CN115112348A - Dynamic simulation experiment system and method for underground water circulating well - Google Patents

Abstract

The invention relates to the technical field of underground water circulating wells, and discloses a dynamic simulation experiment system and method for an underground water circulating well. A dynamic simulation experiment system of an underground water circulating well comprises a seepage groove, a base, a circulating well and a chemical injection well; the seepage groove comprises a rectangular shell with an open upper part and an aqueous medium arranged in the shell; the circulating well comprises a first round pipe vertically arranged at the center of the seepage groove, and the first round pipe is formed by connecting a lower solid pipe, a lower sieve pipe, a middle solid pipe, an upper sieve pipe and an upper solid pipe from bottom to top; a watertight diaphragm is horizontally arranged in the middle of the middle solid pipe; the injection well comprises a second round pipe arranged in the seepage groove. The invention can simulate the hydraulic circulation characteristics of the underground water circulation well under various different conditions, can accurately monitor and amplify the influence radius of the underground water circulation well, can simulate the repair experiment of the underground water circulation well under various different conditions, and provides theoretical basis and technical support for the research, popularization and application of the underground water circulation well repair technology.

Description

A dynamic simulation experiment system and method for groundwater circulation wells

technical field

The invention relates to the technical field of groundwater circulation wells, in particular to a dynamic simulation experiment system and method for groundwater circulation wells.

Background technique

Groundwater is an important part of freshwater resources and plays a pivotal role in the development of human society. However, with the development of my country's industry, the pollution of soil and groundwater by non-aqueous liquids (NAPL) represented by petroleum pollutants getting more serious.

Aiming at such groundwater organic pollutants, groundwater circulation well (GCW) technology has the advantages of high removal efficiency, short restoration period, easy control of secondary pollution, etc., and has huge development potential and broad application prospects. Over the years, many scientific researchers have continuously carried out research work on the use of groundwater circulation wells for the remediation of organic pollutants. However, due to the large differences in the hydrogeological conditions and pollutant properties of different groundwater polluted sites, the types of groundwater circulation wells suitable for different sites are Very different.

Up to now, the research and application of GCW repair technology in my country is still in its infancy, and the related research work is mostly limited to laboratory experiments and numerical simulations, and there is no mature application case of GCW repair technology. Although the numerical simulation is not limited by the experimental conditions, the error of the simulation results is relatively large because the boundary conditions of the site and the properties of the water-containing medium are often simplified. bigger.

In addition, studies have shown that groundwater circulation wells are suitable for aquifers with high horizontal permeability coefficient (>0.30m/d) and anisotropy of 3-10, but when the anisotropy of the aquifer is greater than 10, the circulation wells cannot be operated . Because of this, groundwater circulation wells in low-permeability aquifers often encounter the problems of too small influence radius and too low pollutant remediation efficiency. How to increase the influence radius of the circulating well and expand the hydraulic circulation range is one of the factors restricting the development of the circulating well technology.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the purpose of the present invention is to provide a dynamic simulation experiment system and method for groundwater circulating wells, which can simulate various conditions (different water-bearing media, different groundwater flow rates, different circulating well structures, different Circulation mode) The hydraulic circulation characteristics of groundwater circulation wells can accurately monitor and expand the influence radius of groundwater circulation wells, and can simulate the remediation experiments of groundwater circulation wells for different types of organic pollutants under various conditions, which solves the problem in the prior art. The dynamic restoration process of organic pollutants by groundwater circulation wells cannot be studied comprehensively and accurately, and it has the advantages of reasonable structure, simple operation, high efficiency and practicality.

In order to achieve the above objects, the present invention adopts the following technical solutions to achieve.

A dynamic simulation experiment system for groundwater circulation well, including seepage tank, base, circulation well and medicine injection well;

The seepage tank includes a rectangular casing with an upper opening and an aqueous medium arranged in the casing; the upper end of the right wall of the casing is provided with a first water outlet, the lower end of the left wall of the casing is provided with a first water inlet, and the bottom of the casing is close to the first water outlet. A first water outlet is arranged at the water inlet; a first baffle is vertically arranged in the casing near the first water outlet, and a second baffle is arranged vertically in the casing near the first water inlet. The first baffle and the second baffle are arranged vertically. The second baffle plate is respectively provided with a plurality of holes, the lower ends of the first baffle plate and the second baffle plate are respectively fixedly connected with the upper surface of the bottom wall of the casing, and the front and rear sides of the first baffle plate and the second baffle plate are respectively connected with the front wall of the casing It is fixedly connected with the rear wall, the heights of the first baffle and the second baffle are flush with the first water inlet, and the first baffle and the right wall of the casing and the second baffle and the left wall of the casing are formed respectively. Water supply compartment; the front wall of the casing between the first baffle and the second baffle is provided with a plurality of second water outlets; the rear wall of the casing between the first baffle and the second baffle is provided with a plurality of sampling The sampling port is provided with a sampling pipeline, and the sampling pipeline is provided with a valve; it also includes a first peristaltic pump for adding water and a second peristaltic pump for adding pollutants, and the first water inlet is respectively connected with the first peristaltic pump through the connecting pipeline. The pump and the water outlet of the second peristaltic pump are connected;

The base is arranged at the bottom of the shell, and the lower surface of the bottom wall of the shell is fixedly connected with the upper surface of the base; the upper surface of the base is also provided with a pressure measuring plate, and a plurality of pressure measuring pipes are vertically arranged on the pressure measuring plate; the plurality of second water outlets are respectively Connect with the lower ends of a plurality of pressure measuring tubes through pipes;

The circulation well includes a first circular tube vertically arranged on the bottom surface of the seepage tank, the top of the first circular tube is provided with a top cover, and the bottom is closed; The screen tube and the upper solid tube are connected; the walls of the lower solid tube, the middle solid tube and the upper solid tube are impermeable to water, and the walls of the lower screen tube and the upper solid tube are provided with a plurality of water permeable holes; a water-permeable diaphragm; the inner center of the first round pipe is provided with a coaxial first pipe, and the lower end of the first pipe passes through the top cover and the diaphragm in sequence and extends downward to the lower screen pipe; also includes a second pipe, the first pipe The lower end of the second pipeline passes through the top cover and extends downward to the upper screen pipe; it also includes a circulating pump, the upper end of the first pipeline is connected to the water inlet of the circulating pump; the upper end of the second pipeline is connected to the water outlet of the circulating pump;

The injection well includes a second round pipe; the second round pipe is vertically arranged on one side of the first round pipe in the seepage tank, the bottom of the second round pipe is closed, and the pipe wall of the second round pipe is provided with a plurality of permeable screen holes, and also It includes a dosing tube and a third peristaltic pump, the head end of the dosing tube is connected with the output end of the third peristaltic pump, and the end of the dosing tube extends into the second round tube.

Preferably, the number of the second water outlets is 50, which are evenly arranged in 5 rows from top to bottom, 10 second water outlets in each row are evenly arranged from left to right, and the distance between two adjacent second water outlets is 100mm .

Preferably, the number of pressure measuring tubes is 50.

Preferably, the number of sampling ports is 50, evenly arranged in 5 rows from top to bottom, 10 sampling ports in each row are evenly arranged from left to right, and the distance between two adjacent sampling ports is 100mm.

Preferably, the base is a stainless steel bracket, and a sliding wheel is provided on the outer side of the lower surface of the stainless steel bracket.

Preferably, the right side of the first baffle plate and the left side of the second baffle plate are respectively provided with a stainless steel screen or a nylon screen.

Preferably, the outer side walls of the first circular tube and the second circular tube are respectively provided with a stainless steel screen or a nylon screen.

Preferably, the aqueous medium includes any one or more of coarse sand, medium sand, fine sand, silt or clay.

A dynamic simulation experiment method for a groundwater circulation well, comprising the following steps:

Step 1, put a circulation well and a drug injection well in the seepage tank, and then fill the water-containing medium in the seepage tank;

Step 2: Turn on the first peristaltic pump to flow water into the seepage tank to simulate groundwater. After the water-containing medium is saturated, turn on the circulating pump to start the circulating well, and add an equal amount of tracer every 100 mm along the horizontal direction at 50 mm below the upper surface of the water-containing medium. , trace and characterize the hydraulic circulation characteristics of groundwater in circulating wells;

Step 3: After the circulation well is running stably, observe the variation range of the water level in each piezometric tube, and calculate the influence radius of the circulation well by measuring the distance between the two piezometric tubes in the same row where the water level changes significantly and the farthest from the circulation well;

Step 4: Turn off the circulating pump, turn on the second peristaltic pump, and release the supersaturated solution of organic pollutants with known concentration from the first water inlet of the seepage tank to simulate the migration process of organic pollutants in different aqueous media;

Step 5: Turn off the second peristaltic pump, take samples to measure the concentration of pollutants therein; turn on the circulating pump to start the circulating well, turn on the third peristaltic pump after the circulating well runs stably, and deliver chemicals to the aqueous medium, and then turn off the circulating pump and the third peristaltic pump , sample and analyze the concentration of pollutants in groundwater, and obtain the remediation efficiency of groundwater circulation wells for the organic pollutants.

Further preferably, it also includes step 6, replacing the circulating pump in steps 1 to 3 with a variable frequency pump to adjust the circulating flow rate of groundwater in the water-containing medium; The generated high-pressure water directly acts on the water-containing medium 2 in the seepage tank 1 to change the porosity or permeability coefficient of the water-containing medium, and conduct an amplification simulation experiment of the influence radius of the groundwater circulation well.

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

The groundwater circulating well dynamic simulation experiment system and method of the present invention can accurately simulate the organic pollution of groundwater circulating wells to various organic pollutions of different properties under various conditions (different water-bearing media, different groundwater flow rates, different circulating well structures, and different circulating modes). Remediation experiments of organic pollutants, the experimental device has various functions, can comprehensively and accurately simulate the dynamic remediation process of groundwater circulation wells on organic pollutants, can accurately monitor and expand the influence radius of groundwater circulation wells, and can be used for the research and development of groundwater circulation well remediation technology. Provide theoretical basis and technical support for popularization and application.

Description of drawings

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

Fig. 1 is the overall structure schematic diagram of the simulation experiment system of the present invention;

Fig. 2 is the left side view of the simulation experiment system;

Fig. 3 is the top view of the simulation experiment system;

Fig. 4 is the structural representation of circulating well;

Fig. 5 is the structural schematic diagram of the injection well;

Fig. 6 is the schematic diagram of the three-dimensional elliptical flow field after the circulating well is running stably;

Reference numerals are: 1. Seepage tank, 2. Base, 3. Circulation well, 4. Injection well, 11. Housing, 12. Aqueous medium, 13. First water outlet, 14. First water inlet, 15 .First drain, 16. First baffle, 17. Second baffle, 18. Second water outlet, 19. Sampling port, 21. Pressure measuring plate, 22. Pressure measuring tube, 31. First round pipe, 32. Diaphragm, 33. First pipe, 34. Second pipe, 35. Lower solid pipe, 36. Lower screen pipe, 37. Middle solid pipe, 38. Upper screen pipe, 39. Upper solid pipe, 41. The second round tube, 42. The permeable mesh, 43. The dosing tube.

Detailed ways

The embodiments of the present invention will be described in detail below in conjunction with the examples, but those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

Referring to FIG. 1 , it is a schematic diagram of the overall structure of the simulation experiment system of the present invention. Figures 2 and 3 are the left and top views of the experimental system, respectively.

A dynamic simulation experiment system for groundwater circulation wells, comprising a seepage tank 1, a base 2, a circulation well 3 and a drug injection well 4;

The seepage tank 1 includes a rectangular casing 11 with an upper opening and an aqueous medium 12 arranged in the casing; also includes a first peristaltic pump for adding water and a second peristaltic pump for adding pollutants; the upper end of the right wall of the casing A first water outlet 13 is provided, the first water outlet 13 is provided with a first water outlet pipe, and a valve is arranged on the first water outlet pipe; the lower end of the left wall of the casing is provided with a first water inlet 14, and the first water inlet 14 is connected through a pipe It is respectively connected with the water outlet of the first peristaltic pump and the second peristaltic pump, and the connecting pipe is provided with a valve; the bottom of the casing is provided with a first water outlet 15 near the first water inlet; A first baffle 16 is provided in the vertical direction, and a second baffle 17 is vertically arranged in the casing near the first water inlet. The first baffle and the second baffle are respectively provided with a plurality of holes, in order to prevent the water-containing medium from entering the water supply. In the compartment, the right side of the first baffle and the left side of the second baffle are respectively provided with stainless steel screens or nylon screens.

The lower ends of the first baffle plate 16 and the second baffle plate 17 are respectively fixedly connected to the upper surface of the bottom wall of the casing. The front and rear sides of the first baffle plate 16 and the second baffle plate 17 are respectively fixedly connected to the front wall and the rear wall of the casing. The heights of a baffle 16 and a second baffle 17 are flush with the first water inlet, and a water supply compartment is formed between the first baffle and the right wall of the casing and between the second baffle and the left wall of the casing; The water outlet of a peristaltic pump is connected to the first water inlet through a pipeline, and the first peristaltic pump inputs distilled water into the water supply compartment between the first baffle and the left wall of the shell, and the distilled water gradually drives out the air in the pores of the aqueous medium, infiltrating the water. Aqueous medium. In this example, distilled water is used to simulate groundwater.

The front wall of the casing 11 between the first baffle 16 and the second baffle 17 is provided with a plurality of second water outlets 18; the rear wall of the casing 11 between the first baffle 16 and the second baffle 17 is provided with There are a plurality of sampling ports 19, the sampling ports are provided with sampling pipes, the sampling pipes are provided with valves, and the sampling ports are used to take water samples and measure the concentration of pollutants therein.

The base is arranged at the bottom of the casing 11, and the lower surface of the bottom wall of the casing 11 is fixedly connected with the upper surface of the base 2; the upper surface of the base 2 is also provided with a pressure measuring plate 21, and a plurality of pressure measuring tubes 22 are vertically arranged on the pressure measuring plate; The second water outlets 18 are respectively communicated with the lower ends of the plurality of piezometric tubes through pipes; the piezometric tubes are used to display the water levels of the plurality of second water outlets, and the water level value of the piezometric tubes is recorded after the water level is stabilized.

Specifically, the seepage tank is made of plexiglass, the shell size is 1200mm×400mm×600mm, the base is a stainless steel bracket with sliding wheels, and there are water supply compartments with a width of 100mm on the left and right sides of the seepage tank. In order to simulate different water-bearing media, any one of coarse sand, medium sand, fine sand, silt or clay can be used to simulate homogeneous groundwater aquifers, or different combinations of various water-bearing media can be used to simulate heterogeneous groundwater aquifers Floor. The first water inlet can be connected to a first peristaltic pump with adjustable flow through a hose, thereby simulating different groundwater flow rates. In this embodiment, the hose is a latex tube.

Specifically, in order to realize the measurement of the influence radius of the groundwater circulation well, 50 second water outlets are set on the front wall of the shell between the first baffle plate and the second baffle plate, with a total of 5 rows and 10 columns, and the spacing is 100mm. There are 1-5 rows and 1-10 columns from top to bottom, from left to right, and 50 glass pressure measuring tubes are vertically arranged on the side pressure plate. The above-mentioned 50 second water outlets are communicated with the lower part of the 50 glass pressure measuring tubes through the latex tube, and the top of the pressure measuring tube is communicated with the atmosphere, so as to discharge the air in the pores of the aqueous medium; between the first baffle plate and the second baffle plate There are 50 sampling ports on the rear wall of the shell, a total of 5 rows and 10 columns, with a spacing of 100mm, 1-5 rows and 1-10 columns from top to bottom, left and right, respectively, for taking water samples and measuring The concentration of pollutants in it.

Referring to FIG. 4, it is a schematic diagram of the structure of the circulation well; the circulation well 3 includes a first circular pipe 31 vertically arranged on the bottom surface of the seepage tank 1, the top of the first circular pipe 31 is provided with a top cover, and the bottom is closed; From bottom to top, the lower solid pipe 35, the lower screen pipe 36, the middle solid pipe 37, the upper screen pipe 38 and the upper solid pipe 39 are connected; There are a plurality of water permeable holes in the pipe wall of the upper screen and the upper screen; the middle part of the solid pipe 37 is horizontally provided with an impermeable diaphragm 32; It passes through the top cover and the diaphragm 32 in sequence and extends downward to the lower screen pipe 36; also includes a second pipe 34, the lower end of the second pipe 34 passes through the top cover and extends down to the upper screen pipe 38; also includes a circulating pump,

The upper end of the first pipe 33 is connected to the water inlet of the circulation pump; the upper end of the second pipe 34 is connected to the water outlet of the circulation pump; the connection mode of the circulation pump can be changed. Wherein, the position of the first round pipe 31 in the seepage tank 1 can be moved as required.

Specifically, the circulating well adopts a plexiglass circular tube with a diameter of 200-300 mm and a height of 600-900 mm. The outer side wall of the plexiglass circular tube is provided with a stainless steel screen or a nylon screen; in order to simulate circulating wells of different structures, the organic glass The glass round tube is designed as 5 independent round tubes connected by snaps. From bottom to top, they are the lower solid tube 35, the lower screen tube 36, the middle solid tube 37, the upper screen tube 38 and the upper solid tube 39. The pipe wall of the pipe, the middle solid pipe and the upper solid pipe is impermeable to water, and the pipe walls of the lower screen pipe and the upper screen pipe are provided with a plurality of permeable holes; the upper screen pipe and the lower screen pipe can be set with different sieve hole diameters or hole spacing, Different heights of pipes, lower screen pipes, upper solid pipes and lower solid pipes can be selected to realize the change of position and quantity of circulating well solid pipes and screen pipes.

The hydraulic circulation of the circulating well includes two modes: forward circulation and reverse circulation. In the forward circulation mode, the upper end of the first pipe is connected to the water inlet of the circulation pump, the upper end of the second pipe is connected to the water outlet of the circulation pump, and the water flows in from the lower screen. Flow out from the upper screen; the flow direction outside the well is from top to bottom, thus forming an elliptical flow field around the circulation well; in the reverse circulation mode, the upper end of the second pipe is connected to the water inlet of the circulation pump, and the first pipe The upper end of the pump is connected to the water outlet of the circulating pump, so that the flow direction of the water inside and outside the well is opposite to the positive circulation. As shown in Fig. 6, it is a schematic diagram of the three-dimensional elliptical flow field after the circulating well runs stably. By changing the connection mode of the circulating pump with the first pipeline and the second pipeline, the hydraulic circulation operation mode of the circulating well can be switched.

Figure 5 is a schematic diagram of the structure of the injection well. The injection well 4 includes a second round pipe 41; the second round pipe 41 is vertically arranged on one side of the first round pipe 31 in the seepage tank 1, the bottom of the second round pipe 41 is closed, and the wall of the second round pipe is provided with multiple A permeable sieve 42 also includes a dosing tube 43 and a third peristaltic pump 44. The head end of the dosing tube is connected to the output end of the third peristaltic pump, and the end of the dosing tube extends into the second round tube. The position of the second round pipe 41 in the seepage tank 1 is movable.

Specifically, the injection well adopts a plexiglass circular tube with a diameter of 100-200 mm and a height of 600-900 mm, and a plurality of permeable screen holes are arranged on the wall of the plexiglass circular tube with a height of less than 550 mm. A stainless steel screen or a nylon screen is provided; the plexiglass circular tube can be provided with permeable screen holes with different aperture sizes or hole spacings.

A dynamic simulation experiment method for a groundwater circulation well, comprising the following steps:

Step 1, put a circulation well and a drug injection well in the seepage tank, and then fill the water-containing medium in the seepage tank;

In order to simulate different water-bearing media, any one of coarse sand, medium sand, fine sand, silt or clay can be used to simulate homogeneous groundwater aquifers, or different combinations of various water-bearing media can be used to simulate heterogeneous groundwater aquifers Floor. Before sand filling, first determine the positions of the circulation wells and injection wells, and put them into the circulation wells and injection wells; after that, the selected water-bearing medium or combination of water-bearing media can be filled in the seepage tank layer by layer, and the filling height is 550mm. . During the filling process, the water-containing medium is continuously tamped, on the one hand, to ensure that the medium is filled evenly, and on the other hand, to ensure that the circulation well and the injection well are firmly fixed.

Step 2: Turn on the first peristaltic pump to flow water into the seepage tank to simulate groundwater. After the water-containing medium is saturated, turn on the circulating pump to start the circulating well, and add an equal amount of tracer every 100 mm along the horizontal direction at 50 mm below the upper surface of the water-containing medium. , trace and characterize the hydraulic circulation characteristics of groundwater in circulating wells;

In this embodiment, distilled water is fed into the seepage tank to simulate groundwater. Specifically, the first water inlet is connected to the first peristaltic pump so that the distilled water is evenly and slowly filled into the water supply compartment, and the air in the pores of the aqueous medium is gradually displaced. When the top surface of the aqueous medium is completely wet and a thin layer of water overflows, The medium has been completely saturated, and the water level of each pressure measuring tube should be kept flush. Different groundwater flow rates can be simulated by adjusting the flow rate of the first peristaltic pump, and at the same time, the valve of the first water outlet is controlled so that the water level fluctuation in the water supply compartments on both sides does not exceed 5mm. After the groundwater flow rate was stabilized, the circulating pump was turned on, and the circulating well began to run. An equal amount of tracer was added every 100 mm in the horizontal direction at 50 mm below the upper surface of the aqueous medium through a long needle tube. Due to the indication effect of the tracer, the groundwater will form a visualized elliptical flow field around the circulation well, as shown in Figure 6, and the elliptical flow field will gradually expand with the running time of the simulated circulation well.

The hydraulic circulation of the circulating well includes two modes: forward circulation and reverse circulation. In the forward circulation mode, the upper end of the first pipe is connected to the water inlet of the circulation pump, the upper end of the second pipe is connected to the water outlet of the circulation pump, and the water flows in from the lower screen. Flow out from the upper screen; the flow direction outside the well is from top to bottom, thus forming an elliptical flow field around the circulation well; in the reverse circulation mode, the upper end of the second pipe is connected to the water inlet of the circulation pump, and the first pipe The upper end of the circulating pump is connected to the water outlet of the circulating pump, so that the flow direction of the water inside and outside the well is opposite to that of the positive circulation; by changing the connection mode of the circulating pump with the first pipeline and the second pipeline, the hydraulic circulation operation mode of the circulating well can be switched. . The hydraulic circulation characteristics of groundwater circulation wells under different conditions can be described by filling different water-bearing media, changing the combination of real tubes and screen tubes of the circulating well, and changing the operation mode of the circulating well.

Step 3: After the circulation well is running stably, observe the variation range of the water level in each piezometric tube, and calculate the influence radius of the circulation well by measuring the distance between the two piezometric tubes in the same row where the water level changes significantly and the farthest from the circulation well;

After the circulation well operates stably, the water level in each piezometer varies widely. The water level in the piezometer close to the circulation well varies greatly, while the water level in the piezometer far from the circulation well changes little or not. Measure the distance between the two piezometric tubes in the same row where the water level changes significantly and is the farthest from the circulation well. Half of the distance is the influence radius of the circulation well. In the above-mentioned groundwater circulation well simulation repair experiment, open the circulation well and record its water level value after the water level of each piezometer is basically stable, and the influence radius of the circulation well can be calculated.

Step 4: Turn off the circulating pump, turn on the second peristaltic pump, and release the supersaturated solution of organic pollutants with known concentration from the first water inlet of the seepage tank to simulate the migration process of organic pollutants in different aqueous media;

After the circulating pump is turned off and the groundwater flow rate is stabilized, the second peristaltic pump is turned on, and the supersaturated solution of known concentration of organic pollutants is released into the aqueous medium at a certain rate through the first water inlet of the seepage tank. During the release of pollutants, water samples were taken at regular intervals through the sampling ports distributed on the back of the seepage tank and the concentration of pollutants was measured to obtain the migration law of the organic matter in groundwater. By changing the aqueous medium filled in the seepage tank or the type of organic pollutants released, the migration laws of organic pollutants with different properties in different aqueous media can be obtained; in addition, the first peristalsis connected to the first water inlet can be changed by changing The flow rate of the pump can be used to analyze the influence of groundwater flow rate on the transport law of pollutants in the aqueous medium.

Step 5: Turn off the second peristaltic pump, and measure the concentration of pollutants therein; turn on the circulating pump to start the circulating well, turn on the third peristaltic pump after the circulating well runs stably, and deliver the medicine to the aqueous medium, and then turn off the circulating pump and the third peristaltic pump, Sampling and analyzing the concentration of pollutants in groundwater, the remediation efficiency of groundwater circulation wells for the organic pollutants is obtained.

After the groundwater pollution has progressed to the expected time, the second peristaltic pump is turned off, and the water sample is taken through the sampling port to measure the concentration of the pollutants therein. After that, the circulating pump is turned on to make the circulating well run. After the circulating well is stable, the third peristaltic pump is turned on to deliver chemicals of known concentration, such as redox agents, catalysts, surfactants, etc., at a slow rate. After the system runs for a period of time, the circulating pump and the third peristaltic pump are turned off, and after the groundwater level is stabilized, samples are taken at the sampling port to analyze the concentration of pollutants in the groundwater. By comparing the variation law of pollutant concentration at each sampling port before and after the circulation well is opened, the remediation efficiency of the organic pollutants in the groundwater circulation well can be obtained.

Before the remediation experiment starts, the forward/reverse circulation mode should be determined according to the nature and distribution characteristics of the pollutants. Light non-aqueous liquid (LNAPL) pollutants with a specific gravity smaller than water are easy to accumulate in the upper part of the aquifer. In this case, the circulation mode prioritizes reverse circulation, which can avoid the forward circulation carrying and diffusing the upper pollutants to the lower part of the aquifer. Conversely, for heavy non-aqueous phase liquid (DNAPL) pollutants distributed in the lower part of the aquifer, the positive circulation mode is preferred.

Step 6, carry out the amplification simulation experiment of the influence radius of the groundwater circulation well; replace the circulating pump in steps 1 to 3 with a variable frequency pump to adjust the circulating flow rate of groundwater in the aqueous medium; or add an external connection in steps 1 to 3 The high-pressure water gun directly acts the high-pressure water generated by the high-pressure water gun on the water-containing medium in the seepage tank to change the porosity or permeability coefficient of the water-containing medium, thereby changing the circulating flow rate of groundwater in the water-containing medium.

Specifically, by replacing the circulating pump with a variable frequency pump, the influence radius of the circulating well before and after the frequency conversion or before and after the action of the high-pressure water jet can be obtained.

Example 1

Step 1, place the circulation well in the center of the seepage tank, and place the injection well at a distance of 100 mm from the circulation well along the long axis of the seepage tank. The center point of the circulation well and the injection well is on a diameter line. The height of the upper and lower screen tubes of the first circular tube of the circulation well is both 70mm, the height of the lower solid tube is 40mm, the height of the middle solid tube is 380mm, and the height of the upper solid tube is 140mm; Each permeable sieve hole is arranged on the second round pipe wall from the bottom of the second round pipe to the height of 550mm. The diameter of the screen holes of the circulation well and the injection well is 6mm, and the hole spacing is 8mm. After the positions of the circulation well and the injection well are determined, the homogeneous medium sand with a sieved particle size of 0.25-0.5 mm is filled layer by layer into the seepage tank to simulate an aqueous medium. The filling height is 550mm, and it is continuously tamped during the filling process.

Step 2, connect the first water inlet of the seepage tank to the first peristaltic pump so that the distilled water is evenly and slowly filled into the water supply compartment, and the flow rate of the first peristaltic pump is 10ml/min. The air in the pores of the water-containing medium is gradually displaced, so that the water-containing medium is completely saturated; at this time, the water level in the seepage tank is 550 mm. Open the valve of the first water outlet, and adjust the valve so that the fluctuation of the water level in the water supply compartments on both sides does not exceed 5mm. Connect the upper end of the first pipeline to the water inlet of the circulating pump, and the upper end of the second pipeline to the water outlet of the circulating pump. Turn on the circulating pump to make the groundwater circulating well start to circulate positively. The flow rate of the circulating pump is set to 30ml/min. When the circulation well is running stably, the soil non-adsorbable sodium fluorescein tracer solution is added along the long axis of the seepage tank through a long needle tube. 50mm. Through the trajectory of sodium fluorescein tracer, the elliptical flow field formed by groundwater around the circulating well can be observed with the naked eye.

Step 3: After the circulation well is running stably, the water level in each piezometer varies in different amplitudes. The 5th and 6th piezometric pipes near the circulation well have relatively large changes in water level, and the 5th and 1st row piezometric water level rises. The maximum height is 45mm, and the maximum height of the piezometric pipe in the fifth row and fifth row is 73mm; ; The water level of the piezometric pipes in the 8th row and the 1st row is 8mm, and the water level of the 5th row of piezometric pipes is 11mm; while the water levels of the piezometric pipes in the 1st, 2nd and 9th and 10th rows far from the circulation well are basically not Variety. According to the influence radius of the circulation well, 1/2 of the distance between the two piezometric tubes farthest from the circulation well, the water level changes obviously in the same row, and it can be obtained that the flow rate of the groundwater is 10ml/min and the flow rate of the circulation well is 30ml/min. Under the experimental conditions that the height of the upper and lower screens of the circulating well is 70 mm, and the distance between the two screens is 380 mm, the influence radius of the circulating well is 250 mm.

Step 4: Turn off the circulating pump, and after the circulating well stops running, turn on the second peristaltic pump, and release the supersaturated solution of benzene with a concentration of 1800 mg/L through the first water inlet of the seepage tank, and the release rate is synchronized with the groundwater flow rate. is 10ml/min. The release of pollutants continued for 50 days, and sampling was carried out at the sampling port every 5 days. Shimadzu GC-2010 gas chromatographic analyzer was used to measure the concentration of benzene in water samples at different sampling ports, and the migration law of benzene in groundwater was analyzed.

By analyzing the variation law of benzene concentration with time, it can be seen that benzene migrates both horizontally and vertically after entering the groundwater. In the first 10d, only the concentration of benzene can be detected within 300mm from the water inlet. With the prolongation of the release time, the concentration of benzene in the sampling port farther from the release point gradually increased, indicating that the pollution area formed by benzene in the groundwater gradually expanded. On the 40th day of the release, the concentration of benzene can be detected in the water samples taken from all sampling ports, and the pollution has basically covered the entire seepage tank. When the pollution lasted for 50 days, the highest concentration of benzene in all water samples was 99.5 mg/L, and the average concentration was 45.03 mg/L.

Step 5, after the groundwater pollution has progressed to the 50th day, the second peristaltic pump is turned off. Because the density of benzene is lower than that of water, it belongs to light non-aqueous phase fluid (LNAPL). for the reverse cycle. After the circulation well runs stably, the third peristaltic pump is turned on, the flow rate is set to 5ml/min, the potassium permanganate KMnO ₄ solution with a concentration of 500mg/L is delivered to the aqueous medium, and the timing is started, and the circulation well and injection are stopped every 1h. The operation of the medicine well, and the water sample is taken from the sampling port for the determination of the pollutant concentration. With the prolongation of the reaction time, the concentration of pollutants in each sampling port gradually decreased. After accumulative reaction for 9 hours, benzene could not be detected in most of the water samples. Only the individual sampling port at the bottom of the seepage tank and the farthest from the circulation well could detect it. When the concentration of benzene reaches 3 mg/L, the pollutants are fully and effectively degraded, and the degradation rate can reach 93.34-100%.

Step 6, replace the circulating pump in step 1 to step 3 with a variable frequency pump with adjustable frequency, first set the frequency of the variable frequency pump to 25Hz, the circulating flow under this frequency is 30ml/min, and the first peristaltic pump flow is set to 25Hz. It is set as 10ml/min. Under the experimental conditions that the height of the upper and lower screens of the circulating well is 70mm, and the distance between the two screens is 380mm, the influence radius of the circulating well is measured to be 250mm.

Then keep the flow rate of the first peristaltic pump at 10ml/min, increase the frequency of the variable frequency pump to 40Hz, the circulation flow at this frequency is 70ml/min, the height of the upper and lower screen tubes in the circulation well is 70mm, and the distance between the two screen tubes is 70mm. Under the experimental condition of 380mm, the influence radius of the circulating well is measured to be 350mm.

In steps 1 to 3, an external high-pressure water gun is connected. After the water pressure at the water outlet is stabilized, the pressure is measured to be 50 bar, and the high-pressure water sprayed is directly applied to the aqueous medium. Among them, the nozzle of the high-pressure water gun is attached to the top surface of the water-containing medium, and acts a little every 100mm along the long axis of the seepage tank, and the acting time of each point is 10 minutes. Then, under the experimental conditions that the groundwater flow rate is 10ml/min, the flow rate of the circulation well is 30ml/min, the height of the upper and lower screens of the circulation well is 70mm, and the distance between the two screens is 380mm, the circulation well is measured under the experimental conditions. The radius of influence is 350mm.

By comparing the influence radius of the circulating well before and after the variable frequency speed regulation and before and after the action of the high-pressure jet, it can be seen that the influence radius of the circulating well has been expanded from 250mm to 350mm under the same other experimental conditions.

The invention can accurately simulate the remediation experiments of groundwater circulation wells under various conditions, and the experimental devices have various functions, can comprehensively and accurately simulate the dynamic restoration process of groundwater circulation wells to organic pollutants, and can accurately monitor and expand groundwater circulation wells. The influence radius can provide theoretical basis and technical support for the research, popularization and application of groundwater circulation well remediation technology.

Although the present invention has been described in detail with general description and specific embodiments in this specification, some modifications or improvements can be made on the basis of the present invention, which will be obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention fall within the scope of the claimed protection of the present invention.

Claims (10)

1. A dynamic simulation experiment system of an underground water circulating well is characterized by comprising a seepage groove (1), a base (2), a circulating well (3) and a chemical injection well (4);

the seepage groove (1) comprises a rectangular shell (11) with an upper opening and a water-containing medium (12) arranged in the shell; a first water outlet (13) is formed in the upper end of the right wall of the shell, a first water inlet (14) is formed in the lower end of the left wall of the shell, and a first water drainage opening (15) is formed in the bottom of the shell, close to the first water inlet; a first baffle (16) is vertically arranged at a position close to the first water outlet in the shell, a second baffle (17) is vertically arranged at a position close to the first water inlet in the shell, a plurality of holes are respectively formed in the first baffle and the second baffle, the lower ends of the first baffle (16) and the second baffle (17) are respectively fixedly connected with the upper surface of the bottom wall of the shell, the front side and the rear side of the first baffle (16) and the rear side of the second baffle (17) are respectively fixedly connected with the front wall and the rear wall of the shell, the heights of the first baffle (16) and the second baffle (17) are flush with the first water inlet, and water supply compartments are respectively formed between the first baffle and the right wall of the shell and between the second baffle and the left wall of the shell; a plurality of second water outlets (18) are formed in the front wall of the shell (11) between the first baffle plate (16) and the second baffle plate (17); a plurality of sampling ports (19) are arranged on the rear wall of the shell (11) between the first baffle plate (16) and the second baffle plate (17), sampling pipelines are arranged at the sampling ports, and valves are arranged on the sampling pipelines; the device also comprises a first peristaltic pump for adding water and a second peristaltic pump for adding pollutants, wherein the first water inlet (14) is respectively connected with the water outlets of the first peristaltic pump and the second peristaltic pump through connecting pipelines;

the base (2) is arranged at the bottom of the shell (11), and the lower surface of the bottom wall of the shell (11) is fixedly connected with the upper surface of the base (2); the upper surface of the base (2) is also provided with a pressure measuring plate (21), and a plurality of pressure measuring pipes (22) are vertically arranged on the pressure measuring plate; the second water outlets (18) are respectively communicated with the lower ends of the pressure measuring pipes through pipelines;

the circulating well (3) comprises a first circular pipe (31) vertically arranged on the bottom surface of the seepage groove (1), a top cover is arranged at the top of the first circular pipe, and the bottom of the first circular pipe is closed; the first round pipe (31) is formed by connecting a lower solid pipe (35), a lower sieve pipe (36), a middle solid pipe (37), an upper sieve pipe (38) and an upper solid pipe (39) from bottom to top; the pipe walls of the lower solid pipe, the middle solid pipe and the upper solid pipe are watertight, and a plurality of water permeable holes are formed in the pipe walls of the lower sieve pipe and the upper sieve pipe; a watertight diaphragm plate (32) is horizontally arranged in the middle of the middle solid pipe (37); a coaxial first pipeline (33) is arranged in the center of the inner part of the first circular pipe, and the lower end of the first pipeline (33) sequentially penetrates through the top cover and the diaphragm plate (32) and extends downwards to a screen pipe (36); the lower end of the second pipeline (34) penetrates through the top cover and extends downwards to an upper sieve pipe (38); the upper end of the first pipeline (33) is connected with a water inlet of the circulating pump; the upper end of the second pipeline (34) is connected with a water outlet of the circulating pump;

the medicine injection well (4) comprises a second round pipe (41); second pipe (41) are vertical to be set up in one side of first pipe (31) in seepage flow groove (1), and second pipe (41) bottom is sealed, second pipe wall is provided with a plurality of sieve meshes (42) that permeate water, still includes with medicine pipe (43) and third peristaltic pump, add medicine pipe head end with the output of third peristaltic pump is connected, and the end that adds the medicine pipe stretches into in the second pipe.

2. A dynamic simulation experiment system for a groundwater circulation well according to claim 1, wherein the number of the second water outlets (18) is 50, the second water outlets are uniformly arranged in 5 rows from top to bottom, each row of the second water outlets (18) is uniformly arranged in 10 rows from left to right, and the distance between every two adjacent second water outlets (18) is 100 mm.

3. A dynamic simulation experiment system of a ground water circulation well according to claim 1, wherein the number of the pressure measuring pipes (22) is 50.

4. A dynamic simulation experiment system for a groundwater circulation well according to claim 1, wherein the number of the sampling ports (19) is 50, the sampling ports are uniformly arranged in 5 rows from top to bottom, each row of the sampling ports is uniformly arranged in 10 rows from left to right, and the distance between two adjacent sampling ports is 100 mm.

5. A dynamic simulation experiment system for a groundwater circulation well according to claim 1, wherein the base is a stainless steel bracket, and a sliding wheel is arranged on the outer side of the lower surface of the stainless steel bracket.

6. A dynamic simulation experiment system of a groundwater circulation well according to claim 1, wherein a stainless steel screen or a nylon screen is respectively arranged on the right side of the first baffle plate and the left side of the second baffle plate.

7. A dynamic simulation experiment system of a groundwater circulation well according to claim 1, wherein the outer side walls of the first round pipe (31) and the second round pipe (41) are respectively provided with a stainless steel screen or a nylon screen.

8. A dynamic simulation experiment system of a groundwater circulation well according to claim 1, wherein the aqueous medium (12) comprises any one or more of coarse sand, medium sand, fine sand, silt or clay.

9. A dynamic simulation experiment method of an underground water circulating well is characterized by comprising the following steps:

step 1, putting a circulation well and a medicine injection well into a seepage groove, and then filling a water-containing medium into the seepage groove;

step 2, starting a first peristaltic pump to feed water simulation underground water into the seepage groove, starting a circulating pump to start a circulating well after the water-containing medium is saturated with water, adding equal amount of tracer agents at the position 50mm below the upper surface of the water-containing medium along the horizontal direction every 100mm, and tracing and depicting the hydraulic circulation characteristics of the underground water in the circulating well;

step 3, observing the water level change amplitude in each pressure measuring pipe after the circulation well runs stably, and calculating the influence radius of the circulation well by measuring the distance between two pressure measuring pipes which are obviously changed in water level in the same row and are farthest from the circulation well;

step 4, closing the circulating pump, starting the second peristaltic pump, releasing supersaturated solution of organic pollutants with known concentration from the first water inlet of the seepage tank, and simulating the migration process of the organic pollutants in different water-containing media;

step 5, closing the second peristaltic pump, sampling and determining the concentration of the pollutants in the second peristaltic pump; and starting the circulating pump to start the circulating well, starting the third peristaltic pump after the circulating well runs stably to convey the medicament to the aqueous medium, then closing the circulating pump and the third peristaltic pump, and sampling and analyzing the concentration of the pollutants in the underground water to obtain the repairing efficiency of the underground water circulating well for the organic pollutants.

10. The method for simulating the dynamic state of the underground water circulating well according to the claim 9, characterized in that the method further comprises the step 6 of replacing the circulating pump in the steps 1 to 3 with a variable frequency pump to adjust the circulating flow rate of the underground water in the water-containing medium; or externally connecting a high-pressure water gun in the steps 1 to 3, and directly applying high-pressure water generated by the high-pressure water gun to the water-containing medium in the seepage tank so as to change the porosity or permeability coefficient of the water-containing medium and perform an amplification simulation experiment on the influence radius of the underground water circulating well.

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