Micro-variable negative pressure injection - intelligent field in-situ double-ring infiltration equipment with dual water supply control

Abstract

The invention relates to the technical field of hydrogeological parameter measuring equipment, and discloses an intelligent field in-situ double-ring infiltration equipment with double control of micro-variable negative pressure injection and water supply. The invention combines a vacuum pressure sensor with an electromagnetic valve, controls the micro-change of vacuum negative pressure caused by the change of liquid level height in an "inverted" Martens flask, and controls the "air suction-water supply" process and the "no air suction-water injection" process respectively, and uniformly sets the liquid level heights of the inner and outer rings to maintain a constant water head, so that the vacuum negative pressure can ensure the complete cycle of the test process over time. An automated, high-precision, intelligent double-ring infiltration instrument is realized, which can save labor and shorten the observation time to a certain extent, keep the water injection height stable and consistent to improve the observation accuracy, and can completely record the whole process of infiltration rate change including initial infiltration, so as to obtain an accurate soil infiltration rate and grasp the infiltration characteristics of the soil.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogeological parameter measuring equipment, and specifically to an intelligent field in-situ double-ring infiltration equipment with micro-variable negative pressure injection and water supply dual control. Background Art

[0002] Soil infiltration performance determines the amount of surface water, soil water and groundwater resources, and is an important factor affecting the distribution of surface water, soil water and groundwater resources. Infiltration refers to the infiltration of surface water into the underground soil layer. It is the process of natural water cycle redistribution into surface runoff, soil water in the vadose zone and groundwater under rainfall conditions. After rainfall or irrigation water reaches the surface, the part that enters the soil is converted into soil water, and the amount converted into soil water is determined by the soil infiltration performance.

[0003] Therefore, soil infiltration performance is related to the amount of water stored in the soil, which in turn affects the types of surface vegetation and its growth conditions, plant diversity and coverage, etc. In the loess hilly gully area where soil erosion is serious, soil infiltration performance is closely related to soil erosion, and it is a key area for studying surface runoff and soil erosion.

[0004] Rainwater resources are the most important water resources in the Loess Plateau. Fully and effectively utilizing natural precipitation, reducing surface runoff, and increasing soil moisture are the keys to vegetation restoration and reconstruction. Many experts and scholars have proposed "intercepting and storing all precipitation locally" as a strategic decision to control soil erosion and achieve agricultural production in the Loess Plateau, but it has not yet been applied and promoted.

[0005] On the one hand, although the effects of soil physical properties on soil infiltration have been quantified, there is a lack of mechanistic research on the effects of soil chemical properties on infiltration characteristics;

[0006] On the other hand, soil infiltration test methods are somewhat different from the actual situation, and no quantitative rules have been summarized. This makes it very difficult to accurately obtain and describe the infiltration process, and the infiltration test needs to be further designed.

[0007] Specifically, among the many field in-situ test methods for saturated soil infiltration coefficient, the most widely used in-situ test technology for saturated surface soil infiltration coefficient is double-ring infiltration, which is mandatory in the regulations. However, the double-ring infiltration devices currently used have many technical defects and inconveniences in application, such as limited application range of the test range during in-situ testing, unstable test accuracy, and long-term manual operation during the test process, which is time-consuming and labor-intensive. Therefore, the research on the measurement effect and improved device of the ring infiltration instrument is of great significance for improving the measurement accuracy of soil infiltration performance, simplifying the measurement process, and improving the measurement efficiency, and for conducting basic research related to soil infiltration and preferential flow.

[0008] For the field in-situ double ring infiltration test, it is very important to reduce the labor intensity during the measurement process, and it is very valuable to study the automation of the double ring infiltration instrument measurement process. The traditional double ring penetration method not only has poor test accuracy, but also consumes a lot of manpower.

[0009] The stabilization time of a single set of double-ring infiltration in-situ test experiments is different for different media, such as about 2 hours for sand, about 4 hours for sub-clay, and more than 8 hours for clay with a slightly worse permeability coefficient. The specification requires at least 5 discrete points to determine whether the permeability coefficient test is stable, and continuous observation for more than 2 hours is required after stabilization. It shows that the test time often exceeds 6 hours to complete a set of qualified test data using the double-ring infiltration method as required, and the entire test process requires technicians to take turns on duty, and they have to pay attention to the test process for a long time without interruption and take manual readings in a timely manner, which has caused great consumption of manpower and material resources and unnecessary safety hazards.

[0010] It may take several hours or even days to obtain a reliable saturated hydraulic conductivity measurement. It is worth noting that when conducting in-situ tests in the field, technicians consider operability and field operation safety. If the entire test process exceeds 10 hours, or the waiting time between two discrete data points in the Malchow flask exceeds 1 hour, it is considered that the double-ring infiltration method is not suitable for this location.

[0011] In terms of operability and equipment accuracy, technicians have continuously developed and improved the application of traditional double-ring infiltration in-situ testing technology. The existing technology mainly focuses on solving two major problems: inner ring water supply equipment, double ring size and installation method. The former is the main contradiction, including data reading errors, inconvenience in carrying, low measurement accuracy and low degree of automation.

[0012] As the research progresses, the digital display Malpighia flask is further developed towards an integrated type, and an integrated structure of inner and outer Malpighia flasks is designed; the vacuum pressure sensor monitoring negative pressure technology is further promoted and applied, because it and automated data acquisition can greatly improve the accuracy of the double-ring infiltration test, and the calibration value error is only 0.102%.

[0013] However, the automated double-loop infiltration test process under the complete cycle of injection-water supply process based on this has not been mentioned, and there are still many problems to be solved:

[0014] 1) During the field in-situ test, the water supply volume of the Martens flask is limited. When the communicating vessel principle is used to maintain a constant water head to control the height of the water surface in the ring, the water injection operation during the test will cause the pressure value in the flask to change (i.e., the water level band), resulting in human test errors and inconvenience in starting the automated water injection process;

[0015] 2) It cannot ensure that the water injection process does not affect the set water supply process, cannot guarantee the test accuracy during the injection-water supply process, and cannot shorten the observation time;

[0016] 3) It is impossible to realize the automation and intelligent testing process of injection-water supply cycle;

[0017] 4) It cannot reflect the difference in infiltration performance of different soil types on the injection-water supply process cycle.

[0018] Therefore, we need to propose an intelligent field in-situ double-ring infiltration equipment with micro-variable negative pressure injection and water supply dual control to quickly and accurately obtain the soil infiltration rate and master the infiltration characteristics of the soil. Summary of the invention

[0019] The purpose of the present invention is to provide an intelligent field in-situ double-ring infiltration equipment with dual control of micro-variable negative pressure injection and water supply. The vacuum pressure sensor is combined with a solenoid valve to control the slight changes in the vacuum negative pressure caused by the change in the liquid level height in the "inverted" Martens flask, so as to respectively control the "inhalation-water supply" process and the "no-inhalation-water injection" process, and uniformly set the liquid level heights of the inner and outer rings to maintain a constant water head. The vacuum negative pressure ensures that the test process is fully cycled over time, and an automated, high-precision, intelligent double-ring infiltration instrument is realized. While saving labor, the observation time can be shortened to a certain extent, the water injection height can be kept stable and consistent to improve the observation accuracy, and the entire process of the infiltration rate change including the initial infiltration can be completely recorded to obtain an accurate soil infiltration rate and grasp the infiltration characteristics of the soil, so as to solve the problems raised in the above-mentioned background technology.

[0020] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a smart field in-situ double-ring infiltration device with micro-variable negative pressure injection and water supply dual control, comprising an inner ring and an outer ring with the bottom inserted into the ground soil, a water storage bucket, two Malchnitz flasks and a buffer water tank installed above the inner ring and the outer ring through an iron frame of a water supply system, wherein the two Malchnitz flasks are respectively: a rectangular Malchnitz flask for supplying water to the inner ring and a circular Malchnitz flask for supplying water to the outer ring, and a water pump is arranged inside the water storage bucket;

[0021] A water injection solenoid valve is installed on the top water injection port of the rectangular Malchnitz flask, a water supply solenoid valve is installed on the bottom water supply port of the rectangular Malchnitz flask, and a vacuum pressure sensor for testing the vacuum pressure inside the rectangular Malchnitz flask is also installed on the top of the rectangular Malchnitz flask;

[0022] The buffer water tank is connected to the water storage bucket and the water filling port of the rectangular Malchnitz flask respectively. A water supply pipe is connected between the water supply port and the inner ring of the rectangular Malchnitz flask and between the water supply port and the outer ring of the circular Malchnitz flask. An air inlet pipe is connected between the interior of the rectangular Malchnitz flask and the inner ring and between the interior of the circular Malchnitz flask and the outer ring.

[0023] Preferably, it also includes a DC solar panel and a human-machine interface, the DC solar panel is electrically connected to the vacuum pressure sensor, the water injection solenoid valve, the water supply solenoid valve, and the water pump, respectively, the human-machine interface is electrically connected to the vacuum pressure sensor, and the vacuum pressure sensor is electrically connected to the water injection solenoid valve and the water supply solenoid valve, respectively.

[0024] Preferably, the height of the inner ring and the outer ring are both 25 cm, the bottom of the inner ring and the outer ring are both inserted into the ground soil by 15 cm, the height of the inner ring and the outer ring above the ground is 10 cm, and the outer walls of the inner ring and the outer ring are provided with scales at positions 7 cm and 10 cm away from the top of the ring, which are used to record the water level change process of the inner ring and ensure that the water levels of the inner and outer rings are equal.

[0025] Preferably, the bottom of the inner ring and the bottom of the space between the inner ring and the outer ring are provided with cardboard to prevent damage to the surface soil structure caused by directly adding water to the surface.

[0026] Preferably, the distance between the bottom of the rectangular Malchnitz flask and the bottom of the circular Malchnitz flask and the ground is 15 cm, and the distance between the bottom of the buffer water tank and the ground is 115 cm.

[0027] Preferably, a float valve for releasing the pressure of a water pump is provided inside the buffer water tank, and the float valve is connected to the water pump.

[0028] Preferably, the uniform height of the liquid levels of the inner ring and the outer ring is set to 3 cm, and the distance between the bottom of the air inlet pipe and the ground is also 3 cm.

[0029] Preferably, a cover plate for preventing water evaporation is installed on the top of the inner ring and the outer ring, the bottoms of the two air intake pipes pass through the cover plate and are respectively located inside the inner ring and the outer ring, and the bottoms of the two water supply pipes also pass through the cover plate and are respectively located inside the inner ring and the outer ring.

[0030] Preferably, the DC solar panel is used to provide DC power with a voltage of 24V and a current of 100A to the vacuum pressure sensor, the water injection solenoid valve, the water supply solenoid valve, and the water pump. The capacity of the buffer water tank is 2-5L, the capacity of the water storage barrel is 200L, the range of the vacuum pressure sensor is -10 to 10kpa, and the measurement accuracy of the vacuum pressure sensor is 0.5%.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention combines a vacuum pressure sensor with an electromagnetic valve, controls the slight changes in vacuum negative pressure caused by the change in the liquid level height in the "inverted" Martens flask to respectively control the "inhalation-water supply" process and the "no-inhalation-water injection" process, and uniformly sets the inner and outer ring liquid level heights to maintain a constant water head. The vacuum negative pressure ensures that the test process is fully cycled over time, and an automated, high-precision, intelligent double-ring infiltrator is realized. While saving labor, the observation time can be shortened to a certain extent, the water injection height can be kept stable and consistent to improve the observation accuracy, and the entire process of infiltration rate change including the initial infiltration can be completely recorded to obtain an accurate soil infiltration rate and grasp the infiltration characteristics of the soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the present invention;

[0034] Figure 2 This is a diagram of indoor verification results of the alternate cycle of water injection process and water supply process of the present invention;

[0035] Figure 3 This is a schematic diagram of the water supply process in a Malchow flask of the present invention;

[0036] Figure 4 This is a schematic diagram of the water filling process in a Malchow flask of the present invention;

[0037] Figure 5 A schematic diagram of the interface for developing an in-situ test system for soil saturated infiltration coefficient according to the present invention;

[0038] Figure 6 The present invention is an automatic water supply and control system software design flow chart. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] See also Figure 1-6 The present invention provides a technical solution: a smart field in-situ double-ring infiltration equipment with dual control of injection and water supply under slightly variable negative pressure. The soil double-ring infiltration equipment is configured with an automatic integrated device with dual control of injection and water supply. A mode combining a vacuum pressure sensor and an electromagnetic valve is used to control the "inhalation-water supply" process and the "non-inhalation-water injection" process. While saving labor, the observation time can be shortened to a certain extent, and the high stability and consistency of water injection can be maintained to improve the observation accuracy. The whole process of infiltration rate change including initial infiltration can be completely recorded to obtain an accurate soil infiltration rate and grasp the infiltration characteristics of the soil.

[0041] The device includes an inner ring and an outer ring whose bottoms are inserted into the ground soil, a water storage bucket, two Martens flasks and a buffer water tank installed above the inner ring and the outer ring through an iron frame of a water supply system. The bottoms of the inner ring and the outer ring are horizontally inserted into the soil. To ensure the stability of the inner ring and the outer ring, an iron block connector is also provided in the space between the inner ring and the outer ring to connect the inner ring and the outer ring, and the iron block connector is 15 cm away from the bottom of the inner ring and the outer ring.

[0042] The two Martens flasks are respectively a rectangular Martens flask for supplying water to the inner ring and a circular Martens flask for supplying water to the outer ring. A water pump is arranged inside the water storage barrel; the water pump is used to inject water into the buffer water tank.

[0043] During the in-situ test, it takes a long time for the soil to reach stable infiltration. Generally, the infiltration measurement time needs to last for 90 to 100 minutes. When there is insufficient water in the buffer water tank, water needs to be pumped in to replenish the water level in the Malchow flask.

[0044] A water injection solenoid valve is installed on the top water injection port of the rectangular Malchnitz flask, a water supply solenoid valve is installed on the bottom water supply port of the rectangular Malchnitz flask, and a vacuum pressure sensor for testing the vacuum pressure inside the rectangular Malchnitz flask is also installed on the top of the rectangular Malchnitz flask;

[0045] The vacuum pressure sensor is used in conjunction with the human-machine interface to replace manual reading to complete data collection and storage and form a process curve; the vacuum pressure sensor is used in conjunction with the solenoid valve; the function of adding a buffer water tank is to regulate the water injection and water supply process, and form a complete injection-water supply automatic cycle process under slightly negative pressure.

[0046] The buffer water tank is connected to the water storage bucket and the water filling port of the rectangular Malchnitz flask respectively. A water supply pipe is connected between the water supply port and the inner ring of the rectangular Malchnitz flask and between the water supply port and the outer ring of the circular Malchnitz flask. An air inlet pipe is connected between the interior of the rectangular Malchnitz flask and the inner ring and between the interior of the circular Malchnitz flask and the outer ring.

[0047] It also includes a DC solar panel and a human-machine interface. The DC solar panel is electrically connected to a vacuum pressure sensor, a water injection solenoid valve, a water supply solenoid valve, and a water pump, respectively. The human-machine interface is electrically connected to the vacuum pressure sensor, and the vacuum pressure sensor is electrically connected to the water injection solenoid valve and the water supply solenoid valve, respectively.

[0048] The parameters of the above structural equipment are shown in Table 1:

[0049] Table 1: Main structural parameters of infiltration equipment

[0050]

[0051] The height of the inner ring and the outer ring are both 25 cm, the bottom of the inner ring and the outer ring are both inserted into the ground soil by 15 cm, the height of the inner ring and the outer ring above the ground is 10 cm, and the outer walls of the inner ring and the outer ring are provided with scales at the positions 7 cm and 10 cm away from the top of the ring, which are used to record the water level change process of the inner ring and ensure that the water levels of the inner and outer rings are equal.

[0052] The bottom of the inner ring and the bottom of the space between the inner ring and the outer ring are both provided with cardboard to prevent the damage to the surface soil structure caused by directly adding water to the surface.

[0053] The distance between the bottom of the rectangular Malchnitz flask and the bottom of the round Malchnitz flask and the ground is 15 cm, and the distance between the bottom of the buffer water tank and the ground is 115 cm, that is, the distance between the bottom of the buffer water tank and the bottom of the Malchnitz flask is 100 cm.

[0054] A float valve for releasing the pressure of a water pump is arranged inside the buffer water tank, and the float valve is connected to the water pump.

[0055] The uniform height of the liquid levels of the inner ring and the outer ring is set to 3 cm, and the distance between the bottom of the air inlet pipe and the ground is also 3 cm.

[0056] A layer of gravel is laid on the ground. The thickness of the gravel layer is 3cm and the particle size of the gravel is 3-5cm.

[0057] Cover plates are installed on the top of the inner ring and the outer ring to prevent water evaporation. The bottoms of the two air intake pipes pass through the cover plates and are respectively located inside the inner ring and the outer ring. The bottoms of the two water supply pipes also pass through the cover plates and are respectively located inside the inner ring and the outer ring.

[0058] The bottom of the water supply pipe is located inside the gravel layer, and the bottom of the air intake pipe is in contact with the surface of the gravel layer.

[0059] The DC solar panel is used to provide DC power with a voltage of 24V and a current of 100A to the vacuum pressure sensor, water injection solenoid valve, water supply solenoid valve, and water pump. The capacity of the buffer water tank is 2-5L, the capacity of the water storage barrel is 200L, the measuring range of the vacuum pressure sensor is -10 to 10kpa, and the measurement accuracy of the vacuum pressure sensor is 0.5%.

[0060] When using this device:

[0061] According to the pressure value output by the vacuum sensor that changes with time, the test process is divided into two state processes: "unbalanced state" and "balanced state", namely the water injection process and the water supply process, which are alternately cycled to realize the automated double-loop infiltration field in-situ overall test process.

[0062] During the water supply process, the water supply system intermittently inhales air through the air intake pipe and is connected to the atmosphere (0.00kpa). The pressure value drops sharply from the atmospheric pressure and then slowly decreases at a relatively stable slope, which corresponds to the slow water supply process after the Malvern flask inhales and balances. A water supply process lasts for about 25 to 30 seconds before it can be stabilized. The water injection process occurs during the period when the water supply system presents a stable negative pressure state and the time between the next inhalation and the return to the atmospheric pressure value.

[0063] The water injection condition is that the negative pressure is between -2.50 and -3.03 kPa, and the water injection starts after the reading is stable for 3 to 5 seconds. The duration is 30 seconds (it can be adjusted according to different regions. The water addition time can be reduced in areas with fast infiltration rates). Then the water injection is turned off, and a stabilization time of 6 to 10 seconds is required after the water addition is completed. See Table 2 for details.

[0064] A complete injection-water supply process includes the above two processes. As the wetting front gradually moves to the depth of the vadose zone during the process of soil water infiltration, there are slightly different responses in the duration and linear relationship between the pressure curve cycles. After water injection, the curve slowly decreases linearly to a stable negative pressure. The slope of the stable negative pressure after water injection and after ventilation is converted into the water supply rate (see Figure 2 ).

[0065] When the soil infiltration process reaches a one-dimensional stable seepage, the cyclic shape of the curve remains basically the same. When the corresponding slope value remains unchanged, the stable slope value can be converted into the saturated infiltration coefficient value of the corresponding target measurement. Therefore, when the slope value of the curve gradually converges to the same value (consistent for 3 consecutive times, keeping 5 decimal places), it means that the infiltration process gradually reaches equilibrium and stability, that is, the test is stopped, and the average of the last three infiltration rates is taken as the stable soil infiltration rate.

[0066] Table 2 Vacuum pressure sensor combined with solenoid valve control Note - Water supply process setting conditions

[0067]

[0068] The solenoid valve is a normally closed DC24V from Chint, with a coil power of 14W, a pipe diameter of 9.5mm, and is powered by a 24V solar cell. The solenoid valve is installed at the water inlet (solenoid valve a) and water supply port (solenoid valve b) of the inner ring water supply Martens flask according to the direction of water flow. Solenoid valve a is the water injection solenoid valve, and solenoid valve b is the water supply solenoid valve, that is, the water injection solenoid valve is installed at the water inlet of the rectangular Martens flask, and the water supply solenoid valve is installed at the water supply port of the rectangular Martens flask.

[0069] A. "Inhalation-water supply" process: When the equilibrium state is reached (see Figure 3), at this time, there is F0=F1+F2 in the Martens flask; among them, F0 is the pressure of the atmosphere on the water level in the ring; F1 is the pressure of the gas in the closed container on the liquid level in the container; F2 is the pressure of the liquid in the closed container on the water level in the ring. As the water level in the ring continues to drop below the bottom of the air inlet pipe (water level in the ring 2), the "inhalation-water supply" process will occur, and the water supply is (Πr 2 ×h'Π is the radius of the ring, which is known), until the water level in the ring returns to 1, the circulation process stops and returns to the equilibrium state.

[0070] B. "No air suction - water filling" process: If the water in the Martens flask is insufficient (take the Martens flask liquid level 2 as an example), during the water filling process, we add water to the dotted line position indicated by F3, that is, to the Martens flask liquid level 1, the height is h, see Figure 4 .

[0071] (1) According to the ideal gas state equation pV=nRT (p represents gas pressure, V is gas volume, n represents the amount of gas substance, R represents the gas constant, and T represents temperature), we know that when the temperature is constant, the pressure of a certain mass of gas increases as the volume decreases. According to p=F / S, F represents the pressure value and S represents the constant bottom area, we know that F3 must be greater than F1.

[0072] (2) According to F4=F2+ρgΔh×S, we can know that F4 must be greater than F2.

[0073] (3) Therefore, at this time, F3+F4>F0 cannot reach a balanced state. In other words, if the water in the container still flows out during the water filling process, it will not only affect the water supply process (which needs to occur in a balanced state), but also make it impossible to accurately measure the amount of water added. Therefore, during the water filling process, the solenoid valve at the water supply end must be closed.

[0074] Therefore, during the development of this equipment, the solenoid valve control of the injection-water supply process is as follows: after the "air suction-water supply" process, the water supply solenoid valve is closed first, and then the water injection solenoid valve is immediately opened to inject water and start the water injection process; and before the next "air suction-water supply" process begins, the water injection solenoid valve is closed and the water supply solenoid valve is opened. In this way, a complete one-time injection-water supply automation process is formed.

[0075] C. Calculation of water volume: Taking the inner ring diameter of 40cm as an example, in order to meet the experimental requirements, we need to ensure that the water volume in the container is sufficient for at least one complete filling-water supply process.

[0076] If the volume of the Martens flask is 15cm long, 4cm wide and 80cm high. Set the water level in the Martens flask to 75cm at the beginning. After completing a "inhalation-water supply" process, the vacuum negative pressure increases (the absolute value decreases) and starts to fill water 2s after it stabilizes, and the filling process ends 3s before the next inhalation, that is, the filling time is (T1-5s). Assuming that the water injection volume is Q, the interval from closing the water supply solenoid valve and opening the water injection solenoid valve to closing the water injection solenoid valve and opening the water supply solenoid valve is T1. And assume that the converted height of each water supply is h'cm, that is, the water supply each time is 1256×h'cm³. Assume that the experiment requires 70 cycles and there is still a 5cm liquid height in the container after the last water supply, then the following conditions must be met:

[0077] [1256×h'-Q×(T1-5s)] / 15×4=(75-5) / 70, so Q=(1256×h'-60) / (T1-5s)];

[0078] Note: h' in this formula is a fixed value for the same ring. It changes dynamically around a constant head (the height of the liquid level in the ring), and requires field in-situ test verification. And T1 will increase with the infiltration process, so Q calculated using T1 is the maximum water injection volume that can meet the requirements.

[0079] Development of an in-situ test system for soil saturated infiltration coefficient:

[0080] The signal collected by the pressure sensor is converted and output on the human-machine interface through data acquisition, and the curve is automatically output on the computer. The pressure sensor signal is output to the data acquisition card, and the pressure change curve over time is displayed on the human-machine interface (see Figure 2 ). The data acquisition frequency of the equipment in this study is set to once per second. The development interface of the soil saturated infiltration coefficient in-situ test system (see Figure 5 ) It can perform four operation options: manual water filling, manual water filling stop, experiment start and experiment stop, and parameters can also be set on the human-machine interface.

[0081] The software design flow chart of the intelligent double-ring infiltration equipment with micro-variable negative pressure injection and water supply dual control is as follows Figure 6 The process is as follows: turn on the power and perform initialization operations, then the software automatically closes the water inlet valve, water outlet valve and water pump, clicks manual water injection on the human-machine interface, and after the water injection is completed, clicks the experiment start on the human-machine interface to obtain the pressure sensor value, and automatically draws a graph of pressure changes over time, and performs threshold judgment when reading data.

[0082] When the pressure value remains stable at -3.2kpa~-1.9kpa for five consecutive seconds, start the water pump, close the water inlet valve, and open the water outlet valve. Fill the Marriott bottle with water for 30 seconds. When the water filling is completed, turn off the water pump, close the water outlet valve, and open the water inlet valve. Continue to record the pressure sensor value. Repeat this cycle until the pressure change rate of the recorded stable pressure value for five consecutive seconds is equal for five consecutive times, and the test is over.

[0083] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Intelligent field in-situ double-ring infiltration equipment with micro-variable negative pressure injection and water supply dual control, characterized by: It includes an inner ring and an outer ring with the bottom inserted into the ground soil, a water storage bucket, two Malchnitz flasks installed above the inner ring and the outer ring through a water supply system iron frame, and a buffer water tank. The two Malchnitz flasks are respectively: a rectangular Malchnitz flask for supplying water to the inner ring and a circular Malchnitz flask for supplying water to the outer ring. A water pump is arranged inside the water storage bucket. A water injection solenoid valve is installed on the top water injection port of the rectangular Malchnitz flask, a water supply solenoid valve is installed on the bottom water supply port of the rectangular Malchnitz flask, and a vacuum pressure sensor for testing the vacuum pressure inside the rectangular Malchnitz flask is also installed on the top of the rectangular Malchnitz flask; The buffer water tank is connected to the water storage bucket and the water inlet of the rectangular Malchnitz flask respectively. A water supply pipe is connected between the water supply port and the inner ring of the rectangular Malchnitz flask and between the water supply port and the outer ring of the circular Malchnitz flask. An air inlet pipe is connected between the interior of the rectangular Malchnitz flask and the inner ring and between the interior of the circular Malchnitz flask and the outer ring. It also includes a DC solar panel and a human-machine interface. The DC solar panel is electrically connected to a vacuum pressure sensor, a water injection solenoid valve, a water supply solenoid valve, and a water pump, respectively. The human-machine interface is electrically connected to the vacuum pressure sensor, and the vacuum pressure sensor is electrically connected to the water injection solenoid valve and the water supply solenoid valve, respectively. The vacuum pressure sensor is used in conjunction with the human-machine interface to complete data acquisition and storage and form a process curve. The vacuum pressure sensor is used in conjunction with the solenoid valve. A complete injection-water supply automation cycle process is formed under a slightly negative pressure. The solenoid valve control of the injection-water supply process is as follows: after the "inhalation-water supply" process, the water supply solenoid valve is first closed, and then the water injection solenoid valve is immediately opened to inject water and start the water injection process; and before the next "inhalation-water supply" process begins, the water injection solenoid valve is closed and the water supply solenoid valve is opened, thereby forming a complete injection-water supply automation process.

2. According to claim 1, the intelligent field in-situ double-ring infiltration equipment with micro-variable negative pressure injection and water supply dual control is characterized by: The height of the inner ring and the outer ring are both 25 cm, the bottom of the inner ring and the outer ring are both inserted into the ground soil by 15 cm, the height of the inner ring and the outer ring above the ground is 10 cm, and the outer wall of the inner ring and the outer wall of the outer ring are both provided with scales at 7 cm and 10 cm above and below the top of the ring, which are used to record the water level change process of the inner ring and ensure that the water levels of the inner and outer rings are equal.

3. The intelligent field in-situ double-ring infiltration equipment with micro-variable negative pressure injection and water supply dual control according to claim 1 is characterized by: The bottom of the inner ring and the bottom of the space between the inner ring and the outer ring are both provided with cardboard to prevent the damage to the surface soil structure caused by directly adding water to the surface.

4. The intelligent field in-situ double-ring infiltration equipment with micro-variable negative pressure injection and water supply dual control according to claim 1 is characterized by: The distance between the bottom of the rectangular Malchnitz flask and the bottom of the circular Malchnitz flask and the ground is 15 cm, and the distance between the bottom of the buffer water tank and the ground is 115 cm.

5. According to claim 1, the intelligent field in-situ double-ring infiltration equipment with micro-variable negative pressure injection and water supply dual control is characterized by: A float valve for releasing the pressure of a water pump is arranged inside the buffer water tank, and the float valve is connected to the water pump.

6. The intelligent field in-situ double-ring infiltration equipment with micro-variable negative pressure injection and water supply dual control according to claim 1 is characterized by: The uniform height of the liquid levels of the inner ring and the outer ring is set to 3 cm, and the distance between the bottom of the air inlet pipe and the ground is also 3 cm.

7. The intelligent field in-situ double-ring infiltration equipment with micro-variable negative pressure injection and water supply dual control according to claim 1 is characterized by: Cover plates are installed on the top of the inner ring and the outer ring to prevent water evaporation. The bottoms of the two air intake pipes pass through the cover plates and are respectively located inside the inner ring and the outer ring. The bottoms of the two water supply pipes also pass through the cover plates and are respectively located inside the inner ring and the outer ring.

8. The intelligent field in-situ double-loop infiltration equipment with micro-variable negative pressure injection and water supply dual control according to claim 2 is characterized by: The DC solar panel is used to provide DC power with a voltage of 24V and a current of 100A to the vacuum pressure sensor, water injection solenoid valve, water supply solenoid valve, and water pump. The capacity of the buffer water tank is 2-5L, the capacity of the water storage barrel is 200L, the measuring range of the vacuum pressure sensor is -10 to 10kpa, and the measurement accuracy of the vacuum pressure sensor is 0.5%.

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