A rock stratum grouting anti-seepage reinforcement method

Abstract

The present invention discloses a rock stratum grouting anti-seepage reinforcement method, which comprises the following steps: determining a target permeable rock stratum; detecting the target rock stratum using a geophysical prospecting method, analyzing the leakage situation, and determining a target permeable rock stratum that needs to be modified; fracturing the target permeable rock stratum with good continuity to obtain a discontinuous target permeable rock stratum; determining the grouting material and calculating the grouting amount; arranging and drilling holes; and obtaining a sandwich structure of "tough layer-support layer-tough layer" with the determined grouting amount to form an anti-seepage system. Since organic materials are added to the composite grouting material, the violent reaction of the material generates a large amount of heat to heat the generated gas, and the gas expands when heated to form a secondary thrust, thereby ensuring the grouting effect. The composite grouting material has excellent toughness and water absorption and expansion properties, which can not only eliminate the stress concentration phenomenon caused by coal mining disturbances, but also absorb water and expand to reduce the water-permeability of the overlying rock stratum, thereby solving the technical problem that the existing grouting process has a poor effect in treating water-saving coal mining problems.

Description

Technical Field

[0001] The invention belongs to the field of mine anti-seepage reinforcement, and relates to an anti-seepage reinforcement method, in particular to a rock stratum grouting anti-seepage reinforcement method. Background Art

[0002] The concept of water-conserving coal mining is mainly proposed to address a series of environmental problems that arise during the mining of shallow coal seams. The core of water-conserving mining control is to control the ecological water level. The near-surface loose porous medium aquifer with good water-richness is an aquifer with important ecological value and is the target protective layer for water-conserving coal mining in mining areas. Grouting technology is a commonly used and important means of reinforcing weak strata in underground engineering, and it is also an ideal means of achieving water-conserving coal mining. Commonly used grouting materials are mainly cement slurry, clay slurry, cement-clay slurry and chemical slurry. There are many existing grouting materials but the grouting process is single. In some mines with roof water damage and stress concentration problems caused by coal mining disturbances, water-conserving coal mining faces huge challenges, and traditional grouting processes often have poor control effects.

[0003] To address this issue, it is proposed to use a newly developed grouting material with toughness and water-absorbing expansion properties (hereinafter referred to as composite grouting material) combined with cement slurry material. According to different parts of the treatment layer, the type and sequence of grouting materials are set, so that the target rock layer that needs to be modified forms a sandwich structure of "tough layer-support layer-tough layer", thereby achieving the purpose of water-preserving coal mining. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a rock stratum grouting anti-seepage reinforcement method to solve the technical problem that the existing grouting process has a poor effect in treating water-retaining coal mining problems.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A rock stratum grouting anti-seepage reinforcement method is characterized by comprising the following steps:

[0007] Step 1: determine the target permeable rock formation;

[0008] Use geophysical methods to detect target rock formations, analyze leakage conditions, and determine target permeable rock formations that need to be modified;

[0009] Step 2: Fracturing the target permeable rock formation with good continuity to obtain a discontinuous target permeable rock formation;

[0010] Step 2.1: Determine the target permeable rock layer and conduct core sampling to obtain coal reservoir parameters, roof mechanical parameters, rock formation in-situ stress curve, and rock formation porosity;

[0011] Step 2.2: Drill a hole in the roof rock formation using a directional long drill, and use a directional drill to push the staged fracturing equipment to the designated fracturing target section;

[0012] Step 2.3: Seal the borehole with a packer. A constant pressure release high-pressure valve is connected in the middle of the packer. When the injection pressure reaches the set pressure, high-pressure water injection fracturing construction begins.

[0013] Step 2.4: When multiple pressure drops occur and the designed water injection volume is reached, the fracturing construction of the target fracturing section is terminated, and the staged fracturing equipment is moved to the next target fracturing section using a directional drill, and the fracturing construction of all target fracturing sections is completed in sequence.

[0014] During the fracturing operation, the fracturing pressure, flow rate and time are recorded in real time by the automatic data monitoring system;

[0015] Step 3: Determine the grouting material and calculate the grouting amount;

[0016] Step 3.1, dividing the target permeable rock layer into upper layer, middle layer and lower layer;

[0017] Step 3.2: Select composite grouting materials for the upper and lower layers, and cement grout materials for the middle layer;

[0018] The composite grouting material comprises fly ash or coal gangue, organic monomer, cross-linking agent, initiator and water;

[0019] The cement slurry material includes sulphoaluminate cement or ordinary Portland cement and water;

[0020] Step 3.3: Use the following formula to estimate the grouting volume V required for each layer;

[0021] Without revealing large caves or sinkholes,

[0022] V=S×δ×ξ×η×H / ω

[0023] Where:

[0024] S—grouting range, m 2 ;

[0025] H—thickness of the receiving layer, m;

[0026] η—porosity of the injection layer;

[0027] ξ—filling rate;

[0028] δ—loss coefficient;

[0029] ω—slurry setting rate;

[0030] Step 4: hole arrangement and hole forming;

[0031] Step 4.1: Use a surface grouting station to produce slurry, and deliver it to the exploration and treatment borehole through a dedicated slurry pipeline;

[0032] Step 4.2: After the area requiring grouting is determined, the spacing between grouting holes is set according to the diffusion distance of the slurry, and the drill rig and hole-forming device are used to press the drill tool into the rock formation to a predetermined depth to form grouting holes;

[0033] Step 4.3, placing a grouting sleeve into the grouting hole;

[0034] Step five, grouting;

[0035] According to the grouting material determined in step 3.2 and the grouting amount determined in step 3.3, composite grouting material, cement slurry material and composite grouting material are injected sequentially from bottom to top through the grouting sleeve to obtain a sandwich structure of "tough layer-support layer-tough layer" to form an anti-seepage system.

[0036] The present invention also includes the following technical features:

[0037] The fly ash is fine fly ash produced by wind dust removal or electrostatic precipitator in thermal power plants.

[0038] The organic monomer is acrylamide monomer; the cross-linking agent is N,N'-methylenebisacrylamide; and the initiator is ammonium persulfate or potassium persulfate.

[0039] The cement is ordinary Portland cement or sulphoaluminate cement.

[0040] The composite grouting material comprises 40-50 parts of fly ash, 5-15 parts of organic monomer, 1.5-2.5 parts of cross-linking agent, 0.5-1.5 parts of initiator and 60-80 parts of water, with a specific gravity of 1.5-1.9 t / m 3 .

[0041] The cement slurry material includes 60-90 parts of cement, 10-40 parts of fly ash and 80-100 parts of water, and the specific gravity is selected from 1.2-1.6t / m 3 .

[0042] Compared with the prior art, the present invention has the following beneficial technical effects:

[0043] (I) In the present invention, the target permeable rock layer with good continuity is fractured into a discontinuous target permeable rock layer, and then the composite grouting material, cement slurry material and composite grouting material are injected in sequence according to calculation to form an anti-seepage layer. On the one hand, since organic materials are added to the composite grouting material, the degree of material reaction can be controlled by adjusting the initiator dosage. The violent reaction of the material generates a large amount of heat to heat the generated gas, and the gas expands when heated to form a secondary thrust, which presses the slurry into finer pores, so that the grouting effect is guaranteed. On the other hand, the composite grouting material has excellent toughness and water absorption and expansion. The tough structure formed after the material is solidified can not only eliminate the stress concentration phenomenon caused by coal mining disturbance and avoid the generation of water-conducting cracks, but also absorb water and expand to reduce the water-permeability of the overlying rock layer, thereby achieving the treatment effect of water-preserving coal mining, and solving the technical problem that the existing grouting process has poor treatment effect on the problem of water-preserving coal mining.

[0044] (II) The composite grouting material of the present invention has excellent toughness and water absorption and expansion properties. However, when the surrounding environment lacks water, the material will shrink to a certain extent, resulting in the formation of new water-conducting cracks. To prevent the aquifer from being flooded again after the water source is replenished, a layer of cement slurry is injected below the composite grouting material to form a support layer. When water from the aquifer above leaks down, the support layer becomes a temporary impermeable layer to prevent the water from leaking further downward. At this time, the tough layer above begins to absorb water and expand, thereby blocking the water from the aquifer above. The bottom tough layer is provided to alleviate the stress concentration caused by coal mining disturbances, which leads to the formation of new cracks. The tough layer has excellent toughness and can effectively alleviate the stress concentration problem, thereby preventing the formation of new water-conducting cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the sandwich structure of "tough layer-support layer-tough layer" in the present invention.

[0046] The specific contents of the present invention are further explained in detail below with reference to the embodiments. DETAILED DESCRIPTION

[0047] It should be noted that, unless otherwise specified, all components in the present invention are components known in the art.

[0048] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0049] The present invention provides a rock stratum grouting anti-seepage reinforcement method, which specifically includes the following steps:

[0050] Step 1: determine the target permeable rock formation;

[0051] Use geophysical methods to detect target rock formations, analyze leakage conditions, and determine target permeable rock formations that need to be modified;

[0052] Step 2: Fracturing the target permeable rock formation with good continuity to obtain a discontinuous target permeable rock formation;

[0053] Step 2.1: Determine the target permeable rock layer and conduct core sampling to obtain coal reservoir parameters, roof mechanical parameters, rock formation in-situ stress curve, and rock formation porosity;

[0054] Step 2.2: Drill a hole in the roof rock formation using a directional long drill, and use a directional drill to push the staged fracturing equipment to the designated fracturing target section;

[0055] Step 2.3: Seal the borehole with a packer. A constant pressure release high-pressure valve is connected in the middle of the packer. When the injection pressure reaches the set pressure, high-pressure water injection fracturing construction begins.

[0056] Step 2.4: When multiple pressure drops occur and the designed water injection volume is reached, the fracturing construction of the target fracturing section is terminated, and the staged fracturing equipment is moved to the next target fracturing section using a directional drill, and the fracturing construction of all target fracturing sections is completed in sequence.

[0057] During the fracturing construction process, the fracturing pressure, flow rate and time are recorded in real time through the data automatic monitoring system;

[0058] Step 3: Determine the grouting material and calculate the grouting amount;

[0059] Step 3.1, dividing the target permeable rock layer into upper layer, middle layer and lower layer;

[0060] Step 3.2: Select composite grouting materials for the upper and lower layers, and cement grout materials for the middle layer;

[0061] The composite grouting material includes fly ash or coal gangue, organic monomer, cross-linking agent, initiator and water;

[0062] The cement slurry materials include sulphoaluminate cement or ordinary Portland cement and water;

[0063] Step 3.3: Use the following formula to estimate the grouting volume V required for each layer;

[0064] Without revealing large caves or sinkholes,

[0065] V=S×δ×ξ×η×H / ω

[0066] Where:

[0067] S—grouting range, m 2 ;

[0068] H—thickness of the receiving layer, m;

[0069] η—porosity of the injection layer;

[0070] ξ—filling rate;

[0071] δ—loss coefficient;

[0072] ω—slurry setting rate;

[0073] Step 4: hole arrangement and hole forming;

[0074] Step 4.1: Use a surface grouting station to produce slurry, and deliver it to the exploration and treatment borehole through a dedicated slurry pipeline;

[0075] Step 4.2: After the area requiring grouting is determined, the spacing between grouting holes is set according to the diffusion distance of the slurry, and the drill rig and hole-forming device are used to press the drill tool into the rock formation to a predetermined depth to form grouting holes;

[0076] Step 4.3, placing a grouting sleeve into the grouting hole;

[0077] Step five, grouting;

[0078] According to the grouting material determined in step 3.2 and the grouting amount determined in step 3.3, composite grouting material, cement slurry material and composite grouting material are injected sequentially from bottom to top through the grouting sleeve to obtain a sandwich structure of "tough layer-support layer-tough layer" to form an anti-seepage system.

[0079] In the above technical solution, the target permeable rock layer with good continuity is fractured into a discontinuous target permeable rock layer, and then the composite grouting material, cement slurry material and composite grouting material are injected in sequence according to calculations to form an anti-seepage layer. On the one hand, since organic materials are added to the composite grouting material, the degree of material reaction can be controlled by adjusting the initiator dosage. The violent reaction of the material generates a large amount of heat to heat the generated gas, and the gas expands when heated to form a secondary thrust, which presses the slurry into finer pores, ensuring the grouting effect. On the other hand, the composite grouting material has excellent toughness and water absorption and expansion properties. The tough structure formed after the material solidifies can not only eliminate the stress concentration phenomenon caused by coal mining disturbances and avoid the generation of water-conducting cracks, but also absorb water and expand to reduce the water-permeability of the overlying rock layer, thereby achieving the treatment effect of water-preserving coal mining, and solving the technical problem that the existing grouting process has poor treatment effect on the problem of water-preserving coal mining.

[0080] Furthermore, the composite grouting material in this solution possesses excellent toughness and water absorption and expansion properties. However, when the surrounding environment lacks moisture, the material will shrink to a certain extent, leading to the formation of new water-conducting fissures. To prevent the aquifer from flooding again after water is replenished, a layer of cement slurry is injected beneath the composite grouting material to form a support layer. When water from the aquifer above seeps down, the support layer becomes a temporary impermeable layer, preventing further water leakage. At this time, the tough layer above begins to absorb water and expand, thus trapping the water from the aquifer above. The bottommost tough layer is designed to alleviate the stress concentration caused by coal mining disturbances, which can lead to new cracks. The tough layer has excellent toughness and can effectively alleviate stress concentration problems, thereby preventing the formation of new water-conducting fissures.

[0081] Specifically, the fly ash is fine fly ash produced by wind dust removal or electrostatic precipitator in thermal power plants.

[0082] In the above technical solution, the fineness, loss on ignition and other indicators of fine fly ash should meet the Level II standard of the "Technical Specifications for Fly Ash Used in Hydraulic Concrete".

[0083] Specifically, the organic monomer is acrylamide monomer; the cross-linking agent is N,N'-methylenebisacrylamide; and the initiator is ammonium persulfate or potassium persulfate.

[0084] Specifically, the cement used is ordinary Portland cement or sulphoaluminate cement.

[0085] Specifically, the composite grouting material includes 40-50 parts of fly ash, 5-15 parts of organic monomer, 1.5-2.5 parts of cross-linking agent, 0.5-1.5 parts of initiator and 60-80 parts of water, with a specific gravity of 1.5-1.9 t / m 3 .

[0086] Specifically, the cement slurry material includes 60-90 parts of cement, 10-40 parts of fly ash and 80-100 parts of water, and the specific gravity is selected from 1.2-1.6t / m 3 .

Claims

1. A rock stratum grouting anti-seepage reinforcement method, characterized in that: The specific steps include: Step 1: determine the target permeable rock formation; Use geophysical methods to detect target rock formations, analyze leakage conditions, and determine target permeable rock formations that need to be modified; Step 2: Fracturing the target permeable rock formation with good continuity to obtain a discontinuous target permeable rock formation; Step 2.1: Determine the target permeable rock layer and conduct core sampling to obtain coal reservoir parameters, roof mechanical parameters, rock formation in-situ stress curve, and rock formation porosity; Step 2.2: Drill a hole in the roof rock formation using a directional long drill, and use a directional drill to push the staged fracturing equipment to the designated fracturing target section; Step 2.3: Seal the borehole with a packer. A constant pressure release high-pressure valve is connected in the middle of the packer. When the injection pressure reaches the set pressure, high-pressure water injection fracturing construction begins. Step 2.4: When multiple pressure drops occur and the designed water injection volume is reached, the fracturing construction of the target fracturing section is terminated, and the staged fracturing equipment is moved to the next target fracturing section using a directional drill, and the fracturing construction of all target fracturing sections is completed in sequence; During the fracturing operation, the fracturing pressure, flow rate and time are recorded in real time by the automatic data monitoring system; Step 3: Determine the grouting material and calculate the grouting amount; Step 3.1, dividing the target permeable rock layer into upper layer, middle layer and lower layer; Step 3.2: Select composite grouting materials for the upper and lower layers, and cement grout materials for the middle layer; The composite grouting material comprises fly ash or coal gangue, organic monomer, cross-linking agent, initiator and water; The cement slurry material includes sulphoaluminate cement or ordinary Portland cement and water; Step 3.3: Use the following formula to estimate the grouting volume V required for each layer; Without revealing large caves or sinkholes, Where: S—grouting range, m 2 ; —Thickness of the receiving layer, m; —Porosity of the receiving layer; —filling rate; —Collapse coefficient; ω—slurry setting rate; Step 4: hole arrangement and hole forming; Step 4.1: Use a surface grouting station to produce slurry, and deliver it to the exploration and treatment borehole through a dedicated slurry pipeline; Step 4.2: After the area requiring grouting is determined, the spacing between grouting holes is set according to the diffusion distance of the slurry, and the drill rig and hole-forming device are used to press the drill tool into the rock formation to a predetermined depth to form grouting holes; Step 4.3, placing a grouting sleeve into the grouting hole; Step five, grouting; Based on the grouting material determined in step 3.2 and the grouting volume determined in step 3.3, composite grouting material, cement slurry material, and composite grouting material are sequentially injected from bottom to top through the grouting sleeve to obtain a "tough layer-support layer-tough layer" sandwich structure, forming an anti-seepage system.

2. The rock stratum grouting anti-seepage reinforcement method according to claim 1, characterized in that: The fly ash is fine fly ash produced by wind dust removal or electrostatic precipitator in thermal power plants.

3. The rock stratum grouting anti-seepage reinforcement method according to claim 1, characterized in that: The organic monomer is acrylamide monomer; the cross-linking agent is N,N'-methylenebisacrylamide; and the initiator is ammonium persulfate or potassium persulfate.

4. The rock stratum grouting anti-seepage reinforcement method according to claim 1, characterized in that: The composite grouting material comprises 40-50 parts of fly ash, 5-15 parts of organic monomer, 1.5-2.5 parts of cross-linking agent, 0.5-1.5 parts of initiator and 60-80 parts of water, with a specific gravity of 1.5-1.9 t / m 3 .

5. The rock stratum grouting anti-seepage reinforcement method according to claim 1, characterized in that: The cement slurry material includes 60-90 parts of cement, 10-40 parts of fly ash and 80-100 parts of water, and the specific gravity is selected from 1.2-1.6t / m 3 .

Images