A continuous water supply device for permeation testing and method of use thereof

Abstract

A kind of continuous water supply device for permeation test and its using method belong to geotechnical test technical field.Permeation test and its using method include air compressor, water storage pressure device and water supply device control cabinet.Air compressor provides pressure source, water storage pressure device is used for the storage and pressurization of permeation water, and water supply device control cabinet is provided with PLC control module, proportional valve, water replenishment path electromagnetic valve, water supply path electromagnetic valve, differential pressure sensor, pressure transmitter and electromagnetic flowmeter and other elements in it.PLC control module controls two water storage pressure tanks to alternate water replenishment and water supply according to the signals fed back by differential pressure sensor, pressure transmitter and electromagnetic flowmeter, adjusts the air pressure in tank through proportional valve, and realizes the automatic control of permeation water flow pressure or flow rate.Two water storage pressure tanks work alternately when using.The application can improve the control precision of water supply pressure and flow, prolong the continuous water supply time, be suitable for indoor large-size soil sample permeability coefficient test, and has the advantages of easy operation, high test efficiency and good result reliability.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical testing technology, and relates to a continuous water supply device for permeability testing and its usage method, particularly a long-term continuous water supply device and its usage method suitable for indoor large-size specimen permeability testing, applicable to long-term, stable water supply in indoor large-size specimen permeability testing. The device includes an air compressor, a water storage pressure device, and a central control cabinet for the water supply device. Background Technology

[0002] Permeability testing is a test that uses various instruments to determine the permeability coefficient of soil and rock. It is generally divided into two main categories based on the testing location: laboratory tests and field tests. The permeability coefficient is determined in the laboratory. k There are many types of instruments and testing methods, but they can be broadly classified into two types based on their testing principles: the "constant head method" and the "variable head method." Field permeability tests, also known as seepage tests, generally employ pit seepage tests and are a simple method for determining the permeability coefficient of loose layers and rock strata in the vadose zone. Commonly used pit seepage tests include the pit method, the single-ring method, and the double-ring method. While outdoor permeability tests more closely reflect actual soil conditions, they have several drawbacks: limited by site geological conditions, they struggle to accurately characterize soil heterogeneity and anisotropy, and are easily affected by groundwater dynamics and surrounding engineering interference; test accuracy is affected by boundary condition assumption errors and well construction disturbances (such as mud skin effect and water flow short-circuiting); test results at different scales may not match engineering requirements; they are costly and time-consuming to operate, and data interpretation suffers from multiple interpretations and scale effects; they may also trigger environmental risks such as land subsidence and groundwater pollution, and have limitations in testing low-permeability soils or complex fluid characteristics. Therefore, it is necessary to combine indoor experiments, geological exploration, and numerical simulation, and improve the reliability of the results through cross-validation using multiple methods.

[0003] In indoor tests, for highly permeable non-cohesive soils such as sand and gravel, the "constant head method" is typically used. This method involves supplying water to an open water tank with an overflow hole at the top, connected to a water source. When the water level exceeds the overflow hole, excess water overflows, maintaining a constant water level and ensuring stable head at the sample inlet. In simpler scenarios, the head difference can be manually maintained by adjusting a tap water valve. For less permeable cohesive soils, the "variable head method" is usually used. This method uses a small-diameter, vertical glass tube (variable head tube) for water supply. Before the test, water is filled into the tube to a predetermined height. After opening the stop clamp, water slowly permeates through the sample, and the time interval between the water level dropping from the initial height to another height is recorded to calculate the permeability coefficient. Some improved devices also utilize pneumatic or hydraulic systems and electronic pressure sensors to achieve more precise monitoring of head changes. Throughout the water supply process, to ensure the accuracy of the test data, air bubbles in the system must be removed using the air extraction method or the head saturation method. The accuracy of the head difference must be strictly controlled using scales and level sensors, and the diameter of the water supply pipeline must be appropriately set to maintain water flow stability and prevent damage to the soil sample structure. However, the traditional rigid wall permeability test's water supply method and overall testing approach have many shortcomings. First, the test assumes that the soil is homogeneous and isotropic, and the water supply boundary conditions are simplified, which differs significantly from the complex natural soil conditions in reality, making it difficult for the test results to reflect the true permeability characteristics of the soil in the field. Second, the water supply device and test procedure require highly skilled operators; improper operation, such as incomplete air bubble removal or insufficient head difference control accuracy, will introduce significant errors. Third, the test is only applicable to specific types of soil samples; it is ineffective for unsaturated soils, soils with special components or structures, and its application scope is limited.

[0004] For example, Chinese utility model patent (application number 201611041567.9) provides a permeation device capable of achieving variable water pressure. It uses a PLC control cabinet and frequency converter to control a water pump to provide periodically changing water pressure, and collects water pressure difference and flow rate through a differential pressure transmitter and flow meter. This is used to study the permeability characteristics of porous media under dynamic loads such as ocean waves and earthquakes. Chinese utility model patent (application number 2022233-11604.7) provides a batch automatic measurement and control device for the permeability coefficient of cohesive soils, used for batch testing and automatic measurement and control of the permeability coefficient of cohesive soils. While existing technical solutions can improve the water supply control, automated measurement, and testing efficiency of permeation tests, they mostly focus on variable water pressure simulation or batch measurement and control of small cohesive soil samples. For long-term permeation tests of large-size indoor samples, it is still difficult to simultaneously ensure continuous and stable water supply, automatic water replenishment switching, and precise control of pressure or flow rate.

[0005] Furthermore, many scholars have continued to optimize traditional rigid-wall infiltration devices to meet various experimental needs. For example, to simulate the initiation and development of internal erosion caused by seepage in wide-graded coarse-grained soils under rainfall infiltration conditions, scholars have developed a rigid-wall variable-head infiltration apparatus. This apparatus uses an infiltration storage tank, a peristaltic pump, an upstream head measuring pipe, and a head control storage tank to form a water supply system, providing a continuous and stable infiltration flow for infiltration tests. An elastic rubber mold is attached to the inner wall of the rigid-wall cylinder to solve the problem of sidewall seepage along the large pores between the sample and the rigid wall of the infiltration chamber. In addition, some scholars have used self-designed cylindrical infiltration test devices to simulate the erosion effect of vertical seepage (from top to bottom) under different hydraulic gradients. The designated gradient water supply device used in this test apparatus consists of a water tank and an overflow pipe. The head is controlled by changing the height of the overflow pipe opening, and the internal particle state can be observed through camera equipment. Other scholars have used air compressors, pressure regulating valves, and water tanks to form a water supply device, thereby providing an economical, stable, and easily controllable flow of permeation water for permeation experiments.

[0006] However, most of the above devices are only suitable for short-term, low-flow-rate indoor water supply. For large-size indoor permeation samples, the water supply volume and time of these devices are difficult to meet the requirements, and the experimental accuracy is greatly affected by the operation of the test personnel and is difficult to guarantee. Therefore, there is an urgent need for a long-term continuous water supply device suitable for indoor permeation tests on large-size samples. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a continuous water supply device for permeation testing and its usage method, specifically a long-term continuous water supply device and its usage method suitable for indoor permeation testing of large-size samples. When conducting indoor permeation tests, this invention, using this continuous water supply device, can reduce operator workload, improve test accuracy, and achieve long-term continuous water supply during the permeation test process.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A continuous water supply device for osmosis testing, used for long-term continuous water supply in indoor osmosis testing, the continuous water supply device includes an air compressor, a water storage pressure device, and a central control cabinet for the water supply device, specifically: The air compressor is mainly used to provide a pressure source for the permeation water flow. The air compressor's outlet is connected to an air pipe, which is connected to a T-joint. The T-joint divides the air path into two paths, namely the first air inlet path and the second air inlet path.

[0009] The water storage pressure device includes a No. 1 water storage pressure tank and a No. 2 water storage pressure tank with identical structures, mainly used for the storage and pressurization of permeate. The design pressure resistance of both the No. 1 and No. 2 water storage pressure tanks is 1.5 MPa. The No. 1 water storage pressure tank is equipped with an air inlet, an air pressure port, a water pressure port, and a water outlet; the No. 2 water storage pressure tank is equipped with the same air inlet, air pressure port, water pressure port, and water outlet. The arrangement of the openings on the No. 2 water storage pressure tank is the same as that on the No. 1 water storage pressure tank. The following description uses the arrangement of the openings on the No. 1 water storage pressure tank as an example: The air inlet of the No. 1 tank is located at the center of the upper surface of the No. 1 water storage pressure tank. It has an internal thread structure and can be equipped with a quick-connect fitting of the corresponding specification according to the size of the air pipe. It is used to connect the air pipe and supply air into the No. 1 water storage pressure tank.

[0010] The air pressure port of the No. 1 tank is located on the upper surface of the No. 1 water storage pressure tank at a distance of 1 / 2R from the center, where R is the cross-sectional radius of the No. 1 water storage pressure tank. The air pressure port of the No. 1 tank has an internal thread structure. According to the size of the air pipe, a quick-connect fitting of the corresponding specification is installed to connect to the air pressure end of a differential pressure sensor.

[0011] The water pressure hole of the No. 1 tank is located on the side wall of the No. 1 water storage pressure tank, at a distance of 1 / 10H from the lower surface of the No. 1 water storage pressure tank, where H is the vertical height of the No. 1 water storage pressure tank. The water pressure hole of the No. 1 tank has an internal thread structure. According to the size of the water pipe, a corresponding specification connector is installed to connect to the hydraulic end of a differential pressure sensor.

[0012] The water inlet and water pressure port of the No. 1 tank are symmetrically arranged on the side wall of the No. 1 water pressure tank, and are also located at 1 / 10H from the lower surface of the No. 1 water pressure tank. The water inlet of the No. 1 tank has an internal thread structure, and a corresponding specification connector is installed according to the water pipe size for water replenishment and supply to the No. 1 water pressure tank. The arrangement of the air inlet, air pressure port, water pressure port, and water inlet of the No. 2 water pressure tank is the same as that of the No. 1 water pressure tank.

[0013] The central control cabinet of the water supply device is the main part of the device of this invention, mainly including a linear power supply, a PLC control module, a communication interface, one gas filter, one pressure stabilizing tank, one SMC proportional valve, one water supply solenoid valve, one differential pressure sensor, a high-precision pressure transmitter for the first pressure measuring point, a high-precision pressure transmitter for the second pressure measuring point, an electromagnetic flow meter, an inlet valve, an outlet valve, an aluminum alloy electrical control cabinet, one water supply solenoid valve, a load switch, two gas filters, two pressure stabilizing tanks, two SMC proportional valves, two water supply solenoid valves, two differential pressure sensors, and two water supply solenoid valves. Specifically: The aluminum alloy electrical control cabinet is the main body of the central control cabinet of the water supply device. It has a square box structure with bolt holes on the back panel for fixing various electrical components. The aluminum alloy electrical control cabinet is divided into upper and lower layers. The upper layer is used for the installation and connection of gas circuit components, and the lower layer is used for the installation and connection of water circuit components.

[0014] The linear power supply is bolted to the upper left of the upper layer of the aluminum alloy electrical control cabinet. It converts the input voltage into a stable 24V DC output and supplies power to the various electrical components inside the cabinet. The load switch is located between the linear power supply and the household power supply, and is bolted to the right side of the linear power supply. It is used to switch the circuit on and off under normal load, and works with a fuse to provide short-circuit protection.

[0015] The PLC control module is bolted to the right side of the linear power supply. This PLC control module is an industrial control device based on a microprocessor, combining computer technology, automatic control technology, and communication technology. It receives and processes electrical signals from various electrical components and issues control commands based on the processing results. The communication interface is an Ethernet interface, connecting the touchscreen to the PLC control module via a network cable to achieve parameter setting, status monitoring, and operation control of the entire long-term continuous water supply system.

[0016] The first gas filter is bolted below the linear power supply and is used to filter oil or water vapor in the gas, preventing them from entering subsequent gas circuit components and affecting the operation of the device. The first gas filter has threaded holes on both sides and is equipped with quick-connect fittings for air hoses. The left side is an inlet for connecting to the first air inlet, and the right side is an outlet, connected to the left inlet of the first pressure regulator tank via an air hose. The second gas filter is bolted below the first gas filter and is used to filter oil or water vapor in the gas, preventing them from entering subsequent gas circuit components and affecting the operation of the device. The second gas filter also has threaded holes on both sides and is equipped with quick-connect fittings for air hoses. The left side is an inlet for connecting to the second air inlet, and the right side is an outlet, connected to the left inlet of the second pressure regulator tank via an air hose.

[0017] The first-stage pressure stabilizing tank is a steel elliptical gas cylinder, bolted to the right side of the first-stage gas filter to maintain stable input gas pressure. Threaded holes are located in the center of both sides of the first-stage pressure stabilizing tank, and quick-connect fittings for gas hoses are provided. The left-side air inlet connects to the quick-connect fitting on the right side of the first-stage gas filter via a gas hose, and the right-side air outlet connects to the inlet of the first-stage SMC proportional valve via a gas hose. The second-stage pressure stabilizing tank is also a steel elliptical gas cylinder, bolted to the right side of the second-stage gas filter to maintain stable input gas pressure. Threaded holes are located in the center of both sides of the second-stage pressure stabilizing tank, and quick-connect fittings for gas hoses are provided. The left-side air inlet connects to the quick-connect fitting on the right side of the second-stage gas filter via a gas hose, and the right-side air outlet connects to the inlet of the second-stage SMC proportional valve via a gas hose.

[0018] One SMC proportional valve is located on the right side of one pressure stabilizing tank and is bolted to the aluminum alloy electrical control cabinet. This SMC proportional valve communicates with the PLC control module. It has threaded holes on both sides and is equipped with quick-connect air hoses. The left air inlet is connected to the right air outlet of the pressure stabilizing tank via an air hose, and the right air outlet is connected to the air inlet of the first water storage pressure tank via an air hose. This SMC proportional valve is used to adjust the compressed air pressure entering the first water storage pressure tank according to the control signals from the PLC control module.

[0019] The two-way SMC proportional valve is located on the right side of the two-way pressure stabilizing tank and is bolted to the aluminum alloy electrical control cabinet. The two-way SMC proportional valve communicates with the PLC control module. It has threaded holes on both sides and is equipped with quick-connect air hoses. The left air inlet is connected to the right air outlet of the two-way pressure stabilizing tank via an air hose, and the right air outlet is connected to the air inlet of the second water storage pressure tank via an air hose. The two-way SMC proportional valve is used to adjust the compressed air pressure entering the second water storage pressure tank according to the control signals issued by the PLC control module.

[0020] The solenoid valves for the first water supply circuit, the first water supply circuit, the second water supply circuit, and the second water supply circuit are all electrically connected to the PLC control module. The switching signals output by the PLC control module control the energization of the corresponding solenoid valve coils, thereby driving the valve core to switch the valve port on / off state and realize the switching control of the corresponding liquid circuit. All the above solenoid valves are normally closed when not energized.

[0021] The first water supply solenoid valve is installed on the B water pipe and is used to control the flow of water to the No. 1 water pressure tank. The second water supply solenoid valve is installed on the B2 water pipe, with its inlet connected to the tee connector behind the first water supply solenoid valve and its outlet connected to the tee connector before the confluence, and is used to control the flow of water from the No. 1 water pressure tank to the C water pipe. When the PLC control module sends an open signal, the first water supply solenoid valve is energized and opened, allowing water from the No. 1 water pressure tank to flow into the C water pipe through the No. 1 tank water hole, the B1 water pipe, the B2 water pipe, and the first water supply solenoid valve. When the PLC control module stops outputting the open signal, the first water supply solenoid valve is de-energized and closed, thereby cutting off the water supply to the No. 1 water pressure tank.

[0022] The two-way water supply solenoid valve is installed on the A-way water pipe and is used to control the flow of water to the No. 2 water storage pressure tank. The two-way water supply solenoid valve is installed on the A2-way water pipe, with its inlet end connected to the water pipe tee joint behind the two-way water supply solenoid valve and its outlet end connected to the water pipe tee joint before the confluence, and is used to control the flow of water from the No. 2 water storage pressure tank to the C-way water pipe. When the PLC control module sends an open signal, the two-way water supply solenoid valve is energized and opened, and water in the No. 2 water storage pressure tank enters the C-way water pipe through the No. 2 tank water hole, the A1-way water pipe, the A2-way water pipe, and the two-way water supply solenoid valve; when the PLC control module stops outputting the open signal, the two-way water supply solenoid valve is de-energized and closed, thereby cutting off the water supply path to the No. 2 water storage pressure tank.

[0023] One end of the differential pressure sensor is connected to the air pressure port of tank number one, and the other end is connected to the water pressure port of tank number one. It is used to obtain the pressure difference between the gas pressure and the liquid pressure inside tank number one. The differential pressure sensor uses a pressure-sensitive element to sense the pressure difference between the two sides and converts the pressure difference into a standard electrical signal through an internal circuit. Since there is a linear relationship between the liquid level and the pressure difference, the standard electrical signal can reflect the remaining liquid level in tank number one. When the differential pressure sensor is connected to the PLC control module, its output standard electrical signal is input to the analog input module of the PLC control module. The PLC control module acquires, converts, and processes this standard electrical signal to obtain the liquid level data inside tank number one.

[0024] One end of the dual differential pressure sensor is connected to the gas pressure port of tank number two, and the other end is connected to the water pressure port of tank number two. It is used to obtain the pressure difference between the gas pressure and the liquid pressure inside tank number two. The dual differential pressure sensor uses a pressure-sensitive element to sense the pressure difference between the two sides and converts the pressure difference into a standard electrical signal through an internal circuit. Since there is a linear relationship between the liquid level and the pressure difference, the standard electrical signal can reflect the remaining liquid level in tank number two. When the dual differential pressure sensor is connected to the PLC control module, its output standard electrical signal is input to the analog input module of the PLC control module. The PLC control module acquires, converts, and processes this standard electrical signal to obtain the liquid level data inside tank number two.

[0025] The inlet valve is connected to the water source and is used to replenish water to the water supply system. A water pipe is connected to the right side of the inlet valve, leading to the lower level of the water supply device's control cabinet. After entering the control cabinet, the water pipe splits into two pipes, A and B, via a tee connector. Pipe A connects to the two-way replenishment solenoid valve, then connects to another tee connector and splits into pipes A1 and A2. Pipe A1 extends out of the control cabinet and connects to the second water outlet of the second water storage pressure tank. Pipe A2 connects to the two-way supply solenoid valve. Pipe B connects to the first-way replenishment solenoid valve, then connects to another tee connector and splits into pipes B1 and B2. Pipe B1 extends out of the control cabinet and connects to the first water outlet of the first water storage pressure tank. Pipe B2 connects to the first-way supply solenoid valve. After connecting the two water supply solenoid valves and the one water supply solenoid valve respectively, the two water pipes A2 and B2 are connected to the two ends of the water pipe tee joint and then merge into the water pipe C.

[0026] The electromagnetic flowmeter is connected to the C-line water pipe after the water flow converges. Its left end is connected to the C-line water pipe, and its right end is connected to the outlet valve through a water pipe. It is used to measure the water supply flow rate and output a flow signal to the PLC control module. The electromagnetic flowmeter operates based on Faraday's law of electromagnetic induction. When conductive fluid flows through the measuring tube, it cuts the magnetic field generated by the excitation coil and generates an induced electromotive force proportional to the flow velocity at both ends of the electrodes. This induced electromotive force is converted into a standard electrical signal by the signal processing circuit, thereby reflecting the fluid flow velocity. When the electromagnetic flowmeter is connected to the PLC control module, its output standard electrical signal is input to the analog input module of the PLC control module. The PLC control module acquires, linearly converts, and calculates this standard electrical signal to obtain the water supply velocity or water supply flow rate data.

[0027] The outlet valve is located at the outlet end of the electromagnetic flowmeter and is used to control the flow of water between the continuous water supply device and the permeation test device.

[0028] The high-precision pressure transmitter at the first pressure measuring point is connected to the upper end of the test sample via a PU hose to acquire the water pressure at the measuring point on the upper end of the test sample. The high-precision pressure transmitter senses the measured pressure through a pressure-sensitive element. When pressure acts on the pressure-sensitive element, it deforms, causing the built-in Wheatstone bridge to become unbalanced and output a weak electrical signal. After amplification and filtering, this signal is converted into a standard electrical signal. This standard electrical signal has a linear relationship with the measured pressure, thus reflecting the magnitude of the measured pressure. When the high-precision pressure transmitter at the first pressure measuring point is connected to the PLC control module, its output standard electrical signal is input to the analog input module of the PLC control module. The PLC control module acquires, performs A / D conversion, and linear calculations on this standard electrical signal to obtain the pressure data at the first pressure measuring point in real time.

[0029] The high-precision pressure transmitter at the second pressure measuring point is connected to the lower end of the test sample via a PU hose to acquire the water pressure at the measuring point at the lower end of the test sample. The high-precision pressure transmitter senses the measured pressure through a pressure-sensitive element. When pressure acts on the pressure-sensitive element, it deforms, causing the built-in Wheatstone bridge to become unbalanced and output a weak electrical signal. After amplification and filtering, this signal is converted into a standard electrical signal. This standard electrical signal has a linear relationship with the measured pressure, thus reflecting the magnitude of the measured pressure. When the high-precision pressure transmitter at the second pressure measuring point is connected to the PLC control module, its output standard electrical signal is input to the analog input module of the PLC control module. The PLC control module acquires, performs A / D conversion, and linear calculations on this standard electrical signal to obtain the pressure data at the second pressure measuring point in real time.

[0030] The permeation test apparatus includes an inlet valve, a second measuring point, and a first measuring point. The inlet valve is used to control the flow of water into the permeation test apparatus. The first measuring point is used to connect to a high-precision pressure transmitter at the first pressure measuring point to obtain the water pressure at the upper measuring point of the test sample; the second measuring point is used to connect to a high-precision pressure transmitter at the second pressure measuring point to obtain the water pressure at the lower measuring point of the test sample.

[0031] The electrical components and conduits on the lower level of the above electrical control box should be placed in a reasonable position on the lower level of the aluminum alloy electrical control cabinet. Adjustments should be made according to the actual situation, which will not be elaborated here.

[0032] A method for using a continuous water supply device for permeation testing, wherein two water pressure tanks operate alternately. When the water level in one tank drops to a set lower limit, the other tank takes over the water supply, while the first tank is replenished, thus achieving a continuous and stable water supply during the permeation test. Specifically, the method includes the following steps: The first step is to fill the test sample into the rigid wall permeameter according to the test plan, and to complete the compaction, saturation and sealing of the sample according to the test requirements.

[0033] The second step is to assemble the continuous water supply device. Connect the air compressor, the first air inlet, the second air inlet, the water supply device control cabinet, the No. 1 water storage pressure tank, the No. 2 water storage pressure tank, and the permeation test device in sequence, and check whether the connections of each air pipe, water pipe, PU hose and electrical circuit are reliable.

[0034] The third step is to perform equipment debugging before the experiment. Specifically: Step 3.1: Turn on the load switch, connect the power supply, and activate the water filling button on the touch screen. The PLC control module first controls the opening of the solenoid valve of the water replenishment circuit. Water enters the No. 1 water storage pressure tank through the inlet valve, the B-circuit water pipe, the solenoid valve of the B-circuit water replenishment circuit, and the B1-circuit water pipe to replenish the No. 1 water storage pressure tank. At this time, the original gas in the No. 1 water storage pressure tank is discharged through the No. 1 tank air inlet, air pipe, and the SMC proportional valve.

[0035] Step 3.2: During the replenishment process of the No. 1 water storage pressure tank, a differential pressure sensor collects the differential pressure signal in the No. 1 water storage pressure tank in real time and transmits the differential pressure signal to the PLC control module. The PLC control module calculates the liquid level in the No. 1 water storage pressure tank based on the differential pressure signal. When the liquid level in the No. 1 water storage pressure tank reaches the predetermined height, the PLC control module controls the closing of one water replenishment solenoid valve and simultaneously opens the two water replenishment solenoid valves and one water supply solenoid valve. At this time, the PLC control module controls the water source to replenish the No. 2 water storage pressure tank on one hand, and controls one SMC proportional valve to adjust the air pressure in the first air inlet leading to the No. 1 water storage pressure tank on the other hand, so that the No. 1 water storage pressure tank outputs the permeation water flow required for the test. After the No. 2 water storage pressure tank is replenished, the PLC control module controls the closing of the two water replenishment solenoid valves, so that the No. 2 water storage pressure tank is full of water and in standby mode.

[0036] The fourth step is to exhaust the gas and perform test connections.

[0037] Step 4.1: First, set a small venting pressure value. Connect a section of water pipe to the outlet valve and extend the pipe into the sewer or waste tank. Open the outlet valve to allow water in the continuous water supply device to flow out slowly, thus expelling residual air from the water supply device and pipes. Once no more air bubbles are observed flowing out, connect the outlet valve to the inlet valve of the osmosis test device via the water pipe, keeping the inlet valve closed. The small venting pressure value is a pressure value that is less than the target osmosis pressure of the formal test and can drive the water to flow slowly, preferably 5% to 10% of the target osmosis pressure of the formal test.

[0038] Step 4.2: Subsequently, set both the set flow rate and set pressure to 0, and open the inlet valve of the permeation test device. Use a PU hose to connect the high-precision pressure transmitter at the first pressure measurement point to the first measurement point, and use a PU hose to connect the high-precision pressure transmitter at the second pressure measurement point to the second measurement point, so as to obtain the water pressure at the two measurement points of the test sample respectively.

[0039] The fifth step is to control the osmotic pressure and calculate the osmotic parameters.

[0040] Step 5.1: Since the calculation of the hydraulic gradient is affected by the height of the test sample, this invention uses the osmotic pressure difference as the control target and calculates the required hydraulic gradient value through the osmotic pressure difference. Let the pressure value collected by the high-precision pressure transmitter at the first pressure measuring point be... The pressure value obtained by the high-precision pressure transmitter at the second pressure measuring point is... The height difference between the first measuring point and the second measuring point is The density of water is Then the osmotic pressure difference for and The absolute value of the difference, i.e., the formula for calculating the hydraulic gradient, is shown below: in, The target hydraulic gradient is denoted as .

[0041] Step 5.2: During the test, the PLC control module controls one SMC proportional valve to slowly open or close, causing the air compressor to output air pressure into the No. 1 water storage pressure tank through the first air intake, thereby driving the water in the No. 1 water storage pressure tank into the permeation test device. When the absolute value of the pressure difference between the high-precision pressure transmitters at the first and second pressure measuring points reaches the set target permeation pressure difference, or when the flow rate value collected by the electromagnetic flowmeter reaches the set target flow rate value, the real-time water supply flow rate collected by the electromagnetic flowmeter at this time is recorded. Let the radius of the test sample be... Then the permeation velocity Calculate using the following formula: The permeability coefficient of the tested sample is thus obtained. The calculation formula is as follows: Step 6: Implement alternating water supply and automatic water replenishment control between the two water storage pressure tanks. The PLC control module presets target lower limits for liquid level height corresponding to one differential pressure sensor and two differential pressure sensors. These target lower limits include a first target lower limit and a second target lower limit, where the first target lower limit is higher than the second target lower limit. The first target lower limit is used to trigger the pressure pre-balancing control of the backup water storage pressure tank, and the second target lower limit is used to trigger the water supply switching control of the supply water storage pressure tank. Specifically: When the No. 1 water storage pressure tank is in water supply mode, and a differential pressure sensor detects that the liquid level in the No. 1 water storage pressure tank has dropped to the first target lower limit, the PLC control module opens the second SMC proportional valve and adjusts the output air pressure of the second SMC proportional valve to make the air pressure at the top of the No. 2 water storage pressure tank equal to or nearly equal to the air pressure at the top of the No. 1 water storage pressure tank, so as to reduce pressure fluctuations during subsequent water supply switching.

[0042] When the liquid level in the No. 1 water storage pressure tank continues to drop to the second target lower limit, the PLC control module controls the closure of one water supply solenoid valve and one SMC proportional valve, while simultaneously opening the second water supply solenoid valve and one makeup water solenoid valve. At this time, water is supplied to the No. 1 water storage pressure tank through the makeup water solenoid valve, and the No. 2 water storage pressure tank outputs the required permeable water flow for the test under the pressure regulation of the two SMC proportional valves, thus completing the switch from water supply from the No. 1 water storage pressure tank to the No. 2 water storage pressure tank.

[0043] When the No. 2 water storage pressure tank is in water supply mode, and the two differential pressure sensors detect that the liquid level in the No. 2 water storage pressure tank has dropped to the first target lower limit, the PLC control module opens one SMC proportional valve and adjusts the output air pressure of the other SMC proportional valve to make the air pressure at the top of the No. 1 water storage pressure tank equal to or nearly equal to the air pressure at the top of the No. 2 water storage pressure tank. When the liquid level in the No. 2 water storage pressure tank continues to drop to the second target lower limit, the PLC control module controls the closure of the two water supply solenoid valves and the two SMC proportional valves, while simultaneously opening one water supply solenoid valve and the two water replenishment solenoid valves. At this time, water is supplied to the No. 2 water storage pressure tank through the two water replenishment solenoid valves, and the No. 1 water storage pressure tank outputs the required permeation water flow under the pressure regulation of the one SMC proportional valve, thus completing the switch from water supply from the No. 2 water storage pressure tank to the No. 1 water storage pressure tank.

[0044] The first target lower limit range is 3.4~3.6cm; the second target lower limit range is 2.7~2.9cm.

[0045] The seventh step is to repeat the water replenishment, air release, pressure regulation, water supply and switching processes in steps three to six, or repeat the osmotic pressure control, flow acquisition, osmotic parameter calculation and alternating water supply process in steps five to six after the test officially begins, so as to achieve long-term continuous and stable water supply in laboratory osmosis tests.

[0046] The beneficial effects of this invention are as follows: (1) This invention introduces an air compressor as a osmotic pressure source by cooperating with two pressure tanks, thus getting rid of the limitations of insufficient working space and unstable osmotic flow control in traditional osmotic tests; (2) The present invention uses a PLC control module to control the output pressure or flow rate of the permeation water flow, which improves the test accuracy and ensures the accuracy of the test results; (3) The present invention shortens the test time, saves human resources, and reduces the workload of test personnel, thereby indirectly improving the test efficiency.

[0047] In summary, the device of this invention is easy to operate, has low time costs, improves experimental accuracy, and ensures the accuracy of experimental results. Its installation process is simple, and the measurement process is convenient, reducing the workload of experimental personnel in permeability tests, thereby indirectly improving experimental efficiency. It provides a more convenient and effective water supply method for indoor testing of soil permeability coefficients in geotechnical experiments, and has good potential for widespread application. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of a continuous water supply device used for permeation testing; Figure 2 This is a schematic diagram of a commonly used rigid wall permeability testing device; Figure 3 This is a schematic diagram illustrating the usage of a continuous water supply device for osmosis testing. Figure 4 The hydraulic loading time history curve shows a comparison between the expected value of the preset pressure and the measured value of the actual output pressure. Figure 5 The flow-time curve shows the flow values ​​measured by the 3-11 electromagnetic flowmeter under different input pressure values; In the diagram: 1. Air compressor; 2. Water storage pressure device; 3. Water supply device control cabinet; 4. Permeation test device; 1-1 First air intake path; 1-2 Second air intake path; 2-1 No. 1 water storage pressure tank; 2-2 No. 1 tank air inlet; 2-3 No. 1 tank air pressure port; 2-4 No. 1 tank water pressure port; 2-5 No. 1 tank water port; 2-6 No. 2 water storage pressure tank; 2-7 No. 2 tank air inlet; 2-8 No. 2 tank air pressure port; 2-9 No. 2 tank water pressure port; 2-10 No. 2 tank water port; 3-1 Linear power supply, 3-2 PLC control module, 3-3 Communication interface, 3-4 One gas filter, 3-5 One pressure stabilizing tank, 3-6 One SMC proportional valve, 3-7 One water supply solenoid valve, 3-8 One differential pressure sensor, 3-9 High-precision pressure transmitter for the first pressure measuring point, 3-10 High-precision pressure transmitter for the second pressure measuring point, 3-11 Electromagnetic flow meter, 3-12 Inlet valve, 3-13 Outlet valve, 3-14 Aluminum alloy electrical control cabinet, 3-15 One water supply solenoid valve, 3-16 Load switch, 3-17 Two gas filters, 3-18 Two pressure stabilizing tanks, 3-19 Two SMC proportional valves, 3-20 Two water supply solenoid valves, 3-21 Two differential pressure sensors, 3-22 Two water supply solenoid valves.

[0049] 4-1 Inlet valve; 4-2 Second measuring point; 4-3 First measuring point. Detailed Implementation

[0050] The present invention will be further described below with reference to specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0051] A novel continuous water supply device for indoor osmosis testing, such as Figure 1 As shown, this is used to provide a specified pressure or flow rate of permeation water for indoor permeation tests. The novel continuous water supply device mainly includes an air compressor 1, a water storage pressure device 2, and a water supply device control cabinet 3.

[0052] In specific embodiments of the device of the present invention, it should be noted that some terms indicating relative direction or relative position, such as "one side," "upper end," "lower end," "left side," and "right side," are used to describe the orientation or positional relationship of a specific component relative to other components. The above descriptions of orientation or positional relationships are only for the purpose of clearly explaining this embodiment and do not constitute a limitation on the actual installation method. In actual implementation, adaptive adjustments can be made according to the actual conditions such as the size of each component, installation space, and pipeline layout.

[0053] The air compressor 1 is mainly used to provide a pressure source for the permeation water flow. The air outlet of the air compressor 1 is connected to an air pipe, which is first connected to a T-joint, and the air path is divided into two paths through the T-joint: a first air inlet path 1-1 and a second air inlet path 1-2. The first air inlet path 1-1 is used to supply compressed air to the first water storage pressure tank 2-1, and the second air inlet path 1-2 is used to supply compressed air to the second water storage pressure tank 2-6.

[0054] The water storage pressure device 2 includes two identical water storage pressure tanks, No. 1 2-1 and No. 2 2-6, which are mainly used for the storage and pressurization of permeate. Both No. 1 and No. 2 2-6 are designed to withstand a pressure of 1.5 MPa. No. 1 water storage pressure tank 2-1 is equipped with an air inlet 2-2, an air pressure port 2-3, a water pressure port 2-4, and a water port 2-5; No. 2 water storage pressure tank 2-6 is equipped with an air inlet 2-7, an air pressure port 2-8, a water pressure port 2-9, and a water port 2-10.

[0055] The following description uses the No. 1 water storage pressure tank 2-1 as an example to illustrate its opening arrangement. The No. 1 tank air inlet 2-2 is located at the center of the upper surface of the No. 1 water storage pressure tank 2-1. It has an internal thread structure and can be fitted with a quick-connect fitting of appropriate specifications according to the air pipe size for connecting the air pipe and supplying air to the No. 1 water storage pressure tank 2-1. The No. 1 tank air pressure hole 2-3 is located approximately 1 / 2R from the center of the upper surface of the No. 1 water storage pressure tank 2-1, where R is the cross-sectional radius of the No. 1 water storage pressure tank 2-1. The No. 1 tank air pressure hole 2-3 has an internal thread structure and can be fitted with a quick-connect fitting of appropriate specifications according to the air pipe size for connecting the air pressure end of a differential pressure sensor 3-8. The No. 1 water pressure hole 2-4 is located on the side wall of the No. 1 water storage pressure tank 2-1, approximately 1 / 10H from the lower surface of the No. 1 water storage pressure tank 2-1, where H is the vertical height of the No. 1 water storage pressure tank 2-1. The No. 1 water pressure hole 2-4 has an internal thread structure, allowing for the installation of a connector of appropriate specifications according to the water pipe size, for connecting to the hydraulic end of a differential pressure sensor 3-8. The No. 1 water hole 2-5 is symmetrically arranged on the side wall of the No. 1 water storage pressure tank 2-1, also approximately 1 / 10H from the lower surface of the No. 1 water storage pressure tank 2-1. The No. 1 water hole 2-5 has an internal thread structure, allowing for the installation of a connector of appropriate specifications according to the water pipe size, for water replenishment and supply to the No. 1 water storage pressure tank 2-1. The arrangement of the No. 2 tank air inlet 2-7, No. 2 tank air pressure hole 2-8, No. 2 tank water pressure hole 2-9 and No. 2 tank water hole 2-10 of the No. 2 tank water pressure tank 2-6 is the same as that of the No. 1 tank water pressure tank 2-1, and will not be described again here.

[0056] The central control cabinet 3 of the water supply device is the control and pipeline integration part of the device of the present invention, mainly including a linear power supply 3-1, a PLC control module 3-2, a communication interface 3-3, a gas filter 3-4, a pressure stabilizing tank 3-5, an SMC proportional valve 3-6, a water supply solenoid valve 3-7, a differential pressure sensor 3-8, a high-precision pressure transmitter for the first pressure measuring point 3-9, a high-precision pressure transmitter for the second pressure measuring point 3-10, an electromagnetic flowmeter 3-11, an inlet valve 3-12, an outlet valve 3-13, an aluminum alloy electrical control cabinet 3-14, a water supply solenoid valve 3-15, a load switch 3-16, two gas filters 3-17, two pressure stabilizing tanks 3-18, two SMC proportional valves 3-19, two water supply solenoid valves 3-20, two differential pressure sensors 3-21, and two water supply solenoid valves 3-22.

[0057] The aluminum alloy electrical control cabinet 3-14 is the main body of the central control cabinet 3 of the water supply device. It has a square box structure with bolt holes on the back panel for fixing various electrical components. The aluminum alloy electrical control cabinet 3-14 can be customized according to the required dimensions to provide installation space for electrical and piping components. The aluminum alloy electrical control cabinet 3-14 is divided into upper and lower layers. The upper layer is mainly used for the installation and connection of gas circuit components, and the lower layer is mainly used for the installation and connection of water circuit components.

[0058] The linear power supply 3-1 is bolted to the upper left of the upper layer of the aluminum alloy electrical control cabinet 3-14. It is used to convert the input voltage into a stable 24V DC output and to power the various electrical components inside the aluminum alloy electrical control cabinet 3-14. The load switch 3-16 is located between the linear power supply 3-1 and the household power supply, and is bolted to the right side of the linear power supply 3-1. It is used to switch the circuit on and off under normal load, and the load switch 3-16 works with a fuse to provide short-circuit protection.

[0059] The PLC control module 3-2 is bolted to the right side of the linear power supply 3-1. The PLC control module 3-2 is an industrial control device based on a microprocessor and incorporating computer technology, automatic control technology, and communication technology. It receives and processes electrical signals from various electrical components and issues control commands according to a preset program. The communication interface 3-3 is an Ethernet interface, connecting the touchscreen to the PLC control module 3-2 via a network cable, thereby enabling parameter setting, status monitoring, and operation control of the entire long-term continuous water supply system.

[0060] The first gas filter 3-4 is bolted below the linear power supply 3-1 and is used to filter oil or water vapor in the gas, preventing oil or water vapor from entering subsequent gas circuit components and affecting the operation of the device. The first gas filter 3-4 has threaded holes on both sides and is equipped with quick-connect pipe fittings. Its left side is an air inlet for connecting to the first air inlet 1-1, and its right side is an air outlet, connected to the left air inlet of the first pressure regulator 3-5 via a pipe. The second gas filter 3-17 is bolted below the first gas filter 3-4 and is used to filter oil or water vapor in the gas, preventing oil or water vapor from entering subsequent gas circuit components and affecting the operation of the device. The second gas filter 3-17 has threaded holes on both sides and is equipped with quick-connect pipe fittings. Its left side is an air inlet for connecting to the second air inlet 1-2, and its right side is an air outlet, connected to the left air inlet of the second pressure regulator 3-18 via a pipe.

[0061] The first-stage pressure stabilizing tank 3-5 is a steel elliptical gas tank, bolted to the right side of the first-stage gas filter 3-4 to maintain stable input gas pressure. Threaded holes are located in the center of both sides of the first-stage pressure stabilizing tank 3-5, and quick-connect fittings for air hoses are provided. Its left air inlet connects to the quick-connect fitting on the right side of the first-stage gas filter 3-4 via an air hose, and its right air outlet connects to the inlet of the first-stage SMC proportional valve 3-6 via an air hose. The second-stage pressure stabilizing tank 3-18 is a steel elliptical gas tank, bolted to the right side of the second-stage gas filter 3-17 to maintain stable input gas pressure. Threaded holes are located in the center of both sides of the second-stage pressure stabilizing tank 3-18, and quick-connect fittings for air hoses are provided. Its left air inlet connects to the quick-connect fitting on the right side of the second-stage gas filter 3-17 via an air hose, and its right air outlet connects to the inlet of the second-stage SMC proportional valve 3-19 via an air hose.

[0062] The SMC proportional valve 3-6 is located on the right side of the pressure stabilizing tank 3-5 and is bolted to the aluminum alloy electrical control cabinet 3-14. The SMC proportional valve 3-6 is communicatively connected to the PLC control module 3-2. It has threaded holes on both sides and is equipped with quick-connect air hoses. The left air inlet is connected to the right air outlet of the pressure stabilizing tank 3-5 via an air hose, and the right air outlet is connected to the air inlet 2-2 of the first water storage pressure tank 2-1 via an air hose. The SMC proportional valve 3-6 receives electrical signals from the PLC control module 3-2, which correspond to the target air pressure value. The electrical signals drive the proportional electromagnet inside the SMC proportional valve 3-6 to generate corresponding mechanical force, which moves the valve core to adjust the valve opening, thereby controlling the compressed air flow. Simultaneously, the pressure sensor built into the SMC proportional valve 3-6 monitors the output air pressure in real time and feeds back the output air pressure signal to the PLC control module 3-2. The PLC control module 3-2 compares the feedback air pressure signal with the target air pressure signal and automatically adjusts the output through a closed-loop control mechanism, thereby achieving proportional regulation of the air inlet pressure of the No. 1 water storage pressure tank 2-1.

[0063] The dual-channel SMC proportional valve 3-19 is located on the right side of the dual-channel pressure stabilizing tank 3-18 and is bolted to the aluminum alloy electrical control cabinet 3-14. The dual-channel SMC proportional valve 3-19 is communicatively connected to the PLC control module 3-2. It has threaded holes on both sides and is equipped with quick-connect air hoses. The left air inlet is connected to the right air outlet of the dual-channel pressure stabilizing tank 3-18 via an air hose, and the right air outlet is connected to the second tank air inlet 2-7 of the second water storage pressure tank 2-6 via an air hose. The dual-channel SMC proportional valve 3-19 receives electrical signals from the PLC control module 3-2, which correspond to the target air pressure value. The electrical signals drive the proportional electromagnet inside the dual-channel SMC proportional valve 3-19 to generate corresponding mechanical force, which moves the valve core to adjust the valve opening, thereby controlling the compressed air flow. Simultaneously, the pressure sensor built into the dual-channel SMC proportional valve 3-19 monitors the output air pressure in real time and feeds back the output air pressure signal to the PLC control module 3-2. The PLC control module 3-2 compares the feedback air pressure signal with the target air pressure signal and automatically adjusts the output through a closed-loop control mechanism, thereby achieving proportional regulation of the air inlet pressure of the No. 2 water storage pressure tank 2-6.

[0064] The solenoid valves 3-7 (one water supply circuit), 3-15 (one water supply circuit), 3-20 (two water supply circuits), and 3-22 (two water supply circuits) are all electrically connected to the PLC control module 3-2. The PLC control module 3-2 outputs a switching signal to control the energization of the corresponding solenoid valve coils, thereby driving the valve core to switch the valve port on / off state and realizing the switching control of the corresponding liquid circuit. All the above solenoid valves are normally closed when not energized.

[0065] The first water supply solenoid valve 3-7 is installed on the B water pipe and is used to control the flow of water from the first water storage pressure tank 2-1. The first water supply solenoid valve 3-15 is installed on the B2 water pipe, with its inlet connected to the tee joint behind the first water supply solenoid valve 3-7 and its outlet connected to the tee joint before the confluence, and is used to control the flow of water from the first water storage pressure tank 2-1 to the C water pipe. The second water supply solenoid valve 3-20 is installed on the A water pipe and is used to control the flow of water from the second water storage pressure tank 2-6. The second water supply solenoid valve 3-22 is installed on the A2 water pipe, with its inlet connected to the tee joint behind the second water supply solenoid valve 3-20 and its outlet connected to the tee joint before the confluence, and is used to control the flow of water from the second water storage pressure tank 2-6 to the C water pipe.

[0066] One end of the differential pressure sensor 3-8 is connected to the air pressure port 2-3 of tank 1, and the other end is connected to the water pressure port 2-4 of tank 1. It is used to obtain the pressure difference between the gas pressure and the liquid pressure inside tank 2-1. The differential pressure sensor 3-8 uses a pressure-sensitive element to sense the pressure difference and converts it into a standard electrical signal through a built-in circuit. Since there is a linear relationship between the liquid level and the pressure difference, the standard electrical signal reflects the remaining liquid level inside tank 2-1. When the differential pressure sensor 3-8 is connected to the PLC control module 3-2, its output standard electrical signal is input to the analog input module of the PLC control module 3-2. The PLC control module 3-2 collects, converts, and processes this standard electrical signal to obtain the liquid level data inside tank 2-1.

[0067] One end of the dual-channel differential pressure sensor 3-21 is connected to the gas pressure port 2-8 of tank No. 2, and the other end is connected to the water pressure port 2-9 of tank No. 2. It is used to obtain the pressure difference between the gas pressure and the liquid pressure inside tank No. 2 (water storage pressure tank 2-6). The dual-channel differential pressure sensor 3-21 uses a pressure-sensitive element to sense the pressure difference between the two sides and converts the pressure difference into a standard electrical signal through a built-in circuit. Since there is a linear relationship between the liquid level and the pressure difference, the standard electrical signal can reflect the remaining liquid level in tank No. 2 (water storage pressure tank 2-6). When the dual-channel differential pressure sensor 3-21 is connected to the PLC control module 3-2, its output standard electrical signal is input to the analog input module of the PLC control module 3-2. The PLC control module 3-2 collects, converts, and processes this standard electrical signal to obtain the liquid level data inside tank No. 2 (water storage pressure tank 2-6).

[0068] The inlet valve 3-12 is connected to the water source and is used to replenish water to the water supply system. A water pipe is connected to the right side of the inlet valve 3-12, leading the water pipe into the lower layer of the water supply device control cabinet 3. After entering the lower layer of the water supply device control cabinet 3, the water pipe is divided into two water pipes, A and B, via a water pipe tee connector. Water pipe A connects to the second-line replenishment solenoid valve 3-20, and then connects to another water pipe tee connector, dividing it into water pipe A1 and water pipe A2. Water pipe A1 extends out of the water supply device control cabinet 3 and connects to the second tank water hole 2-10 of the second water storage pressure tank 2-6. Water pipe A2 connects to the second-line supply solenoid valve 3-22. After connecting water pipe B to solenoid valve 3-7 of water supply line 1, it is then connected to a water pipe tee connector and splits into water pipe B1 and water pipe B2. Water pipe B1 extends out of the central control cabinet 3 of the water supply device and connects to water outlet 2-5 of water pressure tank 2-1. Water pipe B2 connects to solenoid valve 3-15 of water supply line 1. After connecting water pipes A2 and B2 to solenoid valves 3-22 of water supply line 2 and 3-15 of water supply line 1 respectively, they are connected to the two ends of the water pipe tee connector and converge into water pipe C.

[0069] The electromagnetic flowmeter 3-11 is connected to the C-line water pipe after the water flow convergence. Its left end is connected to the C-line water pipe, and its right end is connected to the outlet valve 3-13 via a water pipe. It is used to measure the water supply flow rate and output a flow signal to the PLC control module 3-2. The electromagnetic flowmeter 3-11 operates based on Faraday's law of electromagnetic induction. When conductive fluid flows through the measuring tube, it cuts the magnetic field generated by the excitation coil and generates an induced electromotive force proportional to the flow velocity at both ends of the electrodes. This induced electromotive force is converted into a standard electrical signal by the signal processing circuit, thereby reflecting the fluid flow velocity. When the electromagnetic flowmeter 3-11 is connected to the PLC control module 3-2, its output standard electrical signal is input to the analog input module of the PLC control module 3-2. The PLC control module 3-2 acquires, linearly converts, and calculates this standard electrical signal to obtain the water supply flow rate data.

[0070] The outlet valve 3-13 is located at the outlet end of the electromagnetic flowmeter 3-11 and is used to control the flow of water between the continuous water supply device and the permeation test device 4. A schematic diagram of the permeation test device 4 is shown below. Figure 2 As shown.

[0071] The high-precision pressure transmitter 3-9 at the first pressure measuring point is connected to the upper end of the test sample via a PU hose to acquire the water pressure at the measuring point at the upper end of the test sample. The high-precision pressure transmitter 3-9 senses the measured pressure through a pressure-sensitive element. When pressure acts on the pressure-sensitive element, it deforms, causing the built-in Wheatstone bridge to become unbalanced and output a weak electrical signal. After amplification and filtering, this signal is converted into a standard electrical signal. This standard electrical signal has a linear relationship with the measured pressure, thus reflecting the magnitude of the measured pressure. When the high-precision pressure transmitter 3-9 is connected to the PLC control module 3-2, its output standard electrical signal is input to the analog input module of the PLC control module 3-2. The PLC control module 3-2 acquires, performs A / D conversion, and linear calculations on this standard electrical signal to obtain the pressure data at the first pressure measuring point in real time.

[0072] The high-precision pressure transmitter 3-10 at the second pressure measuring point is connected to the lower end of the test sample via a PU hose to acquire the water pressure at the measuring point at the lower end of the test sample. The high-precision pressure transmitter 3-10 senses the measured pressure through a pressure-sensitive element. When pressure acts on the pressure-sensitive element, it deforms, causing the built-in Wheatstone bridge to become unbalanced and output a weak electrical signal. After amplification and filtering, this signal is converted into a standard electrical signal. This standard electrical signal has a linear relationship with the measured pressure, thus reflecting the magnitude of the measured pressure. When the high-precision pressure transmitter 3-10 is connected to the PLC control module 3-2, its output standard electrical signal is input to the analog input module of the PLC control module 3-2. The PLC control module 3-2 acquires, performs A / D conversion, and linear calculations on this standard electrical signal to obtain the pressure data at the second pressure measuring point in real time.

[0073] The electrical components and water pipes in the lower layer of the control cabinet 3 of the water supply device can be arranged reasonably according to the actual space, as long as the above-mentioned water connection relationship and control function can be realized. This embodiment does not limit this.

[0074] The following describes the usage of the device of the present invention in conjunction with a specific indoor permeability test operation process.

[0075] A method of using a novel continuous water supply device for indoor osmosis testing, such as... Figure 3 As shown, it includes the following steps: The first step is to fill the test sample into the rigid wall permeameter according to the test plan, and to complete the sample compaction, saturation and sealing treatment according to the test specifications.

[0076] The second step is to assemble the new continuous water supply device according to the above connection relationship. Connect the air compressor 1, the first air inlet 1-1, the second air inlet 1-2, the water storage pressure device 2, the water supply device control cabinet 3, and the permeation test device 4 in sequence, and check whether the connection of each air pipe, water pipe, PU hose and electrical circuit is reliable.

[0077] Third, turn on the load switch 3-16 to connect the power supply, and press the water filling button on the touch screen control panel. The PLC control module 3-2 first controls the opening of the water replenishment solenoid valve 3-7. Water enters the No. 1 water storage pressure tank 2-1 through the inlet valve 3-12, the B-line water pipe, the first water replenishment solenoid valve 3-7, and the B1-line water pipe, replenishing the No. 1 water storage pressure tank 2-1. At this time, the existing gas in the No. 1 water storage pressure tank 2-1 is discharged through the No. 1 tank air inlet 2-2, the air pipe, and the first SMC proportional valve 3-6.

[0078] During the replenishment process of pressure tank 2-1, a differential pressure sensor 3-8 collects the differential pressure signal in real time and transmits it to the PLC control module 3-2. The PLC control module 3-2 calculates the liquid level in pressure tank 2-1 based on this differential pressure signal. When the liquid level in pressure tank 2-1 reaches the predetermined height, the PLC control module 3-2 controls the solenoid valve 3-7 of the replenishment path to close, and simultaneously opens the solenoid valves 3-20 of the second replenishment path and 3-15 of the first water supply path. At this time, the PLC control module 3-2 controls the water source to replenish pressure tank 2-6, and controls the SMC proportional valve 3-6 to adjust the air pressure from the first air inlet 1-1 to pressure tank 2-1, so that pressure tank 2-1 outputs the permeable water flow required for the test. After the second water storage pressure tank 2-6 is replenished with water, the PLC control module 3-2 controls the solenoid valve 3-20 of the second water replenishment circuit to close, so that the second water storage pressure tank 2-6 is full of water and in standby mode.

[0079] Step 4: Perform venting and test connection. First, input a small venting flow rate or venting pressure value on the touchscreen control panel to allow the water to flow slowly. Connect a section of water pipe to the outlet valve 3-13 and extend the pipe into the sewer or waste tank. Open the outlet valve 3-13 to allow the water in the continuous water supply device to flow out slowly, thus expelling any residual air from the water supply device and pipes. Once no more bubbles are observed flowing out, connect the outlet valve 3-13 to the inlet valve 4-1 of the permeation test device 4 via the water pipe, keeping the inlet valve 4-1 closed. Then, set both the set flow rate and set pressure values ​​on the touchscreen control panel to 0 and open the inlet valve 4-1 of the permeation test device 4. Use a PU hose to connect the high-precision pressure transmitter 3-9 at the first pressure measurement point to the first measuring point 4-3, and use a PU hose to connect the high-precision pressure transmitter 3-10 at the second pressure measurement point to the second measuring point 4-2, to obtain the water pressure at the two measuring points of the test sample.

[0080] The fifth step is to control the osmotic pressure and calculate the osmotic parameters. In this embodiment, the hydraulic gradient i is used as the control index for the osmotic test, and the hydraulic gradient i is controlled by controlling the osmotic pressure difference between the two measuring points. Click the pressure control button on the touch screen and input the required target osmotic pressure difference Δu. The PLC control module 3-2 controls one SMC proportional valve 3-6 to slowly open or close, so that the air compressor 1 outputs air pressure into the first water storage pressure tank 2-1 through the first air inlet 1-1, thereby driving the water in the first water storage pressure tank 2-1 into the osmotic test device 4, until the absolute value of the pressure difference between the high-precision pressure transmitter 3-9 at the first measuring point and the high-precision pressure transmitter 3-10 at the second measuring point reaches the set target value.

[0081] Assume the pressure value collected by the high-precision pressure transmitter 3-9 at the first pressure measurement point is... u 1. The pressure value collected by the high-precision pressure transmitter 3-10 at the second pressure measuring point is... u 2. The height difference between the first measuring point 4-3 and the second measuring point 4-2 is: h The density of water is γ w Then the osmotic pressure difference Δ u for u 1 and u The absolute value of the difference, i.e.: When the osmotic pressure difference Δ u Once the set target value is reached and stabilized, read the flow rate displayed on the touchscreen. Q Let the radius of the test sample be... R Then the permeation velocity v Calculate using the following formula: The permeability coefficient k of the tested sample is thus obtained, and the calculation formula is as follows: Step 6: Implement alternating water supply and automatic water replenishment control between the two water storage pressure tanks. The PLC control module 3-2 presets target lower limits for the liquid level corresponding to one differential pressure sensor 3-8 and two differential pressure sensors 3-21. These target lower limits include a first target lower limit and a second target lower limit, where the first target lower limit is higher than the second target lower limit. The first target lower limit is used to trigger the pressure pre-balancing control of the backup water storage pressure tank, and the second target lower limit is used to trigger the water supply switching control of the supply water storage pressure tank. In this embodiment, the first target lower limit is 3.5 cm, and the second target lower limit is 2.8 cm.

[0082] When the No. 1 water storage pressure tank 2-1 is in water supply mode, and the differential pressure sensor 3-8 detects that the liquid level in the No. 1 water storage pressure tank 2-1 has dropped to the first target lower limit, the PLC control module 3-2 opens the second-path SMC proportional valve 3-19 and adjusts the output air pressure of the second-path SMC proportional valve 3-19 to make the air pressure at the top of the No. 2 water storage pressure tank 2-6 equal to or nearly equal to the air pressure at the top of the No. 1 water storage pressure tank 2-1, so as to reduce pressure fluctuations during subsequent water supply switching. When the liquid level in the No. 1 water storage pressure tank 2-1 continues to drop to the second target lower limit, the PLC control module 3-2 controls the closure of the first water supply solenoid valve 3-15 and the first SMC proportional valve 3-6, while simultaneously opening the second water supply solenoid valve 3-22 and the first water replenishment solenoid valve 3-7. At this time, the water source replenishes water to the No. 1 water storage pressure tank 2-1 through the solenoid valve 3-7 of the first water supply line, and the No. 2 water storage pressure tank 2-6 outputs the permeable water flow required for the test under the pressure regulation action of the second SMC proportional valve 3-19, thus completing the switch from water supply from the No. 1 water storage pressure tank 2-1 to water supply from the No. 2 water storage pressure tank 2-6.

[0083] When the No. 2 water storage pressure tank 2-6 is in water supply mode, and the two differential pressure sensors 3-21 detect that the liquid level in the No. 2 water storage pressure tank 2-6 has dropped to the first target lower limit, the PLC control module 3-2 opens one SMC proportional valve 3-6 and adjusts the output air pressure of the other SMC proportional valve 3-6 to make the air pressure at the top of the No. 1 water storage pressure tank 2-1 equal to or nearly equal to the air pressure at the top of the No. 2 water storage pressure tank 2-6. When the liquid level in the No. 2 water storage pressure tank 2-6 continues to drop to the second target lower limit, the PLC control module 3-2 controls the closure of the two water supply solenoid valves 3-22 and 3-19, while simultaneously opening one water supply solenoid valve 3-15 and two water replenishment solenoid valves 3-20. At this time, water is supplied to the No. 2 water storage pressure tank 2-6 via the second water supply solenoid valve 3-20. The No. 1 water storage pressure tank 2-1 outputs the required permeation water flow for the test under the pressure regulation of the first SMC proportional valve 3-6, thus completing the switch from water supply from the No. 2 water storage pressure tank 2-6 to water supply from the No. 1 water storage pressure tank 2-1.

[0084] In this embodiment, the lower limit of the first target is 3.5cm, and the lower limit of the second target is 2.8cm.

[0085] Step 7: During the experiment, the PLC control module 3-2 continuously collects signals from the electromagnetic flowmeter 3-11, the high-precision pressure transmitter 3-9 at the first pressure measuring point, the high-precision pressure transmitter 3-10 at the second pressure measuring point, one differential pressure sensor 3-8, and two differential pressure sensors 3-21. Based on the set target value, it controls one SMC proportional valve 3-6, two SMC proportional valves 3-19, one water supply solenoid valve 3-7, one water supply solenoid valve 3-15, two water supply solenoid valves 3-20 and 3-22. This is achieved by applying the target osmotic pressure difference Δ step by step. u It can achieve long-term continuous and stable water supply and permeability coefficient measurement in indoor permeability tests by cyclically executing the processes of osmotic pressure control, flow acquisition, osmotic parameter calculation, automatic water replenishment, and alternating water supply from dual water storage pressure tanks.

[0086] Figure 4 , Figure 5 These are test results for a new type of continuous water supply device used for indoor infiltration testing. Figure 4 The hydraulic loading time history curve shows a comparison between the expected value of the preset pressure and the measured value of the actual output pressure, and analyzes... Figure 4 It can be seen that the measured pressure value can be stably maintained near the target pressure value, and the pressure fluctuation is basically controlled within the range of ±1 kPa of the target value. Figure 5 The flow-time history curves show the flow rates measured by the 3-11 electromagnetic flowmeter under different input pressure values; analysis... Figure 5 It can be seen that the present invention can accurately monitor the flow rate in real time and has no abnormalities during long-term operation, thus providing a guarantee for the determination of the permeability coefficient.

[0087] In other words, in this embodiment, when conducting a permeation test using the device of the present invention, the measured pressure value can be stably maintained near the target pressure value, and the pressure fluctuation is basically controlled within ±1 kPa of the target value. For the test sample with a height of 600 mm, its hydraulic gradient control accuracy can reach 0.167, indicating that the device of the present invention has high pressure control accuracy and can meet the requirements of conventional indoor permeation tests for long-term continuous and stable water supply.

[0088] The above embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A continuous water supply device for osmosis testing, used for long-term continuous water supply in indoor osmosis testing, characterized in that, The continuous water supply device includes an air compressor (1), a water storage pressure device (2), and a central control cabinet (3) for the water supply device, specifically: The air compressor (1) provides a pressure source for the permeation water flow, and its outlet end divides the air path into a first air inlet path (1-1) and a second air inlet path (1-2) through a three-way connector; The water storage pressure device (2) includes a No. 1 water storage pressure tank (2-1) and a No. 2 water storage pressure tank (2-6) with the same structure, which are used for the storage and pressurization of permeable water; The water supply device's central control cabinet (3) is the main component, including a linear power supply (3-1), a PLC control module (3-2), a communication interface (3-3), a gas filter (3-4), a pressure stabilizing tank (3-5), an SMC proportional valve (3-6), a water supply solenoid valve (3-7), a differential pressure sensor (3-8), a high-precision pressure transmitter for the first pressure measuring point (3-9), a high-precision pressure transmitter for the second pressure measuring point (3-10), and an electromagnetic flowmeter. The system includes: (3-11) inlet valve, (3-12) outlet valve, (3-13) aluminum alloy electrical control cabinet, (3-14) one water supply solenoid valve, (3-15) load switch, (3-16) two gas filters, (3-17) two pressure stabilizing tanks, (3-18) two SMC proportional valves, (3-19) two water replenishment solenoid valves, (3-20) two differential pressure sensors, (3-21) two water supply solenoid valves; specifically: The aluminum alloy electrical control cabinet (3-14) is divided into upper and lower layers. The upper layer is used for the installation and connection of pneumatic components, and the lower layer is used for the installation and connection of water components. The linear power supply (3-1) is fixed on the upper layer of the aluminum alloy electrical control cabinet (3-14) to supply power to various electrical components; the load switch (3-16) is located between the linear power supply (3-1) and the household power supply. The PLC control module (3-2) is installed on one side of the linear power supply (3-1); The first gas filter (3-4) is fixed below the linear power supply (3-1), and has threaded holes on its left and right sides. The left side is the air inlet, which is connected to the first air inlet (1-1), and the right side is the air outlet, which is connected to the air inlet of the first pressure regulator (3-5). The second gas filter (3-17) is fixed below the first gas filter (3-4), and has threaded holes on its left and right sides. The left side is the air inlet, which is used to connect to the second air inlet (1-2), and the right side is the air outlet, which is connected to the air inlet of the second pressure regulator (3-18). The first-stage pressure regulator (3-5) is installed to the right of the first-stage gas filter (3-4), with threaded holes in the center of its left and right sides. The left air inlet is connected to the first-stage gas filter (3-4), and the right air outlet is connected to the air inlet of the first-stage SMC proportional valve (3-6). The second-stage pressure regulator (3-18) is installed to the right of the second-stage gas filter (3-17), with threaded holes in the center of its left and right sides. The left air inlet is connected to the second-stage gas filter (3-17), and the right air outlet is connected to the air inlet of the second-stage SMC proportional valve (3-19). The SMC proportional valve (3-6) is located on the right side of the pressure stabilizing tank (3-5) and fixed inside the aluminum alloy electrical control cabinet (3-14). It is connected to the PLC control module (3-2) and is used to regulate the pressure of compressed air entering the No. 1 water storage pressure tank (2-1). The two-way SMC proportional valve (3-19) is located on the right side of the two-way pressure stabilizing tank (3-18) and fixed inside the aluminum alloy electrical control cabinet (3-14). It is connected to the PLC control module (3-2) for regulating the pressure of compressed air entering the second water storage pressure tank (2-6). The solenoid valves for the one water supply circuit (3-7), the one water supply circuit (3-15), the two water supply circuits (3-20), and the two water supply circuits (3-22) are all electrically connected to the PLC control module (3-2) to control the power supply and drive the valve core to switch the valve port on / off state, thereby realizing the switching control of the corresponding liquid circuit. The first differential pressure sensor (3-8) is used to obtain the pressure difference between the gas pressure and the liquid pressure in the first water storage pressure tank (2-1) and is connected to the PLC control module (3-2); the second differential pressure sensor (3-21) is used to obtain the pressure difference between the gas pressure and the liquid pressure in the second water storage pressure tank (2-6) and is connected to the PLC control module (3-2). The inlet valve (3-12) is connected to the water source; The electromagnetic flowmeter (3-11) is connected to the C-line water pipe after the confluence. Its left end is connected to the C-line water pipe, and its right end is connected to the outlet valve (3-13) through the water pipe. It is used to measure the water supply flow and output the flow signal to the PLC control module (3-2). The outlet valve (3-13) is located at the outlet end of the electromagnetic flowmeter (3-11) to control the flow of water between the continuous water supply device and the permeation test device (4). The first high-precision pressure transmitter (3-9) and the second high-precision pressure transmitter (3-10) are respectively connected to the upper and lower ends of the sample being tested to obtain the water pressure at the measuring point and are connected to the PLC control module (3-2). The permeation test device (4) includes an inlet valve (4-1), a second measuring point (4-2), and a first measuring point (4-3). The inlet valve (4-1) is used to control the water inlet of the permeation test device (4). The first measuring point (4-3) is connected to the high-precision pressure transmitter (3-9) of the first measuring point, and the second measuring point (4-2) is connected to the high-precision pressure transmitter (3-10) of the second measuring point.

2. The continuous water supply device for permeation testing according to claim 1, characterized in that, In the water storage pressure device (2), the design pressure resistance of the No. 1 water storage pressure tank (2-1) and the No. 2 water storage pressure tank (2-6) is 1.5 MPa. The No. 1 water storage pressure tank (2-1) is provided with a No. 1 tank air inlet (2-2), a No. 1 tank air pressure hole (2-3), a No. 1 tank water pressure hole (2-4), and a No. 1 tank water hole (2-5). The No. 2 water storage pressure tank (2-6) is provided with a No. 2 tank air inlet (2-7), a No. 2 tank air pressure hole (2-8), a No. 2 tank water pressure hole (2-9), and a No. 2 tank water hole (2-10). The arrangement of the openings on the No. 2 water storage pressure tank (2-6) is the same as that on the No. 1 water storage pressure tank (2-1). The arrangement of the openings on the No. 1 water storage pressure tank (2-1) will be used as an example for explanation: The air inlet (2-2) of the No. 1 tank is located at the center of the upper surface of the No. 1 water storage pressure tank (2-1). It has an internal thread structure and can be equipped with a quick-connect fitting of the corresponding specification according to the size of the air pipe. It is used to connect the air pipe and supply air into the No. 1 water storage pressure tank (2-1). The No. 1 tank air pressure hole (2-3) is located on the upper surface of the No. 1 water storage pressure tank (2-1) at a distance of 1 / 2R from the center, where R is the cross-sectional radius of the No. 1 water storage pressure tank (2-1); the No. 1 tank air pressure hole (2-3) has an internal thread structure, and a quick-connect fitting for the air pipe is installed according to the size of the air pipe to connect to the air pressure end of a differential pressure sensor (3-8); The water pressure hole (2-4) of the No. 1 tank is located on the side wall of the No. 1 water pressure tank (2-1) and is located at 1 / 10H from the lower surface of the No. 1 water pressure tank (2-1), where H is the vertical height of the No. 1 water pressure tank (2-1). The water pressure hole (2-4) of the No. 1 tank has an internal thread structure. According to the size of the water pipe, a corresponding specification of connector is installed to connect to the hydraulic end of a differential pressure sensor (3-8). The water hole (2-5) and water pressure hole (2-4) of the No. 1 tank are symmetrically arranged on the side wall of the No. 1 water pressure tank (2-1), and are also located at 1 / 10H from the lower surface of the No. 1 water pressure tank (2-1). The water hole (2-5) of the No. 1 tank has an internal thread structure and is used to install a connector according to the water pipe size for water replenishment and water supply to the No. 1 water pressure tank (2-1). The arrangement of the No. 2 tank air inlet (2-7), No. 2 tank air pressure hole (2-8), No. 2 tank water pressure hole (2-9) and No. 2 tank water hole (2-10) of the No. 2 water pressure tank (2-6) is the same as that of the No. 1 water pressure tank (2-1).

3. A continuous water supply device for permeation testing according to claim 2, characterized in that, In the continuous water supply device: The aluminum alloy electrical control cabinet (3-14) is the main part of the central control cabinet (3) of the water supply device. It has a square box structure and bolt holes on the back plate for fixing various electrical components. The load switch (3-16) is used to switch the circuit on and off under normal load, and the load switch (3-16) works with the fuse to achieve short circuit protection. The linear power supply (3-1) is fixed to the upper left position of the upper layer of the aluminum alloy electrical control cabinet (3-14) by bolts, and is used to convert the input voltage into a stable 24V DC output; the communication interface (3-3) is an Ethernet interface, which connects the touch screen to the PLC control module (3-2) through a network cable to realize parameter setting, status monitoring and operation control of the entire long-term continuous water supply device; The threaded hole of the first gas filter (3-4) is equipped with a quick-connect fitting for the air pipe, and the air outlet on the right side is connected to the air inlet on the left side of the first pressure stabilizing tank (3-5) through the air pipe; the threaded hole of the second gas filter (3-17) is equipped with a quick-connect fitting for the air pipe, and the air outlet on the right side is connected to the air inlet on the left side of the second pressure stabilizing tank (3-18) through the air pipe. The first-stage pressure stabilizing tank (3-5) is a steel elliptical gas tank, bolted to the right side of the first-stage gas filter (3-4) to maintain stable input gas pressure. The threaded holes on both sides of the first-stage pressure stabilizing tank (3-5) are equipped with quick-connect tubing connectors. Its left air inlet is connected to the quick-connect tubing connector on the right side of the first-stage gas filter (3-4) via a tubing, and its right air outlet is connected to the air inlet of the first-stage SMC proportional valve (3-6) via a tubing. The second-stage pressure stabilizing tank (3-18) is a steel elliptical gas tank, bolted to the right side of the second-stage gas filter (3-17) to maintain stable input gas pressure. The threaded holes of the second-stage pressure stabilizing tank (3-18) are equipped with quick-connect tubing connectors. Its left air inlet is connected to the quick-connect tubing connector on the right side of the second-stage gas filter (3-17) via a tubing, and its right air outlet is connected to the air inlet of the second-stage SMC proportional valve (3-19) via a tubing. The first SMC proportional valve (3-6) has threaded holes on both sides and is equipped with quick-connect air pipes. The left air inlet is connected to the right air outlet of the first pressure stabilizing tank (3-5) through an air pipe, and the right air outlet is connected to the first tank air inlet (2-2) of the first water storage pressure tank (2-1) through an air pipe. The second SMC proportional valve (3-19) has threaded holes on both sides and is equipped with quick-connect air pipes. The left air inlet is connected to the right air outlet of the second pressure stabilizing tank (3-18) through an air pipe, and the right air outlet is connected to the second tank air inlet (2-7) of the second water storage pressure tank (2-6) through an air pipe.

4. A continuous water supply device for permeation testing according to claim 3, characterized in that, In the continuous water supply device: The solenoid valve (3-7) for the water supply circuit is installed on the B water pipe and is used to control the flow of water from the water source to the No. 1 water storage pressure tank (2-1). The solenoid valve (3-15) for the water supply circuit is installed on the B2 water pipe, with its inlet end connected to the tee connector of the solenoid valve (3-7) and its outlet end connected to the tee connector of the water pipe before the confluence, and is used to control the flow of water from the No. 1 water storage pressure tank (2-1) to the C water pipe. When the PLC control module... (3-2) When the opening signal is issued, the solenoid valve (3-15) of the water supply circuit is energized and opened, and the water in the No. 1 water storage pressure tank (2-1) enters the C water pipe through the No. 1 tank water hole (2-5), water pipe B1, water pipe B2 and the solenoid valve (3-15) of the water supply circuit; when the PLC control module (3-2) stops outputting the opening signal, the solenoid valve (3-15) of the water supply circuit is de-energized and closed, thereby cutting off the water supply path of the No. 1 water storage pressure tank (2-1); The second-path water supply solenoid valve (3-20) is installed on the A-path water pipe and is used to control the flow of water from the source to the No. 2 water storage pressure tank (2-6). The second-path water supply solenoid valve (3-22) is installed on the A2-path water pipe. Its inlet end is connected to the water pipe tee joint behind the second-path water supply solenoid valve (3-20), and its outlet end is connected to the water pipe tee joint before the confluence. It is used to control the flow of water from the No. 2 water storage pressure tank (2-6) to the C-path water pipe. When the PLC control module (3-2) sends an open signal, the solenoid valve (3-22) of the second water supply circuit is energized and opened, and the water in the second water storage pressure tank (2-6) enters the C water pipe through the water hole (2-10) of the second tank, the A1 water pipe, the A2 water pipe, and the solenoid valve (3-22) of the second water supply circuit; when the PLC control module (3-2) stops outputting the open signal, the solenoid valve (3-22) of the second water supply circuit is de-energized and closed, thereby cutting off the water supply path of the second water storage pressure tank (2-6).

5. A continuous water supply device for permeation testing according to claim 4, characterized in that, In the continuous water supply device: One end of the differential pressure sensor (3-8) is connected to the air pressure port (2-3) of the No. 1 tank, and the other end is connected to the water pressure port (2-4) of the No. 1 tank. It is used to obtain the pressure difference between the gas pressure and the liquid pressure in the No. 1 water storage pressure tank (2-1). The differential pressure sensor (3-8) uses a pressure-sensitive element to sense the pressure difference on both sides and converts the pressure difference into a standard electrical signal through a built-in circuit. The standard electrical signal reflects the remaining liquid level in the No. 1 water storage pressure tank (2-1). When the differential pressure sensor (3-8) is connected to the PLC control module (3-2), its output standard electrical signal is connected to the analog input module of the PLC control module (3-2). The PLC control module (3-2) collects, converts and calculates the standard electrical signal to obtain the liquid level data in the No. 1 water storage pressure tank (2-1). One end of the dual differential pressure sensor (3-21) is connected to the gas pressure port (2-8) of the No. 2 tank, and the other end is connected to the water pressure port (2-9) of the No. 2 tank. It is used to obtain the pressure difference between the gas pressure and the liquid pressure in the No. 2 water storage pressure tank (2-6). The dual differential pressure sensor (3-21) uses a pressure-sensitive element to sense the pressure difference on both sides and converts the pressure difference into a standard electrical signal through a built-in circuit. The standard electrical signal reflects the remaining liquid level in the No. 2 water storage pressure tank (2-6). When the dual differential pressure sensor (3-21) is connected to the PLC control module (3-2), its output standard electrical signal is connected to the analog input module of the PLC control module (3-2). The PLC control module (3-2) collects, converts and calculates the standard electrical signal to obtain the liquid level data in the No. 2 water storage pressure tank (2-6).

6. A continuous water supply device for permeation testing according to claim 5, characterized in that, In the continuous water supply device: The water pipe is connected to the right side of the inlet valve (3-12) and enters the lower layer of the water supply device control cabinet (3). After entering the lower layer of the water supply device control cabinet (3), the water pipe is divided into a water pipe A and a water pipe B through a water pipe tee connector. The water pipe A is connected to the second water supply circuit solenoid valve (3-20) and then connected to the water pipe tee connector and divided into a water pipe A1 and a water pipe A2. The water pipe A1 extends out of the water supply device control cabinet (3) and is connected to the second tank water hole (2-10) of the second water storage pressure tank (2-6). The water pipe A2 is connected to the second water supply circuit solenoid valve (3-20). 3-22); After the B water pipe is connected to the solenoid valve of the water supply circuit (3-7), it is connected to the water pipe tee and divided into the B1 water pipe and the B2 water pipe. The B1 water pipe extends out of the central control cabinet (3) of the water supply device and is connected to the No. 1 tank water hole (2-5) of the No. 1 water storage pressure tank (2-1). The B2 water pipe is connected to the solenoid valve of the water supply circuit (3-15). After the A2 water pipe and the B2 water pipe are connected to the two water supply circuit solenoid valves (3-22) and the one water supply circuit solenoid valve (3-15) respectively, they are connected to the two ends of the water pipe tee and merge into the C water pipe.

7. A continuous water supply device for permeation testing according to claim 6, characterized in that, In the continuous water supply device: The electromagnetic flowmeter (3-11) is connected to the PLC control module (3-2). When the conductive fluid flows through the measuring tube, it cuts the magnetic field generated by the excitation coil and generates an induced electromotive force proportional to the flow velocity at both ends of the electrode. The induced electromotive force is converted into a standard electrical signal by the signal processing circuit to reflect the fluid flow velocity. The standard electrical signal output by the electromagnetic flowmeter (3-11) is connected to the analog input module of the PLC control module (3-2). The PLC control module (3-2) collects, linearly converts and calculates the standard electrical signal to obtain the water supply velocity or water supply flow data.

8. A continuous water supply device for permeation testing according to claim 7, characterized in that, In the continuous water supply device: The high-precision pressure transmitter (3-9) at the first pressure measuring point is connected to the upper end of the test sample via a PU hose. It senses the pressure being measured through a pressure-sensitive element and outputs a standard electrical signal. The standard electrical signal output by the high-precision pressure transmitter (3-9) at the first pressure measuring point is connected to the analog input module of the PLC control module (3-2). The PLC control module (3-2) acquires, performs A / D conversion and linear calculation on the standard electrical signal, thereby obtaining the pressure data at the first pressure measuring point in real time. The high-precision pressure transmitter (3-10) at the second pressure measuring point is connected to the lower end of the test sample via a PU hose. It senses the pressure being measured through a pressure-sensitive element and outputs a standard electrical signal. The standard electrical signal output by the high-precision pressure transmitter (3-10) at the second pressure measuring point is connected to the analog input module of the PLC control module (3-2). The PLC control module (3-2) acquires, performs A / D conversion and linear calculation on the standard electrical signal, thereby obtaining the pressure data at the second pressure measuring point in real time.

9. A method of using the continuous water supply device for permeation testing as described in any one of claims 1-8, characterized in that, How to use Includes the following steps: The first step is to fill the test sample into the rigid wall permeameter according to the test plan, and to complete the compaction, saturation and sealing of the sample according to the test requirements. The second step is to assemble the continuous water supply device. Connect the air compressor (1), the first air inlet (1-1), the second air inlet (1-2), the water supply device control cabinet (3), the first water storage pressure tank (2-1), the second water storage pressure tank (2-6), and the permeation test device (4) in sequence, and check whether the air pipes, water pipes, PU hoses and electrical wiring connections are reliable. The third step is to perform equipment debugging before the experiment; specifically: Step 3.1: Turn on the load switch (3-16) to connect the power supply and start the water filling button on the touch screen; the PLC control module (3-2) first controls the opening of the water replenishment solenoid valve (3-7), and the water source enters the No. 1 water storage pressure tank (2-1) through the inlet valve (3-12), the B water pipe, the water replenishment solenoid valve (3-7) and the B1 water pipe to replenish the No. 1 water storage pressure tank (2-1); at this time, the original gas in the No. 1 water storage pressure tank (2-1) is discharged through the No. 1 tank air inlet (2-2), the air pipe and the SMC proportional valve (3-6); Step 3.2: During the water replenishment process of the No. 1 water storage pressure tank (2-1), a differential pressure sensor (3-8) collects the differential pressure signal in the No. 1 water storage pressure tank (2-1) in real time and transmits the differential pressure signal to the PLC control module (3-2). The PLC control module (3-2) calculates the liquid level in the No. 1 water storage pressure tank (2-1) based on the differential pressure signal. When the liquid level in the No. 1 water storage pressure tank (2-1) reaches the predetermined height, the PLC control module (3-2) controls the solenoid valve (3-7) of the first water replenishment path to close, and simultaneously opens the solenoid valves (3-20) of the second water replenishment path and the first... The water supply solenoid valve (3-15) is activated. At this time, the PLC control module (3-2) controls the water source to replenish water into the No. 2 water storage pressure tank (2-6) on the one hand, and controls the SMC proportional valve (3-6) to adjust the air pressure in the No. 1 water storage pressure tank (2-1) through the first air intake channel (1-1), so that the No. 1 water storage pressure tank (2-1) outputs the permeation water flow required for the test. After the No. 2 water storage pressure tank (2-6) is replenished with water, the PLC control module (3-2) controls the second water supply solenoid valve (3-20) to close, so that the No. 2 water storage pressure tank (2-6) is filled with water and put into standby mode. The fourth step is to perform exhaust and test connections; Step 4.1: Set the exhaust pressure value, connect the outlet valve (3-13) to the water pipe, open the outlet valve (3-13) to allow the water in the continuous water supply device to flow out slowly and expel the residual air; when no more bubbles are observed flowing out, connect the outlet valve (3-13) to the inlet valve (4-1) of the permeation test device (4); Step 4.2: Set both the set flow rate and set pressure to 0, and open the inlet valve (4-1) of the permeation test device (4); connect the high-precision pressure transmitter (3-9) of the first pressure measuring point to the first measuring point (4-3), and connect the high-precision pressure transmitter (3-10) of the second pressure measuring point to the second measuring point (4-2) to obtain the water pressure of the test sample at the first measuring point (4-3) and the second measuring point (4-2) respectively; The fifth step is to control the osmotic pressure and calculate the osmotic parameters; Step 5.1: Use the osmotic pressure difference as the control target, and calculate the required hydraulic gradient value using the osmotic pressure difference; assume the pressure value collected by the high-precision pressure transmitter (3-9) at the first pressure measuring point is... The pressure value collected by the high-precision pressure transmitter (3-10) at the second pressure measuring point is... The height difference between the first measuring point (4-3) and the second measuring point (4-2) is The density of water is Then the osmotic pressure difference for and The absolute value of the difference is used to obtain the formula for calculating the hydraulic gradient, as shown below: in, The target hydraulic gradient; Step 5.2: During the test, the PLC control module (3-2) controls one SMC proportional valve (3-6) to slowly open or close, so that the air compressor (1) outputs air pressure to the No. 1 water storage pressure tank (2-1) through the first air inlet (1-1), driving the water in the No. 1 water storage pressure tank (2-1) into the permeation test device (4); when the absolute value of the pressure difference between the high-precision pressure transmitter (3-9) at the first pressure measuring point and the high-precision pressure transmitter (3-10) at the second pressure measuring point reaches the set target permeation pressure difference, or when the flow rate value collected by the electromagnetic flowmeter (3-11) reaches the set target flow rate value, the real-time water supply flow rate collected by the electromagnetic flowmeter (3-11) at this time is recorded. Let the radius of the test sample be... Then the permeation velocity Calculate using the following formula: The permeability coefficient of the tested sample is thus obtained. The calculation formula is as follows: Step 6: Implement alternating water supply and automatic water replenishment control between the two water storage pressure tanks; the PLC control module (3-2) is pre-set with target lower limits for liquid level corresponding to one differential pressure sensor (3-8) and two differential pressure sensors (3-21), including a first target lower limit and a second target lower limit, wherein the first target lower limit is higher than the second target lower limit; the first target lower limit is used to trigger the air pressure pre-balancing control of the backup water storage pressure tank, and the second target lower limit is used to trigger the water supply switching control of the water supply pressure tank; The seventh step is to repeat the water replenishment, air release, pressure regulation, water supply and switching processes in steps three to six, or repeat the osmotic pressure control, flow acquisition, osmotic parameter calculation and alternating water supply process in steps five to six after the test officially begins, so as to achieve long-term continuous and stable water supply in laboratory osmosis tests.

10. The method of using the continuous water supply device for permeation testing according to claim 9, characterized in that, In the aforementioned usage method: In step 4.1, the exhaust pressure value is 5% to 10% of the target osmotic pressure of the formal test; In the sixth step: The lower limit of the first target is 3.4~3.6cm, and the lower limit of the second target is 2.7~2.9cm. When the No. 1 water storage pressure tank (2-1) is in water supply mode, and the differential pressure sensor (3-8) detects that the liquid level in the No. 1 water storage pressure tank (2-1) has dropped to the first target lower limit, the PLC control module (3-2) opens the second SMC proportional valve (3-19) and adjusts the output air pressure of the second SMC proportional valve (3-19) so that the air pressure at the top of the No. 2 water storage pressure tank (2-6) is equal to the air pressure at the top of the No. 1 water storage pressure tank (2-1); When the liquid level in the No. 1 water pressure tank (2-1) continues to drop to the second target lower limit, the PLC control module (3-2) controls the closure of one water supply solenoid valve (3-15) and one SMC proportional valve (3-6), while opening the second water supply solenoid valve (3-22) and one water replenishment solenoid valve (3-7). At this time, water is replenished to the No. 1 water pressure tank (2-1) through the first water replenishment solenoid valve (3-7), and the No. 2 water pressure tank (2-6) outputs the required permeation water flow under the pressure regulation of the two SMC proportional valves (3-19), thus completing the switch from water supply from the No. 1 water pressure tank (2-1) to water supply from the No. 2 water pressure tank (2-6). When the No. 2 water storage pressure tank (2-6) is in water supply mode, and the two differential pressure sensors (3-21) detect that the liquid level in the No. 2 water storage pressure tank (2-6) has dropped to the first target lower limit, the PLC control module (3-2) opens one SMC proportional valve (3-6) and adjusts the output air pressure of the other SMC proportional valve (3-6) to make the air pressure at the top of the No. 1 water storage pressure tank (2-1) equal to the air pressure at the top of the No. 2 water storage pressure tank (2-6); when the liquid level in the No. 2 water storage pressure tank (2-6) continues to drop to the second target lower limit, the PLC control module (3-2) activates the second target lower limit. The control module (3-2) controls the closure of the two-way water supply solenoid valve (3-22) and the two-way SMC proportional valve (3-19), while simultaneously opening the one-way water supply solenoid valve (3-15) and the two-way water replenishment solenoid valve (3-20). At this time, the water source replenishes water to the No. 2 water storage pressure tank (2-6) through the two-way water replenishment solenoid valve (3-20). The No. 1 water storage pressure tank (2-1) outputs the permeation water flow required for the test under the pressure regulation action of the one-way SMC proportional valve (3-6), completing the switch from water supply from the No. 2 water storage pressure tank (2-6) to water supply from the No. 1 water storage pressure tank (2-1).

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