Groundwater pollution prevention and control system and method coupled with vertical barrier and drainage blind ditch

Abstract

The present invention relates to the technical field of groundwater pollution prevention and control, and specifically to a groundwater pollution prevention and control system and method coupled with vertical barriers and drainage blind ditches, comprising a vertical barrier system and an underground drainage blind ditch system; the vertical barrier system is arranged upstream of the pollution corona of the polluted storage yard, and the bottom of the vertical barrier system extends into a relative impermeable layer; an underground drainage blind ditch system is arranged on the upstream side of the vertical barrier system, and the underground drainage blind ditch system drains the clean water upstream of the pollution corona to the downstream of the pollution corona. The present invention organically combines the vertical barrier system and the underground drainage blind ditch system to block and intercept the uncontaminated groundwater upstream and drain it downstream after avoiding the polluted storage yard, thereby minimizing the amount of groundwater entering the pollution source storage yard from the upstream, reducing the generation of pollution, and eliminating the need for long-term operation in the later stage.

Description

Technical Field

[0001] The present invention relates to the technical field of groundwater pollution prevention and control, and in particular to a groundwater pollution prevention and control system and method coupled with vertical barriers and drainage blind ditches. Background Art

[0002] Vertical barrier technology is a commonly used method in groundwater pollution prevention and control. It utilizes different types of low-permeability materials to block the spread of pollution along groundwater runoff pathways. For historical tailings, waste rock piles, landfills, and hazardous waste landfills left in valley depressions, where pollutants continuously release from upstream groundwater flows or soaks through, causing environmental problems downstream and surrounding groundwater and soil contamination, vertical barrier technology is an important and critical technical means for reducing the amount of water leaching solid waste from upstream groundwater recharge sources when implementing on-site control measures.

[0003] Based on the hydrogeological survey of the site where the pile is located, the analysis of the drainage conditions, the acquired data on stratum lithology, thickness, distribution, hydrogeological parameters of each layer, groundwater level, geotechnical parameters, etc., vertical barriers are arranged at appropriate sections upstream of the historical dump and landfill. The vertical curtain permeability coefficient is generally required to be no greater than 1.0×10 -7 cm / s, and needs to penetrate a certain depth into the relative aquiclude below the storage yard to minimize groundwater infiltration. However, the relative aquiclude below most storage yards has a permeability coefficient greater than 1.0×10 -7 cm / s or less than 1.0×10 -7 cm / s is too deep, if the vertical barrier permeability coefficient is less than the relative aquitard, overflow recharge may occur, leading to project failure, or if it is less than 1.0×10 - 7 cm / s relative aquiclude is too deep to be explored and constructed, and the construction is complex, long, and costly. In addition, even if the aquiclude is less than 1.0×10 -7 The vertical barrier substrate can be located at a permeability of less than 1.0×10 -7 cm / s relative aquiclude will cause the groundwater level upstream of the barrier to rise, increasing water pressure. The use of pumping wells to reduce pressure inside the barrier will be indefinite and increase operating costs. Therefore, it is urgent and necessary to find a solution to this problem when using vertical barrier technology. This method must maximize the efficiency of the barrier measure while minimizing adverse effects and be feasible in construction and economy. Summary of the Invention

[0004] The purpose of the present invention is to provide a groundwater pollution prevention and control system and method coupled with vertical barriers and drainage blind ditches, which can minimize the amount of groundwater entering the pollution source pile from upstream, reduce the generation of pollution, and effectively solve the problems of upstream water level rise and water pressure increase caused by a simple vertical barrier system, or the problem of groundwater in the aquifer flowing to its lower part after barrier to continue to replenish the pollution source, as well as the problem of indefinite pumping and drainage operation caused by the combination of vertical barriers and groundwater pumping and drainage wells.

[0005] To achieve the above-mentioned purpose, the technical solution of the present invention is a groundwater pollution prevention and control system coupled with vertical barriers and drainage blind ditches, including a vertical barrier system and an underground drainage blind ditch system; the vertical barrier system is arranged upstream of the pollution corona of the contaminated storage yard, and the bottom of the vertical barrier system extends into the relative impermeable layer; an underground drainage blind ditch system is arranged on the upstream side of the vertical barrier system, and the underground drainage blind ditch system drains the clean water upstream of the pollution corona to the downstream of the pollution corona.

[0006] Furthermore, a coupling system is provided below the underground drainage blind ditch system below the perennially stable groundwater level, and the coupling system is connected to the vertical barrier system.

[0007] Furthermore, the coupling system includes an impermeable bottom plate, which is arranged at the junction of the aquifer and the relative aquiclude or at the junction of the aquifer and the aquifer.

[0008] Furthermore, the underground drainage blind ditch system includes a drainage blind ditch, and the drainage blind ditch located below the perennial stable groundwater level adopts a flower pipe, and the permeability coefficient of the flower pipe is much greater than 1.0×10 -7 cm / s; the drainage blind ditch located above the perennial stable groundwater level line adopts solid pipes.

[0009] Furthermore, the bottom of the vertical barrier system extends at least 3-5 meters into the relative waterproof layer.

[0010] Furthermore, the vertical barrier system includes a vertical barrier wall, and an anti-corrosion layer is provided on the downstream side of the vertical barrier wall.

[0011] Furthermore, the groundwater pollution prevention and control system also includes an emergency system, which includes a liquid level switch, a pumping mechanism and a controller. The water inlet end of the pumping mechanism and the liquid level switch are buried above the perennial stable groundwater level line on the upstream side of the vertical barrier system, and the liquid level switch and the pumping mechanism are both connected to the controller.

[0012] The present invention also provides a groundwater pollution prevention and control method coupled with vertical barrier and drainage blind ditch, comprising the following steps:

[0013] S1. Obtain basic topographic data of the contaminated landfill site, the top and bottom depths of the aquifer, and the top depth of the relative aquiclude, and construct a three-dimensional geological model;

[0014] S2. Based on the 3D geological model and the acquired hydrogeological parameters, the groundwater system of the contaminated landfill site is delineated according to boundary conditions and a hydrogeological conceptual model is established;

[0015] S3. Based on Darcy's law, rainfall infiltration method, water balance analysis method and three-dimensional finite element method of unsteady flow, a three-dimensional unsteady flow mathematical model corresponding to the hydrogeological conceptual model is established, and the initial flow field is obtained through simulation of the three-dimensional unsteady flow mathematical model;

[0016] After simulating the initial flow field, parameter identification and model verification are performed, and the model is corrected to make the simulation results match the actual situation. After obtaining the confirmed flow field data, the engineering scenario is set.

[0017] S4. Design different combinations of the location and depth of the vertical barrier system, coupling system, and underground drainage blind ditch system based on the number of aquifers above the relative aquiclude, the thickness, bottom depth, water yield, permeability coefficient, and perennial stable groundwater level of each aquifer;

[0018] S5. Incorporate different combinations of vertical barrier systems into a three-dimensional unsteady flow mathematical model to calculate the amount of water that can be reduced by upstream and lateral replenishment water entering the contaminated landfill after adding the vertical barrier system. Simulate and predict the increase in head value or overflow replenishment water caused by the water level rise after the barrier.

[0019] S6. Based on the increased head value due to water level rise or the amount of water supplied by overflow, the size of the drainage blind ditch is calculated according to Darcy's law. Different combinations of drainage blind ditch size and location are applied to the three-dimensional unsteady flow mathematical model obtained in step S5. After iterative or repeated debugging is performed to calculate whether the flow that can be intercepted and drained after the vertical barrier system and the drainage blind ditch system are added meets the requirements;

[0020] S7. Through simulation calculations of working conditions in different combinations, combined with considerations of on-site construction conditions and economic costs, determine the location and depth of the vertical barrier system, coupling system, and underground drainage ditch system used in the contaminated landfill, as well as the size of the drainage ditch.

[0021] Furthermore, the mathematical model of the three-dimensional unsteady flow in step S3 is as follows:

[0022]

[0023] H(x,y,z,0)=H0,(x,y,z)∈Ω

[0024]

[0025] H(x,y,z,t)=H1, (x,y,z)∈S1

[0026] Where, Ω: groundwater seepage area, dimension: L 2 ;

[0027] H0: initial groundwater level, dimension: L;

[0028] H1: specified water level, dimension: L;

[0029] S1: first type boundary;

[0030] S2: second type of boundary;

[0031] μ s : Unit water storage coefficient, dimension: L -1 ;

[0032] K xx , K yy , K zz : The permeability coefficients in the x, y, and z directions, respectively, dimension: LT -1 ;

[0033] w: Source and sink items, including evaporation, rainfall infiltration recharge, and well pumping, dimension: T -1 ;

[0034] q(x, y, z, t): represents the flow at different locations on the boundary at different times, dimension: L 3 T -1 ;

[0035] Represents the component of the hydraulic gradient on the boundary normal.

[0036] Furthermore, in step S6, after the working conditions of different combinations are brought into the three-dimensional unsteady flow mathematical model, the rainfall intensity of the multi-year heavy rainstorm is used as the supply input source and sink term w, the head value increased by the water level rise or the amount of water supplied by overflow is calculated, and the position of the liquid level switch and the processing capacity of the pumping and drainage mechanism are designed.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The present invention organically combines a vertical barrier system with an underground drainage blind ditch system to block and intercept uncontaminated groundwater upstream and drain it downstream, avoiding the contaminated pile. This can minimize the amount of groundwater entering the pollution source pile from upstream, reduce the generation of pollution, and eliminate the need for long-term operation in the later stage. It effectively solves the problems of upstream water level rise and water pressure increase caused by a simple vertical barrier system, or the problem of groundwater in the aquifer flowing to its lower part to continue to replenish the pollution source after the barrier, as well as the problem of indefinite pumping and drainage operation caused by the combination of vertical barrier and groundwater pumping and drainage well technology.

[0039] (2) The present invention provides a coupling system below the underground drainage blind ditch system located below the perennial stable groundwater level, thereby supporting the underground drainage blind ditch system. At the same time, the coupling system is connected to the vertical barrier system, which facilitates the entry of upstream groundwater into the underground drainage blind ditch system.

[0040] (3) The present invention further ensures the long-term effectiveness and stability of the entire system by adding an emergency system. In the event of heavy rain or continuous heavy rainfall, when the water level upstream of the vertical barrier system continues to rise and the pressure of the vertical barrier system and the underground drainage blind ditch system increases suddenly, the water level is raised to trigger the liquid level switch urgently, temporarily start the pumping mechanism to relieve the water pressure, and avoid damage to the vertical barrier system and the underground drainage blind ditch system in an emergency.

[0041] (4) The groundwater pollution prevention and control system and method of the present invention are applicable to valley-topped storage yards, and historical tailings slag yards, landfills and other polluted storage yards that have no impermeable layer or whose impermeable layer has been damaged at the bottom of the storage yard. Pollutants will be released during the flow or soaking of groundwater, causing environmental problems. When on-site control is required, the existing terrain can be utilized to apply the technical method of coupling vertical barriers with underground drainage blind ditches to reduce the groundwater entering the storage yard from upstream, so as to achieve the purpose of reducing pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 A schematic plan view of a groundwater pollution prevention and control system coupled with vertical barriers and drainage blind ditches provided in the first embodiment of the present invention;

[0044] Figure 2 for Figure 1 AA view;

[0045] Figure 3for Figure 1 BB view;

[0046] Figure 4 A schematic plan view of a groundwater pollution prevention and control system coupled with vertical barriers and drainage blind ditches provided in the second embodiment of the present invention;

[0047] Figure 5 for Figure 4 AA view;

[0048] Figure 6 for Figure 4 BB view;

[0049] In the figure: 1. Contaminated pile; 2. Contamination halo; 3. Groundwater flow direction; 4. Vertical barrier system; 5. Underground drainage ditch system; 5-1. Underground drainage ditch system at the junction of aquifer 1 and aquifer 2; 5-2. Underground drainage ditch system at the junction of aquifer 2 and relative aquiclude; 5-3. Underground drainage ditch system at the junction of aquifer 1 and relative aquiclude; 6. Coupling system; 7. Emergency system; 8. Ground surface; 9. Aquifer 1; 10. Aquifer 2; 11. Relative aquiclude; 12. Perennial stable groundwater level; 13. Groundwater outflow symbol. DETAILED DESCRIPTION

[0050] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0051] The present invention provides a groundwater pollution prevention and control system coupled with vertical barriers and drainage blind ditch, comprising a vertical barrier system 4 and an underground drainage blind ditch system 5; the vertical barrier system 4 is arranged upstream of the pollution halo 2 of the contaminated storage yard, and the bottom of the vertical barrier system 4 extends into the relative impermeable layer 11; an underground drainage blind ditch system 5 is arranged on the upstream side of the vertical barrier system 4, and the underground drainage blind ditch system 5 guides the clean water upstream of the pollution halo 2 to the downstream of the pollution halo 2.

[0052] The plan of the groundwater pollution prevention and control system is as follows Figure 1 and Figure 4 As shown in the figure, the shapes and lengths of the vertical barrier system 4 and the underground drainage blind ditch system 5 are for reference only and will be set in detail according to the topography and hydrogeological conditions of the contaminated storage site. The pollution halo 2 is a typical feature and will be circled according to the investigation results.

[0053] Based on the different aquifers divided by hydrogeological conditions, it is determined that the relative impermeable layer 11 with a relatively small permeability coefficient and a certain burial depth within the hydrogeological unit where the contaminated landfill is located is located. The above-mentioned vertical barrier system 4 is set in the form of a straight line, broken line or curve at a suitable section upstream of the contaminated halo 2 of the contaminated landfill after clarifying the site's geological, structural and hydrogeological conditions and the current status of the groundwater environment, combined with the topography and stratum distribution, to reduce the upstream groundwater runoff from entering the contaminated landfill or landfill to produce leachate and pollute the environment. The underground drainage blind ditch system 5 coupled to the vertical barrier system 4 diverts uncontaminated underground water from the upstream. Through the design layout, it avoids the contaminated landfill 1 and is drained to the downstream, where it can be directly discharged or merged into other water systems without causing pollution to the environment.

[0054] In the present invention, when on-site control is adopted for polluted storage yards such as valley storage yards or landfills, the vertical barrier system 4 can block the upstream water flow from entering the polluted storage yard or landfill to avoid the generation of leachate to pollute the environment. The underground drainage blind ditch system 5 can divert the blocked upstream water to the maximum extent according to the terrain to avoid overflow recharge due to the vertical barrier system 4 having a lower permeability coefficient than the relative impermeable layer 11 or the water level rise and water pressure increase on the upstream side due to the vertical barrier system 4 having a lower permeability coefficient than the blocked aquifer, which has an adverse effect on the barrier effect. Through the organic combination of the vertical barrier system 4 and the underground drainage blind ditch system 5, the upstream uncontaminated groundwater is blocked, intercepted and drained to the downstream avoiding the polluted storage body 1 to avoid environmental problems. Long-term operation is not required in the later stage, and the operating cost is reduced. It is particularly suitable for valley management areas that do not have operating conditions.

[0055] Furthermore, the vertical barrier system 4 includes a first vertical barrier wall installed directly upstream of the contaminated landfill site's contamination zone 2. When the perennially stable groundwater levels 12 on both sides upstream of the contamination zone 2 are above the top surface of the relative aquiclude 11, second vertical barrier walls can be installed on both sides upstream of the contamination zone 2, with both ends of the first vertical barrier wall integrally connected to the second vertical barrier walls on either side. When the perennially stable groundwater levels 12 on both sides upstream of the contamination zone 2 are below the top surface of the relative aquiclude 11, second vertical barrier wall can be omitted. Furthermore, the bottom of either the first vertical barrier wall or the second vertical barrier wall extends at least 3-5 meters into the relative aquiclude 11 to ensure the water interception and stability of the vertical barrier wall.

[0056] As a further optimization, an anti-corrosion coating is installed on the downstream side of vertical barrier walls 1 and 2. This coating is formed by coating the surface of the vertical barrier walls with existing acid- and alkali-resistant materials. If the groundwater upstream of the contaminated storage yard becomes acidic or alkaline, this coating protects the vertical barrier walls from damage caused by acid or alkali corrosion.

[0057] Furthermore, the underground drainage blind ditch system 5 includes a drainage blind ditch 1 set just upstream of the pollution halo 2 of the contaminated landfill and drainage blind ditches 2 on both sides of the upstream of the pollution halo 2 of the contaminated landfill, and the two ends of the drainage blind ditch 1 are connected to the drainage blind ditches 2 on both sides thereof. The drainage blind ditch 2 can be laid out from high to low along the terrain or with a certain slope in combination with the stratum development, so that the intercepted groundwater is discharged downstream of the pollution halo 2 while meeting the maximum tolerable flow rate, forming an artificially created groundwater runoff advantage channel. Among them, the drainage blind ditch 1 and the drainage blind ditch 2 need to have strong water conduction and pressure bearing capacity and can effectively prevent debris such as rock fragments from entering and blocking the channel. Specifically, when the drainage blind ditch 1 and the drainage blind ditch 2 are located below the perennial stable groundwater level line 12, the drainage blind ditch 1 and the drainage blind ditch 2 can use flower pipes, and the permeability coefficient needs to be much greater than 1.0×10 -7 cm / s. For example, drainage blind ditch 1 and drainage blind ditch 2 can use a permeability coefficient of 1 cm / s. When drainage blind ditch 2 is located above the perennial stable groundwater level 12, it can use a solid pipe to receive the water from drainage blind ditch 1 and discharge it downstream. Using the groundwater watershed and vertical barrier system 4 as the zero-flux boundary, delineate the groundwater recharge range. Calculate and design the internal cross-sectional dimensions of drainage blind ditch 1 and drainage blind ditch 2 to meet the required drainage capacity.

[0058] Furthermore, a coupling system 6 is provided below the underground drainage blind ditch system 5 below the perennially stable groundwater level, and the coupling system 6 is connected to the vertical barrier system 4. The coupling system 6 can support the underground drainage blind ditch system 5 and facilitate the entry of upstream groundwater into the underground drainage blind ditch system 5.

[0059] Furthermore, the coupling system 6 includes an anti-seepage bottom plate 1 arranged just upstream of the pollution halo 2 of the contaminated storage yard, the anti-seepage bottom plate 1 is located below the drainage blind ditch 1, and the anti-seepage bottom plate 1 is connected to the vertical barrier wall 1; when the drainage blind ditch 2 is located below the perennial stable groundwater level line 12, the drainage blind ditch 2 adopts a flower pipe, and an anti-seepage bottom plate 2 can be arranged below it, and the anti-seepage bottom plate 2 is connected to the vertical barrier wall 2, and the two ends of the anti-seepage bottom plate 1 are respectively connected to the anti-seepage bottom plates 2 on both sides thereof to form a whole, the anti-seepage bottom plate can play the role of supporting the drainage blind ditch, and at the same time serve as the waterproof bottom surface of the drainage blind ditch to block water, avoid the water flowing into the blind ditch from seeping in, and is more conducive to the entry of groundwater into the drainage blind ditch; when the drainage blind ditch 2 is located above the perennial stable groundwater level line 12, the drainage blind ditch 2 adopts a solid pipe, and an anti-seepage bottom plate 2 may not be arranged below it.

[0060] Optimally, when the anti-seepage bottom plate 1 and the anti-seepage bottom plate 2 are located below the perennial stable groundwater level line 12, when there is an aquifer above the relative aquiclude 11, the anti-seepage bottom plate 1 and / or the anti-seepage bottom plate 2 are arranged at the junction of the aquifer and the relative aquiclude 11; when there are two aquifers above the relative aquiclude 11, the anti-seepage bottom plate 1 and / or the anti-seepage bottom plate 2 are arranged at the junction of the upper aquifer and the lower aquifer and at the junction of the lower aquifer and the relative aquiclude 11.

[0061] Furthermore, the groundwater pollution prevention and control system also includes an emergency system 7, which can be activated to increase the pumping capacity when the upstream pressure suddenly increases. Specifically, the emergency system 7 includes a liquid level switch, a pumping mechanism and a controller. The water inlet end and the liquid level switch of the pumping mechanism are buried above the perennial stable groundwater level line 12 on the upstream side of the vertical barrier system 4. The liquid level switch and the pumping mechanism are both connected to the controller. When the perennial stable groundwater level line 12 is located above the top surface of the relative aquiclude 11, the emergency system 7 can be set above the perennial stable groundwater level line 12 to further ensure the long-term effectiveness and stability of the entire system. In the event of heavy rain or continuous heavy rainfall, the water level upstream of the vertical barrier system 4 continues to rise, and the pressure of the vertical barrier system 4 and the underground drainage blind ditch system 5 suddenly increases. The liquid level switch is triggered urgently by the rise of the water level, and the pumping mechanism is temporarily activated to relieve the water pressure, thereby avoiding damage to the vertical barrier system 4 and the underground drainage blind ditch system 5 in an emergency.

[0062] The vertical barrier system 4, coupling system 6, underground drainage blind ditch system 5, and emergency system 7 of the present invention, aside from meeting the aforementioned requirements and conditions, have no specific restrictions on the materials, preparation methods, and styles selected, and can be tailored to the actual project needs and requirements. The groundwater pollution control system of this embodiment is primarily suitable for use in scenarios where the depth relative to the aquiclude 11 is shallow and excavation is feasible.

[0063] Example 1

[0064] When the contaminated landfill is located in a valley, there are two aquifers above the relative impermeable layer 11 upstream of the storage area, namely Aquifer 19 and Aquifer 2 10. The bottom of the contaminated landfill is buried deep in the lower Aquifer 2 10. The perennial stable groundwater level 12 just upstream of the storage area and on one side of the upstream is above the bottom of Aquifer 19 in the upper layer, and the perennial stable groundwater level 12 on the other side of the upstream is below the bottom of Aquifer 19 and above the top of Aquifer 2 10. The water from the upstream of the landfill and the mountains on both sides is groundwater recharge from the pollution source.

[0065] like Figure 1-Figure 3As shown, in order to reduce the recharge of groundwater and thus reduce the degree of pollution, this embodiment provides a groundwater pollution prevention and control system coupled with vertical barriers and drainage blind ditches, including a vertical barrier system 4, an underground drainage blind ditch system 5 and a coupling system 6; the vertical barrier system 4 includes a vertical barrier wall 1 set just upstream of the pollution corona 2 of the pollution yard and vertical barrier walls 2 set on both sides of the upstream of the pollution corona 2, and the two ends of the vertical barrier wall 1 are respectively connected to the vertical barrier walls 2 on both sides thereof to form a whole, and the bottoms of the vertical barrier wall 1 and the vertical barrier wall 2 extend into the relative impermeable layer 11; the coupling system 6 includes an anti-seepage bottom plate 1 set just upstream of the pollution corona 2 of the pollution yard and anti-seepage bottom plates 2 set on both sides of the upstream of the pollution corona 2, the junction of the aquifer 1 9 and the aquifer 2 10 just upstream of the pollution corona 2 and the junction of the aquifer 2 10 and the relative impermeable layer 11 are both provided with an anti-seepage bottom plate 1, and the aquifer 2 10 on both sides of the upstream of the pollution corona 2 and the relative impermeable layer 11 are both provided with a anti-seepage bottom plate 1, An anti-seepage bottom plate 2 is provided at the junction of the aquiclude 11. An anti-seepage bottom plate 2 is also provided at the junction of aquifer 1 9 and aquifer 2 10 on the side where the perennially stable groundwater level 12 is located above the bottom surface of aquifer 1 9. An anti-seepage bottom plate 2 is not provided at the junction of aquifer 1 9 and aquifer 2 10 on the side where the perennially stable groundwater level 12 is located below the bottom surface of aquifer 1 9. One side of the anti-seepage bottom plate 1 and the anti-seepage bottom plate 2 are connected to the vertical barrier wall 1 and the vertical barrier wall 2, respectively. The two ends of the anti-seepage bottom plate 1 are connected to the corresponding anti-seepage bottom plates 2 on both sides thereof; the underground drainage blind ditch system 5 includes a drainage blind ditch 1 arranged just upstream of the pollution halo 2 of the contaminated storage yard and a drainage blind ditch 2 arranged on the upstream side of the pollution halo 2. The anti-seepage bottom plate 1 is provided with a drainage blind ditch 1, and the anti-seepage bottom plate 2 is provided with a drainage blind ditch 2. The two ends of the drainage blind ditch 1 are connected to the corresponding drainage blind ditch 2 on both sides thereof, wherein the drainage blind ditch 1 and the drainage blind ditch 2 can both adopt flower pipes.

[0066] The design method of the above-mentioned groundwater pollution prevention and control system is as follows:

[0067] First, the geological and hydrogeological conditions were investigated to obtain basic topographic data, the number of aquifer layers, the thickness of the aquifers, the top and bottom surface depths, and the top surface depth and thickness of the relative aquiclude. A three-dimensional geological model was constructed. Based on the three-dimensional geological model and the obtained hydrogeological parameters, the groundwater system at the storage site was delineated according to boundary conditions and a hydrogeological conceptual model was established. Then, based on Darcy's law, the rainfall infiltration method, the water balance analysis method, and the three-dimensional finite element method for unsteady flow, a three-dimensional unsteady flow mathematical model corresponding to the hydrogeological conceptual model was established. The initial flow field was simulated using the three-dimensional unsteady flow mathematical model.

[0068] The mathematical model of three-dimensional unsteady flow is as follows:

[0069]

[0070] H(x,y,z,0)=H0,(x,y,z)∈Ω

[0071]

[0072] H(x,y,z,t)=H1, (x,y,z)∈S1

[0073] Where, Ω: groundwater seepage area, dimension: L 2 ;

[0074] H0: initial groundwater level, dimension: L;

[0075] H1: specified water level, dimension: L;

[0076] S1: first type boundary;

[0077] S2: second type of boundary;

[0078] μ s : Unit water storage coefficient, dimension: L -1 ;

[0079] K xx , K yy , K zz : The permeability coefficients in the x, y, and z directions, respectively, dimension: LT -1 ;

[0080] w: Source and sink items, including evaporation, rainfall infiltration recharge, and well pumping, dimension: T -1 ;

[0081] q(x, y, z, t): represents the flow at different locations on the boundary at different times, dimension: L 3 T -1 ;

[0082] represents the component of the hydraulic gradient on the boundary normal;

[0083] The three-dimensional unsteady flow mathematical model incorporates Darcy's law, rainfall infiltration, and water balance analysis. This model simulates the initial flow field. After simulating the initial flow field, parameter identification and model verification are performed, and the model is calibrated to ensure that the simulation results match the actual situation. Once the flow field data is confirmed, the engineering scenario is set.

[0084] Then, based on the topography, the thickness of aquifer 1 9 and aquifer 2 10 above the aquifer 11, the bottom burial depth, the water yield or permeability coefficient of each layer, and the stable groundwater level throughout the year, different combinations of the location and depth of the vertical barrier system 4, the coupling system 6, and the underground drainage blind ditch system 5 are listed. For example, an underground drainage blind ditch system 5 can be separately established at the bottom of aquifer 1 9 and the bottom of aquifer 2 10, that is, at the top of the aquifer 11, or they can be jointly established to form an underground drainage blind ditch system 5.

[0085] After the initial layout and depth of the vertical barrier system 4 and the underground drainage blind ditch system 5 were set, the initial flow field was brought into the three-dimensional unsteady flow mathematical model for calculation and simulation. The first hydraulic calculation after the superposition measures only considered the vertical barrier system 4, and the permeability coefficient of this system was 1.0×10 -7 cm / s, calculate the amount of water that can be reduced by the upstream supply water entering the contaminated pile 1 after the vertical barrier, and simulate and predict the head value or the amount of water supplied by the overflow after the barrier; in the second step, based on the calculation and simulation prediction results of the first step, calculate the amount of groundwater that needs to be drained by the underground drainage blind ditch system 5, process the drainage water volume data, calculate the drainage blind ditch size according to Darcy's law, and bring the different combination working conditions of the drainage blind ditch size and setting position into the obtained three-dimensional unsteady flow mathematical model, iteratively or repeatedly debug and calculate whether the flow that can be intercepted and drained meets the requirements after the vertical barrier system is added with the drainage blind ditch system, and simultaneously consider the effect of the coupling system 6, and all of them are brought into the simulation calculation results of the first step.

[0086] Finally, through simulation calculations of different set scenarios, combined with considerations of on-site construction conditions and economic costs, an optimal design scheme for groundwater pollution prevention and control in this plot was obtained, which combines vertical barriers with underground drainage blind ditches.

[0087] To account for the possibility of extremely heavy or sustained rainfall, an emergency system 7 was installed upstream, above the perennially stable groundwater level 12. This rising water level triggers a level switch, activating the pumping mechanism to remove the sudden surge in groundwater, ensuring the long-term effectiveness and stability of the entire system. The scale of emergency system 7 is based on the three-dimensional unsteady flow mathematical model established after incorporating the engineering measures described in step 2. By varying the source-sink term w and using the recharge input of a 20-year extreme rainstorm, the model calculates the additional water volume, thereby designing the position of the level switch and the handling capacity of the pumping mechanism. Emergency system 7 is deployed upstream and on both sides of the contaminated pile 1.

[0088] Example 2

[0089] When a contaminated landfill is located in a valley, there is an aquifer 9 above the relative aquitard 11 upstream of the landfill. The bottom of the landfill is buried deep into the relative aquitard 11, and the bottom of the landfill is also buried deep into the relative aquitard 11 relative to the mountains on either side. Aquifer 11 is thicker just upstream, and the perennially stable groundwater level 12 lies above the bottom of aquifer 11. However, the mountains on either side are narrow and thin, and the perennially stable groundwater level on either side is deeper, essentially below the bottom of aquifer 11. Water from upstream and from the mountains on either side of the landfill provides groundwater recharge for the pollution source.

[0090] like Figure 4-Figure 5 As shown, in order to reduce the recharge of groundwater and thus reduce the degree of pollution, this embodiment provides a groundwater pollution prevention and control system that is coupled with a vertical barrier and a drainage blind ditch, including a vertical barrier system 4, an underground drainage blind ditch system 5 and a coupling system 6; the vertical barrier system 4 includes a vertical barrier wall 1 arranged just upstream of the pollution halo 2 of the contaminated storage yard, and the bottom of the vertical barrier wall 1 extends into the relative impermeable layer 11; the coupling system 6 includes an anti-seepage bottom plate 1 arranged just upstream of the pollution halo 2 of the contaminated storage yard, and the anti-seepage bottom plate 1 is arranged between the aquifer 9 and the relative impermeable layer 11. At the junction of the water layer 11, one side of the anti-seepage bottom plate is connected to the vertical barrier wall 1; the underground drainage blind ditch system 5 includes a drainage blind ditch 1 arranged just upstream of the pollution halo 2 of the contaminated dump and a drainage blind ditch 2 arranged on both sides of the upstream of the pollution halo 2. The two ends of the drainage blind ditch 1 are respectively connected to the drainage blind ditch 2 on both sides. The drainage blind ditch 1 is arranged on the anti-seepage bottom plate 1, and the drainage blind ditch 2 is arranged on the top surface of the relative impermeable layer 11. The drainage blind ditch 1 adopts a flower pipe, and the drainage blind ditch 2 adopts a solid pipe arranged downward along the terrain to drain the groundwater blocked upstream to the downstream.

[0091] The design method of the above-mentioned groundwater pollution prevention and control system is as follows:

[0092] First, based on the geological and hydrogeological conditions obtained from the survey, basic topographic data, the number of aquifer layers, the thickness of the aquifer and the top and bottom surface burial depths, and the top surface burial depth and thickness of the relative aquiclude 11 are obtained to build a three-dimensional geological model. Then, based on the three-dimensional geological model and the obtained hydrogeological parameters, the groundwater system where the storage site is located is delineated according to the boundary conditions, and a hydrogeological conceptual model is established. Then, based on Darcy's law, rainfall infiltration method, water balance analysis method and three-dimensional finite element method of unsteady flow, a three-dimensional unsteady flow mathematical model corresponding to the hydrogeological conceptual model is established, and the initial flow field is obtained by simulating the three-dimensional unsteady flow mathematical model; the three-dimensional unsteady flow mathematical model is the same as that in Example 1.

[0093] After simulating the initial flow field, parameter identification and model verification are performed, and the model is corrected to make the simulation results match the actual situation. After obtaining the confirmed flow field data, the engineering scenario is set.

[0094] Then, based on the topography, the number of aquifer layers above the relative impermeable layer 11, the thickness of each aquifer, the bottom burial depth, the water yield, the permeability coefficient and the perennial stable groundwater level, different combinations of the location and depth of the vertical barrier system 4, the coupling system 6 and the underground drainage blind ditch system 5 are listed.

[0095] After the initial layout and depth of the vertical barrier system 4 and the underground drainage blind ditch system 5 were set, the initial flow field was brought into the three-dimensional unsteady flow mathematical model for calculation and simulation. The first hydraulic calculation after the superposition measures only considered the vertical barrier system 4, and the permeability coefficient of this system was 1.0×10 -7 cm / s, calculate the amount of water that can be reduced by the upstream supply water entering the contaminated pile 1 after the vertical barrier, and simulate and predict the head value or the amount of water supplied by the overflow after the water level rises after the barrier; in the second step, based on the calculation and simulation prediction results of the first step, calculate the amount of groundwater that needs to be drained by the underground drainage blind ditch system 5, process the drainage water volume data, calculate the drainage blind ditch size according to Darcy's law, and bring the drainage blind ditch size and setting position of different combination working conditions into the three-dimensional unsteady flow mathematical model obtained in step S5, iteratively or repeatedly debug and calculate whether the flow that can be intercepted and drained meets the requirements after the vertical barrier system is added with the drainage blind ditch system, and simultaneously consider the role of the coupling system 6, and all of them are brought into the simulation calculation results of the first step.

[0096] Finally, through simulation calculations, combined with on-site construction conditions and economic cost considerations, the optimal design scheme for groundwater pollution prevention and control in this plot was obtained, which is a method that couples vertical barriers with underground drainage blind ditches.

[0097] To account for the possibility of extremely heavy rainstorms or sustained heavy rainfall, an emergency system 7 is installed upstream, above the perennially stable groundwater level line 12. This rise in water level triggers an emergency level switch, which in turn activates the pumping mechanism to remove the sudden increase in groundwater, ensuring the long-term effectiveness and stability of the entire system. The scale of the emergency system 7 is based on the three-dimensional unsteady flow mathematical model established after incorporating the engineering measures in the second step above. By changing the source-sink term w and using the 20-year extreme rainstorm intensity as the recharge input, the model calculates the increased water volume, thereby designing the location of the level switch and the processing capacity of the pumping mechanism. Emergency system 77 is deployed upstream and on both sides of the contaminated pile 1. Emergency system 7 is deployed upstream of the contaminated pile 1.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A groundwater pollution prevention and control system coupled with vertical barrier and drainage blind ditch, characterized by: It includes a vertical barrier system and an underground drainage blind ditch system; the vertical barrier system is arranged upstream of the pollution corona of the contaminated landfill, and the bottom of the vertical barrier system extends into the relative impermeable layer; an underground drainage blind ditch system is arranged on the upstream side of the vertical barrier system, and the underground drainage blind ditch system drains the clean water upstream of the pollution corona to the downstream of the pollution corona; a coupling system is arranged below the underground drainage blind ditch system below the perennial stable groundwater level line, and the coupling system is connected to the vertical barrier system; the coupling system includes an anti-seepage bottom plate, and the anti-seepage bottom plate is arranged at the junction of the aquifer and the relative impermeable layer or at the junction of the aquifer and the aquifer.

2. The groundwater pollution prevention and control system coupled with vertical barrier and drainage blind ditch according to claim 1, characterized in that: The underground drainage blind ditch system includes a drainage blind ditch. The drainage blind ditch located below the perennial stable groundwater level adopts a flower pipe, and the permeability coefficient of the flower pipe is much greater than 1.0×10 -7 cm / s; the drainage blind ditch located above the perennial stable groundwater level line adopts solid pipes.

3. The groundwater pollution prevention and control system coupled with vertical barrier and drainage blind ditch according to claim 1, characterized in that: The bottom of the vertical barrier system extends at least 3-5 meters into the relative waterproof layer.

4. The groundwater pollution prevention and control system coupled with vertical barrier and drainage blind ditch according to claim 1, characterized in that: The vertical barrier system includes a vertical barrier wall, and an anti-corrosion layer is provided on the downstream side of the vertical barrier wall.

5. The groundwater pollution prevention and control system coupled with vertical barrier and drainage blind ditch according to claim 1, characterized in that: It also includes an emergency system, which includes a liquid level switch, a pumping mechanism and a controller. The water inlet end of the pumping mechanism and the liquid level switch are buried above the perennial stable groundwater level line on the upstream side of the vertical barrier system, and the liquid level switch and the pumping mechanism are both connected to the controller.

6. A method for preventing and controlling groundwater pollution by coupling vertical barriers with drainage blind ditches, using the groundwater pollution prevention and control system by coupling vertical barriers with drainage blind ditches as claimed in any one of claims 1 to 5, characterized in that: The method comprises the following steps: S1. Obtain basic topographic data of the contaminated landfill site, the top and bottom depths of the aquifer, and the top depth of the relative aquiclude, and construct a three-dimensional geological model; S2. Based on the 3D geological model and the acquired hydrogeological parameters, the groundwater system of the contaminated landfill site is delineated according to boundary conditions and a hydrogeological conceptual model is established; S3. Based on Darcy's law, rainfall infiltration method, water balance analysis method and three-dimensional finite element method of unsteady flow, a three-dimensional unsteady flow mathematical model corresponding to the hydrogeological conceptual model is established, and the initial flow field is obtained through simulation of the three-dimensional unsteady flow mathematical model; After simulating the initial flow field, parameter identification and model verification are performed, and the model is corrected to make the simulation results match the actual situation; After obtaining the confirmed flow field data, the engineering scenario is set; S4. Design different combinations of the location and depth of the vertical barrier system, coupling system, and underground drainage blind ditch system based on the number of aquifers above the relative aquiclude, the thickness, bottom depth, water yield, permeability coefficient, and perennial stable groundwater level of each aquifer; S5. Incorporate different combinations of vertical barrier systems into a three-dimensional unsteady flow mathematical model to calculate the amount of water that can be reduced by upstream and lateral replenishment water entering the contaminated landfill after adding the vertical barrier system. Simulate and predict the increase in head value or overflow replenishment water caused by the water level rise after the barrier. S6. Based on the increased head value due to water level rise or the amount of water supplied by overflow, the size of the drainage blind ditch is calculated according to Darcy's law. Different combinations of drainage blind ditch size and location are applied to the three-dimensional unsteady flow mathematical model obtained in step S5. After iterative or repeated debugging is performed to calculate whether the flow that can be intercepted and drained after the vertical barrier system and the drainage blind ditch system are added meets the requirements; S7. Through simulation calculations of working conditions in different combinations, combined with considerations of on-site construction conditions and economic costs, determine the location and depth of the vertical barrier system, coupling system, and underground drainage ditch system used in the contaminated landfill, as well as the size of the drainage ditch.

7. The groundwater pollution prevention and control method coupled with vertical barrier and drainage blind ditch according to claim 6, characterized in that: The mathematical model of the three-dimensional unsteady flow in step S3 is as follows: ； ； ； ； Where, Ω: groundwater seepage area, dimension: L 2 ; H0: initial groundwater level, dimension: L; H1: specified water level, dimension: L; S1: first type boundary; S2: second type of boundary; μs: unit water storage coefficient, dimension: L -1 ; K xx , K yy , K zz : The permeability coefficients in the x, y, and z directions, respectively, dimension: LT -1 ; w: Source and sink items, including evaporation, rainfall infiltration recharge, and well pumping, dimension: T -1 ; q(x, y, z, t): represents the flow at different locations on the boundary at different times, dimension: L 3 T -1 ; : Represents the component of the hydraulic gradient on the boundary normal.

8. The groundwater pollution prevention and control method coupled with vertical barrier and drainage blind ditch according to claim 6, characterized in that: In step S6, after the working conditions of different combinations are brought into the three-dimensional unsteady flow mathematical model, the rainfall intensity of the multi-year heavy rainstorm is used as the supply input source and sink term w, and the head value increased by the water level rise or the amount of water supplied by overflow is calculated, and the position of the liquid level switch and the processing capacity of the pumping and drainage mechanism are designed.

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