Thermal-hydraulic coupling super-low permeability swelling soil sample rapid saturation device

Abstract

The application provides a thermal-chemical coupling ultra-low permeability swelling soil sample rapid saturation device, which comprises a saturation device, a temperature control system, a water injection system, a water-salt conversion system, a pressure injection system and a liquid collecting device. The saturation device comprises a top cover, a base, two detachable semicircular sample chambers and a fixed outer wall, and is connected with the liquid collecting device and a solution tank through the top cover and the base respectively; the temperature control system can accommodate the saturation device; the water injection system comprises an air pump, a pressure reducing valve and a solution tank, and the solution tank is connected with the pressure injection system and the base of the saturation device through a pipeline tee joint. The application can realize rapid saturation of low permeability and swelling soil samples under different temperature and chemical solution conditions, can realize complete, high-quality and rapid demolding of the samples, can realize control of saturation time of different materials by setting the pressure injection size, can greatly reduce the time required for saturation of soil samples in soil test, can improve test efficiency, and can meet use requirements under different conditions.

Description

Technical Field

[0001] This invention belongs to the technical field of geotechnical testing instruments and equipment, specifically relating to a rapid saturation device for thermally-chemically coupled ultra-low permeability expansive soil samples. Background Technology

[0002] Expansive soils, bentonite, and expansive clays often possess ultra-low permeability. On the one hand, they are widely used as seepage barriers in nuclear waste geological repositories, CO2 geological sequestration, geothermal energy utilization, dam cores, and landfills. On the other hand, landslides and other geological hazards also involve large amounts of low-permeability, expansive soils. Studying the physical and mechanical properties of saturated ultra-low permeability expansive soils is an important aspect of laboratory geotechnical testing, especially in studies of nuclear waste repositories and CO2 geological sequestration, where the effects of thermo-chemical reactions are unavoidable. Achieving rapid saturation of ultra-low permeability expansive soil samples under controlled temperature and chemical conditions is a crucial problem that needs to be solved.

[0003] Currently, most indoor saturation test apparatuses use water injection from the top and bottom surfaces of the sample to saturate ultra-low permeability soil samples. Obviously, this method has an excessively long saturation time and mostly fails to account for the coupled effects of temperature (thermal) and chemical (chemical) factors; in addition, it is difficult to achieve high-quality demolding of saturated low-permeability soil samples.

[0004] Therefore, there is an urgent need to develop a novel thermo-chemically coupled rapid saturation device for ultra-low permeability expansive soil samples to achieve rapid and efficient saturation of ultra-low permeability expansive soil samples that can be disassembled and demolded, taking into account the coupling effects of temperature (thermal) and chemical (chemical) factors. Summary of the Invention

[0005] This invention provides a rapid saturation device for ultra-low permeability expansive soil samples using a thermo-chemical coupling method. The purpose of this invention is to solve the problems of existing saturation devices, such as failing to meet the thermo-chemical coupling conditions, excessive time consumption, difficulty in sample removal, high testing costs, and large workload.

[0006] To achieve the above objectives, a rapid saturation device for thermo-chemical coupling of ultra-low permeability expansive soil samples is provided. It includes:

[0007] Saturation device, temperature control system, water injection system, water-salt conversion system, pressure injection system, liquid collection device and pipeline system.

[0008] The saturation device includes a top cover, a base, two detachable semi-circular sample chambers, and a fixed outer wall. The top cover has water injection channels on its sides and top surface, and the base has two water injection channels on its sides. A solution chamber is located outside the two detachable semi-circular sample chambers, with a solution channel on its surface and saturation holes on its surface. The fixed outer wall seals the two detachable semi-circular sample chambers. A temperature control system can house the saturation device. The water injection system includes a pneumatic pump, a pressure reducing valve, and a solution tank. The solution tank has pre-drilled holes at its top and bottom, and is connected to the pneumatic pump via the pressure reducing valve. The water-salt conversion system includes a water-salt converter and a pressure gauge. The water-salt converter has pre-drilled holes on its top and bottom surfaces, and is connected to the pressure gauge. The pressure injection system includes a pressure / volume control device and a data monitoring device. The liquid collection device collects the waste liquid discharged from the saturation device.

[0009] The saturation device includes a top cover, a base, two detachable semi-circular sample chambers, and a fixed outer wall. The two detachable semi-circular sample chambers are connected to the top cover and the base through a nested structure. The fixed outer wall is used to seal the two detachable semi-circular sample chambers and is fixed outside the two detachable semi-circular sample chambers. The saturation device is fixed through bolt holes reserved on the top cover and the base.

[0010] The two detachable semi-circular sample chambers can be assembled into a complete circular sample chamber. The interior of the two detachable semi-circular sample chambers is used to place soil samples. The exterior of the two detachable semi-circular sample chambers is provided with a solution chamber for placing a solution for saturating the sample. The solution chambers are connected to each other through a solution channel. The inner surface of the two detachable semi-circular sample chambers is provided with a through saturation hole connected to the solution chamber. The solution for saturating the sample enters the interior of the two detachable semi-circular sample chambers through the saturation hole.

[0011] The top cover is provided with a sample water injection channel, and the lower part of the top cover is provided with a permeable stone. The upper part of the permeable stone is connected to the sample water injection channel on the top cover, and the lower part is connected to the interior of the two detachable semi-circular sample chambers. The top cover is provided with a solution chamber water injection channel, and the lower part of the solution chamber water injection channel on the top cover is connected to the solution chamber.

[0012] The base is provided with a sample water injection channel, and the upper part of the base is provided with a permeable stone. The lower part of the permeable stone is connected to the sample water injection channel on the base, and the upper part is connected to the interior of the two detachable semi-circular sample chambers. The base is provided with a solution chamber water injection channel, and the upper part of the solution chamber water injection channel on the base is connected to the solution chamber.

[0013] The temperature control system can incorporate a saturation device.

[0014] The water injection system includes a pneumatic pump, a pressure reducing valve, and a solution tank. The solution tank has reserved holes at the top and bottom. The solution tank is connected to the pneumatic pump through the pressure reducing valve. The reserved hole at the bottom of the solution tank is connected to the solution chamber water injection channel on the base through a pipe.

[0015] The water-salt conversion system includes a water-salt converter and a pressure gauge. The water-salt converter has two injection holes on its top surface and two valves on its bottom surface. The water-salt converter is connected to a pre-drilled hole on the side of the saturation device base through the pressure gauge.

[0016] The injection system includes a pressure / volume controller and a data monitoring device. The data monitoring device is used to install software on the pressure / volume controller and monitor data changes. The pressure / volume controller is connected to the water-salt converter via a pipeline.

[0017] The saturation device has water injection channels on its side and top surface, which can be connected to pipes. The liquid collection device can be connected to the saturation device top cover through pipes to collect the waste liquid discharged from the saturation device.

[0018] The pipeline system is used to connect the various parts of the rapid saturation device for thermally coupled ultra-low permeability expansive soil samples.

[0019] The above-described solution of the present invention has the following beneficial effects:

[0020] (1) The rapid saturation device provided by the present invention can adjust the saturation injection pressure to achieve rapid saturation of low permeability and expansive soil samples under different dry density conditions. For soil samples with the same dry density, the greater the saturation injection pressure, the shorter the saturation time.

[0021] (2) The rapid saturation device provided by the present invention can saturate the soil sample through two detachable semi-circular sample chambers. After saturation is completed, the device can be easily disassembled and the saturated soil sample can be taken out completely, easily and with high quality, so as to achieve rapid demolding of saturated soil sample and solve the problem that the previous saturation device could not demold quickly and with high quality.

[0022] (3) The rapid saturation device provided by the present invention can be controlled by a temperature control system to adjust the temperature to meet the saturation requirements of soil samples under different temperature conditions.

[0023] (4) The rapid saturation device provided by the present invention can transmit the pressure of the water transmitted by the pressure / volume controller to the corresponding salt solution through the water-salt conversion system, thereby protecting the pressure / volume controller;

[0024] (5) The rapid saturation device provided by the present invention includes a pneumatic pump and a solution tank, which can inject the chemical solution used for saturation into the solution chamber of the saturation device through the pneumatic pump. It can meet the sample saturation requirements under different chemical conditions, and combined with the temperature control device, it can achieve soil sample saturation under the effect of thermal-chemical coupling, thereby solving the defect that the previous saturation device could not achieve the effect of thermal-chemical coupling.

[0025] (6) The rapid saturation device provided by the present invention has multiple sets of through saturation holes in the solution chamber of the two detachable semi-circular sample chambers, which can saturate the soil sample from the side. Unlike the previous saturation device, which could only saturate the sample from the top and bottom, the present invention can saturate from the bottom and side at the same time, thereby achieving rapid saturation of the sample.

[0026] (7) The rapid saturation device provided by the present invention can be disassembled, combined and reused. In addition, the device is simple in composition, easy to manufacture and can be made into different sizes to meet different test needs.

[0027] This invention can quickly saturate low-permeability and expansive soil samples, achieving saturation of soil samples under different thermochemical conditions. After saturation, the soil samples can be demolded intact and with high quality, showing good application effect for indoor soil sample saturation treatment. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the thermal-chemical coupling device for rapid saturation of ultra-low permeability expansive soil samples according to the present invention.

[0029] Figure 2 This is a schematic diagram of the saturation device of the thermal-chemical coupling rapid saturation device for ultra-low permeability expansive soil samples of the present invention.

[0030] Figure 3 The images show a top view and a cross-sectional view of the two detachable semi-circular sample chambers of the thermal-chemically coupled ultra-low permeability expansive soil sample rapid saturation device of the present invention.

[0031] Figure 4 This is a schematic diagram of the base (a) and top cover (b) of the thermal-chemical coupling ultra-low permeability expansive soil sample rapid saturation device of the present invention.

[0032] Figure 5 This is a top view of the base of the thermal-chemically coupled ultra-low permeability expansive soil sample rapid saturation device of the present invention.

[0033] Figure 6 This is a schematic diagram of the temperature control system of the thermal-chemical coupled ultra-low permeability expansive soil sample rapid saturation device of the present invention.

[0034] [Explanation of Labels in the Attached Image]

[0035] 1-Saturation device; 2-Temperature control system; 3-Water injection system; 4-Water-salt conversion system; 5-Pressure injection system; 6-Liquid collection system; 7-Pipeline system; 101-Top cover; 102-Base; 103-Two detachable semi-circular sample chambers; 104-Fixed outer wall; 105-Bolt; 106-Nut; 107-Top cover bolt hole; 108-Top cover sample water injection channel; 109-Top cover solution chamber water injection channel; 110-First valve; 111-Second valve; 112-Top cover side O-ring; 113-Top cover bottom O-ring; 114-Top cover permeable stone; 115-Base support foot; 116-Base sample water injection channel; 117-Base solution chamber water injection channel; 118-Base bolt hole; 119-Third valve; 120-Fourth valve; 121 - O-ring on top of base; 122 - O-ring on side of base; 123 - Permeable stone of base; 124 - Solution chamber; 125 - Solution channel; 126 - Saturation orifice; 127 - Filter paper; 128 - Soil sample; 301 - Pneumatic pump; 302 - Pressure reducing valve; 303 - Fifth valve; 304 - Solution tank; 305 - Sixth valve; 401 - Water-salt converter; 402 - Liquid storage chamber; 403 - Liquid storage chamber injection hole; 404 - Water storage chamber injection hole; 405 - Water storage chamber; 406 - Seventh valve; 407 - Eighth valve; 408 - Piston; 409 - Water storage chamber hole; 410 - Liquid storage chamber hole; 411 - Pressure gauge; 501 - Pressure / volume controller; 502 - Data monitoring device; 701~708 - Pipeline; 709~710 - Pipeline tee; Detailed Implementation

[0036] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0037] This invention addresses the problems of existing saturation devices failing to meet the thermal-chemical coupling conditions, being too time-consuming, difficult to disassemble samples, having high testing costs, and requiring a large workload by providing a rapid saturation device for ultra-low permeability expansive soil samples via thermal-chemical coupling.

[0038] like Figure 1As shown, an embodiment of the present invention provides a rapid saturation device for ultra-low permeability expansive soil samples via thermal-chemical coupling, comprising: a saturation device 1, a temperature control system 2, a water injection system 3, a water-salt conversion system 4, a pressure injection system 5, a liquid collection device 6, and a pipeline system 7; the saturation device 1 includes a top cover 101, a base 102, two detachable semi-circular sample chambers 103, and a fixed outer wall 104, wherein the top cover 101 has water injection channels 108 and 109 on its side and top surface, respectively, the base 102 has two water injection channels 116 and 117 on its side, a solution chamber 124 is provided outside the two detachable semi-circular sample chambers 103, a solution channel 125 is provided outside the solution chamber 124, and a saturation orifice 126 is provided on the surface of the solution chamber 124; the fixed outer wall 104 holds the two detachable semi-circular sample chambers 103 together. The device is sealed; the temperature control system 2 can house the saturation device 1; the water injection system 3 includes a pneumatic pump 301, a pressure reducing valve 302, and a solution tank 304. The solution tank 304 has a fifth valve 303 and a sixth valve 305 at its upper and lower parts, respectively. The solution tank 304 is connected to the pneumatic pump 301 through the pressure reducing valve 302; the water-salt conversion system 4 includes a water-salt converter 401 and a pressure gauge 411. The water-salt converter 401 has two injection holes 403 and 404 at its upper part and two valves 406 and 407 at its lower part. The water-salt converter 401 is connected to the pressure gauge 411; the pressure injection system 5 includes a pressure / volume control device 501 and a data monitoring device 502; the liquid collection device 6 is used to collect the waste liquid discharged from the saturation device 1; the pipeline system 7 is used to connect the various components of the device.

[0039] The following details each system.

[0040] like Figure 2 As shown in the above embodiment of the present invention, the rapid saturation device for thermal-chemical coupling ultra-low permeability expansive soil samples includes a top cover 101, a base 102, two detachable semi-circular sample chambers 103, and a fixed outer wall 104. The two detachable semi-circular sample chambers 103 are connected to the top cover 101 and the base 102 through a nested structure. The fixed outer wall 104 is used to seal the two detachable semi-circular sample chambers 103 and is fixed outside the two detachable semi-circular sample chambers 103. The saturation device 1 is fixed by six bolts 105 and six nuts 106 passing through six bolt holes 107 on the top cover and six bolt holes 118 on the base.

[0041] like Figure 1 , Figure 2 , Figure 3As shown, the two detachable semi-circular sample chambers 103 can be assembled into a complete circular sample chamber. The interior of the two detachable semi-circular sample chambers 103 is used to place a soil sample 128. The soil sample 128 is wrapped with a layer of filter paper 127. Five solution chambers 124 are provided on the outside of the two detachable semi-circular sample chambers 103. The solution chambers 124 are used to place the liquid for solution tank 304. The solution chambers 124 are connected to each other through solution channels 125. The inner surface of the two detachable semi-circular sample chambers 103 is provided with through saturation holes 126 connected to the solution chambers 124. The solution for saturating the sample enters the interior of the two detachable semi-circular sample chambers 103 through the saturation holes 126 to saturate the soil sample 128.

[0042] like Figure 1 , Figure 2 , Figure 4 , Figure 5 As shown, the top cover 101 is provided with a sample water injection channel 108, and a first valve 110 is provided outside the sample water injection channel 108 of the top cover 101. A permeable stone 114 is provided at the lower part of the top cover 101. The upper part of the permeable stone 114 is connected to the sample water injection channel 108 on the top cover 101, and the lower part is connected to the interior of the two detachable semi-circular sample chambers 103. The top cover 101 is provided with a solution chamber water injection channel 109, and a second valve 111 is provided outside the solution water injection channel 109 of the top cover 101. The lower part of the solution chamber water injection channel 109 on the top cover 101 is connected to the solution chamber 124. The top cover 101 is provided with six through bolt holes 107.

[0043] like Figure 1 , Figure 2 , Figure 4 As shown, the base 102 is provided with a sample water injection channel 116, and a fourth valve 120 is provided outside the sample water injection channel 116 of the base 102; a permeable stone 123 is provided on the upper part of the base 102, the lower part of the permeable stone 123 is connected to the sample water injection channel 116 on the base 102, and the upper part is connected to the interior of the two detachable semi-circular sample chambers 103; a solution chamber water injection channel 117 is provided on the base 102, and a third valve 119 is provided outside the solution chamber water injection channel 117 of the base 102; the upper part of the solution chamber water injection channel 117 on the base 102 is connected to the solution chamber 124; four support feet 115 are provided on the lower part of the base 102; six non-through bolt holes 118 are provided on the base 102, and the six screws 105 and six nuts 106 can be fixed in the six bolt holes 118 on the base 102 through the six through bolt holes 107 on the upper part of the top cover 101.

[0044] The rapid saturation device for ultra-low permeability expansive soil samples via thermal-chemical coupling described in the above embodiments of the present invention includes a temperature control system 2 that can house the saturation device 1. Figure 6 As shown, the temperature control system 2 is a blower-type oven.

[0045] like Figure 1 As shown in the above embodiment of the present invention, the rapid saturation device for thermal-chemical coupling ultra-low permeability expansive soil samples includes a water injection system 3 comprising a pneumatic pump 301, a pressure reducing valve 302, and a solution tank 304. A fifth valve 303 and a sixth valve 305 are provided at the upper and lower parts of the solution tank 304. The solution tank 304 is connected to the pneumatic pump 301 via the pressure reducing valve 302. The fifth valve 303 is connected to a pipe tee 710 via a pipe 708. One path of the pipe tee 710 is connected to the pipe 704. The pipe 704 is connected to the solution chamber water injection channel 117 on the base via a third valve 119. The other path is connected to the sample water injection channel 116 on the base via pipe 705, pipe tee 709, and pipe 703 via a fourth valve 120.

[0046] The pneumatic pump 301 can apply air pressure and control the output air pressure through the pressure reducing valve 302. The air pressure is injected into the solution tank 304 through the pipe 305 and the fifth valve 303. It is connected to the pipe 704 through the sixth valve 305, the pipe 708, the pipe tee 710, and one of the pipes. The pipe 704 is connected to the solution chamber water injection channel 117 on the base through the third valve 119. Another path is connected to the sample water injection channel 116 on the base through the pipe 705, the pipe tee 709, the pipe 703, and the fourth valve 120, so as to inject the saturated solution into the saturation device.

[0047] like Figure 1 As shown in the above embodiment of the present invention, the rapid saturation device for thermal-chemical coupling ultra-low permeability expansive soil samples includes a water-salt conversion system 4 comprising a water-salt converter 401 and a pressure gauge 411. The water-salt converter 401 is internally provided with a liquid storage chamber 402, a water storage chamber 404, and a piston 408. The liquid storage chamber 402 is provided with a liquid storage chamber injection hole 403 at the upper part and a liquid storage chamber hole 410 at the lower part. An eighth valve 407 is provided outside the liquid storage chamber hole 410. The water storage chamber 404 is provided with a water storage chamber injection hole 404 at the upper part and a water storage chamber hole 409 at the lower part. A seventh valve 406 is provided outside the water storage chamber hole. The eighth valve 407 is connected to the pressure gauge 411.

[0048] The pressure in the water storage chamber 404 can be applied to the liquid storage chamber 402 by the piston 408, thereby realizing the water-salt conversion.

[0049] The pressure gauge 411 is connected to the pipe tee 709 via pipe 706. One of the pipe tee 709 enters the water injection channel 117 of the base solution chamber through pipe 705, pipe tee 710, pipe 704, and the third valve. The other pipe enters the water injection channel 116 of the base sample through pipe 703 and the fourth valve 120, and saturates the soil sample 128 through the permeable stone 123 of the base.

[0050] like Figure 1 As shown in the above embodiment of the present invention, the rapid saturation device for thermal-chemical coupling ultra-low permeability expansive soil samples includes a pressure / volume controller 501 and a data monitoring device 502. The data monitoring device 502 is used to install software on the pressure / volume controller 501 and monitor data changes.

[0051] The pressure / volume controller 501 is connected to the seventh valve 406 on the water-salt converter 401 via the pipe 707. It transmits pressure to the water storage chamber 405 through the water storage chamber hole 410, and then transmits the pressure to the liquid storage chamber 402 via the piston 408, thereby pressurizing the saturated solution and achieving rapid saturation.

[0052] like Figure 1 As shown, in the above embodiment of the present invention, the rapid saturation device for thermal-chemical coupling ultra-low permeability expansive soil samples, the liquid collection device 6 can be connected to the first valve 110 and the second valve 111 through pipes 701 and 702 respectively, for collecting the waste liquid discharged from the saturation device 1.

[0053] like Figure 1 As shown in the above embodiment of the present invention, the rapid saturation device for thermal-chemical coupling ultra-low permeability expansive soil samples includes a pipeline system 7 for connecting various parts of the device.

[0054] The test method based on the above-mentioned thermo-chemical coupled rapid saturation device for ultra-low permeability expansive soil samples includes the following steps:

[0055] (1) Soil sample installation: First, close all valves, install filter paper 127 on the outside of the soil sample 128 to be saturated, and install it in the two detachable semi-circular sample chambers 103. Apply Vaseline to the O-ring 122 on the side of the bottom cover and the O-ring 121 on the top surface of the base. Then install the two detachable semi-circular sample chambers 103 on the base 102 through a nested structure. Then install the fixed outer wall 104 on the outside of the two detachable semi-circular sample chambers 103. Apply Vaseline to the O-ring 112 on the side of the top cover and the O-ring 113 on the bottom surface of the top cover. Install the top cover 101 on the two detachable semi-circular sample chambers 103 and the fixed outer wall 104. Then fix each part of the saturation device 1 with six bolts 105 and nuts 106.

[0056] (2) Solution placement: The solution to be saturated (deionized water, salt solution, alkaline solution) is injected into the solution tank 304, and the solution to be saturated is injected into the storage chamber 402 of the water-salt converter 401 through the storage chamber injection hole 403. Deionized water is injected into the storage chamber 405 of the water-salt converter 401 through the water storage chamber injection hole 404 for subsequent saturation test.

[0057] (3) Solution Injection: After completing steps (1)-(2), open the first valve 110, the second valve 111, the third valve 119, and the fourth valve 120 in sequence. Turn on the pneumatic pump 301 and use the pressure reducing valve 302 to adjust the injection pressure to 2 kPa. Then open the fifth valve 303 and the sixth valve 305 to inject the solution in the solution tank 304 through the pipe 708 and the pipe tee 710. One path goes through the pipe 704 and the third valve 119, through the water injection hole 117 of the solution chamber in the base, into the solution chamber 124 and through the solution channel 125 to fill the solution chamber 124 with saturated solution. The other path goes through the pipe tee 710, through the pipe 705, and the pipe The tee 709, pipe 706, and fourth valve 120 saturate the soil sample 128 by entering the permeable stone 123 of the base through the sample injection hole 116. In addition, the tee 709 can enter the pipe 706, and the pressure gauge 411 can read the current pressure value in the pipe, which is the injection pressure value. After the solution chamber 124 is filled with saturated solution, the excess saturated liquid can enter the solution collection device 6 through the top cover solution chamber injection hole 109 and the second valve 111 and then through the pipe 702. In addition, the excess saturated solution can enter the solution collection device 6 through the top cover permeable stone 114, the top cover sample injection hole 108, the first valve 110, and through the pipe 701.

[0058] When excess saturated solution flows into the solution collection device 6, the first valve 110, the fourth valve 120, the second valve 111, the third valve 119, the sixth valve 305, and the fifth valve 303 are closed in sequence. The pneumatic pump 301 is turned off, the pipeline 305 is opened, and the fifth valve 303 is opened to release the excess air pressure. After the release is completed, the pipeline 305 and the fifth valve 303 are closed in sequence to complete the entire solution injection process.

[0059] (4) Water injection pressure control: Open the pressure / volume controller 501 and data monitoring device 502, adjust the water injection pressure to 2KPa, and then open the seventh valve 406 and the eighth valve 407 in sequence. Through the water storage chamber hole 409, the pressure in the water storage chamber 405 is transmitted to the liquid storage chamber 402 via the piston 408, and then through the liquid storage chamber hole 410 and the eighth valve 407 to the pressure gauge 411. Then, open the third valve 119 and the fourth valve 120 in sequence. The pipeline path is the same as in step (3) to transmit the water injection pressure to the saturation device 1. After completing the above, after an interval of 1 hour, adjust the water injection pressure of the pressure / volume controller 501 to 200KPa, and then increase the pressure by 400KPa every hour to reach the saturation pressure required for the test.

[0060] (5) Temperature control: Adjust the temperature control system 2 to control the temperature according to the test requirements;

[0061] (6) After several days of saturation, open the first valve 110 and check whether there is a stable and continuous flow of water in the pipe 701. If there is a stable and continuous flow of liquid, the soil sample is considered to be saturated.

[0062] (7) After saturation is completed, depressurize and discharge the saturated solution. Use the pressure / volume controller 501 to adjust the pressure to 0 kPa. Then close the third valve 119, the fourth valve 120, the seventh valve 406, and the eighth valve 407 in sequence. After disassembling the pipeline 704, place the solution collection device 6 under the third valve 119 and open the third valve 119 to discharge the solution used for saturation in the saturation device 1 by gravity.

[0063] (8) Sample removal: Remove soil sample 128 in the order of installation in step (1), end the test, and tidy up the test apparatus.

[0064] Example: Rapid saturation of bentonite under thermo-chemical coupling conditions in 0.05 mol / L NaCl solution at 40°C

[0065] (1) The saturated soil sample was 50 mm in diameter, 100 mm in height, and had a dry density of 1.5 g / cm³. 3For bentonite, first close all valves, install filter paper 127 on the outside of the soil sample 128 to be saturated, and install it in the two detachable semi-circular sample chambers 103. Apply Vaseline to the O-rings 122 on the side of the bottom cover and the O-rings 121 on the top surface of the base. Then install the two detachable semi-circular sample chambers 103 on the base 102 through a nested structure. Then install the fixed outer wall 104 on the outside of the two detachable semi-circular sample chambers 103. Apply Vaseline to the O-rings 112 on the side of the top cover and the O-rings 113 on the bottom surface of the top cover. Install the top cover 101 on the two detachable semi-circular sample chambers 103 and the fixed outer wall 104. Then fix each part of the saturation device 1 with six bolts 105 and nuts 106.

[0066] (2) Solution placement: 0.05 mol / L NaCl solution for saturation is injected into solution tank 304, and 0.05 mol / L NaCl solution for saturation is injected into water-salt converter 401 through storage chamber injection hole 403. Deionized water is injected into water-salt converter 401 through water chamber injection hole 404.

[0067] (3) Open the first valve 110, the second valve 111, the third valve 119, and the fourth valve 120 in sequence to start the pneumatic pump 301. Use the pressure reducing valve 302 to adjust the injection pressure to 2 kPa. Then open the fifth valve 303 and the sixth valve 305 to allow the 0.05 mol / L NaCl solution in the solution tank 304 to enter the solution chamber 124 through the water injection hole 117 of the solution chamber 114 via the pipe 708 and the pipe tee 710, and through the third valve 119 via the pipe 704 and the third valve. Then, fill the solution chamber 124 with 0.05 mol / L solution through the solution channel 125. The NaCl solution enters the base permeable stone 123 via the base sample injection hole 116 through pipe 705, pipe 709, pipe 706 and the fourth valve 120 to saturate the soil sample 128. In addition, the solution can enter the base 706 through pipe 709 and the pressure gauge 411 to read the current pressure value in the pipe, which is the injection pressure value. After the solution chamber 124 is filled with 0.05mol / L NaCl solution, the excess 0.05mol / L NaCl solution can enter the solution collection device 6 through pipe 702 after passing through the top cover solution chamber injection hole 109 and the second valve 111. In addition, the excess 0.05mol / L NaCl solution can enter the solution collection device 6 through pipe 701 through the top cover permeable stone 114, the top cover sample injection hole 108, the first valve 110 and the top cover permeable stone 114.

[0068] When excess 0.05 mol / L NaCl solution flows into the solution collection device 6, the first valve 110, the fourth valve 120, the second valve 111, the third valve 119, the sixth valve 305, and the fifth valve 303 are closed in sequence. The pneumatic pump 301 is turned off, the pipeline 305 is opened, and the fifth valve 303 is opened to release the excess gas pressure. After the release is completed, the pipeline 305 and the fifth valve 303 are closed in sequence to complete the entire 0.05 mol / L NaCl solution injection process.

[0069] (4) Open the pressure / volume controller 501 and data monitoring device 502, adjust the water injection pressure to 2KPa, and then open the seventh valve 406 and the eighth valve 407 in sequence. Through the water storage chamber hole 409, the pressure in the water storage chamber 405 is transmitted to the liquid storage chamber 402 via the piston 408, and the water pressure is transmitted to the pressure gauge 411 through the liquid storage chamber hole 410 and the eighth valve 407. Then, open the third valve 119 and the fourth valve 120 in sequence. The pipeline path is the same as in step (3), and the water injection pressure is transmitted to the saturation device 1. After completing the above, after an interval of 1 hour, adjust the water injection pressure of the pressure / volume controller 501 to 200KPa, and then increase the pressure by 400KPa every hour until it reaches 1MPa.

[0070] (5) Adjust the temperature control system 2 to 40℃ for temperature control;

[0071] (6) After several days of saturation, open the first valve 110 and check whether there is a stable and continuous flow of water in the pipe 701. If there is a stable and continuous flow of liquid, the soil sample is considered to be saturated.

[0072] (7) Use the pressure / volume controller 501 to adjust the pressure to 0 kPa, then close the third valve 119, the fourth valve 120, the seventh valve 406 and the eighth valve 407 in sequence. After disassembling the pipeline 704, place the solution collection device 6 under the third valve 119 and open the third valve 119 to discharge the 0.05 mol / L NaCl solution in the saturation device 1 by gravity.

[0073] (8) Sample removal: Remove soil sample 128 in the order of installation in step (1), end the test, and tidy up the test apparatus.

[0074] Compared to traditional saturation devices at the upper and lower ends of the sample, this device can rapidly saturate low-permeability and expansive soil samples under different temperature and chemical solution conditions. It can achieve complete, high-quality, and rapid demolding of the sample, and the saturation time of different materials can be controlled by setting the injection pressure. This can significantly reduce the time required to saturate soil samples in geotechnical tests, improve test efficiency, and meet the needs of different conditions.

[0075] The above description is an embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A rapid saturation device for thermally-chemically coupled ultra-low permeability expansive soil samples, characterized in that, include: Saturation device, temperature control system, water injection system, water-salt conversion system, pressure injection system, liquid collection device and piping system; The saturation device includes a top cover, a base, two detachable semi-circular sample chambers, and a fixed outer wall. The top cover has water injection channels on its sides and top surface, and the base has two water injection channels on its sides. A solution chamber is located outside the two detachable semi-circular sample chambers, with a solution channel on its surface and saturation holes on its surface. The fixed outer wall seals the two detachable semi-circular sample chambers. A temperature control system can house the saturation device. The water injection system includes a pneumatic pump, a pressure reducing valve, and a solution tank. The solution tank has pre-drilled holes at its top and bottom, and is connected to the pneumatic pump via the pressure reducing valve. The water-salt conversion system includes a water-salt converter and a pressure gauge. The water-salt converter has two injection holes on its top surface and two valves on its bottom surface, and is connected to the pressure gauge. The pressure injection system includes a pressure / volume control device and a data monitoring device. The liquid collection device collects the waste liquid discharged from the saturation device.

2. The rapid saturation device for thermal-chemical coupled ultra-low permeability expansive soil samples according to claim 1, characterized in that, The saturation device includes a top cover, a base, two detachable semi-circular sample chambers, and a fixed outer wall. The two detachable semi-circular sample chambers are connected to the top cover and the base through a nested structure. The fixed outer wall is used to seal the two detachable semi-circular sample chambers and is fixed outside the two detachable semi-circular sample chambers. The saturation device is fixed by bolt holes reserved on the top cover and the base.

3. The rapid saturation device for ultra-low permeability expansive soil samples via thermal-chemical coupling according to claim 1, characterized in that, The two detachable semi-circular sample chambers can be assembled into a complete circular sample chamber. The interior of the two detachable semi-circular sample chambers is used to place soil samples. The exterior of the two detachable semi-circular sample chambers is provided with a solution chamber for placing a solution for saturating the sample. The solution chambers are connected to each other through a solution channel. The inner surface of the two detachable semi-circular sample chambers is provided with a through saturation hole connected to the solution chamber. The solution for saturating the sample enters the interior of the two detachable semi-circular sample chambers through the saturation hole.

4. The rapid saturation device for ultra-low permeability expansive soil samples via thermal-chemical coupling according to claim 1, characterized in that, The top cover is provided with a sample water injection channel, and the lower part of the top cover is provided with a permeable stone. The upper part of the permeable stone is connected to the sample water injection channel on the top cover, and the lower part is connected to the interior of the two detachable semi-circular sample chambers. The top cover is provided with a solution chamber water injection channel, and the lower part of the solution chamber water injection channel on the top cover is connected to the solution chamber.

5. The rapid saturation device for ultra-low permeability expansive soil samples via thermal-chemical coupling according to claim 1, characterized in that, The base is provided with a sample water injection channel, and the upper part of the base is provided with a permeable stone. The lower part of the permeable stone is connected to the sample water injection channel on the base, and the upper part is connected to the interior of the two detachable semi-circular sample chambers. The base is provided with a solution chamber water injection channel, and the upper part of the solution chamber water injection channel on the base is connected to the solution chamber.

6. The rapid saturation device for thermal-chemical coupled ultra-low permeability expansive soil samples according to claim 1, characterized in that, The temperature control system can incorporate a saturation device.

7. The rapid saturation device for ultra-low permeability expansive soil samples via thermal-chemical coupling according to claim 1, characterized in that, The water injection system includes a pneumatic pump, a pressure reducing valve, and a solution tank. The pneumatic pump is connected to the solution tank through the pressure reducing valve, and the solution tank is connected to a pre-drilled hole on the side of the saturation device base through a pipe.

8. The rapid saturation device for ultra-low permeability expansive soil samples via thermal-chemical coupling according to claim 1, characterized in that, The water-salt conversion system includes a water-salt converter and a pressure gauge. The water-salt converter has reserved holes on its top and bottom surfaces. The water-salt converter is connected to the reserved hole on the side of the saturation device base through the pressure gauge.

9. The rapid saturation device for ultra-low permeability expansive soil samples via thermal-chemical coupling according to claim 1, characterized in that, The injection system includes a pressure / volume controller and a data monitoring device. The data monitoring device is used to install software on the pressure / volume controller and monitor data changes. The pressure / volume controller is connected to the water-salt converter through a pipeline.

10. The rapid saturation device for ultra-low permeability expansive soil samples via thermal-chemical coupling according to claim 1, characterized in that, The liquid collection device is used to collect the waste liquid discharged from the saturation device; The piping system is used to connect the various parts of the thermo-chemically coupled ultra-low permeability expansive soil sample rapid saturation device.

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