CN111257055A - Portable underground water depth-setting sampling device, sampling system and sampling method - Google Patents

Abstract

The portable groundwater depth-fixing sampling device, sampling system and sampling method of the present invention belong to the field of site pollution investigation and risk assessment, and the stagnant water located at the upper and lower ends of the groundwater sampling probe in the well pipe is effectively blocked by arranging a movable barrier airbag, It can accurately collect groundwater samples at the depth where the sampling probe is located, avoiding the problem of sample dilution caused by the mixing of upper and lower water samples in the well pipe during the traditional method of well cleaning and sampling, and improving the accuracy of detected concentrations. The invention can accurately collect groundwater samples of different depths in the same monitoring well, realize fixed-depth sampling, and significantly reduce the cost. In addition, the invention effectively blocks the stagnant water in the upper and lower layers of the groundwater sampling probe in the well pipe, which can reduce the volume of well cleaning before sampling, save the sampling time, improve the sampling efficiency, reduce the amount of waste water generated from the well cleaning, and further reduce the sampling cost. Reduce the disturbance to the groundwater in the well pipe and ensure the accuracy of the detected concentration.

Description

A portable groundwater depth-determining sampling device, sampling system and sampling method

technical field

The invention belongs to the field of site pollution investigation and risk assessment, in particular to a portable groundwater depth-fixing sampling device, a sampling system and a sampling method.

Background technique

According to Chinese laws and regulations, before the redevelopment and utilization of the land left by industrial enterprises after the closure and relocation, the soil and groundwater pollution status of the plot shall be investigated in accordance with relevant national technical specifications, and risk assessment shall be carried out in combination with the future land use planning of the site. Among them, for the investigation of groundwater pollution status, the main method is to collect typical groundwater samples for pollutant detection to characterize the pollution status. Due to the anisotropic spatial heterogeneity of site hydrogeology, the vertical distribution of pollutants in groundwater is usually uneven, especially for sites with thick aquifers, the phenomenon of vertical uneven distribution is more obvious. Therefore, carrying out fixed-depth sampling and analyzing pollutants by collecting groundwater samples at different depths are the main technical means to characterize the vertical distribution of pollutants in groundwater.

The traditional way to collect typical groundwater samples at different depths is to set up a group of wells at the same monitoring point, and to collect typical groundwater samples at different depths by setting screens at different depths of the aquifer. Due to the need to construct wells in this traditional method, the cost of drilling and constructing wells is relatively high. If the groundwater is buried deeper and the aquifer is thicker, the cost increase is more obvious, which has become the main obstacle restricting the popularization and application of this technology. At the same time, with this sampling method, due to the large volume of stagnant water in the well pipe, it takes a long time to clean the well before sampling, the sampling efficiency is reduced, and more well-flushing wastewater is generated, which further increases the application cost of this technology.

The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a portable groundwater depth-determining sampling device, sampling system and sampling method, in order to solve the technical problem that the traditional method of collecting typical samples of groundwater of different depths requires the construction of wells, and the cost of drilling and construction of wells is relatively high. Especially when the groundwater is buried deep and the aquifer is thick, the cost increase is more obvious; and the volume of stagnant water in the well pipe is large, it takes a long time to clean the well before sampling, the sampling efficiency is reduced, and more well-flushing wastewater is generated. , the technical problem of increasing the application cost.

In order to solve the above-mentioned technical problems, the present invention provides a portable groundwater depth sampling device, comprising:

The sampling probe is a hollow structure and has a hole on its side wall for pollutants to enter;

The barrier airbag includes a probe top airbag connected to the top of the sampling probe and a probe bottom airbag connected to the bottom end of the sampling probe, the top and bottom of the probe top airbag are connected through a second connecting pipe, and the probe top airbag and the probe The bottom airbags are also communicated through the first connecting pipe;

The air supply mechanism includes an inflation tube connected to the top of the airbag at the probe tip and an inflation device connected to the end of the inflation tube, and the inflation tube is provided with a barometer and an airtight valve;

The well cleaning and sampling mechanism includes a sampling pipe connected to the top of the airbag at the probe tip and a self-priming sampling pump connected to the end of the sampling pipe, the sampling pipe is provided with an air-tight valve, and the self-priming sampling pump is A sampling pump outlet pipe is connected.

Preferably, a centering device is provided on the outer casing of the sampling probe, and the centering device is a plate-like structure, and a probe limiting hole for the sampling probe to pass through is opened at the center of the centering device. The connecting pipe limit hole through which the connecting pipe passes.

Preferably, the centralizer is also provided with water passage holes symmetrically.

Preferably, the sampling probe includes an inner liner, an outer casing sleeved outside the inner liner, and connected between the top of the inner liner and the top of the outer casing, and between the bottom of the inner liner and the bottom of the outer casing The plugging cap between the two, the inner liner and the outer casing are both provided with pores, and the pore diameter of the pores on the inner liner is larger than the pore diameter of the outer casing, the plugging cap is connected with a quick connector, and the The sampling probe is respectively communicated with the airbag at the top of the probe and the airbag at the bottom of the probe through the quick joints at both ends.

Preferably, the first connecting pipe and the second connecting pipe are both rigid pipes made of corrosion-resistant material, and the sampling pipe and the inflation pipe are both flexible pipes of corrosion-resistant material.

In addition, the present invention also provides a portable groundwater depth-sampling system, including the above-mentioned portable groundwater depth-sampling device, and further comprising:

The well pipe device is arranged vertically along the center of the well hole, and includes a screen pipe, a solid pipe connected to the top of the screen pipe, and a pipe plug sealingly connected to the bottom of the screen pipe, and the sampling probe and the blocking airbag are all arranged in the screen pipe;

The filter material and the blocking device include a filter material layer, a barrier layer and a sealing layer in order from bottom to top, the filter material layer is arranged between the outer wall of the screen tube and the wall of the well hole, and the top of the filter material layer is beyond the screen tube. top.

Preferably, the diameter of the sampling probe is 1/2 of the inner diameter of the screen tube, and the length of the sampling probe is 0.5m-1.5m.

Preferably, the filter material layer is quartz sand, the barrier layer is bentonite slurry, and the sealing layer is cement slurry.

In addition, the present invention also provides a method for sampling using the above-mentioned portable groundwater depth sampling system, comprising the following steps:

Step 1. Determine groundwater sampling monitoring points and drill to form wells;

Step 2. Install the well pipe device vertically in the wellbore to ensure that the well pipe device is located in the center of the wellbore;

Step 3: Filling the filter material layer, the barrier layer and the sealing layer between the outer wall of the well pipe device and the wall of the well hole to ensure that the top of the filter material layer exceeds the top of the screen pipe;

Step 4. Install the portable groundwater depth sampling device;

Step 5. After placing the portable groundwater depth-fixing sampling device along the inner side wall of the well pipe device to the designed sampling depth, open the air-tight valve on the inflatable pipe, start the inflatable device, and inflate the airbag at the top of the probe and the airbag at the bottom of the probe until The airbag at the top of the probe and the airbag at the bottom of the probe are close to the inner wall of the sieve tube;

Step 6. Close the airtight valve on the inflatable pipe, close the inflatable device, open the airtight valve on the sampling pipe, open the self-priming sampling pump, and start well cleaning;

Step 7: Connect the outlet pipe of the sampling pump to the self-priming sampling pump to collect groundwater samples;

Step 8. Close the airtight valve on the sampling tube, close the self-priming sampling pump, open the airtight valve on the inflation tube, and release the pressure of the airbag at the top of the probe and the airbag at the bottom of the probe;

Step 9: Lower the portable groundwater depth-fixing sampling device to another design sampling depth, repeat steps 5 to 8, and collect groundwater samples at the corresponding depth.

Preferably, the installation method of the portable groundwater depth sampling device in the fourth step includes the following steps:

Step 1. Connect the probe top airbag and the probe bottom airbag to the two ends of the sampling probe respectively, and connect the two ends of the first connecting pipe to the probe top airbag and the probe bottom airbag respectively;

Step 2, connect one end of the sampling tube with the top of the probe tip airbag, and the other end is communicated with the airtight valve and the self-priming sampling pump;

Step 3. Connect one end of the inflation tube to the top of the probe tip airbag, and the other end to communicate with the air pressure gauge, the airtight valve and the inflation device.

Compared with the prior art, the characteristics and beneficial effects of the present invention are:

(1) The portable groundwater depth-fixing sampling system of the present invention effectively blocks the stagnant water located at the upper and lower ends of the groundwater sampling probe in the well pipe by setting a movable barrier airbag, and can accurately collect groundwater samples at the depth where the sampling probe is located, avoiding the need for a In the traditional method, the problem of sample dilution caused by the mixing of the upper and lower water samples in the well pipe during the well cleaning and sampling process improves the accuracy of the detected concentration.

(2) The portable groundwater depth sampling system of the present invention can accurately collect groundwater samples of different depths in the same monitoring well by moving the blocking airbag up and down to realize fixed depth sampling.

(3) The portable groundwater depth-fixing sampling system of the present invention effectively blocks the stagnant water in the upper and lower layers of the groundwater sampling probe in the well pipe by using the barrier airbag during the sampling process, which can reduce the volume of well cleaning before sampling, save the sampling time, and improve the sampling rate. efficiency, reduce the amount of well-washing wastewater, and further reduce sampling costs.

(4) The portable groundwater depth-fixing sampling system of the present invention effectively blocks the stagnant water in the upper and lower layers of the groundwater sampling probe in the well pipe by using the blocking air bag, effectively reducing the disturbance to the groundwater in the well pipe and ensuring the accuracy of the detected concentration.

(5) The portable groundwater depth-fixing sampling system of the present invention is simple in structure, convenient in installation, and simple in sampling method, which is of great significance for improving the current groundwater sampling technology system and supporting groundwater pollution investigation of polluted sites in my country.

Description of drawings

Figure 1 is a schematic diagram of the structure of a portable groundwater depth-sampling device.

FIG. 2 is a schematic diagram of the plane structure of the centralizer.

Figure 3 is a schematic view of the elevation structure of the probe tip airbag.

FIG. 4 is a schematic top-view structural diagram of a probe tip airbag.

FIG. 5 is a schematic view of the vertical structure of the airbag at the bottom end of the probe.

FIG. 6 is a schematic structural diagram of a sampling probe.

Figure 7 is a schematic structural diagram of a portable groundwater depth-sampling system.

FIG. 8 is a schematic structural diagram of a well tubular device.

Note in the drawings: 1-sampling probe, 101-inner liner, 102-outer casing, 103-blocking cap, 2-blocking airbag, 21-probe top airbag, 22-probe bottom-end airbag, 3-first connecting pipe , 4- Inflatable tube, 5- Inflatable device, 6- Sampling tube, 7- Self-priming sampling pump, 8- Sampling pump outlet pipe, 9- Centering device, 91- Probe limit hole, 92- Connecting pipe limit Hole, 93-water hole, 10-second connecting pipe, 11-screen pipe, 12-solid pipe, 13-pipe plug, 14-filter material layer, 15-barrier layer, 16-sealing layer.

Detailed ways

In order to make the technical means, innovative features, achieved goals and effects of the present invention easy to understand and understand, the present invention is further described below.

The embodiments described herein are specific embodiments of the present invention, are used to illustrate the concept of the present invention, are illustrative and exemplary, and should not be construed as limiting the embodiments of the present invention and the scope of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims and the description of the present application, and these technical solutions include any obvious technical solutions to the embodiments described herein. Alternative and modified technical solutions.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end" and "the other end" The orientation or positional relationship indicated by etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, with a specific orientation. The orientation configuration and operation are therefore not to be construed as limitations of the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense, for example, "connected" may be a fixed connection It can also be a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or the internal communication between the two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

As shown in Figure 1-6, it is a portable groundwater depth sampling device, including a sampling probe 1, a barrier air bag 2, a gas supply mechanism, and a well cleaning and sampling mechanism.

The sampling probe 1 is a hollow structure and has a hole on its side wall for contaminants to enter. The sampling probe 1 specifically includes an inner liner 101, an outer casing 102 sleeved outside the inner liner 101, and connected between the top of the inner liner 101 and the top of the outer casing 102, and connected to the bottom and the outside of the inner liner 101 The plug cap 103 between the bottom of the casing 102, the inner liner 101 and the outer casing 102 are both provided with pores, and the pore diameter of the pores on the inner liner 101 is larger than the pore diameter of the outer casing 102, the plugging The cap 103 is connected with a quick connector, and the sampling probe 1 communicates with the probe top airbag 21 and the probe bottom airbag 22 respectively through the quick connectors at both ends. The inner liner 101 has a wall thickness of 1.5 mm, a diameter of 22 mm and a height of 60 cm. The inner liner 101 is provided with 8 rows of holes with a diameter of 4 mm. The outer sleeve 102 has a wall thickness of 0.4 mm, a diameter of 24 mm and a height of 60 cm. The outer sleeve 102 has an 18 mesh opening. Both ends of the sampling probe 1 are provided with external thread quick joints, the inner diameter of the joint is 8-10 mm, and the sampling probe 1 is respectively connected to the probe top airbag 21 and the probe bottom airbag 22 through the quick joints.

In order to ensure that the sampling probe 1 does not move during the sampling process, the present invention is provided with a centering device 9 on the outer casing of the sampling probe 1, and the centering device 9 is a plate-like structure, and a center position is provided for the sampling probe 1 to pass through. The probe limiting hole 91 of the central device 9 is also provided with a connecting pipe limiting hole 92 for the first connecting pipe 3 to pass through. The probe limiting hole 91 is a threaded hole, and the connecting pipe limiting hole 92 is a circular hole whose diameter is slightly larger than the outer diameter of the first connecting pipe 3 . In order to reduce the barrier of the centralizer 9 to the liquid, the centralizer 9 of the present invention is also provided with water passage holes 93 symmetrically. The centralizer 9 adopts 2/3 of the inner diameter of the well pipe, and the thickness is 20-30mm.

The blocking airbag 2 includes a probe tip airbag 21 connected to the top end of the sampling probe 1 and a probe bottom end airbag 22 connected to the bottom end of the sampling probe 1. The top and bottom of the probe tip airbag 21 are communicated through the second connecting pipe 10, so The probe top airbag 21 and the probe bottom airbag 22 are also communicated through the first connecting pipe 3 . The first connecting pipe 3 and the second connecting pipe 10 are both rigid pipes made of corrosion-resistant material. The function of the second connecting pipe 10 is mainly to ensure the connectivity of the entire groundwater sampling pipeline and the air tightness of the barrier airbag, so as to ensure that the barrier airbag can expand after inflation. If there is no second connecting pipe 10, the gas enters the pipe through the sampling probe 1 after inflation, aerates the water in the well pipe, and the barrier air bag cannot be expanded, and groundwater samples cannot be taken. The function of the first connecting pipe 3 is to connect the probe top airbag 21 and the probe bottom airbag 22, so that it can be inflated through the air inlet of the probe top airbag 21, and the two airbags can be inflated at the same time and then inflated.

The center of the top of the airbag 21 at the top of the probe is provided with an external thread socket-type airtight quick connector, and the fastener thread fixes the airtight quick connector on the top of the airbag 21 at the probe tip. The inner diameter of the airtight quick connector is the same as the sampling tube. 6 to match the outer diameter, usually 6-8mm. One side of the air-tight quick connector is also provided with another external thread socket-type air-tight quick connector. The fastener thread fixes the air-tight quick connector on the top of the probe tip airbag 21, and the inner diameter of the connector is the same as that of the inflation tube 4. to match the outer diameter, usually 4-6mm.

The center of the bottom end of the airbag 21 at the top of the probe is also provided with an external thread socket-type airtight quick connector, and the fastener thread fixes the airtight quick connector to the bottom of the airbag 21 at the probe tip. The inner diameter of the airtight quick connector is related to the sampling The outer diameter of the threaded interface at the top of the probe 1 is matched, and the air-tight quick connector is connected to the quick connector on the top of the sampling probe 1 in a threaded connection manner. One side of the air-tight quick connector is also provided with an external thread socket type air-tight quick connector, and the fastener threadedly fixes the air-tight quick connector to the bottom of the airbag 21 at the top of the probe. The inner diameter matches the outer diameter of the first connecting pipe 3, usually 4-6 mm. Both ends of the second connecting pipe 10 are airtightly connected to the airtight quick connectors at both ends of the probe tip airbag 21 in a socket-insertion manner.

The center of the top end of the airbag 22 at the bottom of the probe is provided with an external thread socket-type airtight quick connector, and the fastener thread fixes the airtight quick connector on the top of the airbag 22 at the bottom of the probe. The inner diameter of the airtight quick connector Connect with the quick connector at the bottom end of the sampling probe 1, one side of the air tight quick connector is provided with another air tight quick connector, the inner diameter of the air tight quick connector matches the outer diameter of the first connecting pipe 3, usually 4 -6mm.

The air supply mechanism includes an inflation tube 4 connected to the top of the probe tip airbag 21 and an inflation device 5 connected to the end of the inflation tube 4. The inflation tube 4 is provided with a barometer and an airtight valve. The inflation tube 4 is a flexible tube made of corrosion-resistant material.

The well cleaning and sampling mechanism includes a sampling pipe 6 connected to the top of the probe tip airbag 21 and a self-priming sampling pump 7 connected to the end of the sampling pipe 6. The sampling pipe 6 is provided with an airtight valve, and the self-priming The sampling pump 7 is connected with a sampling pump outlet pipe 8 . The sampling tube 6 is a flexible tube made of corrosion-resistant material.

As shown in Figures 7-8, a portable groundwater depth-sampling system includes the above-mentioned portable groundwater depth-sampling device, as well as a well pipe device, a filter material and a blocking device.

The well pipe device is vertically arranged along the center of the well hole, including a screen pipe 11, a solid pipe 12 connected to the top of the screen pipe 11, and a pipe plug 13 sealed at the bottom of the screen pipe 11. The sampling probe 1 and the blocking air bag 2 All are arranged in the screen tube 11 . The diameter of the sampling probe 1 is 1/2 of the inner diameter of the screen tube 11, and the length of the sampling probe 1 is 0.5m-1.5m.

The filter material and the blocking device sequentially include a filter material layer 14, a barrier layer 15 and a sealing layer 16 from bottom to top, the filter material layer 14 is arranged between the outer wall of the screen tube 11 and the wall of the well hole, and the The top is beyond the top of screen 11. The filter material layer 14 is quartz sand, the barrier layer 15 is bentonite slurry, and the sealing layer 16 is cement slurry.

The method of sampling using the portable groundwater depth sampling system as described above includes the following steps:

Step 1: According to the information such as the distribution of pollution facilities on the site, historical monitoring data and on-site pollution traces, screen and determine the groundwater sampling monitoring points, and use a drilling rig to drill at the determined groundwater sampling monitoring points to form wells. During the drilling process, the casing is followed up throughout the process to prevent the sidewall of the well from collapsing.

Step 2: Install the well pipe device vertically in the wellbore to ensure that the well pipe device is located in the center of the wellbore.

Step 3: Fill the filter material layer 14 , the barrier layer 15 and the sealing layer 16 between the outer wall of the well pipe device and the well hole wall to ensure that the top of the filter material layer 14 exceeds the top of the screen pipe 11 . In the field installation process, the filter material layer 14 and the barrier layer 15 can be filled with a funnel on the ground directly from the ground along the gap. Among them, in the process of filling the barrier layer 15, for every 0.5m of dry bentonite particles filled, no less than 2 L of clean water should be added to the barrier layer 15 to ensure that the dry bentonite particles expand after absorbing water. When the barrier layer 15 is filled to about 0.5 m above the ground, the sealing layer 16 is injected until it is about 0.1 m above the ground.

Step 4. Install the portable groundwater depth sampling device. The installation method of the portable groundwater fixed depth sampling device includes the following steps:

A. Fix the centralizer 9 on both ends of the sampling probe 1 through the probe limiting holes 91, and ensure that the centers of the connecting pipe limiting holes 92 on the centralizer 9 at both ends are on the same straight line. Then, connect the first connecting pipe 3 to the connecting pipe limiting holes 92 on the centralizers 9 at both ends.

B. Connect the probe top airbag 21 and the probe bottom airbag 22 to the two ends of the sampling probe 1 respectively, and connect the two ends of the first connecting pipe 3 to the probe top airbag 21 and the probe bottom airbag 22 respectively. Specifically, firstly, the probe tip airbag 21 is threadedly connected to the top end of the sampling probe 1 , and the probe tip airbag 21 is threadedly connected to the top end of the first connecting pipe 3 . Then, the airbag 22 at the bottom end of the probe is threadedly connected to the bottom end of the sampling probe 1 , and the airbag 22 at the bottom end of the probe is threadedly connected to the bottom end of the first connecting pipe 3 .

C. Connect one end of the sampling tube 6 to the top of the probe tip airbag 21 , and the other end to communicate with the airtight valve and the self-priming sampling pump 7 .

D. Connect one end of the inflation tube 4 to the top of the probe tip airbag 21 , and the other end to communicate with the barometer, the airtight valve and the inflation device 5 .

Step 5. After placing the portable groundwater depth-fixing sampling device along the inner side wall of the well pipe device to the designed sampling depth, open the air-tight valve on the inflatable pipe 4, start the inflatable device 5, and adjust the probe top airbag 21 and the probe bottom airbag 22. Inflate until the barometer shows that the system pressure is not less than 0.05MPa higher than the hydrostatic pressure at the bottom of the airbag 22 at the bottom of the probe, to ensure that the airbag 21 at the top of the probe and the airbag 22 at the bottom of the probe are close to the inner wall of the screen tube 11 .

Step 6. Close the airtight valve on the inflatable pipe 4, close the inflatable device 5, open the airtight valve on the sampling pipe 6, open the self-priming sampling pump 7, and start cleaning the well until the well cleaning volume is the bottom end of the probe. 3-5 times the stagnant water volume accumulated in the well pipe between the airbag 22 and the airbag 21 at the probe tip.

Step 7: Connect the sampling pump outlet pipe 8 to the self-priming sampling pump 7 to collect groundwater samples until the collected underground sample volume meets the volume requirements of the laboratory for pollutant concentration detection.

Step 8: Close the airtight valve on the sampling tube 6, close the self-priming sampling pump 7, open the airtight valve on the inflation tube 4, and release the pressure of the probe top airbag 21 and the probe bottom airbag 22.

Step 9: Lower the portable groundwater depth-fixing sampling device to another design sampling depth, repeat steps 5 to 8, and collect groundwater samples at the corresponding depth.

The above embodiments are only to describe the preferred embodiments of the present invention, but do not limit the scope of the present invention. On the premise of not departing from the design spirit of the present invention, various modifications made by those of ordinary skill in the art to the technical solutions of the present invention and improvements, all should fall within the protection scope determined by the claims of the present invention.

Claims (10)

1. The utility model provides a portable groundwater depthkeeping sampling device which characterized in that includes:

the sampling probe (1) is of a hollow structure, and the side wall of the sampling probe is provided with a pore for pollutants to enter;

the separation air bag (2) comprises a probe top end air bag (21) connected to the top end of the sampling probe (1) and a probe bottom end air bag (22) connected to the bottom end of the sampling probe (1), the top and the bottom of the probe top end air bag (21) are communicated through a second connecting pipe (10), and the probe top end air bag (21) and the probe bottom end air bag (22) are also communicated through a first connecting pipe (3);

the gas supply mechanism comprises an inflation tube (4) connected with the top of the probe top end airbag (21) and an inflation device (5) connected with the end part of the inflation tube (4), and a barometer and an air tightness valve are arranged on the inflation tube (4);

well washing and sampling mechanism includes sampling tube (6) of being connected with probe top gasbag (21) top and connects self-priming sample pump (7) at sampling tube (6) tip, be equipped with the gas tightness valve on sampling tube (6), be connected with sample pump outlet pipe (8) on self-priming sample pump (7).

2. A portable groundwater depth sampling device according to claim 1, wherein: the sampling probe (1) is sleeved with a centering device (9), the centering device (9) is of a plate-shaped structure, a probe limiting hole (91) for the sampling probe (1) to pass through is formed in the center of the centering device, and a connecting pipe limiting hole (92) for the first connecting pipe (3) to pass through is further formed in the centering device (9).

3. A portable groundwater depth sampling device according to claim 2, wherein: the centering device (9) is also symmetrically provided with water through holes (93).

4. A portable groundwater depth sampling device according to claim 1, wherein: sampling probe (1) is established outside sleeve pipe (102) outside inside bushing pipe (101) including inside bushing pipe (101), cover and is connected between inside bushing pipe (101) top and outside sleeve pipe (102) top, connects stifled cap (103) between inside bushing pipe (101) bottom and outside sleeve pipe (102) bottom, all seted up the hole on inside bushing pipe (101) and outside sleeve pipe (102) to the aperture of hole is greater than the aperture of hole on outside sleeve pipe (102) on inside bushing pipe (101), be connected with quick-operation joint on stifled cap (103), sampling probe (1) communicates with probe top gasbag (21) and probe bottom gasbag (22) respectively through the quick-operation joint at both ends.

5. A portable groundwater depth sampling device according to claim 1, wherein: the first connecting pipe (3) and the second connecting pipe (10) are both rigid pipes made of corrosion-resistant materials, and the sampling pipe (6) and the gas filling pipe (4) are both flexible pipes made of corrosion-resistant materials.

6. A portable groundwater depth-fixing sampling system, characterized by comprising a portable groundwater depth-fixing sampling apparatus according to any one of claims 1 to 5, further comprising:

the well pipe device is vertically arranged along the center of a well hole and comprises a sieve pipe (11), a solid pipe (12) which is continuously connected to the top of the sieve pipe (11) and a pipe plug (13) which is connected to the bottom of the sieve pipe (11) in a sealing way, wherein the sampling probe (1) and the blocking air bag (2) are both arranged in the sieve pipe (11);

the filter material and the blocking device sequentially comprise a filter material layer (14), a blocking layer (15) and a sealing layer (16) from bottom to top, wherein the filter material layer (14) is arranged between the outer wall of the sieve tube (11) and the wall of the well hole, and the top of the filter material layer (14) exceeds the top of the sieve tube (11).

7. A portable groundwater depth referencing sampling system according to claim 6, wherein: the diameter of the sampling probe (1) is 1/2 of the inner diameter of the sieve tube (11), and the length of the sampling probe (1) is 0.5m-1.5 m.

8. A portable groundwater depth referencing sampling system according to claim 6, wherein: the filter material layer (14) is quartz sand, the blocking layer (15) is bentonite slurry, and the sealing layer (16) is cement slurry.

9. A method for sampling with a portable groundwater depth sampling system according to any one of claims 6 to 8, characterized by comprising the steps of:

step one, determining a groundwater sampling monitoring point position and drilling to form a well hole;

vertically installing the well pipe device in the well hole to ensure that the well pipe device is positioned in the center of the well hole;

filling a filter material layer (14), a barrier layer (15) and a sealing layer (16) between the outer wall of the well pipe device and the wall of the well hole, and ensuring that the top of the filter material layer (14) exceeds the top of the sieve pipe (11);

step four, installing the portable underground water depth-fixing sampling device;

fifthly, after the portable underground water depth-setting sampling device is placed downwards along the inner side wall of the well pipe device to set the sampling depth, an air tightness valve on an inflation pipe (4) is opened, an inflation device (5) is started, and a probe top end air bag (21) and a probe bottom end air bag (22) are inflated until the probe top end air bag (21) and the probe bottom end air bag (22) are tightly attached to the inner wall of the sieve pipe (11);

step six, closing an air tightness valve on the gas filling pipe (4), closing the gas filling device (5), opening the air tightness valve on the sampling pipe (6), starting the self-suction sampling pump (7), and starting well washing;

connecting a water outlet pipe (8) of the sampling pump with a self-suction sampling pump (7) to collect an underground water sample;

step eight, closing an air tightness valve on the sampling tube (6), closing the self-suction sampling pump (7), opening the air tightness valve on the inflation tube (4), and decompressing a probe top end air bag (21) and a probe bottom end air bag (22);

and step nine, lowering the portable groundwater depth-fixing sampling device to another designed sampling depth, repeating the step five to the step eight, and collecting groundwater samples with corresponding depths.

10. A method for sampling by using a portable groundwater depth positioning sampling system according to claim 9, wherein the method for installing the portable groundwater depth positioning sampling device in the fourth step comprises the following steps:

step one, a probe top end air bag (21) and a probe bottom end air bag (22) are respectively connected to two ends of a sampling probe (1), and two ends of a first connecting pipe (3) are respectively connected with the probe top end air bag (21) and the probe bottom end air bag (22);

step two, one end of a sampling tube (6) is connected with the top of a probe top end air bag (21), and the other end of the sampling tube is communicated with an air tightness valve and a self-suction sampling pump (7);

and step three, connecting one end of an inflation tube (4) with the top of the probe top end air bag (21), and communicating the other end with a barometer, an airtight valve and an inflation device (5).

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