A soil gas component monitoring sampling device and a monitoring sampling method

Abstract

The application provides a soil gas component monitoring and sampling device and a monitoring and sampling method.The monitoring and sampling device comprises a sampling pipe, an injection pipe, a differential pressure measuring device, a vacuum pump, a constant-volume container, a monitoring container and a gas sensor.The lower part of the monitoring container is inserted into soil, a water-permeable membrane is arranged at a position close to the bottom in the monitoring container, and a water inlet porous section is arranged on the side wall.The application can obtain underground fluid samples in a monitoring area through multiple points, realize matrix type large area monitoring, quickly understand the information of abnormal point positions in the soil through the cooperation of sample data and the gas sensor, combine multi-point sample mixing sampling and single-point sampling, and monitor the change conditions of the components and gas content in the soil gas in detail.The application can adjust the shallow underground soil environment and atmosphere in the monitoring area through the injection of modified gas.The application can realize normal monitoring in a waterlogged environment through the arrangement of the water-permeable device and the water inlet porous section.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil monitoring, and particularly relates to a soil gas component monitoring and sampling device and a monitoring and sampling method. BACKGROUND

[0002] There are Rn, He, O2, N2, H2, CO2, NH3, CH4, N2O and other gases in the soil, and the main components of the soil gas are significantly different under different soil environments, and understanding the component proportion of each substance in the soil gas has a significant effect on the study of the soil environment. The increase of the concentration of greenhouse gases in the atmosphere is the main factor leading to global warming, and CO2, NH4 and N2O in the atmosphere are the main gases causing the greenhouse effect or global warming. Monitoring the content of CO2, CH4, N2O and other gases in the soil environment, and finding out the source and sink and migration path of the gases can be effectively applied to the field of environmental monitoring. The gases such as CO2, H2, CH4, He and Rn with deep source information are present in each layer of the earth, and the gases in the deep part of the earth are most likely to escape upward in the crust-mantle activity. The stratum fracture zone is a good channel for the escape of various underground gases, and the change of the concentration of the gases can sensitively and objectively reflect the change of the fault activity, and monitoring the components of the above-mentioned gases can understand the movement of the underground fault, and can be used in the field of earthquake prediction and stratum research.

[0003] In order to alleviate the greenhouse effect and energy problems, humans have conducted a large number of studies and carried out CCS, CO2-EOR, CO2-ECBM and other CO2 geological storage field experiments. In order to verify the sealing effect of the above experiments, explore the changes of Rn, He, O2, N2, H2, CO2, NH3, CH4, N2O components in the underground soil environment and soil gas, whether it is to monitor the safety of CO2 and other sealing gas leakage along the fault or other geological survey work such as mine adjustment, earthquake monitoring, environmental monitoring, etc. The proportion of the above gases in the soil is quite different, the solubility of different gases in water is also different, and the accuracy of the monitoring method and monitoring instrument is also significantly different. The water content in the stratum and soil at different water levels will affect the monitoring of the above gas components. The water content, permeability, pH value, root system of plants and physiological metabolism of microorganisms in the underground soil will all affect the soil gas composition and emission. Changes in soil moisture will affect the aeration of the soil, and need to promote or hinder the diffusion of CO2 generated in the soil and CO2 leaked underground. With the increase of soil water content, the permeability of the soil will also decrease. Due to the water level in the waterlogged environment, ordinary monitoring instruments cannot be used, and the methods for monitoring the soil environment (such as pH, ORP), physical parameters (porosity, permeability coefficient) and soil gas content in the past usually collect samples on site for laboratory analysis, monitor the soil environment through laboratory data, or use expensive experimental instruments for on-site survey. It is difficult to monitor the changes of soil environment and gas composition in real time, and it is also difficult to large-scale multi-point sampling and monitoring. It is difficult to understand the changes of underground soil environment and soil gas in the monitoring area in detail in a timely manner, it is difficult to modify the shallow environment of the soil through the above method, and it is also difficult to monitor a large area in the shallow stratum, and it is difficult to obtain the comprehensive apparent parameters of the stratum (permeability coefficient, water level, etc.), the content and flow of each gas in the gas sample.

[0004] Therefore, the following technical difficulties need to be overcome at present: how to improve the monitoring efficiency of the changes of underground soil environment and soil gas composition, how to quickly and effectively monitor the apparent characteristics such as water level, permeability coefficient and water content of underground soil environment and the proportion of Rn, He, O2, N2, H2, CO2, NH3, CH4, N2O components in the stratum soil gas, how to overcome the influence of the waterlogged environment on the monitoring device, how to carry out multi-point and multi-parameter large-area monitoring of the shallow stratum environment and soil gas composition in the monitoring area, and understand the physical and chemical changes of the underground stratum through the monitored soil environment and soil gas composition, how to modify the soil atmosphere according to the monitoring data, etc. SUMMARY

[0005] The application aims to provide a soil gas component monitoring and sampling device and method, which can overcome the influence of waterlogging environment on the monitoring device, and can monitor the underground shallow stratum environment of a large area in multiple parameters, and understand the physical and chemical changes of the underground monitoring area by obtaining the stratum comprehensive apparent parameters (permeability coefficient k, water level, etc.), the proportion of each gas component and the gas flow.

[0006] The application provides a soil gas component monitoring and sampling device, which comprises a monitoring container and a sampling pipe.

[0007] One end of the sampling pipe is connected to the monitoring container, the other end of the sampling pipe is connected to a vacuum pump, and a differential pressure measuring device and a constant volume container are connected to the sampling pipe between the monitoring container and the vacuum pump.

[0008] The application can prevent the internal part of the monitoring and sampling device from being flooded when the water level is high, so as to affect the monitoring and sampling effect, and make the monitoring and sampling device normally monitor in the waterlogging environment. When the water level is normal, the water and gas in the soil slowly enter the monitoring container through the water inlet porous section and the water permeable membrane, until the sample environment in the monitoring container is consistent with the soil environment. When the water level is too high, the excess water enters the monitoring container through the water inlet porous section, and is discharged to the soil through the water permeable membrane at the bottom, so as to control the internal water level of the monitoring container.

[0009] The application can quickly understand the information of abnormal points in the soil by combining the sample data and the gas sensor, and can combine the multi-point sample mixing sampling and the single-point sampling, so as to monitor the change of the component and the gas content in the soil gas in detail.

[0010] In some embodiments, the water permeable device is a water permeable membrane. The water permeable membrane is a bidirectional water permeable membrane. The water permeable membrane is a hydrophilic material, and water can normally pass through the water permeable membrane.

[0011] In some embodiments, the water permeable membrane is installed in the monitoring container through a support, and the support is arranged below the water permeable membrane. The support can support the water permeable membrane, so that a certain space is left between the water permeable membrane and the soil, and the water permeable membrane is prevented from being punctured by sand and stone after being in contact with the soil.

[0012] In some embodiments, the material of the water inlet porous section is ceramic or metal. The water inlet porous section is fixedly embedded in the side wall of the monitoring container. Further, the metal can be stainless steel to prevent rusting.

[0013] In some embodiments, an injection pipe is further included, which is inserted into the monitoring container. According to the monitored apparent parameter information of the underground shallow formation and soil environment (such as the permeability coefficient, water level, pH, gas content ratio, etc.), a modified gas can be injected into the monitoring container through the injection pipe, so as to modify the shallow soil environment in the monitoring area.

[0014] In some embodiments, the sampling pipe and the injection pipe are respectively and sealingly connected to the upper part of the monitoring container. The closed structure of the monitoring container can prevent other gases in the air from affecting the soil gas monitoring and protect the gas sensor.

[0015] In some embodiments, the differential pressure measuring device includes a damping pipe, a one-way valve, and a differential pressure gauge for measuring the pressure difference between the two ends of the damping pipe. The damping pipe and the one-way valve are connected between the monitoring container and the constant volume container, the one-way valve is connected between the damping pipe and the constant volume container, and the differential pressure gauge is connected in parallel through a branch pipe to the sampling pipes at the two ends of the damping pipe. A structure of the differential pressure measuring device is provided, which can replace the commercially available differential pressure flowmeter and reduce the cost.

[0016] The differential pressure gauge is used to measure the pressure difference between the two ends of the damping pipe. With the passage of time, the pressure difference between the two sides of the damping pipe will automatically decay. According to the decay curve of the pressure difference, the permeability of the underground soil environment can be determined.

[0017] The one-way valve is a standard one-way valve, which is fixed in the direction from the underground soil to the constant volume container. The one-way valve can prevent the fluid in the external air from flowing back to the monitoring container above the monitoring point soil and polluting the internal sample environment, thereby affecting the specific values of each gas component and the pressure decay in the device. In addition, the one-way valve can increase the vacuum pumping effect of the vacuum pump and the representativeness of the underground fluid sample.

[0018] The damping pipe is a capillary tube, a porous pipe, or a material with a fixed permeability coefficient, such as various rock cores, which can increase the time of pressure decay after the monitoring and sampling device is pumped to vacuum, and generate a pressure difference between the two sides of the damping pipe. The pressure decay between the two sides of the damping pipe is monitored by the differential pressure gauge. In the case of a fixed permeability coefficient of the damping pipe, the permeability of the underground soil environment can be determined according to the different pressure decay curves of the damping pipe, and the apparent characteristics and water level of the underground environment can be determined according to the gas sample analysis data.

[0019] In some embodiments, the differential pressure measuring device is a differential pressure flow meter. By using a commercially available differential pressure flow meter instead of the differential pressure flow device described above, the monitoring sampling device can be directly installed, simplifying the structure.

[0020] In some embodiments, a first control valve is arranged on the sampling pipe between the vacuum pump and the constant volume container, and a second control valve is arranged on the injection pipe. The first control valve is used to control the opening and closing of the sampling pipe, and the second control valve is used to control the opening and closing of the injection pipe.

[0021] Another aspect of the present application provides a method for monitoring and sampling soil gas components, which uses the monitoring and sampling device for soil gas components described above, and includes the following steps:

[0022] S1. A plurality of monitoring and sampling devices are arranged at different monitoring positions in the monitoring area, and the soil gas components and contents at the monitoring positions are preliminarily monitored by the gas sensor to observe whether the monitoring data is abnormal.

[0023] S2. When the data monitored by the gas sensor at a monitoring position is abnormal, the first control valve of the monitoring and sampling device at the monitoring position is opened, and the vacuum pump is started to sample the soil gas at the monitoring position, and the soil gas is extracted into the constant volume container for further experimental analysis, and the permeability of the soil environment is determined by the monitoring data of the differential pressure measuring device.

[0024] S3. Whether the soil in the monitoring area needs to be modified is determined according to the experimental analysis data, and when the soil in the monitoring area needs to be modified, the factors that need to be modified are determined, the injection pipe is opened, and the modified gas is introduced into the monitoring container through the injection pipe, and the modified gas enters the soil outside the monitoring container through the water inlet porous section to modify the soil.

[0025] In some embodiments, a plurality of monitoring and sampling devices are arranged in a matrix in the monitoring area to form a matrix monitoring. By obtaining underground fluid samples at multiple points in the monitoring area, matrix large-area monitoring is achieved, and the apparent permeability of the underground soil is obtained through multi-point monitoring to timely feedback the changes of the underground comprehensive parameters, and combined with the geological model, the inversion of the underground parameters (water level, permeability coefficient, water content, gas content and proportion) and the tectonic movement state can be realized, and the position and possible leakage amount of the underground leakage point can be inverted.

[0026] The present application has the following advantages:

[0027] (1) The present application sets a water permeable device and a water inlet porous section on the monitoring container to prevent the monitoring and sampling device from being flooded when the water level is high, thereby affecting the monitoring and sampling effect, and enabling the monitoring and sampling device to normally monitor in a waterlogged environment.

[0028] (2) The application can quickly understand the information of abnormal point positions in the soil through the cooperation of sample data and gas sensors, and can combine multi-point sample mixing sampling and single-point sampling to monitor the changes of components and gas content in the soil gas in detail;

[0029] (3) The application realizes matrix large-area monitoring by acquiring underground fluid samples in the monitoring area, and obtains the apparent permeability of the underground soil through multi-point monitoring to timely feedback the changes of the underground comprehensive parameters, and combines the geological model to realize relatively fine inversion of the underground parameters (water level, permeability coefficient, moisture content, gas content and proportion) and tectonic movement state, and inversion of the position and possible leakage amount of the underground leakage point;

[0030] (4) The application can adjust the shallow underground soil environment and atmosphere in the monitoring area by injecting modified gas through the monitoring data. BRIEF DESCRIPTION OF DRAWINGS

[0031] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the drawings, in which:

[0032] In the drawings:

[0033] Figure 1 FIG. 1 is a structural schematic diagram of a soil gas component monitoring and sampling device in an embodiment of the present application;

[0034] Figure 2 FIG. 3 is a matrix arrangement schematic diagram of a monitoring and sampling device in an embodiment of the present application;

[0035] Figure 3 FIG. 5 is a differential pressure decay curve of soil with different permeabilities in embodiment 1 of the present application;

[0036] Reference signs:

[0037] 1-injection pipe; 2-second control valve; 3-gas sensor; 4-monitoring container; 5-water inlet porous section; 6-water permeable membrane; 7-sampling pipe; 8-damping pipe; 9-differential pressure gauge; 10-one-way valve; 11-constant volume container; 12-first control valve; 13-vacuum pump; 14-soil; 15-water level; 16-monitoring and sampling device. DETAILED DESCRIPTION

[0038] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the drawings. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0039] The soil gas component monitoring and sampling device and the monitoring and sampling method of the embodiments of the present application are described below with reference to the drawings.

[0040] AsFigure 1 As shown, the embodiment of the present application provides a soil gas component monitoring and sampling device, which comprises a monitoring container 4 and a sampling pipe 7. The lower part of the monitoring container 4 is inserted into the soil 14. The lower end of the monitoring container 4 is provided with an opening. The monitoring container 4 is provided with a water permeable device at a position above the opening. The sidewall of the monitoring container 4 is provided with a water inlet porous section 5, which is arranged above the water permeable device. The monitoring container 4 is provided with a gas sensor 3, which is arranged above the water inlet porous section 5.

[0041] One end of the sampling pipe 7 is connected to the monitoring container 4, and the other end of the sampling pipe 7 is connected to a vacuum pump 13. The vacuum pump 13 is a standard product, which provides power for soil gas sampling. The sampling pipe 7 between the monitoring container 4 and the vacuum pump 13 is connected with a differential pressure measuring device and a constant volume container 11, which is connected between the differential pressure measuring device and the vacuum pump 13. The constant volume container 11 can increase the internal volume of the monitoring and sampling device, store soil samples in the monitoring area, and increase the sample amount during each fluid sampling. The volume can be determined according to the monitoring and sampling requirements, which can be 1L, 2L or other specifications.

[0042] In some specific embodiments, the monitoring container 4 is in a cylindrical shape. The opening at the lower part of the monitoring container 4 is directly connected to the ground soil 14. The monitoring container 4 covers the monitoring point. The upper part of the monitoring container 4 is connected to the sampling pipe 7 and the injection pipe 1, forming a closed structure. The gas sensor 3 is installed in the monitoring container 4. The monitoring container 4 is provided with the water inlet porous section 5 and the water permeable device. The moisture in the stratum enters the monitoring container 4 through the water inlet porous section 5. The gas in the stratum also enters the monitoring container 4 through the water inlet porous section 5 after reaching the depth of the water inlet porous section 5. The excess moisture is discharged through the water permeable device at the bottom. The moisture can normally pass through the water permeable device. The water inlet porous section 5 and the water permeable device can control the water level 15 in the monitoring container 4 to be maintained at the depth of the water inlet porous section 5, preventing the flooded water from affecting the inside of the monitoring container 4.

[0043] In some specific embodiments, the water inlet porous section 5 is arranged at the middle section of the monitoring container 4.

[0044] In some specific embodiments, the water permeable device is a water permeable membrane 6. The water permeable membrane 6 is a bidirectional water permeable membrane. The water permeable membrane 6 is a hydrophilic material, and the moisture can normally pass through the water permeable membrane 6.

[0045] In some specific embodiments, the water permeable membrane 6 is installed in the monitoring container 4 by a support, which is arranged below the water permeable membrane 6. The support supports the water permeable membrane 6, leaving a certain space between the water permeable membrane 6 and the soil, preventing the water permeable membrane 6 from being pierced by sand and stones after contacting the soil. The specific structure of the support can have various forms, which is a prior art and will not be described here.

[0046] In some specific embodiments, the water inlet porous section 5 is made of a porous material, specifically, the material of the water inlet porous section 5 is ceramic or metal. The water inlet porous section 5 is fixedly embedded on the side wall of the monitoring container 4. The fixed manner is a prior art, which is not described here. Further, the metal can be made of stainless steel to prevent rust.

[0047] In some specific embodiments, the number and type of the gas sensors 3 are determined according to the target of the monitoring work, and the content changes of Rn, He, O2, N2, H2, CO2, NH3, CH4, N2O, etc. in the underground soil of the monitoring container 4 can be monitored in real time for a long time. Because the contents of different gases are significantly different, the accuracy of the gas sensors 3 cannot be completely covered, and the gas sensors 3 only preliminarily monitor the contents and percentages of the underground gases. When the monitoring data of the gas sensors 3 are abnormal, the vacuum pump 13 is used to finely sample the monitoring area with abnormalities, and detailed detection is performed in a laboratory environment. Through the change of the content of each gas, it can be understood whether there is tectonic movement and chemical reaction underground, whether the sealing gas in the monitoring area leaks, and the leakage position and leakage amount are determined according to the sampling point.

[0048] In some specific embodiments, the injection pipe 1 is further included, and the injection pipe 1 is inserted into the monitoring container 4 from the upper end of the monitoring container 4. According to the monitored apparent parameter information of the shallow stratum and soil environment underground (such as the permeability coefficient, water level, pH, gas content ratio, etc.), the modified gas can be injected into the monitoring container 4 through the injection pipe 1, and the shallow soil environment in the monitoring area can be modified. The injected gas is determined according to the underground environment and the required environment.

[0049] In some specific embodiments, the sampling pipe 7 and the injection pipe 1 are respectively and sealingly connected to the upper part of the monitoring container 4, and the closed structure of the monitoring container 4 can prevent other gases in the air from affecting the soil gas monitoring and protect the gas sensors 3.

[0050] In some specific embodiments, the connection between the sampling pipe 7 and the monitoring container 4 is located at the upper end of the monitoring container 4, that is, the sampling pipe 7 is connected to the upper end of the monitoring container 4. The gas sensors 3 are arranged on the upper end face inside the monitoring container 4 and close to the connection between the sampling pipe 7 and the monitoring container 4.

[0051] In some specific embodiments, the differential pressure measuring device is a differential pressure flowmeter.

[0052] In some embodiments, the differential pressure measuring device can also be a damping tube 8, a one-way valve 10, and a differential pressure gauge 9. The damping tube 8 and the one-way valve 10 are connected between the monitoring container 4 and the constant volume container 11, the one-way valve 10 is connected between the damping tube 8 and the constant volume container 11, and the differential pressure gauge 9 is connected in parallel through a branch pipe to the sampling pipe 7 at both ends of the damping tube 8. Instead of the differential pressure flow meter described above, the cost can be reduced.

[0053] The differential pressure gauge 9 is used to measure the pressure difference at both ends of the damping tube 8. Over time, the pressure difference on both sides of the damping tube 8 will automatically decay. According to the decay curve of the pressure difference, the permeability of the underground soil environment can be determined.

[0054] The one-way valve 10 is a standard one-way valve, which is fixed in the direction from the underground soil to the constant volume container 11. The one-way valve 10 can prevent the fluid in the external air from flowing back to the monitoring container 4 above the monitoring point soil and polluting the internal sample environment, thereby affecting the specific values of the gas components and the pressure decay in the device. The one-way valve 10 can also increase the vacuum effect of the vacuum pump 13 and the representativeness of the underground fluid sample.

[0055] The damping tube 8 is a capillary tube, a porous tube, or a material with a fixed permeability coefficient, such as various rock cores, which can increase the time of pressure decay after the monitoring and sampling device is vacuumed and generate a pressure difference on both sides of the damping tube 8. The pressure difference decay on both sides of the damping tube 8 is monitored by the differential pressure gauge 9. In the case of a fixed permeability coefficient of the damping tube 8, the permeability of the underground soil environment can be determined according to the different pressure decay curves of the damping tube 8. The apparent characteristics and water level of the underground environment can be determined according to the gas sample analysis data.

[0056] In some embodiments, the sampling pipe 7 is provided with a first control valve 12 for controlling the on-off of the sampling pipe 7. The first control valve 12 is arranged between the vacuum pump 13 and the constant volume container 11. The sampling pipe 7 is used to collect the fluid sample of the underground soil in the monitoring area and measure the permeability of the soil by connecting other components. When some gas sensors 3 are expensive or have a short service life, the soil sample can be collected by sampling to supplement the gas sensors 3. When the measurement parameters of the gas sensors 3 are abnormal, the underground soil gas can be collected by the sampling pipe 7 to transport the soil gas sample to related experimental equipment for further detailed testing.

[0057] In some embodiments, the injection pipe 1 is provided with a second control valve 2 for controlling the on-off of the injection pipe 1.

[0058] Another aspect of the present application provides a method for monitoring and sampling soil gas components, which uses the soil gas component monitoring and sampling device described above, and includes the following steps:

[0059] S1, several monitoring sampling devices 16 are arranged at different monitoring positions in the monitoring area, the composition and content of the shallow soil gas at each monitoring position are preliminarily monitored by the gas sensor 3, and whether the monitoring data of each monitoring position is abnormal is observed;

[0060] S2, when the data monitored by the gas sensor 3 at a monitoring position is abnormal, or when the soil atmosphere at a monitoring position needs to be understood, the first control valve 12 and the vacuum pump 13 of the monitoring sampling device at the monitoring position are opened, the soil gas at the monitoring position is sampled, the soil gas is extracted into the constant-volume container 11 for further experimental analysis, and the permeability of the soil environment is judged by the monitoring data of the differential pressure measuring device to obtain the apparent permeability coefficient of the soil;

[0061] S3, whether the soil in the monitoring area needs to be modified is judged according to the experimental analysis data, when the soil in the monitoring area needs to be modified, the factor (such as the pH value of the soil) that needs to be modified is determined, the second control valve 2 is opened, and the injection pipe 1 is opened, the modified gas is introduced into the monitoring container 4 through the injection pipe 1, the modified gas enters the soil outside the monitoring container 4 through the water inlet porous section 5 to modify, and the soil atmosphere is changed through the reaction.

[0062] The water in the soil enters the monitoring container 4 through the water inlet porous section 5 and is slowly discharged through the water permeable membrane 6, so that the monitoring sampling device can still work normally in the waterlogged environment.

[0063] The monitoring sampling device is vacuumed during sampling, due to the different permeability coefficients of the underground soil environment, a pressure difference is formed in the monitoring sampling device, the decay curves of the pressure differences of different permeability coefficients of the soil are different, the permeability of the underground soil environment can be fed back through the decay curves, and the soil atmosphere and affinity can be understood through the gas composition content in the sampling sample and the gas sensor 3.

[0064] As shown in Figure 2 In some specific embodiments, a plurality of monitoring sampling devices 16 are arranged equidistantly in the monitoring area for matrix monitoring, the soil conditions and fluid samples can be obtained at multiple points in the monitoring area, and the fluid characteristics can be accurately understood.

[0065] A plurality of monitoring sampling devices 16 are arranged equidistantly in the monitoring area, the number of which is determined according to the size of the monitoring area and the monitoring demand. The monitoring sampling devices 16 are arranged in a matrix arrangement as shown in Figure 2 The underground fluid samples and soil gas comprehensive parameters can be obtained at multiple points and multiple parameters. The detailed position of the abnormal point can be inversely calculated through the monitoring data of the plurality of monitoring sampling devices 16, and the corresponding fluid can be injected into the shallow underground soil in the monitoring area through mixed and single-point sampling of the monitoring parameters to modify the underground environment atmosphere.

[0066] This application enables relatively precise monitoring, providing feedback on shallow surface data and underground soil environment such as water level, soil permeability, pH value, and the content and proportion of gaseous substances such as Rn, He, O2, N2, H2, CO2, NH3, CH4, and N2O. Based on the monitoring data and geological modeling, the apparent characteristics and geological movement of the strata can be inverted.

[0067] When the water level is at a normal level (15), moisture and gas in the soil slowly enter the monitoring container 4 through the porous inlet section 5 and the permeable membrane 6 until the sample environment inside the monitoring container 4 matches the soil environment. When the water level is too high (15), excess water enters the monitoring container 4 through the porous inlet section 5 and is discharged into the soil 14 through the permeable membrane 6 at the bottom. Controlling the water level inside the monitoring container 4 prevents waterlogging from affecting the monitoring and ensures that the device can work for a long time in complex underground environments in the field.

[0068] The present application will be further illustrated below through specific embodiments.

[0069] Example 1

[0070] like Figure 1 As shown, this embodiment proposes a soil gas composition monitoring and sampling device, including: a monitoring container 4, a gas sensor 3, a sampling tube 7, a damping tube 8, a differential pressure gauge 9, a one-way valve 10, a constant volume container 11, an injection tube 1, a first control valve 12, and a second control valve 2.

[0071] The monitoring container 4 is cylindrical, with its lower part inserted into the soil 14. An opening is located at the lower end of the container 4, and a permeable membrane 6 is installed inside the container 4 above this opening. The permeable membrane 6 is a bidirectional permeable membrane. It is made of a hydrophilic material, allowing water to pass through normally. The permeable membrane 6 is mounted inside the monitoring container 4 via a support structure positioned below it. The support structure supports the permeable membrane 6, ensuring sufficient space between it and the soil to prevent sand or gravel from puncturing it upon contact.

[0072] A porous water inlet section 5 is located in the middle of the side wall of the monitoring container 4. The porous water inlet section 5 is located above the permeable membrane 6 and is made of stainless steel. It is fixedly embedded in the side wall of the monitoring container 4. A gas sensor 3 is located inside the monitoring container 4, above the porous water inlet section 5.

[0073] The opening of the monitoring container 4 at the lower part is directly connected with the ground soil 14, and the monitoring container 4 covers the monitoring point. When the water level 15 is normal, the water and gas in the soil slowly enter the monitoring container 4 through the water inlet porous section 5 and the water permeable membrane 6 until the sample environment in the monitoring container 4 is consistent with the soil environment. When the water level 15 is too high, the excess water enters the monitoring container 4 through the water inlet porous section 5 and is discharged to the soil 14 through the water permeable membrane 6 at the bottom, so as to control the internal water level of the monitoring container 4 and prevent the monitoring from being affected by the waterlogging, thereby ensuring that the device can work in the complex underground environment for a long time.

[0074] One end of the sampling pipe 7 is connected with the upper end of the monitoring container 4, and the other end of the sampling pipe 7 is connected with the vacuum pump 13. The gas sensor 3 is arranged at the upper end face of the monitoring container 4 and close to the connection between the sampling pipe 7 and the monitoring container 4. The damping pipe 8, the one-way valve 10, the constant volume container 11 and the first control valve 12 are sequentially connected on the sampling pipe 7 between the monitoring container 4 and the vacuum pump 13, and the differential pressure meter 9 is connected in parallel on the sampling pipe 7 at the front and rear ends of the damping pipe 8 through branch pipes. The differential pressure meter 9 is used for measuring the pressure difference between the front and rear ends of the damping pipe 8. With the passage of time, the pressure difference between the two sides of the damping pipe 8 will automatically decay, and the permeability of the underground soil environment can be judged according to the decay curve of the pressure difference. The one-way valve 10 is a standard one-way valve, and the direction is a fixed direction from the underground soil 14 to the constant volume container 11.

[0075] The damping pipe 8 can increase the pressure decay time after the monitoring sampling device is vacuumized, generate a pressure difference between the front and rear ends of the damping pipe 8, and monitor the pressure decay between the two sides of the damping pipe 8 through the differential pressure meter 9. In the case that the permeability coefficient of the damping pipe 8 is fixed, the permeability of the underground soil environment can be judged according to the different pressure decay curves of the damping pipe 8, and the apparent characteristics and water level of the underground environment can be deduced according to the gas sample analysis data.

[0076] In the embodiment, in the experimentally determined soils with different environments with water contents of 15%, 35% and 55%, the tested pressure differences P1, P2 and P3 have the relationship as shown in the following table, and the apparent permeability coefficient k of the soil can be deduced according to the decay curve. Figure 3

[0077] The injection pipe 1 is inserted into the monitoring container 4 from the upper end of the monitoring container 4. According to the monitored apparent parameter information (such as the permeability coefficient, water level, pH, gas content ratio, etc.) of the underground shallow stratum and soil environment, the modified gas can be injected into the monitoring container 4 through the injection pipe 1, so as to modify the shallow soil environment in the monitoring area. The injected gas is determined according to the underground environment and the required environment.

[0078] ​The sampling pipe 7 and the injection pipe 1 are respectively sealedly connected to the upper part of the monitoring container 4, and the closed structure of the monitoring container 4 can prevent other gases in the air from affecting the monitoring of the soil gas and protect the gas sensor 3.

[0079] The embodiment provides a monitoring and sampling method for soil gas components, and utilizes the monitoring and sampling device for soil gas components.

[0080] S1, a plurality of monitoring and sampling devices 16 are arranged at different monitoring positions in a monitoring area, and the gas sensor 3 is used to preliminarily monitor the soil gas components and contents at the monitoring positions, and whether the monitoring data at the monitoring positions is abnormal is observed.

[0081] S2, when the data monitored by the gas sensor 3 at a monitoring position is abnormal, or when the soil atmosphere at a monitoring position needs to be understood, the first control valve 12 and the vacuum pump 13 of the monitoring and sampling device at the monitoring position are opened, the soil gas at the monitoring position is sampled, the soil gas is extracted into the constant-volume container 11 for further experimental analysis, the permeability of the soil environment is judged through the monitoring data of the differential pressure measuring device, and the apparent permeability coefficient of the soil is obtained.

[0082] S3, whether the soil in the monitoring area needs to be modified is judged according to the experimental analysis data, when the soil in the monitoring area needs to be modified, the factor (such as the pH value of the soil) needing to be modified is determined, the second control valve 2 is opened, and the injection pipe 1 is opened, so that the modified gas is introduced into the monitoring container 4 through the injection pipe 1, the modified gas enters the soil outside the monitoring container 4 through the water inlet porous section 5 to modify the soil, and the soil atmosphere is changed through the reaction.

[0083] The water in the soil 14 enters the monitoring container 4 through the water inlet porous section 5 and is slowly discharged through the water-permeable membrane 6, so that the monitoring and sampling device can still work normally in a waterlogged environment.

[0084] In the embodiment, the monitoring and sampling device is vacuumized during sampling, due to different permeability coefficients of underground soil environments, a pressure difference is formed in the monitoring and sampling device, the decay curves of the pressure differences of different permeability coefficient soils are different, the permeability of the underground soil environment can be fed back through the decay curves, and the soil atmosphere and affinity can be understood through the gas sensor 3 and the content of each gas component in the sampling sample.

[0085] The plurality of monitoring and sampling devices 16 are arranged equidistantly in the monitoring area to perform matrix monitoring, and the soil conditions and fluid samples can be obtained at multiple points in the monitoring area, and the fluid characteristics can be accurately understood.

[0086] The plurality of monitoring and sampling devices 16 are arranged equidistantly in the monitoring area, and the number thereof is determined according to the size of the monitoring area and monitoring requirements. Figure 2The matrix arrangement shown can obtain underground fluid samples and soil gas comprehensive parameters in multiple points and multiple parameters. Through the monitoring data of the plurality of monitoring sampling devices 16, the detailed position of the abnormal point can be inverted, and the monitoring parameters of the matrix monitoring can be mixed and single-point sampling. The abnormal single-point information can be quickly measured by the dichotomy, and various underground environment monitoring and sampling tasks can be coped with. Through the monitoring parameters, the corresponding fluid can be injected into the shallow underground soil of the monitoring area to reform the underground environment atmosphere.

[0087] The embodiment can realize relatively fine monitoring, and feedback apparent data of shallow ground and underground soil environment such as water level, soil permeability, pH value, Rn, He, O2, N2, H2, CO2, NH3, CH4, N2O and other gas content and proportion, and invert apparent characteristics and geological movement conditions of the stratum according to the monitoring values and geological modeling.

[0088] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0089] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0090] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or in communication with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication or interaction relationship of two elements, unless otherwise specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0091] In the present application, unless specifically stated and limited otherwise, a first feature "on" or "under" a second feature can be directly in contact with the second feature, or indirectly in contact with the second feature through an intermediate medium. Also, a first feature "over", "above" and "on top of" a second feature can be directly above or obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. A first feature "under", "below" and "underneath" a second feature can be directly below or obliquely below the second feature, or simply means that the first feature is horizontally lower than the second feature.

[0092] In the present application, the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" mean that a particular feature, structure, material or characteristic is included in at least one embodiment or example of the present application. Exemplary representations of the above terms in the present specification are not necessarily directed to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any suitable manner in one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0093] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A method for monitoring and sampling soil gas components, characterized in that, The monitoring and sampling devices used include: A monitoring container, the lower part of which is inserted into the soil, has an opening at the lower end, a water permeable device located above the opening inside the monitoring container, a water inlet porous section located on the side wall of the monitoring container above the water permeable device, a gas sensor located inside the monitoring container above the water inlet porous section, and the water permeable device being a water permeable membrane. A sampling tube, one end of which is connected to a monitoring container and the other end of which is connected to a vacuum pump. A differential pressure measuring device and a constant volume container are connected to the sampling tube between the monitoring container and the vacuum pump. The constant volume container is connected between the differential pressure measuring device and the vacuum pump. When the water level is normal, moisture and gas in the soil slowly enter the monitoring container through the water inlet porous section and the permeable membrane until the sample environment inside the monitoring container is consistent with the soil environment; when the water level is too high, excess water enters the monitoring container through the water inlet porous section and is discharged into the soil through the permeable membrane, thereby controlling the internal water level of the monitoring container. The monitoring and sampling method includes the following steps: S1. Several monitoring and sampling devices are set up at different monitoring locations within the monitoring area. The composition and content of soil gas at each monitoring location are initially monitored by gas sensors, and the monitoring data are observed to see if there are any abnormalities. S2, when the data monitored by the gas sensor at a certain monitoring location is abnormal, the first control valve and vacuum pump of the monitoring sampling device at that monitoring location are opened to sample the soil gas at that monitoring location, extract the soil gas into a fixed volume container for further experimental analysis, and use the monitoring data of the differential pressure measuring device to determine the permeability of the soil environment. S3. Based on the experimental analysis data, determine whether the soil in the monitoring area needs to be modified. When the soil in the monitoring area needs to be modified, determine the factors that need to be modified, open the injection pipe, and introduce the modified gas into the monitoring container through the injection pipe. The modified gas enters the soil outside the monitoring container through the water inlet porous section for modification.

2. The method for monitoring and sampling soil gas components according to claim 1, characterized in that, The permeable membrane is installed inside the monitoring container via a bracket, which is located below the permeable membrane.

3. The method for monitoring and sampling soil gas components according to claim 1, characterized in that, The porous inlet section is made of ceramic or metal.

4. The method for monitoring and sampling soil gas components according to claim 1, characterized in that, It also includes an injection tube, which is inserted into the monitoring container.

5. The method for monitoring and sampling soil gas components according to claim 4, characterized in that, The sampling tube and injection tube are respectively sealed and connected to the upper part of the monitoring container.

6. The method for monitoring and sampling soil gas components according to claim 1, characterized in that, The differential pressure measuring device includes a damping tube, a one-way valve, and a differential pressure gauge for measuring the pressure difference between the two ends of the damping tube. The damping tube and the one-way valve are connected between the monitoring container and the constant volume container. The one-way valve is connected between the damping tube and the constant volume container. The differential pressure gauge is connected in parallel to the sampling tubes at both ends of the damping tube through a branch pipe.

7. The method for monitoring and sampling soil gas components according to claim 1, characterized in that, The differential pressure measuring device is a differential pressure flow meter.

8. The method for monitoring and sampling soil gas components according to any one of claims 1-7, characterized in that, Several of the monitoring and sampling devices are arranged in a matrix within the monitoring area.

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