A coal rock drilling multi-stage solid pipe reverse osmosis high pressure grouting method

Abstract

The present invention relates to the field of high-pressure grouting reinforcement and water blocking of coal rock mass in mining engineering, and specifically to a method for multi-stage solid pipe reverse osmosis high-pressure grouting in coal rock mass drilling, including determining the ultimate grouting pressure and the cementing casing level, determining the diameter parameters of each level of cementing casing and the cementing drilling construction size matched therewith; determining the length of each level of cementing casing according to the ultimate grouting pressure that the cementing structure can withstand and the cementing casing level and diameter of the cementing structure; installing the cementing structure and the grouting pipe, and performing multi-stage solid pipe reverse osmosis high-pressure grouting. Based on the force analysis of multi-stage solid pipe reverse osmosis high-pressure grouting, the present invention provides a method for determining the length of the cementing casing and the cementing casing level, so as to avoid the problem of cementing casing blowing out due to excessive grouting pressure during high-pressure grouting in broken coal rock mass or weak coal rock mass, avoid the problem of slurry leakage due to insufficient cementing casing length selection, and avoid the problem of material waste due to excessive cementing casing length selection.

Description

Technical Field

[0001] The invention relates to the field of high-pressure grouting reinforcement and water blocking of coal rock mass in mining engineering, and in particular to a coal rock mass drilling multi-stage solid pipe reverse osmosis high-pressure grouting method. Background Art

[0002] Grouting, also known as grouting, is a construction technology that applies pressure to a gelling slurry or chemical solution with a certain concentration using grouting equipment or the slurry's own weight, so that the slurry is injected into the layer section through a borehole. Its essence is to make the slurry penetrate, fill, and diffuse in the injected layer, and solidify and harden it after a certain period of time, so as to achieve the purpose of strengthening the injected layer and making it impermeable and waterproof. Grouting methods can be divided into reinforcement grouting, water blocking grouting, and filling grouting according to their uses. The present invention is mainly used in the fields of reinforcement grouting and water blocking grouting.

[0003] Grouting for water blocking in mines is to press cement slurry or chemical slurry into the gaps and cracks of the underground rock formation through drilling holes. After a certain period of time, it solidifies and hardens, making the rock formation have higher strength, density and impermeability, thereby sealing and cutting off the water supply and strengthening the formation. It is one of the important means of preventing and controlling water disasters in mines.

[0004] Mine grouting reinforcement is a reinforcement technology for easily broken soft coal rock. It is to inject solidifying material slurry into the coal rock mass, fill and consolidate the cracks in the soft coal rock mass with slurry to improve the strength of the coal mass around the grouting section, increase the adhesion, compressive resistance and plasticity of the coal rock mass, and achieve the purpose of reinforcing the coal rock mass, increasing the stability of the end face distance and extending the stability time, improving the overall strength of the coal rock mass, and reducing the probability of spalling and roof collapse.

[0005] In the past, chemical slurries were mostly used for grouting reinforcement and water plugging in mines. This was because chemical slurries had good diffusivity, a short solidification time, and could quickly increase pressure, so a high grouting pressure was not required to achieve the grouting purpose. Due to the pollution and heat accumulation of chemical slurries, the use of chemical slurries was restricted, and cement-based slurries were widely used. In order to achieve good grouting reinforcement effects, high-pressure grouting was often used.

[0006] The existing high-pressure grouting technology in mines usually uses a single-stage cementing casing to grout and plug water and reinforce the coal rock mass. However, in broken and weak coal rock mass, due to the low strength, low cohesion and poor bearing capacity of the coal rock mass, if the grouting pressure is too high, it will increase the probability of coal rock mass being destroyed and cementing casing being blown out and slurry leaking due to high-pressure grouting. Therefore, a multi-stage cementing pipe reverse osmosis high-pressure grouting method for drilling coal rock mass is invented. By using multi-stage cementing pipes, cementing slurry is injected into the pores between the cementing casing and the cementing borehole, the ability of the coal rock mass around the cementing casing to resist damage is increased, and reinforcement or plugging of water is achieved through reverse osmosis high-pressure grouting, which is of great significance.

[0007] However, the prior art does not provide any suggestions on how to select the number of cementing casings for a multi-stage cementing casing and how to determine the size of the cementing casing. This makes technical personnel in the field rely more on experience when selecting. If the length of the cementing casing is not selected enough, it is easy to cause coal rock damage, cementing casing blowout, and slurry leakage. If the length of the cementing casing is too long, it is easy to cause material waste. Summary of the invention

[0008] In order to solve or alleviate the problems of coal rock mass damage, cementing casing blowout and slurry leakage caused by high-pressure grouting, and at the same time solve the problem of lack of basis for selecting the cementing casing stage and length during multi-stage cementing casing high-pressure grouting, the present invention proposes a coal rock mass drilling multi-stage cementing pipe reverse osmosis high-pressure grouting method, which adopts multi-stage cementing casing high-pressure grouting, and provides a method for selecting the cementing casing stage and length based on mechanical analysis, which specifically includes the following steps:

[0009] Step 1: Determine the grouting pressure required for high-pressure grouting of coal and rock mass P 0, take a certain safety factor to determine the ultimate grouting pressure that the cementing structure of the high-pressure grouting drilling can withstand P ; When 3MPa≤ P ≤5MPa, adopting two-stage cementing structure, when P >5MPa, adopt three-stage cementing structure;

[0010] Step 2: Determine the diameter parameters of cementing casings at each level and the corresponding cementing drilling construction dimensions;

[0011] Step 3: Based on the ultimate grouting pressure that the cementing structure can withstand P The length of each cementing casing is determined by the cementing casing stage number and diameter of the cementing structure to meet the following requirements:

[0012]

[0013] In the formula, R 1 is the cementing drilling radius corresponding to the outermost cementing casing; R i is the cementing drilling radius corresponding to the innermost cementing casing; L 1 is the outermost cementing casing and its corresponding cementing drilling length; L i is the innermost cementing casing and its corresponding cementing drilling length; C is the cohesion of the coal-rock mass at the cementing structure, φ is the friction angle of coal rock mass at the cementing structure;

[0014] Step 4: Install the cementing structure and grouting pipe, and carry out multi-stage cementing pipe reverse osmosis high-pressure grouting.

[0015] Preferably, in step 1, the safety factor is 1.2 to 1.5.

[0016] Preferably, in step 2, when a two-stage cementing structure is adopted, the diameter of the outermost cementing casing is 153 mm, corresponding to a cementing borehole diameter of 180 mm, and the diameter of the innermost cementing casing is 94 mm, corresponding to a cementing borehole diameter of 133 mm.

[0017] Preferably, in step 2, when a three-stage cementing structure is adopted, the diameter of the outermost cementing casing is 180 mm, corresponding to a cementing borehole diameter of 210 mm, the diameter of the intermediate cementing casing is 133 mm, corresponding to a cementing borehole diameter of 160 mm, and the diameter of the innermost cementing casing is 89 mm, corresponding to a cementing borehole diameter of 120 mm.

[0018] Preferably, in step three, when three-level cementing casing is used, the cementing drilling length corresponding to the intermediate cementing casing does not exceed the line connecting the cementing drilling bottom angle of the innermost cementing casing and the cementing drilling bottom angle of the outermost cementing casing.

[0019] Preferably, step 4 specifically includes: a. constructing an outermost cementing borehole and installing an outermost cementing casing at the center thereof, and injecting cementing slurry to fix the outermost cementing casing;

[0020] b. If a three-stage cementing structure is used, perform this step. If a two-stage cementing structure is used, skip this step and perform step c. Construct an intermediate cementing borehole and install an intermediate cementing casing at its center, inject cementing slurry to fix the intermediate cementing casing;

[0021] c. Construct the innermost cementing borehole and install the innermost cementing casing at its center, and inject cementing slurry to fix the innermost cementing casing;

[0022] d. Construct high-pressure grouting drilling holes, install sealing flanges, install grouting pipes in the center of the sealing flanges, and keep the bottom of the grouting pipes at a certain distance from the bottom of the high-pressure grouting drilling holes; open the valve and conduct reverse osmosis high-pressure grouting.

[0023] The beneficial technical effects of the present invention are as follows: 1. The present invention selects the cementing casing stage according to different grouting pressures, adopts multi-stage cementing casing high-pressure grouting, and injects cementing slurry between the cementing casing and the cementing borehole to reinforce the cementing casing; then the grouting pipe is extended into the high-pressure grouting borehole, and a certain distance is left between the bottom of the grouting pipe and the bottom of the high-pressure grouting borehole, so that the slurry flows back and fills the high-pressure grouting borehole and then evenly diffuses into the coal rock cracks to achieve reinforcement and water blocking.

[0024] 2. Based on the stress analysis of multi-stage cemented pipe reverse osmosis high-pressure grouting, the present invention provides a method for determining the length of cementing casing and the number of cementing casing stages, thereby avoiding the problems of coal rock damage, cementing casing blowout and slurry leakage during high-pressure grouting caused by insufficient cementing casing length selection, and avoiding the problem of material waste caused by excessive cementing casing length selection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the flow of multi-stage solid pipe reverse osmosis high-pressure grouting slurry of the present invention;

[0026] Figure 2 It is a schematic diagram of the force analysis of multi-stage solid pipe reverse osmosis high-pressure grouting of the present invention;

[0027] Figure 3 It is a schematic diagram of cementing drilling hole dimensions corresponding to the multi-stage cementing pipe reverse osmosis high-pressure grouting cementing casing of the present invention;

[0028] In the figure, 1. Outermost cementing casing; 2. Innermost cementing casing; 3. Grouting pipe; 4. Valve; 5. High-pressure grouting drilling; 6. Sealing flange; 7. Shear failure surface. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] The present invention proposes a coal rock drilling multi-stage solid pipe reverse osmosis high pressure grouting method, such as Figure 1-3 As shown, the following steps are included:

[0031] Step 1: If Figure 1 As shown in the figure, the grouting pressure required for high-pressure grouting of the coal-rock mass is determined according to the strength of the coal-rock mass, the development of cracks, and the need for reinforcement or water blocking. P 0; In order to ensure the safety of high-pressure grouting and avoid the problem of cementing casing blowout and slurry leakage during high-pressure grouting, a certain safety factor is taken to determine the ultimate grouting pressure that the cementing structure of the high-pressure grouting borehole 5 can withstand P , P =(1.2~1.5) P 0; Based on the ultimate grouting pressure that the cementing structure can withstand P Determine the level of cementing casing in the cementing structure; when P <3MPa, the limit grouting pressure is small, there is no need to set up multi-stage cementing casing, and a single-stage cementing structure is sufficient, which is not within the scope of the present invention; when 3MPa≤ P ≤5MPa, adopting two-stage cementing structure, when P >5MPa, adopt three-stage cementing structure;

[0032] Grouting pressure required for high pressure grouting of coal rock mass PThe higher the value of 0, the greater the possibility of cementing structure being damaged. As the number of cementing casings increases, the ability of cementing structure to resist damage increases, that is, the ultimate grouting pressure that cementing structure can withstand. P Increase, high pressure grouting reinforcement or water blocking is more stable.

[0033] Step 2: If Figure 1 , Figure 3 As shown, the diameter parameters of the cementing casing and the corresponding cementing drilling construction dimensions are determined; when a two-stage cementing structure is adopted, the diameter of the outermost cementing casing (first-stage cementing casing) 1 is 153 mm, corresponding to a cementing drilling diameter of 180 mm, and the diameter of the innermost cementing casing 2 (second-stage cementing casing) is 94 mm, corresponding to a cementing drilling diameter of 133 mm;

[0034] When a three-stage cementing structure is adopted, the diameter of the outermost cementing casing (first-stage cementing casing) 1 is 180 mm, corresponding to a cementing borehole diameter of 210 mm, the diameter of the intermediate cementing casing (second-stage cementing casing) is 133 mm, corresponding to a cementing borehole diameter of 160 mm, and the diameter of the innermost cementing casing 2 (third-stage cementing casing) is 89 mm, corresponding to a cementing borehole diameter of 120 mm;

[0035] The above cementing casing sizes are all standard sizes, which are convenient for material selection and do not require processing cementing casings with special diameters;

[0036] Step 3: Based on the ultimate grouting pressure that the cementing structure can withstand P The length of each cementing casing is determined by the cementing casing stages and diameters of the cementing structure;

[0037] like Figure 2 As shown in the figure, it is the stress diagram of cementing structure during high-pressure grouting of multi-stage solid pipe reverse osmosis. A certain safety factor is taken, and the grouting pressure during high-pressure grouting is the limit grouting pressure. P The cementing structure is subjected to a force perpendicular to the wall of the high-pressure grouting borehole 5, that is, a force radially outward along the high-pressure grouting borehole 5. P 2, and the force perpendicular to the sealing flange 6, that is, the force axially outward along the high-pressure grouting drilling 5 P 1; P 1= P 2= P ;

[0038] According to the ultimate grouting pressure P It should not be greater than the maximum bearing capacity of the cementing structure, that is, the shear stress borne by the cementing structure (mainly refers to the coal rock mass reinforced by cementing grouting in the cementing structure. Cementing grouting specifically refers to the grouting of cementing casing, which refers to the grouting between the outer wall of the cementing casing and the cementing borehole. During cementing grouting, the cementing slurry will reinforce the coal rock mass around the cementing borehole, which is different from reverse osmosis high-pressure grouting) τLess than its shear strength τ 0, τ < τ 0;

[0039] According to the Mohr-Coulomb strength criterion, the shear strength of the coal rock mass at the cementing structure can be known. τ The relationship between 0 and normal stress is:

[0040]

[0041] Where, σ is the normal stress of the coal-rock mass at 7 points on the shear failure surface of the cementing structure, C is the cohesion of the coal-rock mass at the cementing structure, φ is the friction angle of coal rock mass at the cementing structure;

[0042] like Figure 2 As shown, the surface where the shear failure of the cementing structure occurs is the line connecting the bottom angle of the cementing borehole of the innermost cementing casing 2 and the bottom angle of the cementing borehole of the outermost cementing casing 1; α is the angle between the shear failure surface 7 and the axial direction of the high-pressure grouting borehole 5; based on the force diagram of the cementing structure during multi-stage solid pipe reverse osmosis high-pressure grouting, it can be obtained

[0043]

[0044] Then the shear strength calculation formula of cementing structure is obtained as follows:

[0045]

[0046] like Figure 2 As shown in Figure 2, based on the stress diagram of the cementing structure during multi-stage solid pipe reverse osmosis high-pressure grouting, the actual shear stress borne by the coal rock mass at the cementing structure after cementing grouting is:

[0047]

[0048] like Figure 2-3 As shown, cosα and sinα can be expressed by the length and radius of the cementing casing.

[0049]

[0050] Depend on τ < τ 0 available

[0051]

[0052] In the formula, R 1 is the cementing drilling radius corresponding to the outermost cementing casing 1; R i is the cementing drilling radius corresponding to the innermost cementing casing 2; L1 is the outermost cementing casing 1 and its corresponding cementing drilling length; L i The innermost cementing casing 2 and its corresponding cementing drilling length;

[0053] Need to explain, Figure 1-3 Only the outermost cementing casing 1 and the innermost cementing casing 2 are shown. When two-stage cementing casings are used, the cementing structure is Figure 1-Figure 3 In the form shown, when three-stage cementing casing is used, there is also an intermediate cementing casing between the outermost cementing casing 1 and the innermost cementing casing 2, and the length of the intermediate cementing casing and the corresponding cementing borehole does not exceed 7 shear failure surfaces;

[0054] Determine the length of the outermost cementing casing 1 based on the above formula L 1 and the length of the innermost cementing casing 2 L i , if a three-level cementing casing is used, the length of the intermediate cementing casing is selected so that the corresponding cementing drilling length does not exceed 7 shear failure surfaces;

[0055] Step 4: Install the cementing structure and grouting pipe 3, and perform multi-stage cementing pipe reverse osmosis high-pressure grouting;

[0056] like Figure 1-3 As shown, a. According to the cementing drilling radius corresponding to the outermost cementing casing 1 R 1 and length L 1. constructing an outermost cementing borehole in the coal rock mass; installing an outermost cementing casing 1 at the center of the outermost cementing borehole; injecting cementing slurry between the outermost cementing casing 1 and the outermost cementing borehole to fix the outermost cementing casing 1;

[0057] b. If a three-stage cementing structure is used, perform this step. If a two-stage cementing structure is used, skip step b and perform step c. Construct an intermediate cementing borehole in the coal rock mass according to the radius and length of the cementing borehole corresponding to the intermediate cementing casing; install the intermediate cementing casing at the center of the intermediate cementing borehole; inject cementing slurry between the intermediate cementing casing and the intermediate cementing borehole to fix the intermediate cementing casing;

[0058] c. According to the cementing drilling radius corresponding to the innermost cementing casing 2 R i and length L i Constructing an innermost cementing borehole in the coal rock mass; installing an innermost cementing casing 2 at the center of the innermost cementing borehole; injecting cementing slurry between the innermost cementing casing 2 and the innermost cementing borehole to fix the innermost cementing casing 2;

[0059] d. Construct high-pressure grouting drilling hole 5 to the designed depth, with the high-pressure grouting drilling hole 5, cementing drilling holes at all levels, and cementing casings at all levels sharing the same central axis; install the sealing flange 6, and use bolts to connect the sealing flange 6 and cementing casings at all levels; install the grouting pipe 3 at the center of the sealing flange 6, with the bottom of the grouting pipe 3 at a certain distance from the bottom of the high-pressure grouting drilling hole 5; open the valve 4 to carry out reverse osmosis high-pressure grouting.

[0060] Of course, the above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It should be noted that all equivalent substitutions and obvious deformation forms made by any technician familiar with the field under the guidance of this specification fall within the essential scope of this specification and should be protected by the present invention.

Claims

1. A coal rock drilling multi-stage solid pipe reverse osmosis high pressure grouting method, characterized in that: The steps include: Step 1: Determine the grouting pressure required for high-pressure grouting of coal and rock mass P 0, take the safety factor to determine the ultimate grouting pressure that the cementing structure of the high-pressure grouting drilling can withstand P ; When 3MPa≤ P ≤5MPa, adopting two-stage cementing structure, when P >5MPa, adopt three-stage cementing structure; Step 2: Determine the diameter parameters of cementing casings at each level and the corresponding cementing drilling construction dimensions; Step 3: Based on the ultimate grouting pressure that the cementing structure can withstand P The length of each cementing casing is determined by the cementing casing stage number and diameter of the cementing structure to meet the following requirements: ， In the formula, R 1 is the cementing drilling radius corresponding to the outermost cementing casing; R i is the cementing drilling radius corresponding to the innermost cementing casing; L 1 is the outermost cementing casing and its corresponding cementing drilling length; L i is the innermost cementing casing and its corresponding cementing drilling length; C is the cohesion of the coal-rock mass at the cementing structure, φ is the friction angle of coal rock mass at the cementing structure; Step 4: a. construct the outermost cementing borehole and install the outermost cementing casing at the center thereof, and inject cementing slurry to fix the outermost cementing casing; b. If a three-stage cementing structure is used, perform this step. If a two-stage cementing structure is used, skip this step and perform step c. Construct an intermediate cementing borehole and install an intermediate cementing casing at its center, inject cementing slurry to fix the intermediate cementing casing; c. Construct the innermost cementing borehole and install the innermost cementing casing at its center, and inject cementing slurry to fix the innermost cementing casing; d. Construct high-pressure grouting drilling holes, install sealing flanges, install grouting pipes in the center of the sealing flanges, and leave a gap between the bottom of the grouting pipe and the bottom of the high-pressure grouting drilling hole; open the valve and carry out reverse osmosis high-pressure grouting.

2. The multi-stage solid pipe reverse osmosis high-pressure grouting method according to claim 1, characterized in that: In step 1, the safety factor is 1.2~1.

5.

3. The multi-stage solid pipe reverse osmosis high-pressure grouting method according to claim 1, characterized in that: In step 2, when a two-stage cementing structure is used, the diameter of the outermost cementing casing is 153 mm, corresponding to a cementing borehole diameter of 180 mm, and the diameter of the innermost cementing casing is 94 mm, corresponding to a cementing borehole diameter of 133 mm.

4. The multi-stage solid pipe reverse osmosis high-pressure grouting method according to claim 1 or 3, characterized in that: In step 2, when a three-stage cementing structure is used, the diameter of the outermost cementing casing is 180 mm, corresponding to a cementing borehole diameter of 210 mm, the diameter of the intermediate cementing casing is 133 mm, corresponding to a cementing borehole diameter of 160 mm, and the diameter of the innermost cementing casing is 89 mm, corresponding to a cementing borehole diameter of 120 mm.

5. The multi-stage solid pipe reverse osmosis high-pressure grouting method according to claim 1, characterized in that: In step three, when three-level cementing casing is used, the cementing borehole length corresponding to the intermediate cementing casing does not exceed the line connecting the cementing borehole bottom angle of the innermost cementing casing and the cementing borehole bottom angle of the outermost cementing casing.

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