Wetland recovery method for coal mining subsidence area

Abstract

The invention belongs to the technical field of coal mining subsidence area treatment, and particularly relates to a coal mining subsidence area wetland recovery method which comprises the following steps: observing the flow in a non-rainy season before coal mining; observing settlement to determine the repair opportunity; reinforcing the bottom plate of the wetland after coal mining; observing the flow of the wetland in a non-rainy season after coal mining; predicting the maximum flow of the wetland in the rainy season after coal mining; predicting the maximum flow velocity of the wetland in the rainy season after coal mining; measuring the porosity ratio of shallow soil of the wetland after coal mining; constructing a flow velocity and void ratio correlation model; microbial solidification is carried out on the basis of a model prediction void ratio improvement target. The method is simple and easy to implement, and does not need a large amount of engineering; the basic structure of the ecological wetland is kept, and the recovery degree is higher; the cost is lower, grouting reinforcement of a large-scale project in an underground rock-soil layer is reduced, and the superficial surface is mainly cured by microorganisms, so that the method is more environment-friendly; the influence of coal mining on flood is considered, water and soil loss is effectively controlled, and the subsequent maintainability is recovered better.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mining subsidence area treatment, and in particular relates to a method for restoring wetlands in coal mining subsidence areas. Background Art

[0002] Wetlands in ecologically fragile areas are important biodiversity areas that need to be restored after coal mining.

[0003] Traditional ecological wetland restoration methods mainly involve direct artificial reconstruction or simple restoration, which have the following problems:

[0004] 1) Coal mining subsidence areas directly damage ecological wetlands, and artificially recreated systems lose ecological diversity and often only support part of the ecological wetland vegetation.

[0005] 2) The drainage effect of rainstorms after coal mining is not taken into account. Coal mining may cause changes in drainage units or vegetation degradation, which may easily form torrents on the surface. Torrents can cause ecological soil erosion in wetlands, which means that subsequent maintenance is poor.

[0006] 2) The large-scale chemical material grouting reinforcement of ecological wetlands has caused the degradation of the ecological environment, that is, it only protects the physical framework of the ecological wetlands but does not protect the wetland vegetation.

[0007] In view of this, the inventors hope to provide a method for restoring wetlands in coal mining subsidence areas. Summary of the Invention

[0008] The purpose of the present invention is to overcome the above-mentioned problems existing in traditional technologies and provide a method for restoring wetlands in coal mining subsidence areas.

[0009] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0010] The present invention provides a method for restoring wetlands in coal mining subsidence areas, comprising the following steps:

[0011] S1, before coal mining, observe the wetland water flow in the non-rainy season, recorded as Q0;

[0012] S2. Observe the subsidence of wetlands and wetland confluence areas during coal mining to determine the starting time for wetland restoration;

[0013] S3. After the determined wetland restoration time point, grouting reinforcement is carried out in the wetland area, and the grouting reinforcement drilling is carried out from the coal mine underground to the top;

[0014] S4. After coal mining, the water flow into the wetland in the non-rainy season is observed and recorded as Q1;

[0015] S5. After coal mining, the water flow into the wetland during the rainy season is calculated and recorded as Q2;

[0016] S6. After coal mining, the water flow rate into the wetland during the rainy season is calculated and recorded as V3;

[0017] S7. After coal mining, the surface soil of the wetland is sampled to determine its porosity ratio e0;

[0018] S8. After coal mining, the surface soil of the wetland was sampled to prepare soil samples with different porosity ratios, and scouring experiments were carried out to measure the starting scouring speed of the soil samples with different porosity ratios. The fitting method was used to construct the relationship e = f(V);

[0019] S9. Green solidification is performed on the shallow soil of the wetland. The standard for the end of solidification is that the soil porosity ratio reaches e1, e1=f(V3).

[0020] Furthermore, in step S1, when observing the wetland water flow in the non-rainy season, the flow is measured at least three times and the average value is taken.

[0021] Furthermore, in step S2, observation is conducted every 3 to 5 days until the additional amount of settlement is less than 0.1 meters for three consecutive times or the total additional amount of settlement is less than 5% of the total settlement for three consecutive times, which is the starting time point of wetland restoration.

[0022] Furthermore, in step S3, the termination criteria for grouting reinforcement are as follows:

[0023] First, representative water samples were selected from the wetland to determine the conventional ion composition;

[0024] Secondly, the ions with the 4th or higher content are selected as characterizing ions from the conventional ions, wherein the conventional ions refer to the ions determined by simple water quality analysis;

[0025] Next, the characterizing ions were continuously and evenly placed in the wetland, and the conventional ion content was measured in the water samples received downhole;

[0026] Finally, the termination standard is that the content of characteristic ions in the conventional ions of the water sample received downhole decreases by 90% or more or is no more than 1.1 times the initial content of the characteristic ions.

[0027] Furthermore, in step S4, the observation method is to observe three times and take the average value, with the interval between adjacent observations being 1 to 3 days; when Q1≤0.6Q0, the underground mine water is treated and discharged into the wetland after meeting the current emission standards until Q1>0.6Q0.

[0028] Furthermore, in step S5, the calculation method is the maximum water flow Q3 observed after the rainy season, and the water flow of the maximum rainfall in the past 10 years is compared with the current rainfall. The calculation formula is as follows:

[0029] Q2=Q3×P2÷P3

[0030] Where P2 and P3 are the rainfall during observation and the maximum rainfall intensity in 10 years, respectively.

[0031] Furthermore, in step S6, the calculation method is that the flow velocity at the rainfall intensity of the rainy season P2 is V2, and the water flow of the maximum rainfall in the past 10 years is compared with the water flow of this rainfall. The calculation formula is as follows:

[0032] V3=V2×P3÷P2

[0033] Where P2 and P3 are the rainfall during observation and the maximum rainfall intensity in 10 years, respectively.

[0034] Furthermore, in step S7, the measurement method is to take samples from different wetland units, measure at least 3 times, and take the average value.

[0035] Furthermore, in step S9, the solidifying material is prepared by mixing urea, calcium chloride, and Bacillus megaterium dry powder in a mass ratio of 1-2:1-2:0.5-2; wherein each gram of Bacillus megaterium dry powder contains more than 100 million viable bacteria.

[0036] The beneficial effects of the present invention are:

[0037] 1. Underground grouting reinforcement applies the principle of ion tracer in water, that is, the naturally weak ions in the water are rare in rock and soil and can be used as tracer ions for shallow water entering the mine.

[0038] 2. The prediction of water inflow adopts the analogy method, that is, the water inflow and rainfall during the observation period have a good correlation.

[0039] 3. Soil and water loss is affected by the starting flow velocity, which is mainly related to the porosity of the soil. Therefore, the porosity ratio e can be constrained by the flow velocity V.

[0040] 4. Chemical materials cannot be used to reinforce shallow topsoil, so green microbial mineralization materials are used. Bacillus megaterium can produce urease, which hydrolyzes to form carbonate ions, which crystallize into calcite, effectively sealing the soil's pores. Furthermore, this material itself can release phosphorus and potassium fertilizers into the soil. Existing research suggests that wetland bottom soil is rich in various substances that can be converted into forms that can be absorbed by vegetation. Furthermore, microbial mineralization can reduce the release of heavy metals, thereby reducing soil erosion and purifying water quality in wetlands.

[0041] 5. The present invention is simple and easy to implement, and does not require a large amount of engineering. It maintains the basic structure of the ecological wetland and has a higher degree of restoration. It costs less and reduces the need for large-scale grouting reinforcement in underground rock and soil layers. The shallow surface is mainly solidified by microorganisms, which is more environmentally friendly. It takes into account the impact of coal mining on floods, effectively controls soil erosion, and has better recovery and subsequent maintenance.

[0042] Of course, any product implementing the present invention does not necessarily need to achieve all of the above advantages at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. 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 creative work.

[0044] Figure 1 Schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0045] 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 any creative efforts shall fall within the scope of protection of the present invention.

[0046] like Figure 1 As shown, this embodiment provides a method for restoring wetlands in coal mining subsidence areas, comprising the following steps:

[0047] S1. Before coal mining, observe the wetland water flow in the non-rainy season, recorded as Q0; when observing the wetland water flow in the non-rainy season, measure it at least 3 times and take the average value.

[0048] S2. During the coal mining process, settlement observations are conducted on wetlands and wetland confluence areas to determine the starting time point for wetland restoration. Observations are conducted every 3 to 5 days until the additional settlement is less than 0.1 meters for three consecutive times or the total additional settlement is less than 5% of the total settlement for three consecutive times. This is the starting time point for wetland restoration.

[0049] S3. After the determined wetland restoration time point, grouting reinforcement of the wetland area shall be carried out. Grouting reinforcement drilling shall be carried out from the coal mine underground upwards. The completion criteria of grouting reinforcement are as follows:

[0050] First, representative water samples were selected from the wetland to determine the conventional ion composition;

[0051] Secondly, the ions with the 4th or higher content are selected as characterizing ions from the conventional ions, wherein the conventional ions refer to the ions determined by simple water quality analysis;

[0052] Next, the characterizing ions were continuously and evenly placed in the wetland, and the conventional ion content was measured in the water samples received downhole;

[0053] Finally, the termination standard is that the content of characteristic ions in the conventional ions of the water sample received downhole decreases by 90% or more or is no more than 1.1 times the initial content of the characteristic ions.

[0054] S4. After coal mining, the water flow into the wetland in the non-rainy season is observed and recorded as Q1. The observation method is to observe three times and take the average value, with an interval of 1 to 3 days between adjacent observations. When Q1 ≤ 0.6Q0, the underground mine water is treated and discharged into the wetland after meeting the current emission standards, until Q1 > 0.6Q0.

[0055] S5. After coal mining, the water flow into the wetland during the rainy season is calculated and recorded as Q2. The calculation method is the maximum water flow observed after the rainy season, Q3. The water flow of the maximum rainfall in the past 10 years is compared with the water flow of this rainfall. The calculation formula is as follows:

[0056] Q2=Q3×P2÷P3

[0057] Where P2 and P3 are the rainfall during observation and the maximum rainfall intensity in 10 years, respectively.

[0058] S6. After coal mining, the flow rate of water flowing into the wetland during the rainy season is calculated and recorded as V3. The calculation method is to use the flow rate at the rainfall intensity P2 during the rainy season as V2, and compare the water flow of the maximum rainfall in the past 10 years with that of this rainfall. The calculation formula is as follows:

[0059] V3=V2×P3÷P2

[0060] Where P2 and P3 are the rainfall during observation and the maximum rainfall intensity in 10 years, respectively.

[0061] S7. After coal mining, the surface soil of the wetland is sampled to determine its porosity e0; the determination method is to take samples from different wetland units, measure at least 3 times, and take the average value.

[0062] S8. After coal mining, the surface soil of the wetland was sampled to prepare soil samples with different porosity ratios, and scouring experiments were carried out to measure the starting scouring speed of the soil samples with different porosity ratios. The fitting method was used to construct the relationship e = f(V);

[0063] S9. Green solidification of shallow wetland soils. The solidification material consists of a mixture of urea, calcium chloride, and Bacillus megaterium powder in a mass ratio of 1-2:1-2:0.5-2. Each gram of Bacillus megaterium powder contains at least 100 million viable bacteria. Solidification is completed when the soil porosity reaches e1, where e1 = f(V3).

[0064] A specific application of this embodiment is:

[0065] A coal mine is located in an ecologically fragile area, but there is an ecological wetland in the area. Due to the close proximity of the wetland to the coal seam, coal mining has caused ecological degradation in the wetland. Traditional methods of chemical grouting were used to reinforce the wetland, but the ecological environment still did not improve. To better restore the functionality of the ecological wetland, this technology was used to restore the wetland. The specific steps are as follows:

[0066] S1. Before coal mining, observe the wetland water flow Q0=21.4m in the non-rainy season 3 / h, measure at least 3 times and take the average value.

[0067] S2. During coal mining, subsidence monitoring will be conducted in wetlands and their catchment areas every five days. Restoration will commence when the incremental subsidence is less than 0.1 meters for three consecutive times, or when the total incremental subsidence is less than 5% of the total subsidence for three consecutive times. Stable subsidence standards will be achieved after 265 days of coal mining.

[0068] S3: After the time point of step S2, grouting reinforcement is carried out in the wetland area. Grouting reinforcement drilling is carried out from the bottom of the coal mine to the top. The completion criteria of grouting reinforcement are as follows:

[0069] First, representative water samples were selected from the wetland to determine the general ion composition.

[0070] Secondly, among the conventional ions, the ions with the highest content after the 4th position are selected as the characterizing ions Mg 2+ The conventional ions refer to the ions tested in simple water quality analysis.

[0071] Then, the characterizing ion MgCl2 was continuously and evenly added to the wetland, and the conventional ion content in the water sample received in the well was tested to be 19.27 mol / L.

[0072] Finally, the termination standard is that the content of characteristic ions in the conventional ions of the water samples received underground drops by 90% or more to 1.12 mol / L.

[0073] S4. After coal mining, the water flow into the wetland in the non-rainy season was observed to be Q1 = 16.6m 3 The observation method is to observe three times and take the average value, with an interval of 1 to 3 days between adjacent observations.

[0074] Since Q1>0.6Q, there is no need to treat the underground mine water to meet the current discharge standards before discharging it into the wetland.

[0075] S5. After coal mining, the water flow into the wetland during the rainy season is calculated as Q2 = 162.6m 3 / h. The calculation method is the maximum water flow observed after rainfall in the rainy season, Q3 = 42.9m 3 / h, based on the analogy between the maximum rainfall in the past 10 years and the water flow of this rainfall, the calculation formula is as follows:

[0076] Q2=Q3×P2÷P3=42.9×72÷19=162.6m 3 / h, where P2 and P3 are the rainfall during observation and the maximum rainfall intensity in 10 years, respectively.

[0077] S6. After coal mining, the flow rate of water flowing into the wetland during the rainy season was calculated as V3 = 665.4 m / h. The calculation method is to use the flow rate at the rainfall intensity P2 during the rainy season as V2. Based on the water flow rate of the maximum rainfall in the past 10 years and the current rainfall, the calculation formula is as follows: V3 = V2 × P3 ÷ P2 = 175.6 × 72 ÷ 19 = 665.4 m / h, where P2 and P3 are the rainfall at the time of observation and the maximum rainfall intensity in the past 10 years, respectively.

[0078] S7. After coal mining, the surface soil of the wetland is sampled and tested to determine whether its porosity ratio e0 is 0.69. The test method is to sample different wetland units, test them at least three times, and take the average value.

[0079] S8. After coal mining, the surface soil of the wetland was sampled to prepare soil samples with different porosity ratios, and scouring experiments were carried out to measure the starting scouring speed of soil samples with different porosity ratios. The fitting method was used to construct the relationship e=0.06lnV+0.03.

[0080] S9. Green solidification of the shallow wetland soil is performed using a mixture of urea, calcium chloride, and Bacillus megaterium powder in a mass ratio of 1:1:1. Each gram of Bacillus megaterium powder contains at least 100 million viable bacteria. The standard for completion of solidification is when the soil porosity reaches e1 = 0.42, calculated as follows: e1 = f(V3) = 0.06ln665.4 + 0.03 = 0.42, where V3 is obtained in step S5 and e = f(V) is obtained in step S8.

[0081] Through the application of this technology, the ecological wetland has restored its functions, the related vegetation has not experienced large-scale degradation, and no obvious soil and water erosion has occurred.

[0082] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for restoring wetlands in coal mining subsidence areas, characterized in that: The steps include: S1, before coal mining, observe the wetland water flow in the non-rainy season, recorded as Q0; S2. Observe the subsidence of wetlands and wetland confluence areas during coal mining to determine the starting time for wetland restoration; S3. After the determined wetland restoration time point, grouting reinforcement is carried out in the wetland area, and the grouting reinforcement drilling is carried out from the coal mine underground to the top; S4. After coal mining, the water flow into the wetland in the non-rainy season is observed and recorded as Q1; S5. After coal mining, the water flow into the wetland during the rainy season is calculated and recorded as Q2; S6. After coal mining, the water flow rate into the wetland during the rainy season is calculated and recorded as V3; S7. After coal mining, the surface soil of the wetland is sampled to determine its porosity ratio e0; S8. After coal mining, the surface soil of the wetland was sampled to prepare soil samples with different porosity ratios, and scouring experiments were carried out to measure the starting scouring speed of the soil samples with different porosity ratios. The fitting method was used to construct the relationship e = f(V); S9. Green solidification is performed on the shallow soil of the wetland. The standard for the end of solidification is that the soil porosity ratio reaches e1, e1=f(V3).

2. The method for restoring wetlands in coal mining subsidence areas according to claim 1, characterized in that: In step S1, when observing the wetland water flow in the non-rainy season, at least three measurements are made and an average value is taken.

3. The method for restoring wetlands in coal mining subsidence areas according to claim 1, characterized in that: In step S2, observation is conducted every 3 to 5 days until the additional sedimentation is less than 0.1 meters for three consecutive times or the total additional sedimentation is less than 5% of the total sedimentation for three consecutive times. This is the starting time point of wetland restoration.

4. The method for restoring wetlands in coal mining subsidence areas according to claim 1, characterized in that: In step S3, the termination criteria for grouting reinforcement are as follows: First, representative water samples were selected from the wetland to determine the conventional ion composition; Secondly, the ions with the 4th or higher content are selected as characterizing ions from the conventional ions, wherein the conventional ions refer to the ions determined by simple water quality analysis; Next, the characterizing ions were continuously and evenly placed in the wetland, and the conventional ion content was measured in the water samples received downhole; Finally, the termination standard is that the content of characteristic ions in the conventional ions of the water sample received downhole decreases by 90% or more or is no more than 1.1 times the initial content of the characteristic ions.

5. The method for restoring wetlands in coal mining subsidence areas according to claim 1, characterized in that: In step S4, the observation method is to observe three times and take the average value, with the interval between adjacent observations being 1 to 3 days; when Q1≤0.6Q0, the underground mine water is treated and discharged into the wetland after meeting the current emission standards until Q1>0.6Q0.

6. The method for restoring wetlands in coal mining subsidence areas according to claim 1, characterized in that: In step S5, the calculation method is to use the maximum water flow Q3 observed after the rainy season, and compare the water flow of the maximum rainfall in the past 10 years with that of this rainfall. The calculation formula is as follows: Q2=Q3×P2÷P3 Where P2 and P3 are the rainfall during observation and the maximum rainfall intensity in 10 years, respectively.

7. The method for restoring wetlands in coal mining subsidence areas according to claim 1, characterized in that: In step S6, the calculation method is that the flow velocity at the rainfall intensity of the rainy season P2 is V2, and the water flow of the maximum rainfall in the past 10 years is compared with the water flow of this rainfall. The calculation formula is as follows: V3=V2×P3÷P2 Where P2 and P3 are the rainfall during observation and the maximum rainfall intensity in 10 years, respectively.

8. The method for restoring wetlands in coal mining subsidence areas according to claim 1, characterized in that: In step S7, the measurement method is to take samples from different wetland units, measure at least 3 times, and take the average value.

9. The method for restoring wetlands in coal mining subsidence areas according to claim 1, characterized in that: In step S9, the solidifying material is prepared by mixing urea, calcium chloride, and Bacillus megaterium dry powder in a mass ratio of 1-2:1-2:0.5-2; wherein each gram of the Bacillus megaterium dry powder contains more than 100 million viable bacteria.

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