Elastic material for consolidation of closed fractures in goaf and construction method of elastic material

Abstract

The invention discloses an elastic material for consolidation of closed fractures in a goaf and a construction method of the elastic material. The elastic material is prepared by mixing a component A and a component B according to the mass ratio of 1: 3 and reacting, the component A is prepared from 70 to 75 parts of 1, 4-phenyl diisocyanate, 18 to 25 parts of polytetrahydrofuran and 0.5 to 2 parts of waste phosphoric acid; the component B is prepared from 2 to 7 parts of diethyltoluenediamine, 48 to 55 parts of slag powder, 35 to 42 parts of diisodecyl adipate and 2 to 6 parts of calcium oxide. In the grouting construction process of the elastomer, cutting before grouting, punching before grouting, crack sealing before grouting and crack grouting consolidation construction are sequentially carried out. Materials used in the method have no harm to human bodies and the environment, the materials can meet the use requirements of the goaf, and due to the fact that the materials have elasticity after the cracks are solidified, no new cracks are generated on the sealing wall even if the sealing wall is affected by secondary stress, and the needed effect is achieved.

Description

Technical Field

[0001] The invention relates to a material for crack consolidation and a construction method thereof, in particular to an elastic material for consolidating closed cracks in goaf areas and a construction method thereof, belonging to the technical field of coal mine crack plugging and consolidation. Background Art

[0002] In the process of coal mining, the area that has been mined is called the goaf. Since coal is still an important source of energy in my country, coal mining is always going on, so the goaf is becoming more and more. In order to prevent a series of dangers caused by air leakage in the goaf, the goaf needs to be sealed. In the process of coal mining, the advancement of the working face will cause the formation of mobile bearing pressure on both sides of the goaf; the construction of large-scale construction projects above the goaf, groundwater and ground stress disturbances and other factors will also cause the goaf to activate and produce stress redistribution. Under the influence of secondary stress, the surrounding rock falls, breaks and deforms, and cracks are generated in the closed wall of the goaf. The cracks will cause air leakage in the goaf. The flow of fresh air into the goaf will increase the risk of spontaneous combustion of the coal in the goaf. Air leakage in the goaf may also cause the gas accumulated in the goaf to leak or even explode, causing huge casualties and property losses.

[0003] Therefore, it is particularly important to carry out efficient prevention and control of air leakage in closed fissures in goafs. Shotcrete (hard materials such as cement, high-water quick-setting materials or clay) is generally used on site, or polymer materials such as injected mary powder, polyurethane or epoxy resin are used to seal air leakage in closed fissures in goafs. However, due to the continuous mining of the adjacent working face, the stress in the goaf is redistributed, and new cracks will appear in the sealed goaf treated by shotcrete. The reason for the cracks is that the hardness of the plugging material is high after solidification, and it is very easy to break under stress, resulting in new cracks. Therefore, it is impossible to achieve long-term continuous plugging of air leakage; in addition, most of the polymer materials currently used are harmful to the human body and the environment, and the reaction generates a lot of heat during operation, which is easy to cause secondary dangers.

[0004] To sum up, how to provide a new consolidation material and construction method for sealing cracks in goafs, in which the materials used are harmless to the human body and the environment, and the materials can meet the requirements for use in goafs, and even after the cracks are consolidated, the sealed wall will not produce new cracks even if it is affected by secondary stress. This is the research direction required by the present invention. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides an elastic material for consolidating closed cracks in goaf areas and a construction method thereof, which can effectively solve the above-mentioned technical problems.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an elastic material for consolidating closed cracks in goaf areas, wherein the elastic material is prepared by mixing component A and component B in a mass ratio of 1:3, wherein component A is a semi-prepolymer and component B is a curing agent.

[0007] Furthermore, the component A includes: 70-75 parts of 1,4-phenylene diisocyanate, 18-25 parts of polytetrahydrofuran, and 0.5-1.5 parts of waste phosphoric acid; the component B includes: 7-10 parts of diethyltoluenediamine, 48-55 parts of slag powder, 35-42 parts of diisodecyl adipate, and 3-5 parts of calcium oxide.

[0008] Furthermore, the component A includes: 73 parts of 1,4-phenylene diisocyanate, 22 parts of polytetrahydrofuran, and 1 part of waste phosphoric acid; the component B includes: 8 parts of diethyltoluenediamine, 53 parts of slag powder, 38 parts of diisodecyl adipate, and 4 parts of calcium oxide.

[0009] The construction method of the elastic material used for consolidating closed cracks in goaf areas comprises the following specific steps:

[0010] Step 1: Cutting before grouting: First observe the distribution of closed cracks, and pre-cut the closed wall to form cracks according to the situation for subsequent grouting;

[0011] Step 2: Drilling before grouting: Use a drilling machine to alternately construct oblique holes along the closed wall surface on both sides of each crack. Each oblique hole must pass through the crack. After drilling, use a cleaning agent to clean the coal powder and dust around each oblique hole, and then install grouting nails in each oblique hole. After completion, if the width of the closed crack is greater than 1 cm, proceed to step 3; otherwise, proceed directly to step 4.

[0012] Step 3: Sealing the cracks before grouting: Use sealing tape to seal the crack surface;

[0013] Step 4: Grouting to consolidate cracks: Mix component A and component B in a mass ratio of 1:3 and stir evenly, then use a grouting machine to grout the cracks of the closed wall through the grouting nails in each inclined hole.

[0014] Furthermore, the step 1 is specifically as follows: if the cracks are concentrated and the directions are basically consistent, the distance between each crack is first determined, and the middle position of the two cracks with the largest distance is selected to cut the closed wall with a handheld cutter to form a crack; if the cracks are concentrated and the directions are inconsistent, the closed wall is cut with a handheld cutter to form a crack, and the cut cracks connect the cracks with inconsistent directions. In this way, grouting is performed after cutting, and the elastic materials in the cracks are connected together, which can more effectively resist the influence of secondary stress in the goaf.

[0015] Furthermore, the cleaning agent used in step 2 is prepared by uniformly mixing 4 parts of sodium dodecyl sulfate (SDS) and 96 parts of water according to mass fraction.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) The consolidation material used in the present invention is a flame-retardant elastic material that can meet the requirements for use in goaf areas, wherein component A and component B will not produce toxic or harmful substances during the reaction process, and the elastomer after curing is also non-toxic. Its curing speed meets the construction requirements, and since it will form an elastic elastomer after curing, it has good mechanical properties such as compression resistance, tension resistance and shear resistance, has good adhesion to the closed wall of the goaf, and can partially deform and buffer when subjected to new stress, thereby preventing new cracks from being generated under the action of secondary stress in the goaf.

[0018] (2) In the present invention, during the cutting work before grouting, pre-cutting is performed according to the distribution of cracks (stress conditions), and the places where the closed wall is most affected by stress are artificially cut to form cracks, i.e. new cracks. Grouting is also performed on the cut cracks to fill the positions with elastic materials, thereby preventing new cracks from being generated when stress acts again.

[0019] (3) The elastic material used in the present invention is an organic polymer material. Although heat is released during the reaction, in the grouting process of the present invention, components A and B are stirred in advance, and heat release is completed before grouting is completed. There is no risk of spontaneous combustion of coal due to the increase in temperature in the goaf due to the heat release of the reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the cutting in Example 1 in which the cracks are concentrated and in the same direction;

[0021] Figure 2 It is a cutting schematic diagram of Example 2 in which cracks are concentrated and have inconsistent directions;

[0022] Figure 3 It is a schematic diagram of the drilling before grouting of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described below.

[0024] Example 1: The elastic material of this example is prepared by mixing component A and component B in a mass ratio of 1:3, wherein component A is a semi-prepolymer and component B is a curing agent; the component A comprises, in parts by mass: 72 parts of 1,4-phenylene diisocyanate, 24 parts of polytetrahydrofuran, and 0.6 parts of waste phosphoric acid; the component B comprises, in parts by mass: 10 parts of diethyltoluenediamine, 49 parts of slag powder, 42 parts of diisodecyl adipate, and 3 parts of calcium oxide.

[0025] The construction method of the elastic material in this embodiment comprises the following specific steps:

[0026] Step 1: Cutting before grouting: First observe the distribution of closed cracks, and pre-cut the closed wall to form cracks according to the situation. Specifically: if the distance between the cracks is less than 5m, it can be considered that the cracks are concentrated; if Figure 1 As shown, in this embodiment, the cracks are concentrated and their directions are basically consistent, so the distance between each crack is first determined, and the middle position between the two cracks with the largest distance is selected to use a handheld cutting machine to cut the closed wall to form cracks, i.e. new cracks. The width of the cut cracks is about 0.1 cm and the depth is about 50 cm, so that the horizontal distance between each crack is less than 2 m for subsequent grouting.

[0027] Step 2: Drilling before grouting: Figure 3 As shown, along the closed wall surface on both sides of each crack, inclined holes are alternately constructed with a puncher. Each inclined hole needs to pass through the crack. The diameter of the inclined hole is about 2.5 cm, and the vertical distance between the two holes is generally 50 cm. After drilling, the coal powder and dust around each inclined hole are cleaned with a cleaning agent. The cleaning agent used is made by mixing 4 parts of sodium dodecyl sulfate (SDS) and 96 parts of water according to the mass fraction. Then, grouting nails are installed in each inclined hole. After completion, if the closed crack width is greater than 1 cm, proceed to step three; otherwise, proceed directly to step four.

[0028] Step 3: Sealing the cracks before grouting: Use sealing tape to seal the crack surface;

[0029] Step 4: Grouting to consolidate cracks: Mix component A and component B in a mass ratio of 1:3 and stir evenly, then use a grouting machine to grout the cracks of the closed wall through the grouting nails in each inclined hole.

[0030] Example 2: The elastic material of this example is prepared by mixing component A and component B in a mass ratio of 1:3, wherein component A is a semi-prepolymer and component B is a curing agent; the component A comprises, in parts by mass: 73 parts of 1,4-phenylene diisocyanate, 22 parts of polytetrahydrofuran, and 1 part of waste phosphoric acid; the component B comprises, in parts by mass: 8 parts of diethyltoluenediamine, 53 parts of slag powder, 38 parts of diisodecyl adipate, and 4 parts of calcium oxide.

[0031] The construction method of the elastic material in this embodiment is basically the same as the construction method in the embodiment, and the only difference is the process of cutting the cracks in step 1, specifically: if the distance between the cracks is less than 5m, it can be considered that the cracks are concentratedly distributed; Figure 2 As shown, in this embodiment, the cracks are concentrated and the directions are inconsistent, so a handheld cutting machine is used to cut the closed wall to form cracks, and the cut cracks are used to connect the cracks with inconsistent directions for subsequent grouting.

[0032] Example 3: The elastic material of this example is prepared by mixing component A and component B in a mass ratio of 1:3, wherein component A is a semi-prepolymer and component B is a curing agent; the component A comprises, in parts by mass: 74 parts of 1,4-phenylene diisocyanate, 19 parts of polytetrahydrofuran, and 1.5 parts of waste phosphoric acid; the component B comprises, in parts by mass: 7 parts of diethyltoluenediamine, 55 parts of slag powder, 37 parts of diisodecyl adipate, and 5 parts of calcium oxide.

[0033] The construction method of the elastic material in this embodiment is the same as that in embodiment 1.

[0034] The mechanical properties of the elastic materials of Examples 1 to 3 were tested, and the test results are shown in Table 1:

[0035] Table 1 Mechanical properties test table of elastic materials

[0036] Test items Example 1 Example 2 Example 3 Tensile strength(MPa) 5.1 5.1 4.3 Compressive strength(MPa) 8.2 8.2 8.8 Shear strength(MPa) 3.4 3.4 3.7 Adhesion strength (MPa) 3.7 3.7 3.2 Solid content (wt%) 98.7 98.7 99.1 Bubble content inside the finished product after curing (%) 0 0 0 Elongation at break (%) 770 780 810 Limiting Oxygen Index (LOI) 37.8 37.8 36.7

[0037] It can be seen from Table 1 that the elastic materials of Examples 1 to 3 have good tensile, compressive, shear and other mechanical properties, and there are no bubbles inside the solid after curing, and they are flame retardant, which can meet the crack consolidation requirements required in the goaf.

[0038] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An elastic material for consolidating closed cracks in goaf, characterized in that: The elastic material is prepared by mixing component A and component B in a mass ratio of 1:3, wherein component A is a semi-prepolymer and component B is a curing agent.

2. The elastic material for consolidating closed cracks in goaf according to claim 1, characterized in that: The component A comprises: 70-75 parts of 1,4-phenylene diisocyanate, 18-25 parts of polytetrahydrofuran, and 0.5-1.5 parts of waste phosphoric acid; the component B comprises: 7-10 parts of diethyltoluenediamine, 48-55 parts of slag powder, 35-42 parts of diisodecyl adipate, and 3-5 parts of calcium oxide.

3. The elastic material for consolidating closed cracks in goaf according to claim 2, characterized in that: The component A comprises: 73 parts of 1,4-phenylene diisocyanate, 22 parts of polytetrahydrofuran, and 1 part of waste phosphoric acid; the component B comprises: 8 parts of diethyltoluenediamine, 53 parts of slag powder, 38 parts of diisodecyl adipate, and 4 parts of calcium oxide.

4. A construction method of elastic material for consolidation of closed cracks in goaf according to any one of claims 1 to 3, characterized in that: The specific steps are: Step 1: Cutting before grouting: First observe the distribution of closed cracks, and pre-cut the closed wall to form cracks according to the situation for subsequent grouting; Step 2: Drilling before grouting: Use a drilling machine to alternately construct oblique holes along the closed wall surface on both sides of each crack. Each oblique hole must pass through the crack. After drilling, use a cleaning agent to clean the coal powder and dust around each oblique hole, and then install grouting nails in each oblique hole. After completion, if the width of the closed crack is greater than 1 cm, proceed to step 3; otherwise, proceed directly to step 4. Step 3: Sealing the cracks before grouting: Use sealing tape to seal the crack surface; Step 4: Grouting to consolidate cracks: Mix component A and component B in a mass ratio of 1:3 and stir evenly, then use a grouting machine to grout the cracks of the closed wall through the grouting nails in each inclined hole.

5. The construction method according to claim 4, characterized in that: The step 1 is specifically as follows: if the cracks are concentrated and have basically the same direction, first determine the distance between each crack, select the middle position between the two cracks with the largest distance, and use a handheld cutting machine to cut the closed wall to form a crack; If the cracks are concentrated and inconsistent in direction, use a handheld cutting machine to cut the closed wall to form cracks, and make the cut cracks connect the cracks with inconsistent directions.

6. The construction method according to claim 4, characterized in that: The cleaning agent used in the step 2 is prepared by uniformly mixing 4 parts of sodium dodecyl sulfate (SDS) and 96 parts of water according to mass fraction.

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