0008] The core test part is composed of a pressure rod, a pressure measuring tube and a plastic top plate. The pressure measuring tube is installed in the pressure rod, the pressure rod is installed on the top of the bracket, and the pressure rod can be raised and lowered; the plastic top plate is installed at the bottom of the pressure rod;

[0009] The bottom pedestal and the slide groove extend from the static pressure loading device portion to the core test portion, and the main device is mounted on the slide groove and has a sliding motion along the slide groove; the main device can be slidably placed under the hydraulic device or under the plastic top plate along the slide groove;

[0010] The main device includes a water reservoir and a sample tube, the water reservoir is composed of a first partition and a second partition, and the sample tube is composed of a third partition and a fourth partition; the second partition and the third partition form a vertical guide layer, and a water inlet is arranged on the second partition; the third partition can be raised and lowered, and the fourth partition is provided with a vent hole;

[0011] A bottom drainage layer is arranged at the bottom of the sample tube, and heating resistance wires and cooling resistance wires are built into the vertical drainage layer and the bottom drainage layer; the bottom drainage layer and the vertical drainage layer are both provided with drainage ports;

[0012] A vent and a humidifier are arranged on the outside of the second partition, and a first valve and a second valve are arranged at the bottom of the pressure rod; an exhaust port is arranged on the plastic top plate for vacuuming; a barometer is installed on the fourth partition for detecting changes in air pressure inside the device body.

[0013] In a preferred embodiment, the water reservoir is provided with a maximum water level line; a pull ring is provided at the water inlet, and the pull ring is used to control the opening and closing of the water inlet; a breathable layer is provided at the bottom of the plastic top plate; the pressure measuring tube is provided with scale lines, and the pressure rod is a transparent rod.

[0014] In a preferred embodiment, a dial indicator is arranged above the vertical conductive layer, and the dial indicator is rotatable in a plane; and a thermometer is installed above the vertical conductive layer.

[0015] In a preferred embodiment, the main device includes a filling layer, and a lower permeable stone is provided at the bottom of the sample tube;

[0016] The humidifier is connected to a nozzle, an expansion board is arranged at the nozzle, and the nozzle and the expansion board are installed in the vertical guide layer.

[0017] The present invention also provides a method for testing the permeability of soil under the effects of dry-wet or freeze-thaw cycles, using the permeability tester; the testing method comprises the following steps:

[0018] Step 1: Control the compaction degree of the sample (material) through the static pressure loading device and compact it in the sample tube of the main device; after static pressure loading and standing for 2-3 hours, keep the sample (material) from deformation and move the main device to the bottom of the pressure rod and the pressure measuring tube through the slide;

[0019] Step 2: After placing filter paper and upper permeable stone of corresponding sizes on the sample in sequence, align the position of the plastic top plate with the main device, i.e., the top of the sample, and move the plastic top plate downwards by controlling the pressure rod through the computer to seal the main device, and continue to move downwards until the plastic top plate contacts the top of the sample (material), then stop moving downwards, and fix the position of the pressure rod so that the plastic top plate remains in this position throughout the test;

[0020] Step 3: After ensuring that the plastic top plate is completely fixed on the surface of the sample, check the air tightness of the main device. After ensuring that the main device does not leak, close the drain port and the water inlet; the third partition does not move upward and remains unchanged; the first valve and the second valve are closed, the humidifier is closed, the air extraction port is closed, and the power switch of the equipment is ensured to be turned off before the test;

[0021] Step 4: Fill the reservoir with the test solution, the maximum capacity of the test solution not exceeding the height of the main device;

[0022] Step 5: After ensuring the air tightness of the main device, turn on the vacuum pump through computer control, evacuate the main device through the air evacuation port on the plastic top plate, and observe the air pressure change inside the sample through a barometer. The evacuation lasts for about 4 to 5 hours.

[0023] Step 6: After the main device is completely vacuumed, turn off the vacuum pump, lift the third baffle upward and fix it to keep it in place, open the water inlet, and allow the solution in the reservoir to enter the sample through the air holes of the fourth baffle to saturate it;

[0024] Step 7: According to the change of the barometer reading, turn on the vacuum pump again to perform appropriate air saturation. After the barometer reading is stable, move the third partition downward and close all water inlets to keep the sample in a closed state. After the sample is saturated with back pressure for 24 hours, the sample is saturated.

[0025] Step 8: Open the first valve and the second valve at the same time, conduct a corresponding permeability test, and read the drop value of the water head height of the solution in the pressure measuring tube within a corresponding time period to calculate the permeability coefficient;

[0026] Step 9: After the test, open the drain port of the vertical drainage layer to drain the solution in the vertical drainage layer.

[0027] In a preferred embodiment, in the test method, if a saturation operation is required, step 6 is retained, and if a saturation operation is not required, step 6 is omitted;

[0028] If step 6 is omitted, it is necessary to ensure that no solution enters the vertical drainage layer during the entire test process.

[0029] The present invention also provides a method for testing the permeability of soil under the effect of dry-wet cycles, using the permeability tester; the testing method includes a drying process and a saturation process, and before the drying process and the saturation process, the steps 1-3 are first performed;

[0030] The drying process includes the following steps:

[0031] Step 11, move the third partition upward to ensure that the vertical drainage layer is fully dry and no liquid penetrates, then open the vent and connect the blower, turn on the blower through the computer, and control the wind force and wind speed of the blower and the type of wind through the computer, the wind type includes hot wind and cold wind;

[0032] Step 12, drying the sample through the air holes of the vertical guide layer and the fourth partition, and controlling the temperature and efficiency of the heating resistance wire or the cooling resistance wire through a computer;

[0033] The saturation process includes the following steps:

[0034] Step 21: After drying, close the vent, keep the third baffle in place, open the water inlet, and allow the solution in the reservoir to pass through the vertical drainage layer and then through the air holes on the fourth baffle into the sample, so that the sample is fully saturated;

[0035] Step 22, open the water inlet, and then move the third partition downward to isolate the sample and the vertical drainage layer to prevent the solution from entering the fully saturated sample;

[0036] Step 23, turn on the vacuum pump to properly saturate the sample through the suction port, and observe the changes in the reading of the barometer to determine whether the pores in the sample are completely exhausted, so that the pore gas generated during the saturation process of the sample is completely exhausted, that is, the saturation exhaust process of the sample is completed;

[0037] Step 24, open the drain port of the bottom drainage layer, open the first valve and the second valve, inject the same solution as that in the reservoir into the upper part of the pressure measuring tube in the pressure rod, conduct a permeability test on the sample, and record the corresponding data for calculation;

[0038] Step 25, open all drain ports to drain the liquid;

[0039] The multiple dry-wet cycle test steps are to cycle based on steps 11-12 and steps 21-23, and perform the final operation of step 24 after the cycle is completed.

[0040] The present invention also provides a method for testing the permeability of soil under the effect of freeze-thaw cycles, using the permeability tester; the testing method includes a freezing process and a thawing process, and before the freezing process and the thawing process, the steps 1-3 are first performed;

[0041] The freezing process includes the following steps:

[0042] Step 111, move the third partition upward to ensure that the vertical drainage layer is fully dry and no liquid penetrates, then open the vent and connect the blower, turn on the blower through the computer, and control the wind force and wind speed of the blower and the type of wind through the computer, the type of wind is cold wind;

[0043] Step 112, freezing the sample through the air holes of the vertical guide layer and the fourth partition, and controlling the temperature and efficiency of the refrigeration resistance wire through a computer;

[0044] The melting process is carried out by using a saturated solution or by using a constant temperature and humidity curing system;

[0045] The multiple dry-wet cycle test steps are to cycle based on the freezing process and the melting process, and perform the last step of the melting process after the cycle is completed.

[0046] In a preferred embodiment, the melting process using solution saturation comprises the following steps:

[0047] Step A, keep the third partition in the upward position, open the water inlet, and allow the solution to enter the sample through the vertical drainage layer and the air holes of the fourth partition, so that the sample is fully saturated and fully melted;

[0048] Step B: After the melting is completed, the drain port of the vertical drainage layer is opened to drain the solution in the vertical drainage layer.

[0049] In a preferred embodiment, the melting process using constant temperature and humidity curing includes the following steps:

[0050] Step a: After ensuring that the solution in the vertical drainage layer is completely discharged, the sample is melted under constant temperature and humidity curing conditions (20 degrees Celsius) to ensure that the third partition is fixed in the upward position;

[0051] Step b, controlling the temperature in the vertical conductive layer to remain constant at room temperature by means of the heating resistance wire and the cooling resistance wire in the vertical conductive layer, using a computer to control the humidifier to input gas (with a certain humidity), and then turning on the humidifier to humidify the inside of the sample in cooperation with the resistance wire;

[0052] Step c, after the sample is fully thawed, the humidifier is turned off, and the third partition is moved downward to isolate the vertical guide layer from the sample, so as to prevent the external solution from entering the sample after the sample is fully saturated;

[0053] Step d, opening the drain port of the vertical drainage layer to drain the solution in the vertical drainage layer;

[0054] Step e: Finally, after adding the corresponding solution into the pressure measuring tube in the pressure (the solution is determined according to the test requirements), open the first valve, the second valve and the drainage port of the bottom drainage layer to conduct a permeability test.

[0055] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0056] 1. By setting up a soil permeability tester under the effects of dry-wet or freeze-thaw cycles, the function of continuous testing of permeability-related parameters with a single device and a single sample without taking out the sample is realized, which effectively simplifies the corresponding operation steps and equipment and eliminates the influence of sample loss caused by the test on the test results.

[0057] 2. The main device is transferred between the static pressure loading device and the core test part by setting the slide, so as to realize the compaction of the sample and the test of the permeability coefficient. The test process is complete and the steps are closely linked to each other, ensuring that there is no external or human interference in the test process and the accuracy of the test results.

[0058] 3. The settings for dry-wet and freeze-thaw cycle effects are more reasonable, which can ensure that the two effects are in direct contact with the sample, which is more in line with the actual application scenarios of the sample, and the transmission between various effects is more uniform and reasonable.

[0059] 4. This permeability tester can be compatible with a variety of tests, including permeability test of samples (materials) under the coupling of dry-wet-freeze-thaw cycles, permeability test of samples (materials) under different overlying loads, crack characterization test of sample surface under different dry-wet or freeze-thaw cycle effects, and expansion test of samples (materials). BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a side view of the overall structure of the permeability tester in a specific embodiment of the present invention;

[0061] Figure 2 It is a top view of the overall structure of the permeability tester in a specific embodiment of the present invention;

[0062] Figure 3 It is a structural side view of the static pressure loading device part in a specific embodiment of the present invention;

[0063] Figure 4 It is a structural side view of the core test part in a specific embodiment of the present invention;

[0064] Figure 5 It is a detailed structural diagram of the main device in a specific embodiment of the present invention;

[0065] Figure 6 It is a top view of the main body device and the plastic top plate in a specific embodiment of the present invention;

[0066] Figure 7 It is a top view of the main body of the main body of the main body in the specific embodiment of the present invention;

[0067] Figure 8 This is a distribution diagram of the drainage outlet at the bottom of the main body of the main body in a specific embodiment of the present invention;

[0068] Fig. 9 for Figure 5 A detailed enlarged schematic diagram of the A position in the middle;

[0069] Fig.10 for Figure 5 A detailed enlarged diagram of the B position in the middle

[0070] Fig.11 for Figure 5 A detailed enlarged diagram of the C position in the middle

[0071] Fig.12 It is a schematic diagram of providing ventilation holes on the fourth partition in a specific embodiment of the present invention.

[0072] Description of the accompanying drawings: 1. Main device; 11. Dial indicator; 111. Support; 12. Upper permeable stone; 13. Filling layer; 131. Air-permeable and water-permeable layer; 14. Barometer; 15. Water reservoir; 151. First baffle; 152. Second baffle; 1521. First water inlet; 1522. Second water inlet; 1523. Third water inlet; 1524. Fourth water inlet; 1525. Pull ring; 153. Highest water level line; 16. Sample cylinder; 161. Third baffle; 162. Fourth baffle; 1621. Air hole; 163. Iron pad; 17. Vertical drainage layer; 171. Heating resistance wire; 172. Refrigeration resistance wire; 173. Thermometer; 18. Bottom drainage layer; 181. First drain outlet; 182. Second drain outlet; 183. Third drain outlet; 184. Fourth drain outlet; 185. Fifth drain outlet; 19. Lower permeable stone; 101. Ventilation outlet; 102. Ventilation duct; 103. Humidifier; 104. Humidification duct; 105. Nozzle; 106. Extension board; 2. Iron bracket; 21. Iron base; 3. Hydraulic device; 4. Bottom pedestal; 5. Hydraulic rod; 6. Slide; 7. Pressure rod; 71. First valve; 72. Second valve; 8. Pressure measuring tube; 9. Plastic top plate; 91. Exhaust port; 92. Exhaust duct; 10. Breathable layer. DETAILED DESCRIPTION

[0073] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0074] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0075] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection through an intermediate medium. It can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0076] refer to Figure 1-Figure 12 This embodiment provides a soil permeability tester under the effects of dry-wet or freeze-thaw cycles, including a static pressure loading device part and a core test part, both of which are connected and fixed by a bracket.

[0077] The static pressure loading device part includes a hydraulic device 3, a hydraulic rod 5, a main device 1, a bottom pedestal 4 and a slide 6. The hydraulic device 3 is arranged at the driving end of the hydraulic rod 5. The hydraulic rod 5 can be raised and lowered by a computer. The hydraulic device 3 is connected to the hydraulic rod 5. The hydraulic rod 5 is installed on the top of the bracket through a fixing device, and the main device 1 is installed below the hydraulic device 3. The main device 1 is used to hold the sample (material) to be tested. The hydraulic device 3 is driven by the hydraulic rod 5 to rise or fall and prepare the sample (material) in the main device 1. The slide 6 is arranged on the bottom pedestal 4, and the main device 1 is installed on the slide 6. The main device 1 has a sliding motion along the slide 6.

[0078] The core test part includes a pressure rod 7, a pressure measuring tube 8, a plastic top plate 9, and a dial indicator 11. The slide groove 6 and the bottom pedestal 4 in the bracket extend from the static pressure loading device part to the core test part. The sliding main body device 1 can slide from the static pressure loading device part to the core test part along the slide groove 6. The pressure measuring tube 8 is installed in the pressure rod 7, and the bottoms of both are connected to the plastic top plate 9. The tops of the pressure measuring rod and the pressure rod 7 are installed on the iron frame through a fixing device. When the main body device 1 slides to the core test part, the main body device 1 slides to the bottom of the pressure measuring rod and the pressure rod 7. The main body device 1 can slide at the bottom through the slide groove 6 and be fixed at the corresponding position. The slide groove 6 is set with a certain slope at the connection between the static pressure loading device part and the core test part to facilitate the transfer of the main body device 1.

[0079] Among them, the construction of the bracket includes a frame formed by an iron bracket 2 and an iron base 21 for bottom support. Vertical connecting rods and horizontal connecting rods for stable support are installed on the frame. The bottom pedestal 4 is built on the iron base 21. A slide groove 6 is laid on the bottom pedestal 4 to facilitate the sliding of the main device 1; the hydraulic rod 5 and the pressure rod 7 are connected to the computer, and the compaction and permeability coefficient tests of the samples are realized through the computer program system.

[0080] The permeability tester is divided into two parts. The first part is the static pressure loading part of the sample, and the second part is the core part of the permeability test. The compaction quality of the sample (material) can be determined according to the optimal moisture content and maximum dry density obtained by compacting the sample.

[0081] First, slide the main device 1 through the slide 6 to the bottom of the hydraulic device 3 and fix it at this position, add the sample (material) into the main device 1, control the hydraulic rod 5 through the computer, lower the hydraulic device 3 to compact the sample and continue compacting for 1-2 hours.

[0082] After continuous compaction for 1-2 hours, the hydraulic rod 5 is raised, the main device 1 is released and moved to the core test part, moved to the bottom of the pressure measuring tube 8 and the pressure rod 7 and fixed at this position, and the rise and fall of the pressure rod 7 is controlled by a computer, and the plastic top plate 9 connected to the bottom of the pressure rod 7 is moved downward to the upper part of the sample. The pressure rod 7 is stopped when the plastic top plate 9 moves down to the surface of the sample through computer control. Then, in this state, it is determined whether to continue loading the sample and complete the penetration test or to complete the penetration test without loading according to the test needs.

[0083] The penetration tester has different test functions, as follows:

[0084] (a) Permeability test of samples (materials) under the coupling of dry-wet-freeze-thaw cycles: By combining the basic process of a single dry-wet and freeze-thaw cycle, the permeability performance test of samples (materials) under the coupling of two different conditions can be completed;

[0085] (b) Permeability test of the sample (material) under different overlying loads: The pressure rod 7 is controlled by the computer to apply different loads to the upper part of the sample (material). The load loading range is determined by the material of the pressure rod 7 (the loading range is 0-800 kPa). Then, according to the same operating steps as in (a), the sample (material) is subjected to permeability test under overlying pressure and different pressures;

[0086] (c) Crack characterization test of the sample surface under different drying and wetting or freeze-thaw cycle effects: after each cycle, the pressure rod 7 is moved upward by a computer, and then the state of the sample surface is photographed and saved by a camera, and the crack development law of the sample (material) surface under different drying and wetting or freeze-thaw cycle conditions is calculated according to the corresponding software or program;

[0087] (d) Test of expansion of the sample (material): The pressure rod 7 is lowered to the surface of the sample by computer control. The position of the pressure rod 7 is not fixed so that the plastic top plate 9 can move upward freely when the sample expands and deforms. The expansion and deformation of the sample is measured and recorded by a dial indicator 11 in combination with a ruler.

[0088] The specific structure design of the core test part is as follows:

[0089] The pressure measuring tube 8 is installed inside the pressure rod 7 and fixed on the top of the bracket with the pressure rod 7. The bottom of the pressure measuring tube 8 and the pressure rod 7 are both provided with air extraction holes with the plastic top plate 9, and the dial gauge 11 is respectively fixed on both sides of the plastic top plate 9 through the support 111, and the dial gauge 11 is in contact with the top of the plastic top plate 9.

[0090] The pressure rod 7 is used to control the expansion and deformation of the sample (material) or prevent expansion sliding or particle dispersion. The outside of the pressure rod 7 is transparent, and the scale lines on the pressure measuring tube 8 inside it can be observed to facilitate reading the changes in the head of the solution in the pressure measuring tube 8.

[0091] When testing the permeability coefficient of the sample, after partially compacting the sample through the static pressure loading device, a filter paper with the same size as the sample is placed on its surface, and then the upper permeable stone 12 is placed on the filter paper. The pressure rod 7 is controlled by a computer to make the plastic top plate 9 drop to just touch the upper surface of the compacted sample, and the pressure rod 7 is controlled to remain fixed at this position. At this time, the plastic top plate 9 limits the expansion and deformation of the sample and the dispersion of the material.

[0092] If the influence of the upper pressure of the sample is considered when testing the permeability coefficient, the pressure rod 7 can be pressed down by remote control of the computer and pressure can be applied to the sample through the plastic top plate 9, and the permeability test of the sample material can be carried out in combination with the pressure measuring tube 8.

[0093] The pressure measuring tube 8 passes through the inside of the plastic top plate 9 and the air permeable layer 10. The lowest point of the pressure measuring tube 8 can pass through the top surface of the upper permeable stone 12. A permeability test can be performed by injecting a solution into the pressure measuring tube 8, and the change in the solution height of the pressure measuring tube 8 can be observed through the transparent pressure rod 7.

[0094] The pressure measuring tube 8 is arranged in the pressure rod 7. The pressure measuring tube 8 can be connected to the bracket through a horizontal connecting rod and bolts, and the position of the upward or downward movement can be adjusted by operating the bolts. A first valve 71 and a second valve 72 are arranged at the port where the pressure rod 7 contacts the plastic top plate 9. The first valve 71 and the second valve 72 are used to control the solution in the pressure measuring tube 8 to pass through the sample. A scale line is arranged on the pressure measuring tube 8 to measure the difference in the water head drop of the solution in different time periods.

[0095] The material of the plastic top plate 9 is a light plastic and relatively hard, so that it can be moved upward during the free expansion test. Having the corresponding hardness can ensure that it is not damaged under different pressures. Due to the different test solutions, the material of the plastic top plate 9 also has the characteristics of acid resistance, alkali resistance, heat resistance, and chemical corrosion resistance, and the plastic top plate 9 is impermeable and airtight. The plastic top plate 9 is used to seal the top of the sample, and the plastic top plate 9 is placed on the upper permeable stone 12.

[0096] There are two exhaust ports 91 on the plastic top plate 9. The two exhaust ports 91 are arranged on the surface of the plastic top plate 9, and two exhaust pipes 92 are connected to the outside of the exhaust ports 91. The exhaust pipes 92 are connected to the upper end of the breathable layer 10 through the exhaust ports 91. The vacuum pump is controlled by a computer to exhaust air from the sample through the exhaust pipes 92, and the changes in the air pressure inside the device body are detected by the barometer 14.

[0097] The air permeable layer 10 is made of an air permeable and water-impermeable material, so as to prevent the moisture in the sample from being extracted when the sample passes through the air extraction pipe 92 and the air extraction port 91 for vacuum extraction, thereby protecting the equipment from water ingress. The air extraction port 91 passes through the plastic top plate 9, but not through the air permeable layer 10, and only allows air to enter the air extraction pipe 92 and be extracted, thereby ensuring that the solution is not extracted by the vacuum extractor.

[0098] The size of the upper permeable stone 12 can be changed according to the size of the sample. At this time, the upper permeable stone 12 should be selected in accordance with the size of the filling layer 13 and the size of the sample, and it should not be damaged under a certain upper load and can withstand a certain pressure.

[0099] The filling layer 13 is used to fully fill the space in the main device 1. The filling is used to control the height and diameter of the sample. The filling inside the main device 1 can be performed according to the size of the selected sample. The material used for the filling layer 13 is selected to have a certain strength to resist the sliding deformation and expansion and dispersion of the particles of the sample under the action of the solution during the test. The filling layer 13 can produce a slight deformation under the pressure of the pressure rod 7, but the lateral expansion deformation of the sample during the saturation process or the extrusion caused by other external forces will not affect the filling layer 13, and the filling layer 13 has a certain pressure resistance.

[0100] If the test solution is a salt ion solution or a real leachate, the material of the filling layer 13 needs to be acid-resistant, alkali-resistant and chemically resistant. At the same time, the material of the filling layer 13 is a breathable material (can transmit heat, cold air, and moisture), has heat resistance (drying conditions), heat dissipation and moisture dissipation performance (fast heat dissipation after drying, easy dehumidification and drying after humidification), is not easy to deform and damage, can be vertically compressed, and cannot pass granular substances.

[0101] The structure of the main device 1 includes a water reservoir 15 and a sample tube 16. The water reservoir 15 is a space area formed by the first partition 151 and the second partition 152, and is used to store the solution. The sample tube 16 is a space area formed by the third partition 161 and the fourth partition 162. Four iron pads 163 are set at the bottom of the sample tube 16 for support.

[0102] A protective layer should be attached to the outside of the iron pad 163 to prevent it from rusting and being damaged in the environment or in different electrolyte solutions, which would affect the stability of the device. The iron pad 163 is placed at the bottom of the entire device to support the device.

[0103] The water reservoir 15 is sealed by setting a plastic plate on the upper part of the water reservoir 15 to prevent evaporation of the solution and entry of pollutants. A maximum water level line 153 is set on the upper part of the water reservoir 15 to ensure that the solution in the water reservoir 15 does not overflow the device. The space formed by the first partition 151 is square, and the space formed by the second partition 152 is cylindrical. The second partition 152 is arranged on the outer periphery of the sample tube 16. The materials of the first partition 151 and the second partition 152 are both acid-resistant, alkali-resistant, and chemically resistant.

[0104] Four water inlets are arranged on the side wall of the second partition 152 , which are divided into a first water inlet 1521 , a second water inlet 1522 , a third water inlet 1523 and a fourth water inlet 1524 . The opening and closing of the water inlets are controlled by a pull ring 1525 , thereby controlling the solution in the water reservoir 15 to flow into and out of the sample tube 16 .

[0105] There is a gap between the second partition 152 and the third partition 161 outside the sample tube 16. The second partition 152 and the third partition 161 form a sealed space, which serves as a vertical drainage layer 17. A bottom drainage layer 18 is set at the bottom of the sample tube 16. The upper part of the vertical drainage layer 17 is sealed. Whether the vertical drainage layer 17 and the bottom drainage layer 18 are filled with solution is controlled according to the test requirements. A heating resistance wire 171 and a cooling resistance wire 172 are arranged in the vertical drainage layer 17 and the bottom drainage layer 18. The resistance wires are set at the side and bottom of the sample tube 16. The test is completed by controlling the heating or cooling of the resistance wires by a computer according to the test requirements. The resistance wire should have the properties of acid resistance, alkali resistance, chemical corrosion resistance, high temperature resistance and low temperature resistance.

[0106] A thermometer 173 is installed on the upper part of the vertical conductive layer 17, and a probe of the thermometer 173 is inserted into the vertical conductive layer 17 to test the internal temperature. Fig. 9 .

[0107] The third partition 161 has heat resistance, frost resistance, acid resistance, alkali resistance, and chemical corrosion resistance. The third partition 161 is configured to be movable upward and fixed, and its main body is annular (can rise or fall). The third partition 161 is not fixed, and the third partition 161 can rise or fall, and can be adjusted according to the test needs, and a fixing device is provided on the plastic top plate 9 to fix the third partition 161.

[0108] The fourth partition 162 is an inner partition of the sample tube 16. The fourth partition 162 is fixed and has air holes 1621. The air holes 1621 allow heat, cold air and solution to be transferred into the sample. An air-permeable and water-permeable layer 131 is provided on the inner side of the fourth partition 162. In the absence of the filling layer 13, the air-permeable and water-permeable layer 131 isolates the sample from the external environment and prevents the components in the sample (material) from being lost during the test.

[0109] A lower permeable stone 19 is disposed at the bottom of the sample tube 16. The lower permeable stone 19 is disposed between the bottom drainage layer 18 and the sample to isolate the sample from the bottom drainage layer 18 and play a role of air and water permeability. The size of the lower permeable stone 19 can be made according to the maximum size of the sample, and the size and height of the sample are controlled by the filling layer 13. The size of the lower permeable stone 19 is fixed.

[0110] The thickness of the bottom drain layer 18 is set at 1-2 cm, and a slope is set in the bottom drain layer 18 for more convenient drainage of the solution. The material of the drain layer can transfer and dissipate heat and cold air, and has good thermal conductivity and cooling effects. The material of the drain layer should be acid-resistant, alkali-resistant, chemical-resistant, able to withstand greater pressure and not easily deformed.

[0111] A first drain outlet 181 is provided on the bottom drainage layer 18, and the first drain outlet 181 cooperates with the slope. The solution is gathered at the first drain outlet 181 through the slope, and the solution that has passed through the sample is discharged through the first drain outlet 181. At the same time, the solution can be collected through the first drain outlet 181, and the collected solution is used to measure the corresponding flow rate and the conductivity of the solution.

[0112] Four drain ports are provided on the outermost layer of the bottom drainage layer 18 for draining the solution in the vertical drainage layer 17, which are divided into the second drain port 182, the third drain port 183, the fourth drain port 184 and the fifth drain port 185. The thickness of the outermost plastic plate of the bottom drainage layer 18 is set at 2-3 mm. The outermost plastic plate of the bottom drainage layer 18 is acid-resistant, alkali-resistant and chemically resistant. The second drain port 182, the third drain port 183, the fourth drain port 184 and the fifth drain port 185 can be extended to the corresponding collection tank outside the device by external pipes for measuring the seepage volume and the conductivity of the solution.

[0113] A partition is provided on the vertical guide layer 17, and a dial gauge 11 is made and installed on the partition, and the dial gauge 11 is used to test the expansion deformation of the sample. The dial gauge 11 is installed on the partition through a support 111, and the dial gauge 11 can be rotated in a plane through the support 111 to observe the expansion deformation of the sample.

[0114] Eight ventilation holes 101 are arranged around the entire main body device 1. The eight ventilation holes 101 are divided into two layers, with four ventilation holes 101 in each layer, respectively marked as T1-T8. Figure 6-7 The eight ventilation holes 101 can accelerate the drying of moisture in the main device 1, thereby achieving the purpose of drying and dehumidification.

[0115] The vent 101 is connected to a ventilation duct 102, and the eight ventilation ducts 102 are connected to a blower outside the device. The wind speed and strength of the blower are controlled by a computer. At the same time, a vent hole 1621 is provided on the fourth partition plate 162 to dry or cool the sample in cooperation with the ventilation duct 102 and the vent 101. Fig.12 .

[0116] The heating resistor 171 and the cooling resistor 172 are connected to a computer, and the temperature is controlled by the computer to heat or cool, and the sample is dried or cooled through the ventilation duct 102 and the vent 101 in cooperation with the blower. The temperature of the heating resistor 171 varies in the range of 0 to 300°C, and the temperature of the cooling resistor 172 varies in the range of -200 to 0°C. The heating resistor 171 or the cooling resistor 172 is used to heat or cool in cooperation with the vent 101 and the air permeability of the fourth partition 162 to dry or freeze the inside of the sample.

[0117] Twelve humidifiers 103 are arranged around the entire main device 1. The humidifiers 103 are arranged on the outer surface of the second partition 152. The 12 humidifiers 103 are arranged in two rows from top to bottom, with 6 humidifiers in each row, respectively marked as Z1-Z12. Figure 6-7 The humidifying gas connection is provided with a humidifying pipe 104, and the humidifying pipe 104 is connected to the humidifier outside the device. The humidifying operation is performed by controlling the motor part of the humidifier through a computer. The humidity and speed of the gas blown out of the humidifier are controlled by a computer, and the size and strength of the wind are controlled at the same time.

[0118] The humidifier 103 is connected to a nozzle 105, and an expansion plate 106 is arranged at the nozzle 105. The nozzle 105 and the expansion plate 106 are installed in the vertical guide layer 17. According to the arrangement of the humidifier 103, 35 nozzles 105 are installed correspondingly, so as to better diffuse the steam evenly into the sample. The nozzle 105 and the expansion plate 106 have fire resistance, heat resistance, acid resistance, alkali resistance, and chemical corrosion resistance. The humidifier 103 has a waterproof function and corrosion resistance. Through the nozzle 105 and the expansion plate 106, the steam passes through the fourth partition 162 and fully enters the sample.

[0119] A protective layer is provided on the outside of the resistance wire, the humidifier 103, the ventilation duct 102, the humidification duct 104 and the expansion board 106. These devices and the outside that are in contact with the solution need to be coated with a layer of protective material to prevent corrosion from the chemical solution.

[0120] The barometer 14 is mounted on the fourth partition plate 162 and directly monitors the air pressure inside the sample through the air-permeable and water-permeable layer 131 to determine whether the inside of the sample is in a vacuum state. Fig. 9 .

[0121] The test functions of the penetration performance tester are as follows:

[0122] The first test, conventional permeability test operation steps (this test step refers to the requirements of GBT50123-2019 "Geotechnical Test Method Standard"):

[0123] Step 1: Control the compaction degree of the sample (material) through the static pressure loading device and compact it in the main device 1. Install the permeable stone 19 at the bottom of the sample (material) before static pressure loading. After static pressure loading and standing for 2-3 hours, keep the sample (material) from deformation, and move the main device 1 through the slide 6 to the bottom of the pressure rod 7 and the pressure measuring tube 8;

[0124] Step 2: After placing filter paper and upper permeable stone 12 of corresponding size on the sample in sequence, align the position of the plastic top plate 9 with the main device 1, i.e., the top of the sample, and move the plastic top plate 9 downward by controlling the pressure rod 7 through a computer to seal the main device 1, and continue to move downward until the plastic top plate 9 contacts the top of the sample (material), then stop moving downward, and fix the position of the pressure rod 7 so that the plastic top plate 9 maintains the position unchanged throughout the test;

[0125] Step 3, after ensuring that the plastic top plate 9 is completely fixed on the surface of the sample, check the air tightness of the main device 1. After ensuring that the main device 1 is leak-proof, close all drain ports, including the first drain port 181, the second drain port 182, the third drain port 183, the fourth drain port 184 and the fifth drain port 185; close all water inlets, including the first water inlet 1521, the second water inlet 1522, the third water inlet 1523 and the fourth water inlet 1524; the third partition plate 161 does not move upward and remains unchanged; the first valve 71 and the second valve 72 are closed, all humidifiers 103 are closed, the air extraction port 91 is closed, and the air extraction pipe 92, the ventilation pipe 102 and the humidification pipe 104 are respectively connected to the vacuum pump, the blower and the humidifier; and before the test, ensure that the power switch of the equipment is turned off;

[0126] Step 4, filling the water reservoir 15 with the test solution according to the highest water level line 153 of the water reservoir 15, wherein the maximum capacity of the test solution does not exceed the height of the main device 1;

[0127] Step 5: After ensuring that the air tightness of the main device 1 is good, the vacuum pump is turned on by computer control, and the main device 1 is evacuated through the connection between the evacuation port 91 at the plastic top plate 9 and the evacuation pipeline 92, and the air pressure change inside the sample is observed by the barometer 14. The evacuation is carried out for about 4 to 5 hours;

[0128] Step 6: After the main device 1 is completely vacuumed, the vacuum pump is turned off, the third partition 161 is lifted up and fixed by the fixing device on the plastic top plate 9 to keep it in place, then the pull ring 1525 is pulled open, all water inlets are opened, and the solution in the water reservoir 15 is allowed to enter the sample through the air vent 1621 of the fourth partition 162 to saturate it;

[0129] Step 7: According to the reading change of the barometer 14, the vacuum pump is turned on again to perform appropriate air extraction and saturation. After the reading of the barometer 14 stabilizes, the third partition 161 is moved downward, and all water inlets are closed to make the sample in a closed state. After the sample is saturated with back pressure for 24 hours, the sample is saturated;

[0130] Step 8, open the first valve 71 and the second valve 72 at the same time, perform a corresponding permeability test, and read the drop value of the water head height of the solution in the pressure measuring tube 8 within a corresponding time period to calculate the permeability coefficient;

[0131] Step 9: After the test is finished, the second drain port 182 , the third drain port 183 , the fourth drain port 184 and the fifth drain port 185 are opened to drain the solution in the vertical drainage layer 17 .

[0132] In conventional permeability test operation, if the saturation operation is not performed but the permeability coefficient test is performed directly, step 6 can be omitted. If step 6 is not performed, it is necessary to keep the vertical drainage layer 17 free of solution during the entire test process, that is, all water inlets are always closed. If the sample needs to be saturated in advance, the vertical drainage layer 17 must be filled with solution.

[0133] The second test, the penetration test under dry-wet cycle operation steps:

[0134] The compaction, installation and fixation of the specimen are the same as steps 1-3 in the conventional penetration test operation procedure;

[0135] The basic process of drying:

[0136] Step 11, move the third partition plate 161 upward to ensure that the vertical drainage layer 17 is fully dry and no liquid penetrates, then open all the vents 101, connect them to the external blower through the ventilation duct 102 connected thereto, turn on the blower through the computer, and control the wind force and wind speed of the blower and the type of wind through the computer, and the wind type includes hot wind and cold wind;

[0137] Step 12: Dry or freeze and humidify (thaw) the sample through the vertical guide layer 17 and the air holes 1621 of the fourth partition plate 162, and control the temperature and efficiency of the heating resistance wire 171 or the cooling resistance wire 172 through a computer.

[0138] The basic process of saturation:

[0139] Step 21: After drying, close all the vents 101, keep the third partition 161 in place, open all the water inlets, and allow the solution in the reservoir 15 to pass through the vertical drainage layer 17 and then through the air holes 1621 on the fourth partition 162 into the sample, so that the sample is fully saturated;

[0140] Step 22, open all water inlets, and then move the third partition 161 downward to isolate the sample and the vertical drainage layer 17 to prevent the solution from entering the fully saturated sample;

[0141] Step 23, simultaneously open the vacuum valve of the vacuum pump, and properly saturate the sample through the vacuum pipe 92 and the vacuum port 91, and observe the reading change of the barometer 14 to determine whether the pores in the sample are completely exhausted, so that the pore gas generated during the saturation process of the sample is completely exhausted, that is, the saturation exhaust process of the sample is completed;

[0142] Step 24, open the first drain port 181, and open the first valve 71 and the second valve 72, inject the same solution as that in the reservoir 15 into the upper part of the pressure measuring tube 8 in the pressure rod 7, perform a permeation test on the sample, and record the corresponding data for calculation;

[0143] Step 25, open all drain ports to drain the liquid in the vertical drainage layer 17 for the next test operation;

[0144] Completing steps 1-3 in the conventional permeability test operation steps, steps 11-12 in the basic process of drying, and steps 21-25 in the basic process of saturation is the operation process of the permeability test of the sample under one dry-wet cycle. If the dry-wet cycle amplitude of the sample is to be controlled, it can be determined according to the change in the moisture content of the sample, but this needs to be further determined by a preliminary test before the test (ring knife sample).

[0145] The above test process is in the order of dry first and then wet. In actual tests, this order can be adjusted according to needs. Either dry first and then wet or wet first and then dry can be achieved (it depends on whether the permeability test is carried out under unsaturated conditions or saturated conditions). The time and temperature of the dry-wet cycle can be set according to actual test needs.

[0146] The third test, multiple dry-wet cycle test steps:

[0147] On the basis of the permeability test operation steps under dry-wet cycle, the permeability test steps under a single dry-wet cycle, including steps 11-12 and steps 21-23, are cycled as the basis, and step 24 in the basic saturation process is operated last.

[0148] During the whole wet-dry cycle, all drains are always closed, and the solution in the water reservoir 15 is replenished after each cycle and the water reservoir 15 is kept full of sufficient solution, but the solution must not exceed the maximum water level.

[0149] However, after each saturation process, that is, after step 23, the second drain port 182, the third drain port 183, the fourth drain port 184 and the fifth drain port 185 need to be opened to drain the solution in the vertical drainage layer 17, and then all drain ports are closed. Then all vents 101 are opened to allow the vertical drainage layer 17 to dry completely, and then the next drying and saturation process is performed. After the last dry-wet cycle is completed, step 24 is performed to perform penetration tests on samples with different dry-wet cycle times.

[0150] The fourth test, the penetration test under freeze-thaw cycle, operation steps:

[0151] The compaction, installation and fixation of the specimen are the same as steps 1-3 in the conventional penetration test operation procedure;

[0152] The basic process of freezing:

[0153] This process is the same as steps 11-12 in the basic drying process, except that the freezing process mainly needs to be achieved through the cooling resistance wire 172.

[0154] The cooling effect is achieved through the cooling resistor wire 172 and in conjunction with all the vents 101 . The third partition 161 is lifted up and fixed in place to ensure that the vertical drainage layer 17 is fully dry and free of solution. The blower is turned on and cold air is delivered to the interior of the sample through the ventilation duct 102 .

[0155] The computer controls the wind force and wind speed of the blower through the terminal program, and ensures that the air blown in is cold air. The cold air is blown into the vertical guide layer 17 through the ventilation duct and blown into the sample through the fourth partition 162 to achieve a cooling effect.

[0156] The temperature during the freezing process of the sample is controlled by a computer, and the temperature in the main device 1 is monitored in real time in combination with a thermometer 173 .

[0157] The basic process of melting (you can choose melting method 1 or melting method 2):

[0158] Melting method 1. Solution saturation:

[0159] Step A: Keep the third partition 161 in the upward position, open all water inlets, and allow the solution to enter the sample through the vertical drainage layer 17 and the air holes 1621 of the fourth partition 162, so that the sample is fully saturated and melted. This step takes a relatively longer time.

[0160] Step B: After the melting is completed, the second drain port 182 , the third drain port 183 , the fourth drain port 184 and the fifth drain port 185 are opened to discharge the solution in the vertical conductive layer 17 .

[0161] Melting method 2: Constant temperature and humidity maintenance:

[0162] Step a: After ensuring that the solution in the vertical drainage layer 17 is completely discharged, the sample is melted under the curing conditions of constant temperature and humidity (20 degrees Celsius), ensuring that the third partition plate 161 is fixed in the upward position;

[0163] Step b, the temperature in the vertical conductive layer 17 is kept constant at room temperature by controlling the heating resistance wire 171 and the cooling resistance wire 172 in the vertical conductive layer 17, the humidifier is input with a computer to control the gas (with a certain humidity), and then the humidification pipeline 104 and the humidifier 103 are opened to humidify the inside of the sample in cooperation with the resistance wire;

[0164] Step c, after the sample is fully thawed, all humidification pipes 104 and humidifiers 103 are closed, and the third partition plate 161 is moved downward to isolate the vertical drainage layer 17 from the sample, so as to prevent the external solution from entering the sample after the sample is fully saturated;

[0165] Step d, opening the second drain port 182, the third drain port 183, the fourth drain port 184 and the fifth drain port 185 to discharge the solution in the vertical drainage layer 17 for the next test;

[0166] Step e: Finally, after adding the corresponding solution into the pressure measuring tube 8 in pressure (the solution is determined according to the test requirements), open the first valve 71, the second valve 72 and the first drain port 181 to conduct a permeation test.

[0167] The above-mentioned permeability test operation steps under freeze-thaw cycles are the operation process of the permeability test of the sample (material) under one freeze-thaw cycle, and the time and temperature of the freeze-thaw cycle are set according to the actual test requirements.

[0168] The fifth test, multiple freeze-thaw cycle test operation steps:

[0169] The cycle is performed based on the other steps except step e in the permeability test operation steps under the freeze-thaw cycle, and step e is performed last.

[0170] During the whole wet-dry cycle, all drains are closed. After each cycle, the solution in the reservoir 15 is replenished and the reservoir 15 is ensured to be filled with enough solution but not exceeding the highest water level.

[0171] However, after each saturation process, the second drain port 182, the third drain port 183, the fourth drain port 184 and the fifth drain port 185 need to be opened to drain the solution in the vertical drainage layer 17, and then all drain ports are closed. Then all vents 101 are opened to allow the vertical drainage layer 17 to dry completely, and then the next drying and saturation process is performed. After the last dry-wet cycle is completed, step e is performed to perform permeation tests on samples under different dry-freeze-thaw cycles.

[0172] The above is only a preferred specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any technician familiar with the technical field who uses this concept to make non-substantial changes to the present invention within the technical scope disclosed by the present invention shall be deemed to infringe the protection scope of the present invention.

Claims

1. The permeability tester of soil under the effects of dry-wet or freeze-thaw cycles, characterized by: It includes a static pressure loading device part and a core test part, and the two parts are connected and fixed by a bracket; The static pressure loading device is composed of a hydraulic device, a hydraulic rod, a main device, a bottom pedestal and a slideway; the hydraulic rod drives the hydraulic device to move up and down; the hydraulic rod is fixed on the top of the bracket; The core test part is composed of a pressure rod, a pressure measuring tube and a plastic top plate. The pressure measuring tube is installed in the pressure rod, the pressure rod is installed on the top of the bracket, and the pressure rod can be raised and lowered; the plastic top plate is installed at the bottom of the pressure rod; The bottom pedestal and the slide groove extend from the static pressure loading device portion to the core test portion, and the main device is mounted on the slide groove and has a sliding motion along the slide groove; the main device can be slidably placed under the hydraulic device or under the plastic top plate along the slide groove; The main device includes a water reservoir and a sample tube, the water reservoir is composed of a first partition and a second partition, and the sample tube is composed of a third partition and a fourth partition; the second partition and the third partition form a vertical guide layer, and a water inlet is arranged on the second partition; the third partition can be raised and lowered, and the fourth partition is provided with a vent hole; A bottom drainage layer is arranged at the bottom of the sample tube, and heating resistance wires and cooling resistance wires are built into the vertical drainage layer and the bottom drainage layer; the bottom drainage layer and the vertical drainage layer are both provided with drainage ports; A vent and a humidifier are arranged on the outside of the second partition, and a first valve and a second valve are arranged at the bottom of the pressure rod; an exhaust port is arranged on the plastic top plate for vacuuming; a barometer is installed on the fourth partition for detecting changes in air pressure inside the device body.

2. The soil permeability tester under the effects of dry-wet or freeze-thaw cycles according to claim 1, characterized in that: The water reservoir is provided with a maximum water level line; a pull ring is provided at the water inlet, and the pull ring is used to control the opening and closing of the water inlet; a breathable layer is provided at the bottom of the plastic top plate; the pressure measuring tube is provided with scale lines, and the pressure rod is a transparent rod.

3. The soil permeability tester under the effects of dry-wet or freeze-thaw cycles according to claim 1, characterized in that: A dial gauge is arranged above the vertical conductive layer, and the dial gauge is rotatable in a plane; a thermometer is installed above the vertical conductive layer.

4. The soil permeability tester under the effects of dry-wet or freeze-thaw cycles according to claim 1, characterized in that: The main device includes a filling layer, and a lower permeable stone is arranged at the bottom of the sample tube; The humidifier is connected to a nozzle, an expansion board is arranged at the nozzle, and the nozzle and the expansion board are installed in the vertical guide layer.

5. The method for testing the permeability of soil under the effects of dry-wet or freeze-thaw cycles is characterized by: The penetration performance tester according to any one of claims 1 to 4 is used; the testing method comprises the following steps: Step 1: Control the compaction degree of the sample (material) through the static pressure loading device and compact it in the sample tube of the main device; after static pressure loading and standing for 2-3 hours, keep the sample (material) from deformation and move the main device to the bottom of the pressure rod and the pressure measuring tube through the slide; Step 2: After placing filter paper and upper permeable stone of corresponding sizes on the sample in sequence, align the position of the plastic top plate with the main device, i.e., the top of the sample, and move the plastic top plate downwards by controlling the pressure rod through the computer to seal the main device, and continue to move downwards until the plastic top plate contacts the top of the sample (material), then stop moving downwards, and fix the position of the pressure rod so that the plastic top plate remains in this position throughout the test; Step 3: After ensuring that the plastic top plate is completely fixed on the surface of the sample, check the air tightness of the main device. After ensuring that the main device does not leak, close the drain port and the water inlet; the third partition does not move upward and remains unchanged; the first valve and the second valve are closed, the humidifier is closed, the air extraction port is closed, and the power switch of the equipment is ensured to be turned off before the test; Step 4: Fill the reservoir with the test solution, the maximum capacity of the test solution not exceeding the height of the main device; Step 5: After ensuring the air tightness of the main device, turn on the vacuum pump through computer control, evacuate the main device through the air evacuation port on the plastic top plate, and observe the air pressure change inside the sample through a barometer. The evacuation lasts for about 4 to 5 hours. Step 6: After the main device is completely vacuumed, turn off the vacuum pump, lift the third baffle upward and fix it to keep it in place, open the water inlet, and allow the solution in the reservoir to enter the sample through the air holes of the fourth baffle to saturate it; Step 7: According to the change of the barometer reading, turn on the vacuum pump again to perform appropriate air saturation. After the barometer reading is stable, move the third partition downward and close all water inlets to keep the sample in a closed state. After the sample is saturated with back pressure for 24 hours, the sample is saturated. Step 8: Open the first valve and the second valve at the same time, conduct a corresponding permeability test, and read the drop value of the water head height of the solution in the pressure measuring tube within a corresponding time period to calculate the permeability coefficient; Step 9: After the test, open the drain port of the vertical drainage layer to drain the solution in the vertical drainage layer.

6. The method for testing the permeability of soil under the effects of dry-wet or freeze-thaw cycles according to claim 5, characterized in that: In the test method, if a saturation operation is required, step 6 is retained; if a saturation operation is not required, step 6 is omitted; If step 6 is omitted, it is necessary to ensure that no solution enters the vertical drainage layer during the entire test process.

7. A method for testing the permeability of soil under dry-wet cycle effects, characterized in that: The permeability tester according to any one of claims 1 to 4 is used; the test method includes a drying process and a saturation process, and before the drying process and the saturation process are performed, steps 1 to 3 in claim 7 are performed first; The drying process includes the following steps: Step 11, move the third partition upward to ensure that the vertical drainage layer is fully dry and no liquid penetrates, then open the vent and connect the blower, turn on the blower through the computer, and control the wind force and wind speed of the blower and the type of wind through the computer, the wind type includes hot wind and cold wind; Step 12, drying the sample through the air holes of the vertical guide layer and the fourth partition, and controlling the temperature and efficiency of the heating resistance wire or the cooling resistance wire through a computer; The saturation process includes the following steps: Step 21: After drying, close the vent, keep the third baffle in place, open the water inlet, and allow the solution in the reservoir to pass through the vertical drainage layer and then through the air holes on the fourth baffle into the sample, so that the sample is fully saturated; Step 22, open the water inlet, and then move the third partition downward to isolate the sample and the vertical drainage layer to prevent the solution from entering the fully saturated sample; Step 23, turn on the vacuum pump to properly saturate the sample through the suction port, and observe the changes in the reading of the barometer to determine whether the pores in the sample are completely exhausted, so that the pore gas generated during the saturation process of the sample is completely exhausted, that is, the saturation exhaust process of the sample is completed; Step 24, open the drain port of the bottom drainage layer, open the first valve and the second valve, inject the same solution as that in the reservoir into the upper part of the pressure measuring tube in the pressure rod, conduct a permeability test on the sample, and record the corresponding data for calculation; Step 25, open all drain ports to drain the liquid; The multiple dry-wet cycle test steps are to cycle based on steps 11-12 and steps 21-23, and perform the final operation of step 24 after the cycle is completed.

8. A method for testing the permeability of soil under freeze-thaw cycle effects, characterized in that: The permeability tester according to any one of claims 1 to 4 is used; the test method includes a freezing process and a melting process, and before the freezing process and the melting process are performed, steps 1 to 3 in claim 7 are performed first; The freezing process includes the following steps: Step 111, move the third partition upward to ensure that the vertical drainage layer is fully dry and no liquid penetrates, then open the vent and connect the blower, turn on the blower through the computer, and control the wind force and wind speed of the blower and the type of wind through the computer, the type of wind is cold wind; Step 112, freezing the sample through the air holes of the vertical guide layer and the fourth partition, and controlling the temperature and efficiency of the refrigeration resistance wire through a computer; The melting process is carried out by using a saturated solution or by using a constant temperature and humidity curing system; The multiple dry-wet cycle test steps are to cycle based on the freezing process and the melting process, and perform the last step of the melting process after the cycle is completed.

9. The method for testing the permeability of soil under freeze-thaw cycle effect according to claim 8, characterized in that: Melting by solution saturation includes the following steps: Step A, keep the third partition in the upward position, open the water inlet, and allow the solution to enter the sample through the vertical drainage layer and the air holes of the fourth partition, so that the sample is fully saturated and fully melted; Step B: After the melting is completed, the drain port of the vertical drainage layer is opened to drain the solution in the vertical drainage layer.

10. The method for testing the permeability of soil under freeze-thaw cycle effect according to claim 8, characterized in that: Melting by constant temperature and humidity curing includes the following steps: Step a: After ensuring that the solution in the vertical drainage layer is completely discharged, the sample is melted under constant temperature and humidity curing conditions (20 degrees Celsius) to ensure that the third partition is fixed in the upward position; Step b, controlling the temperature in the vertical conductive layer to remain constant at room temperature by means of the heating resistance wire and the cooling resistance wire in the vertical conductive layer, using a computer to control the humidifier to input gas (with a certain humidity), and then turning on the humidifier to humidify the inside of the sample in cooperation with the resistance wire; Step c, after the sample is fully thawed, the humidifier is turned off, and the third partition is moved downward to isolate the vertical guide layer from the sample, so as to prevent the external solution from entering the sample after the sample is fully saturated; Step d, opening the drain port of the vertical drainage layer to drain the solution in the vertical drainage layer; Step e: Finally, after adding the corresponding solution into the pressure measuring tube in the pressure (the solution is determined according to the test requirements), open the first valve, the second valve and the drainage port of the bottom drainage layer to conduct a permeability test.

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