Coal face roof weathering abnormal body treatment method

Abstract

The invention discloses a coal face roof weathering anomalous body treatment method which comprises the following steps: exploring and partitioning a coal face roof weathering anomalous body, and determining a coal seam roof strong weathering area, a coal seam roof weak weathering area and a coal seam roof non-weathering area; total replacement pile top plate replacement is implemented in the coal seam top plate strong weathering area; a plurality of supporting anchor rods used for connecting the coal seam roof strong-weathering area and the coal seam roof weak-weathering area are arranged in the coal seam roof weak-weathering area and close to a transition area of the coal seam roof strong-weathering area and the coal seam roof weak-weathering area in the trend; and real-time grouting reinforcement is conducted on the coal seam roof weak weathering area, and coal face roof weathering abnormal body treatment is completed. By the adoption of the method, targeted transformation measures can be taken according to the weathering degree of the coal seam roof, dead-corner-free all-directional transformation of the weathered rock stratum of the coal seam roof is achieved through the comprehensive method of full replacement pile roof replacement, anchor rod deformation resistance and grouting crack reinforcement, and sand and mud bursting accidents are effectively prevented.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine roof treatment, and relates to a method for treating abnormal weathering of the roof of a coal mining face. Background Art

[0002] In 2023, my country's raw coal production will reach 4.66 billion tons, and the total energy consumption will be 5.72 billion tons of standard coal. Coal consumption accounts for 55.3% of the total energy consumption. Coal will remain the main energy source in my country for a long time. Safe and efficient mining of coal mines is a necessary guarantee for the efficient development of coal resources. However, affected by coal mining conditions, coal mining often encounters many difficulties. Among them, during coal mining, the roof rock layer is strongly weathered and broken and there is no complete bedrock, that is, the coal-rock interface is strongly weathered. Not only is the rock layer at a certain height of the coal seam roof strongly weathered, but the top of the coal seam is also weathered. There is a cavity in the weathering zone, and there is a small amount of residual water in the cavity. When the working face is mined to the lower part of the weathering anomaly body of the interface, due to the incomplete roof, poor cementation and certain voids, muddy water, rock blocks, slag, sludge, red soil and even weeds pour out from the front of the frame, and serious mud collapse occurs in front of the hydraulic support, which seriously affects the normal movement of the support and seriously threatens the safety of underground coal mines. There will also be large and deep sinkholes on the ground corresponding to the roof leakage area in front of the hydraulic support, which seriously threatens the ecological safety of the surface. Therefore, there is an urgent need for safe and effective methods to solve the problem of strong weathering and breaking of the roof rock layer of the coal mining working face, promote safe and efficient mining of coal mines, and ensure safety and environmental protection in coal mines.

[0003] The existing coal mining face roof grouting transformation method is suitable for small-scale roof transformation such as roof cracks and fault zones. Specifically, it uses drilling to target the roof cracks or voids, injects specific grouting materials such as cement slurry and chemical slurry into the grouting hole, and uses the diffusion effect of the grouting material to fill the roof cracks or voids to achieve coal mine roof transformation. However, this method has the following defects: the target area is difficult to judge, the drilling position is difficult to determine, the slurry flow range is uncontrollable, and the effect of slurry filling cracks or voids is difficult to guarantee. When the weathering anomaly of the bottom plate of the coal mining face is the entire roof area, it is difficult to ensure that all the internal voids of the anomaly are blocked by the above-mentioned roof grouting transformation technology. Once there are unfilled through voids in the working face mining process, the upper strongly weathered rock blocks and the overlying red soil, loess, and water will mix and flow to the working face, causing mud collapse and causing major safety incidents. Summary of the invention

[0004] In view of the defects and shortcomings in the prior art, the present invention provides a method for treating weathered abnormal bodies in the roof of a coal mining face, so as to solve the technical problems in the prior art of safety accidents caused by mud collapse in the working face due to cracks or inadequate sealing of gaps in the grouting transformation of the roof of the coal mining face.

[0005] To achieve the above object, the present invention adopts the following technical scheme:

[0006] A method for treating abnormal weathering of roof of a coal mining face comprises the following steps:

[0007] Step 1, explore and zone the weathering anomaly of the roof of the coal mining face to determine the strongly weathered area of ​​the coal seam roof, the weakly weathered area of ​​the coal seam roof and the unweathered area of ​​the coal seam roof;

[0008] Step 2: Implement full replacement pile roof replacement in the strongly weathered area of ​​the coal seam roof;

[0009] Step 3: In the transition area between the strongly weathered area and the weakly weathered area of ​​the coal seam roof, a plurality of support anchor rods for connecting the strongly weathered area and the weakly weathered area of ​​the coal seam roof are arranged;

[0010] Step 4: Perform real-time grouting reinforcement on the weakly weathered area of ​​the coal seam roof to complete the treatment of abnormal weathering on the roof of the coal mining face.

[0011] The present invention also has the following technical features:

[0012] Specifically, the strongly weathered area of ​​the coal seam roof meets the following conditions: drilling fluid consumption ≥ 60L / m, core mining area rate ≤ 50% and RQD ≤ 45%;

[0013] The weakly weathered area of ​​the coal seam roof meets the following conditions: 30L / m ≤ drilling fluid consumption < 60L / m, 50% < core mining area rate ≤ 80% and 45% <RQD≤75%;

[0014] The unweathered area of ​​the coal seam roof meets the following conditions: drilling fluid consumption <30L / m, core mining area rate >80% and RQD >75%

[0015] Furthermore, the full replacement pile top plate replacement described in step 2 specifically includes the following sub-steps:

[0016] Step 2.1, construct the first row of replacement piles along the length of the transition zone in the strongly weathered area of ​​the coal seam roof near the transition zone;

[0017] Step 2.2, in the strongly weathered area of ​​the coal seam roof, construct a second row of replacement piles along the length of the transition zone, and the second row of replacement piles are arranged at intervals from the first row of replacement piles;

[0018] Step 2.3, constructing a third row of replacement piles between the second row of replacement piles and the first row of replacement piles, and the third row of replacement piles can respectively engage with the second row of replacement piles and the first row of replacement piles to form engaged piles;

[0019] Step 2.4, use the second row of replacement piles as the first row of replacement piles, return to step 2.2, until the construction of all replacement piles in the strongly weathered area of ​​the coal seam roof is completed, and the replacement of the roof with all replacement piles is completed.

[0020] Furthermore, the diameter of the replacement pile is 1.6m to 2.6m, and the bite thickness of adjacent replacement piles is determined by the following formula:

[0021] d-2(kL+q)≥50mm

[0022] In the formula,

[0023] d is the occlusal thickness of the adjacent replacement posts, in mm;

[0024] k is the verticality of the replacement pile, which is 1‰;

[0025] L is the length of the replacement pile, in mm;

[0026] q is the allowable value of drilling hole positioning error, in mm.

[0027] Furthermore, the replacement pile comprises a plugging mold bag, a concrete layer, a cement-mixed soil layer and an original soil layer which are sequentially arranged from bottom to top; and quick-setting materials are pre-installed in the plugging mold bag.

[0028] Furthermore, the diameter of the plugging mold bag is determined by the following formula:

[0029] d m =(1.0~1.15)*D

[0030] The height of the blocking mold bag is determined by the following formula:

[0031] h=(1.8~3.2)*d m

[0032] In the formula,

[0033] d m is the diameter of the sealing mold bag, in m;

[0034] D is the diameter of the replacement pile, in m;

[0035] h is the height of the sealing mold bag, in meters.

[0036] Furthermore, the construction method of the replacement pile is as follows:

[0037] Step S1, sleeve the foldable plugging mold bag on the bottom end of the catheter and fix it with a self-detachable bag clamp; lower the catheter with the foldable plugging mold bag fixed to the bottom of the drilled hole;

[0038] Step S2, injecting the quick-setting material into the plugging mold bag through the catheter, and the plugging mold bag falls off from the catheter under the action of gravity;

[0039] Step S3, injecting concrete into the borehole to a first designed height by means of a conduit;

[0040] Step S4, tamping cement-mixed soil into the borehole to a second designed height;

[0041] Step S5: Fill the original soil to the ground to complete the construction of the replacement pile.

[0042] Furthermore, the first design height in the first row of replacement piles is determined by the following formula:

[0043] H y =H m +(5~20)

[0044] In the formula,

[0045] H y is the first design height in the first row of displacement piles, in meters;

[0046] H m It is the height of the nearly horizontal coal seam caving zone, in meters.

[0047] Furthermore, the first design height of the second row of replacement piles into the nth row of replacement piles is determined by the following formula:

[0048] H y '=(0.22~0.28)*H m

[0049] In the formula,

[0050] H y ' is the first design height from the second row of replacement piles to the nth row of replacement piles, in meters;

[0051] H m It is the height of the nearly horizontal coal seam caving zone, in meters.

[0052] Furthermore, the height of the nearly horizontal coal seam caving zone is determined by the following method:

[0053] When the rock saturated compressive strength is 40-60 MPa, H m =(4~5)×h c ;

[0054] When the rock saturated compressive strength is 20-40 MPa, H m =(3~4)×h c ;

[0055] When the rock saturated compressive strength is less than 20MPa, Hm =(1~2)×h c ;

[0056] Among them, h c It is the mining height of coal seam, in m.

[0057] Furthermore, the second design height is 5 to 6 meters above the top of the strongly weathered zone of the coal seam roof.

[0058] Furthermore, in the cement-mixed soil, the mass of cement accounts for 5-6% of the mass of the soil in terms of mass percentage.

[0059] Compared with the prior art, the present invention has the following beneficial technical effects:

[0060] (1) The method of the present invention divides the abnormal weathering body of the roof of the coal mining face into zones according to the weathering degree of the coal seam roof, and can take targeted transformation measures according to the weathering degree of the coal seam roof. Through the comprehensive method of full replacement pile roof replacement-anchor rod anti-deformation-grouting crack reinforcement, the weathered rock layer of the coal seam roof can be transformed in all directions without dead angles, effectively preventing sand and mud collapse accidents. The present invention constructs replacement piles on the coal seam roof in the strongly weathered area of ​​the coal seam roof, which not only saves the injected concrete materials, but also improves the strength of the roof.

[0061] (2) The replacement piles used in the present invention include a plugging mold bag, a concrete layer, a cement-mixed soil layer and an original soil layer arranged in sequence from bottom to top, wherein the plugging film bag can effectively prevent the loss of slurry along the voids or cracks, which can cause the problems of reduced construction efficiency and increased grouting cost; the concrete with the same strength as the corresponding stratum rock can effectively improve the strength and structural stability of the transformation layer; the cement-mixed soil layer has both certain strength and certain flexibility, which provides certain strength and great toughness for the replacement piles, and the original soil is backfilled to achieve surface ecological restoration; the middle piles of the present invention are engaged with each other, and the rows are engaged with each other. The key position engagement piles can be expanded along the axial direction of the pile body to construct a mortise and tenon structure in the pile, so that the engagement relationship of the replacement top plate is more stable.

[0062] (3) In the method of the present invention, anchor rods are set in the transition zone between the strongly weathered zone and the weakly weathered zone of the coal seam roof, and the fiberglass anchor rods and the weathered strata are bonded together using cement slurry, thereby achieving the upper and lower pulling effect of the weathered strata and preventing the deformation of the weathered rock strata on the lower roof due to mining. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a schematic diagram of the planar layout of the replacement piles for treating the strongly weathered area of ​​the coal seam roof in Example 1;

[0064] Figure 2 This is a schematic cross-sectional diagram of the treatment of the weathered area of ​​the coal seam roof in Example 1;

[0065] Figure 3 Schematic diagram of the construction sequence of a single replacement pile in the first column of Example 1;

[0066] Figure 4 The following is a construction sequence diagram of each row of replacement piles in Example 1;

[0067] Figure 5 is a cross-sectional view of a replacement pile of Example 1;

[0068] Figure 6 It is a schematic structural diagram of the foldable sealing mold bag of Example 1;

[0069] Figure 7 This is a schematic diagram of the connection between the foldable sealing mold bag and the catheter in Example 1;

[0070] Figure 8 It is a schematic diagram of folding and lowering the foldable sealing mold bag of Example 1;

[0071] Fig. 9 A cross-sectional view of the mortise and tenon structure in the replacement pile in Example 1;

[0072] Fig.10 This is a photo of coring the inspection hole in Example 1.

[0073] 1-loose layer; 2-unweathered rock layer; 3-weathered rock layer on the roof; 4-coal seam to be mined; 5-goaf; 6-hydraulic support; 7-support anchor rod; 8-replacement pile; 9-coal wall; 10-unweathered area on the roof of the coal seam, 11-strongly weathered area on the roof of the coal seam; 12-weakly weathered area on the roof of the coal seam; 81-sealing mold bag; 82-concrete; 83-cement mixed soil layer; 84-original soil; 85-cracks or voids; 86-material injection port; 87-self-detachable bag clamp; 88-conduit; 89-quick-setting material.

[0074] The present invention is described in detail below with reference to the accompanying drawings and specific implementation methods. DETAILED DESCRIPTION

[0075] In accordance with the above technical scheme, 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 changes made on the basis of the technical scheme of this application fall within the protection scope of the present invention.

[0076] The terms "upper", "lower", "front", "back", "top", "bottom", etc. used in the present invention to indicate directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. "Inside" and "outside" refer to the inside and outside of the contour of the corresponding components, and the above terms should not be understood as limitations on the present invention.

[0077] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0078] Unless otherwise specified, the parts and raw materials used in the present invention are commercially available.

[0079] RQD: An important indicator for evaluating rock mass integrity and quality classification, reflecting the degree to which the rock mass is cut by various structural surfaces.

[0080] The present invention is further described in detail below with reference to the embodiments.

[0081] Example 1

[0082] In accordance with the above technical solution, this embodiment provides a method for treating abnormal weathering of the roof of a coal mining face. Figure 1 The coal seam roof weathering area shown in the figure is treated. The coal rock layers in this area are distributed as follows Figure 2 As shown, governance consists of the following steps:

[0083] Step 1: Detect and partition the weathering anomaly of the roof of the coal mining face to determine Figure 1 The coal seam roof strongly weathered area, coal seam roof weakly weathered area and coal seam roof unweathered area are shown;

[0084] The existing drilling technology is used to complete the preliminary engineering geological exploration and hydrogeological exploration, determine the drilling coring rate and RQD value of the coal mining face roof in the exploration area, and determine the buried depth of the weathering anomaly body on the coal mining face roof, the size of the fracture space, the longitudinal boundary range and the weathering degree of the coal seam roof based on the obtained exploration data. Then, the coal seam roof is divided into strongly weathered zone, weakly weathered zone and unweathered zone according to the following evaluation criteria, and the boundaries between the strongly weathered zone and the weakly weathered zone, and the boundaries between the weakly weathered zone and the unweathered zone are delineated.

[0085] The coal seam roof strong weathering area meets the following conditions: drilling fluid consumption ≥ 60L / m, core mining area rate ≤ 50% and RQD ≤ 45%;

[0086] The weakly weathered area of ​​the coal seam roof meets the following conditions: 30L / m ≤ drilling fluid consumption < 60L / m, 50% < core mining area rate ≤ 80% and 45% <RQD≤75%;

[0087] The unweathered area of ​​the coal seam roof meets the following conditions: drilling fluid consumption <30L / m, core mining area rate >80% and RQD >75%.

[0088] Then, a comprehensive method of full-replacement pile roof replacement-anchor rod anti-deformation-grouting fissure reinforcement was used to treat the strongly weathered area and the weakly weathered area of ​​the coal seam roof, so as to achieve stable roof deformation resistance during coal seam mining.

[0089] Step 2: Implement full replacement pile roof replacement in the strongly weathered area of ​​the coal seam roof, specifically including the following sub-steps:

[0090] Step 2.1, construct the first row of replacement piles along the length of the transition zone in the strongly weathered area of ​​the coal seam roof near the transition zone;

[0091] Specifically, Figure 1 , Figure 3 and Figure 4 As shown in the figure, the transition zone between the strong weathering zone and the weak weathering zone of the coal seam roof is defined as I-I' in this embodiment; the replacement pile number is Z xy express;

[0092] The drilling sequence is: first drill along the transition zone I-I' Z 1y The construction of the replacement piles is carried out in series, and they are numbered along the direction of transition zone I-I' to obtain Z 11 , Z 12 , Z 13 ,......,Z 1n , the construction sequence is: construct Z first 11 , then construct Z 13 , then construct Z 12 , so that Z 12 Respectively with Z 11 and Z 13 Occlusion. Construction completed 12 Reconstruction Z 15 , then construct Z 14 , so that Z 14 Respectively with Z 13 and Z 15 In this way, the construction of the first row of replacement piles is completed;

[0093] Step 2.2, in the strongly weathered area of ​​the coal seam roof, construct a second row of replacement piles along the length of the transition zone, and the second row of replacement piles are arranged at intervals from the first row of replacement piles;

[0094] Specifically, in Z 1y After the replacement piles are constructed, Z 3y Column replacement pile construction, construction method and Z 1y The columns are the same.

[0095] Step 2.3, constructing a third row of replacement piles between the second row of replacement piles and the first row of replacement piles, and the third row of replacement piles can respectively engage with the second row of replacement piles and the first row of replacement piles to form engaged piles;

[0096] Specifically, in Z 3y After the replacement piles are constructed, Z 2y Column replacement pile construction, construction method is the same as Z1 y The columns are the same.

[0097] Thus achieving Z 2y Listed in Z 1y Column and Z 3y The bite design between the columns.

[0098] Step 2.4, use the second row of replacement piles as the first row of replacement piles, return to step 2.2, until the construction of all n rows of replacement piles in the strongly weathered area of ​​the coal seam roof is completed, and the replacement of the roof of the whole replacement pile is completed.

[0099] And so on, until the construction of all n rows of replacement piles in the strongly weathered area of ​​the coal seam roof is completed. The advantage of adopting the above construction sequence is that it can effectively prevent the adjacent rows of replacement piles from not interlocking due to the replacement pile construction, resulting in missed weathering zone crack areas on the roof of the coal mining face, causing coal seam mining accidents.

[0100] Among them, when constructing a single replacement pile, first use a full-casing fully rotary drilling rig to complete the drilling construction according to the replacement pile setting position, drilling diameter and drilling depth, so that the drilling reaches the designed hole diameter and designed hole depth.

[0101] As a preferred solution of this embodiment, the diameter of the replacement pile is 1.6m to 2.6m, and the bite thickness d of adjacent replacement piles is selected according to the length of the replacement pile. The shorter the replacement pile, the smaller the bite thickness (but the minimum is not less than 100mm), and the longer the replacement pile, the larger the bite thickness. The bite thickness of adjacent replacement piles is determined by the following formula:

[0102] d-2(kL+q)≥50mm

[0103] In the formula,

[0104] d is the occlusal thickness of the adjacent replacement posts, in mm;

[0105] k is the verticality of the replacement pile, which is 1‰;

[0106] L is the length of the replacement pile, in mm;

[0107] q is the allowable value of drilling hole positioning error, in mm. In this embodiment, the value of q is 5 mm.

[0108] As a preferred solution of this embodiment, Figure 5 As shown, the replacement pile includes a plugging mold bag, a concrete layer, a cement mixed soil layer and an original soil layer arranged in sequence from bottom to top; the plugging mold bag is pre-set with quick-setting material.

[0109] The advantages of this structural setting of replacement piles are: the sealing membrane bag can effectively prevent the slurry from leaking along the voids or cracks, which will reduce the construction efficiency and increase the grouting cost; the concrete layer with the same strength as the corresponding stratum rock can effectively improve the strength and structural stability of the transformed layer; the cement-mixed soil layer has both certain strength and flexibility, which provides certain strength and toughness for the replacement piles; backfilling the original soil realizes the restoration of the surface ecology.

[0110] The construction steps of the replacement pile are as follows:

[0111] Step S1, sleeve the foldable plugging mold bag on the bottom end of the catheter, and lower the catheter with the foldable plugging mold bag fixed to the bottom of the drilled hole;

[0112] As a preference, Figure 6 and Figure 7 As shown, the folding method of the foldable plugging mold bag in this embodiment is: first, the plugging mold bag is folded along the length direction of the catheter, and then a plurality of folding points (A, B, C, D, E, F, G, H, I, J) are selected at equal intervals on the plugging mold bag along the radial direction of the catheter, and the plugging mold bag is pressed at each folding point to press the plugging mold bag to points a, b, c, d, e, f, g, j, i, and j of the catheter respectively, and then the foldable plugging mold bag is fixed to the casing with a self-detachable bag clamp;

[0113] Preferably, the diameter of the plugging mold bag is determined by the following formula:

[0114] d m =(1.0~1.15)*D

[0115] The height of the sealing mold bag is determined by the following formula:

[0116] h=(1.8~3.2)*d m

[0117] In the formula,

[0118] d m is the diameter of the sealing mold bag, in m;

[0119] D is the diameter of the replacement pile, in m;

[0120] h is the height of the sealing mold bag, in meters.

[0121] In actual operation, the coefficients in brackets in the calculation of the plugging mold bag diameter and the plugging mold bag height are determined according to the size of the large voids detected in the early stage. The larger the void, the larger the coefficient.

[0122] Step S2: Figure 8As shown, the quick-setting material is injected into the plugging mold bag through the catheter, and the plugging mold bag falls off from the catheter under the action of gravity; the quick-setting material used in this embodiment is fiber quick-setting concrete slurry, and the fiber is preferably cotton fiber. The mechanical properties of the concrete slurry are similar to those of the formation rock. The initial setting time of the concrete slurry is 20 to 25 minutes. The toughness of the quick-setting material is improved by adding fiber, so that it can resist shear damage, and the setting time of the concrete slurry is shortened, the diffusion range is reduced, and the quick-setting material is prevented from diffusing along the cavity, affecting the grouting effect and efficiency.

[0123] Step S3, after completion, injecting concrete into the borehole to a first designed height by means of a conduit;

[0124] The first design height H in the first row of displacement piles is 1y Determined by the following formula:

[0125] H 1y =H m +(5~20);

[0126] In the formula,

[0127] H y is the first design height in the first row of displacement piles, in meters;

[0128] H m It is the height of the nearly horizontal coal seam caving zone, in meters.

[0129] Among them, 5 to 20 depends on the properties of the rock layer and the development of cracks. When cracks are not developed, the value is small, and when cracks are developed, the value is large.

[0130] The first design height from the second row of replacement piles to the nth row of replacement piles is determined by the following formula:

[0131] H y '=(0.22~0.28)*H m

[0132] In the formula,

[0133] H y ' is the first design height from the second row of replacement piles to the nth row of replacement piles, in meters;

[0134] H m It is the height of the nearly horizontal coal seam caving zone, in meters.

[0135] The height of the caving zone of the nearly horizontal coal seam is determined by the following method:

[0136] When the rock saturated compressive strength is 40-60 MPa, H m =(4~5)×h c ;

[0137] When the rock saturated compressive strength is 20-40 MPa, H m =(3~4)×h c ;

[0138] When the rock saturated compressive strength is less than 20MPa, H m =(1~2)×h c ;

[0139] Among them, h c It is the mining height of coal seam, in m.

[0140] like Figure 3 As shown, the above arrangement realizes the concrete in the first row of replacement piles, that is, Z 1y The concrete height in the replacement pile is greater than Z 2y , Z 3y , Z 4y ...Z ny The concrete height of the first row of displacement piles is Z 1y The concrete inside is connected to form a barrier curtain, which serves as a constraining boundary for drilling and grouting.

[0141] Step S4, tamping cement-mixed soil into the borehole to a second designed height;

[0142] The second design height is 5 to 6 meters above the top of the strongly weathered area of ​​the coal seam top. In the cement-mixed soil used, the mass of cement is 5 to 6% of the mass of the soil in terms of mass percentage.

[0143] Step S5: Fill the original soil above the cement-mixed soil layer to the ground to complete the construction of the replacement piles.

[0144] As a preferred method, the replacement piles at key locations can be locally expanded along the axial direction of the pile body to form a ring structure such as Fig. 9 The mortise and tenon structure in the pile shown makes the occlusal relationship more stable.

[0145] Step 3: In the transition zone between the strong weathering zone and the weak weathering zone of the coal seam roof in the weak weathering zone of the coal seam roof, a plurality of support anchor rods for connecting the strong weathering zone and the weak weathering zone of the coal seam roof are arranged. The support anchor rods are 8m long and 22mm in diameter.

[0146] Preferably, the support anchor rod in this embodiment is a glass fiber reinforced plastic anchor rod, which is implanted in a drill hole arranged near the transition zone between the strongly weathered zone and the weakly weathered zone of the coal seam roof.

[0147] The implantation method is: connect a measuring rope to the tail of the FRP anchor rod, lower the FRP anchor rod into the borehole, and monitor whether it is lowered to the bottom of the hole through the measuring rope during the lowering process to ensure that each FRP anchor rod can be implanted at the bottom of the hole and effectively bonded to the stratum. Then, high-pressure cement slurry is injected through the borehole mouth. The cement slurry diffuses along the cracks and gaps of the weathered stratum in the weakly weathered zone of the coal seam roof. After the slurry filling encounters resistance, the pressure is raised to the end of the hole. The cement slurry can bond the FRP anchor rod and the weathered stratum together, achieving the effect of the FRP anchor rod pulling the weathered stratum up and down. The support anchor rod and the slurry stone body are bonded to the interface weathered stratum through grouting to form vertical tie bars. Boundary connection and transition are achieved in the transition zone between the strong weathering zone and the weak weathering zone.

[0148] Step 4: Perform real-time grouting reinforcement on the weakly weathered area of ​​the coal seam roof to complete the treatment of abnormal weathering on the roof of the coal mining face.

[0149] Effect verification:

[0150] In this embodiment, five inspection holes GJ1 to GJ5 are randomly constructed in the replacement pile layout area in the strongly weathered area of ​​the coal seam roof, and drilled and cored. The inspection hole drilling and coring pictures are shown in FIG. Fig.10 Then, the drilling fluid consumption during the inspection hole construction process, the length of the concrete pile exposed by the inspection hole, the core mining area rate and RQD of the replacement pile, and the compressive strength of the core of the concrete part inside the replacement pile are used to reveal the treatment effect of the abnormal weathering body on the roof of the coal mining face.

[0151] The results are shown in Table 1: The drilling fluid was consumed normally, and the height of the exposed replacement pile concrete body met the design requirements and matched the concrete pouring height during the construction process;

[0152] By checking the core recovery rate and RQD value in the hole (Table 2), it can be determined that:

[0153] The concrete piles have good integrity, continuity and reliability.

[0154]

[0155] Table 1. Overview of inspection hole construction

[0156]

[0157] Table 2. Inspection hole core sampling rate and RQD value

[0158] The rock compressive strength test was carried out on the GJ1~GJ5 cores, and the 28d unconfined compressive strength was ≥20MPa. The strength of the concrete pile body was consistent with the strength of the injected rock layer.

[0159] The above test results show that the replacement piles are complete and the occlusion between the replacement piles is good.

[0160] The above implementation process is only an example for clearly explaining the present application, and is not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of this application.

Claims

1. A method for treating abnormal weathering of roof of coal mining working face, characterized in that: The following steps are involved: Step 1, explore and zone the weathering anomaly of the roof of the coal mining face to determine the strongly weathered area of ​​the coal seam roof, the weakly weathered area of ​​the coal seam roof and the unweathered area of ​​the coal seam roof; Step 2: Implement full replacement pile roof replacement in the strongly weathered area of ​​the coal seam roof; Step 3: In the transition area between the strongly weathered area and the weakly weathered area of ​​the coal seam roof, a plurality of support anchor rods for connecting the strongly weathered area and the weakly weathered area of ​​the coal seam roof are arranged; Step 4: Perform real-time grouting reinforcement on the weakly weathered area of ​​the coal seam roof to complete the treatment of abnormal weathering on the roof of the coal mining face.

2. The method for treating abnormal weathering of roof of coal mining face according to claim 1, characterized in that: The coal seam roof strong weathering area meets the following conditions: drilling fluid consumption ≥ 60L / m, core mining area rate ≤ 50% and RQD ≤ 45%; The weakly weathered area of ​​the coal seam roof meets the following conditions: 30L / m ≤ drilling fluid consumption < 60L / m, 50% < core mining area rate ≤ 80% and 45% <RQD≤75%; The unweathered area of ​​the coal seam roof meets the following conditions: drilling fluid consumption <30L / m, core mining area rate >80% and RQD >75%.

3. The method for treating abnormal weathering of roof of coal mining face according to claim 1, characterized in that: The full replacement pile top plate replacement described in step 2 specifically includes the following sub-steps: Step 2.1, construct the first row of replacement piles along the length of the transition zone in the strongly weathered area of ​​the coal seam roof near the transition zone; Step 2.2, in the strongly weathered area of ​​the coal seam roof, construct a second row of replacement piles along the length of the transition zone, and the second row of replacement piles are arranged at intervals from the first row of replacement piles; Step 2.3, constructing a third row of replacement piles between the second row of replacement piles and the first row of replacement piles, and the third row of replacement piles can respectively engage with the second row of replacement piles and the first row of replacement piles to form engaged piles; Step 2.4, use the second row of replacement piles as the first row of replacement piles, return to step 2.2, until the construction of all replacement piles in the strongly weathered area of ​​the coal seam roof is completed, and the replacement of the roof with all replacement piles is completed.

4. The method for treating abnormal weathering of roof of coal mining face according to claim 1, characterized in that: The replacement pile comprises a plugging mold bag, a concrete layer, a cement mixed soil layer and an original soil layer which are sequentially arranged from bottom to top; quick-setting materials are pre-placed in the plugging mold bag.

5. The method for treating abnormal weathering of roof of coal mining face according to claim 1, characterized in that: The diameter of the replacement pile is 1.6m to 2.6m, and the bite thickness of adjacent replacement piles is determined by the following formula: d-2(kL+q)≥50mm In the formula, d is the occlusal thickness of the adjacent replacement posts, in mm; k is the verticality of the replacement pile, which is 1‰; L is the length of the replacement pile, in mm; q is the allowable value of drilling hole positioning error, in mm.

6. The method for treating abnormal weathering of roof of coal mining face according to claim 4, characterized in that: The diameter of the plugging mold bag is determined by the following formula: d m =(1.0~1.15)*D The height of the blocking mold bag is determined by the following formula: h=(1.8~3.2)*d m In the formula, d m is the diameter of the sealing mold bag, in m; D is the diameter of the replacement pile, in m; h is the height of the sealing mold bag, in meters.

7. The method for treating abnormal weathering of roof of coal mining face according to claim 3, characterized in that: The construction method of the replacement pile is as follows: Step S1, sleeve the foldable sealing mold bag on the bottom end of the catheter and fix it with a self-detachable bag clamp; lower the catheter with the foldable sealing mold bag fixed to the bottom of the drilled hole; Step S2, injecting the quick-setting material into the plugging mold bag through the catheter, and the plugging mold bag falls off from the catheter under the action of gravity; Step S3, injecting concrete into the borehole to a first designed height by means of a conduit; Step S4, tamping cement-mixed soil into the borehole to a second designed height; Step S5: Fill the original soil to the ground to complete the construction of the replacement pile.

8. The method for treating abnormal weathering of roof of coal mining face according to claim 7, characterized in that: The first design height within the first row of replacement piles is determined by the following formula: H y =H m +(5~20) In the formula, H y is the first design height in the first row of displacement piles, in meters; H m It is the height of the nearly horizontal coal seam caving zone, in meters.

9. The method for treating abnormal weathering of roof of coal mining face according to claim 7, characterized in that: The first design height of the second row of replacement piles into the nth row of replacement piles is determined by the following formula: H y ’=(0.22~0.28)*H m In the formula, H y ' is the first design height from the second row of replacement piles to the nth row of replacement piles, in meters; H m It is the height of the nearly horizontal coal seam caving zone, in meters.

10. The method for treating abnormal weathering of roof of coal mining face according to claim 9, characterized in that: The height of the nearly horizontal coal seam caving zone is determined by the following method: When the rock saturated compressive strength is 40-60 MPa, H m =(4~5)×h c ; When the rock saturated compressive strength is 20-40 MPa, H m =(3~4)×h c ; When the rock saturated compressive strength is less than 20MPa, H m =(1~2)×h c ; Among them, h c It is the mining height of coal seam, in m.

11. The method for treating abnormal weathering of roof of coal mining face according to claim 7, characterized in that: The second design height is 5 to 6 meters above the top of the strongly weathered zone of the coal seam roof.

12. The method for treating abnormal weathering of roof of coal mining face according to claim 4 or 7, characterized in that: In the cement-mixed soil, the mass of cement accounts for 5-6% of the mass of the soil in terms of mass percentage.

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