A hard roof classification pre-cracking in-situ grouting modification filling anti-scouring method and system

Abstract

The present application relates to the technical field of coal mining, and provides a hard roof classification pre-cracking in-situ grouting modification filling and anti-bumping system. In this method, the collapse zone height of the goaf is determined based on the average value of the expansion coefficient of the rock layer in the overlying rock mass within the maximum fracture zone height of the working face, which is thicker than the coal seam thickness; the rock layer in the overlying rock mass within the maximum fracture zone height, which is thicker than the preset coal seam thickness and has a uniaxial compressive strength greater than a preset strength threshold, is determined as an effective key layer, and according to the number of effective key layers, the effective key layers are divided into single-layer key layers and multi-layer key layers; for single-layer key layers, based on the collapse zone height of the goaf and the distance from the effective key layer closest to the coal roof to the coal roof, the roof is classified and pre-cracked; for multi-layer key layers, the rock layers are divided into zones based on the collapse zone height, and the different zones are classified and pre-cracked; and the collapse zone is reinforced by grouting to fill the goaf.

Description

Technical Field

[0001] The present application relates to the technical field of coal mining, and in particular to a method and system for preventing impact by in-situ grouting, modification and filling of hard roof classification pre-cracking. Background Art

[0002] With the increase in coal mining depth and mining intensity, rock burst disasters are becoming more frequent, posing a serious threat to coal mine safety. Typically, the hard, thick roof above the coal seam is the primary source of rock burst disasters, especially the hard rock strata at a certain distance from the mined coal seam. After mining, goafs form. If not promptly filled, the hard rock strata above the goaf will become suspended. When the suspended roof reaches a certain area, the hard rock strata will suddenly fracture, acting as a source of high-energy stress waves. These stress waves carry energy that is transferred to the surrounding rock of the roadway, causing instability and inducing rock bursts.

[0003] Therefore, there is an urgent need to provide a technical solution to the above-mentioned deficiencies in the existing technology. Summary of the Invention

[0004] The purpose of this application is to provide a hard roof classification pre-cracking in-situ grouting modification filling anti-collision method and system to solve or alleviate the problems existing in the above-mentioned prior art.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] The present application provides a hard roof classification pre-cracking in-situ grouting modification filling anti-scouring method, comprising: step S101, according to the maximum crack zone height of the working face The thickness of the overlying rock mass within the range is greater than the thickness of the coal seam. The average value of the rock expansion coefficient , to determine the height of the collapse zone in the goaf ; Step S102, determine the maximum crack zone height The rock layer with a thickness greater than the preset coal seam thickness and a uniaxial compressive strength greater than the preset strength threshold within the overlying rock mass is an effective key layer, and according to the number of the effective key layers, the effective key layers are divided into a single-layer key layer and a multi-layer key layer; step S103, in response to the effective key layer being the single-layer key layer, based on the collapse zone height of the goaf and the distance from the effective key layer closest to the coal top to the coal top , classify and pre-crack the roof, and perform grouting reinforcement on the collapsed area to fill the goaf; in response to the effective key layer being the multi-layer key layer, based on the height of the collapsed zone The rock formations are divided into zones, different zones are classified and pre-cracked, and the collapsed areas are reinforced by grouting to fill the mined-out areas.

[0007] Preferably, step S101 includes: according to the formula:

[0008]

[0009] Determine the maximum fracture zone height of the working face Where, is the thickness of the coal seam;

[0010] Maximum crack height for working surface The overlying rock mass within the range is sampled and the formula is used:

[0011]

[0012] Determine the maximum crack height of the working surface The expansion coefficient of each rock layer in the overlying rock mass within the range of The maximum crack height of the working surface The overlying rock mass within The rock expansion coefficient of each rock layer; The first The volume of a rock layer after crushing; The first The volume of a rock layer before it breaks down;

[0013] According to the formula:

[0014]

[0015] Determine that the thickness of the rock layer in the overlying rock mass is greater than the thickness of the coal seam The average value of the rock expansion coefficient Where, The thickness of the rock layer in the overlying rock mass is greater than the thickness of the coal seam The total number of rock layers; , All are positive integers.

[0016] Preferably, in step S101, according to the formula:

[0017]

[0018] Determine the height of the collapse zone ;in, is the thickness of the coal seam; The thickness of the rock layer in the overlying rock mass is greater than the thickness of the coal seam The average value of the rock expansion coefficient; Coal seam inclination.

[0019] Preferably, in step S103, in response to the effective key layer being the single layer key layer, the height of the collapse zone in the goaf is and the distance from the effective key layer closest to the coal top to the coal top , classify and pre-crack the roof, and reinforce the collapsed area with grouting to fill the goaf, including: determining the distance from the preferred key layer to the coal roof : wherein the preferred key layer is the effective key layer closest to the coal top;

[0020] In response to the distance from the preferred key layer to the coal top Greater than the height of the collapse zone , grouting reinforcement is carried out on the rock mass that falls during mining to fill the mined-out area;

[0021] In response to the distance from the preferred key layer to the coal top Less than the height of the collapse zone , determine the effective key layer located at the height of the collapse zone The rock layer within is the key layer; the key layer is located at the height of the collapse zone. Within, the key layer is fully pre-cracked and the collapsed area is reinforced by grouting to fill the goaf; in response to the key layer being partially located at the height of the collapsed zone, Based on the expansion criterion of hydraulic fractures after encountering the layer, the key layer is located at the height of the collapse zone. Directional hydraulic fracturing is performed on the part within to divide the key layer, and pre-cracks are performed on the part of the key layer located in the collapse area after division, and grouting reinforcement is performed on the collapse area to fill the goaf.

[0022] Preferably, in step S103, in response to the effective key layer being the multi-layer key layer, the rock layer is partitioned based on the height of the collapse zone, different partitions are classified and pre-cracked, and the collapse zone is grouting reinforced to fill the goaf, including: The rock strata within the area are divided into low-lying areas, the rock strata in the low-lying areas are subjected to blasting pre-cracking treatment, and the collapsed areas are reinforced by grouting to fill the mined-out areas;

[0023] The whole is located at the height of the collapse zone Outside and located at the maximum fracture zone height The rock strata within the middle zone are divided into the middle zone, the rock strata in the middle zone are subjected to hydraulic fracturing treatment, and the collapsed zone is reinforced by grouting to fill the mined-out area;

[0024] A portion of the whole is placed at the height of the collapse zone Within, part of the height of the collapse zone The rock formations outside the composite area are divided into composite areas, and the rock formations in the composite area are based on the expansion criterion after the hydraulic fractures encounter the surface, and the height of the collapse zone is After hydraulic directional cutting of the rock formation within the range, the low-level area and the middle-level area methods are used for classification processing.

[0025] Preferably, in step S103, in response to the distance from the preferred key layer to the coal top Greater than the height of the collapse zone Or, the key layer is located at the height of the collapse zone as a whole. Or, the multi-layer key layer is located in the low area or the middle area, according to the formula:

[0026]

[0027] Determine the height of the grouting borehole from the coal top Where, is the thickness of the coal seam;

[0028] In response to the key layer being located at the height of the collapse zone Or, the multi-layer key layer is located in the composite area, according to the formula:

[0029]

[0030] Determine the height of the grouting borehole from the coal top .

[0031] Preferably, step S103 further includes: according to the formula:

[0032]

[0033] Determine the total width of the grouting borehole and grouting drilling spacing Where, is the width of the goaf; is the effective diffusion radius of the grouting slurry; is the treatment length of the goaf; For coal mining efficiency.

[0034] Preferably, the method further comprises: according to the formula:

[0035]

[0036] Determine the theoretical filling height of the goaf ;in, is the thickness of the coal seam; For coal mining efficiency; is the average value of the expansion coefficient; is the coal seam inclination;

[0037] According to the formula:

[0038]

[0039] Determine the evaluation index for grouting filling in goaf ;

[0040] Where, is the actual filling height of the goaf, is the compressive strength of the breaking key layer; It is the sum of the self-load of the critical fracture layer and the uniformly distributed load transferred from the overlying rock layer; is the breaking step distance of the breaking key layer; is the thickness of the critical fracture layer; wherein the critical fracture layer is a rock layer that has been fully pre-cracked and hydraulically cut in the single-layer critical layer, or a rock layer that has been subjected to blasting pre-crack treatment, hydraulic fracturing treatment, and hydraulically cut in multiple layers of critical layers;

[0041] When the rock layer is not broken, according to the formula:

[0042]

[0043] Determine the breaking step ;

[0044] In response to the breaking of the rock formation, according to the formula:

[0045]

[0046] Determine the breaking step ;

[0047] Where, is the tensile strength of the breaking key layer, is the Poisson's ratio of the critical fracture layer.

[0048] Preferably, it also includes:

[0049] In response to , the goaf is filled twice using blasting, crushing, drilling and grouting, according to the formula:

[0050]

[0051] Determine the total width of the blasting drill hole and height Where, is the width of the goaf; is the thickness of the coal seam;

[0052] According to the formula:

[0053]

[0054] Determining the distance between two adjacent blasting and fragmentation drill holes;

[0055] Where, , are all positive integers, and , the number of drill holes for said blasting; is the thickness of the critical fracture layer; is the tensile strength of the breaking key layer; is the uniformly distributed load on the critical fracture layer.

[0056] The embodiment of the present application also provides a hard roof classification pre-cracking in-situ grouting modified filling anti-collision system, including: a collapse zone height unit, configured to be based on the maximum crack zone height of the working face The thickness of the overlying rock mass within the range is greater than the thickness of the coal seam. The average value of the rock expansion coefficient , to determine the height of the collapse zone in the goaf ;

[0057] Horizontal division unit, configured to determine the maximum fracture zone height The rock layers within the overlying rock mass with a thickness greater than the preset coal seam thickness and a uniaxial compressive strength greater than the preset strength threshold are effective key layers, and according to the number of effective key layers, the effective key layers are divided into single-layer key layers and multi-layer key layers;

[0058] The pre-splitting grouting filling unit is configured to respond to the effective key layer being a single-layer key layer and based on the height of the collapse zone in the goaf. and the distance from the effective key layer closest to the coal top to the coal top , pre-crack the roof in a classified manner, and reinforce the collapsed area with grouting to fill the goaf;

[0059] In response to the effective key layer being a multi-layer key layer, based on the collapse zone height The rock formation is divided into zones, different pre-cracking operations are taken for different zones, and grouting reinforcement is carried out on the collapsed areas to fill the mined-out areas.

[0060] Beneficial effects:

[0061] In the hard roof classification pre-cracking in-situ grouting modification filling anti-scouring method provided in the embodiment of the present application, first, the largest crack zone of the working face is determined. The thickness of the overlying rock mass within the range is greater than the thickness of the coal seam. The average value of the coefficient of expansion ; and based on the average value of the coefficient of expansion , determine the height of the collapse zone in the goaf ; Then, determine the maximum fracture zone The thickness of the overlying rock mass within the range is greater than the preset coal seam thickness (5 meters) and the uniaxial compressive strength is greater than the preset strength threshold ( Greater than ) is the effective key layer, and according to the number of effective key layers, the mine key layer is divided into a single layer key layer and a multi-layer key layer; when the mine key layer is a single layer key layer, based on the height of the collapse zone of the goaf Pre-crack the roof and reinforce the collapsed area with grouting to fill the goaf; when the key layer of the mine is a multi-layer key layer, based on the height of the collapsed zone The rock formations are divided into zones, and different pre-cracking operations are adopted for different zones. Grouting is then carried out to reinforce the collapsed areas to fill the goaf. Thus, by classifying and treating the hard and thick roof overlying the coal rock, it can be collapsed in a timely and efficient manner. The broken rock in the collapsed area is promptly reinforced by in-situ grouting, artificially forming an in-situ modified filling zone, and the goaf is filled in a timely and efficient manner, achieving a "top-to-bottom connection" structure, achieving the effect of supporting the overlying hard roof, avoiding the sudden fracture of the hard roof with accumulated elastic energy, generating stress waves and inducing rock burst disasters, and maximizing the safety of mining at the working face. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The drawings and descriptions that constitute part of this application are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. Among them:

[0063] Figure 1 A schematic flow chart of a hard roof slab classified pre-cracking in-situ grouting modification filling anti-scouring method provided according to some embodiments of the present application;

[0064] Figure 2 A logic diagram of a hard roof slab classified pre-cracking in-situ grouting modification filling anti-scouring method provided according to some embodiments of the present application;

[0065] Figure 3 A schematic diagram of pre-cracking in-situ grouting modification and backfilling for anti-scouring of a key layer in a single layer according to some embodiments of the present application;

[0066] Figure 4A schematic diagram of pre-cracking in-situ grouting modification and filling for anti-collision in multi-layer key layers according to some embodiments of the present application;

[0067] Figure 5 This is a structural schematic diagram of a hard roof slab classified pre-cracking in-situ grouting modified filling anti-collision system provided according to some embodiments of the present application. DETAILED DESCRIPTION

[0068] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. Each example is provided by way of explanation of the present application and does not limit the present application. In fact, it will be clear to those skilled in the art that modifications and variations can be made in the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as part of one embodiment can be used in another embodiment to produce yet another embodiment. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention should fall within the scope of protection of the embodiments of the present invention.

[0069] During the coal mining process, in the existing top-caving filling methods, first, pre-cracking is often carried out after the key layer is found, but in reality, not all key layers need pre-cracking; second, the treatment method for the key layer is too isolated, and the treatment problem of multiple key layers is not considered; third, only the goaf is filled during filling, and there is a lack of specific filling effect inspection, and a lack of measures to be taken when the filling effect is not ideal; fourth, a "one-size-fits-all" approach is used to treat the key layer, resulting in a waste of resources.

[0070] Based on this, the present application proposes a method for pre-cracking and in-situ grouting modification and filling to prevent impact on hard roof. Based on the crushing and swelling properties of the rock mass, the hard and thick roof overlying the coal rock is classified and processed according to the thickness of the coal body and the geological conditions of the working face, so that it can collapse in a timely and efficient manner; the broken rock in the collapsed area is promptly reinforced by in-situ grouting, and an in-situ modified filling area is artificially formed to achieve the effect of supporting the overlying hard roof. A specific filling effect inspection method is given, and the use of deep hole blasting to increase crushing is proposed to improve the poor filling effect, and to fill the goaf in a timely and efficient manner to achieve a "top-to-bottom" structural form, to avoid the sudden fracture of the hard roof with accumulated elastic energy, which generates stress waves and induces impact ground pressure disasters, and to maximize the protection of safe mining of the working face.

[0071] like Figures 1 to 4 As shown, the hard roof classification pre-cracking in-situ grouting modification filling anti-scouring method includes:

[0072] Step S101: According to the maximum fracture zone height of the working surface The thickness of the overlying rock mass within the range is greater than the thickness of the coal seam. The average value of the rock expansion coefficient , to determine the height of the collapse zone in the goaf

[0073] In this application, first, according to the formula:

[0074]

[0075] Determine the maximum fracture zone height of the working face Where, is the coal seam thickness.

[0076] Then, the maximum fracture zone height of the working face The overlying rock mass within the range is sampled and the formula is used:

[0077]

[0078] Determine the maximum fracture zone height of the working face The expansion coefficient of each rock layer in the overlying rock mass within the range of Height of the maximum fracture zone in the working face The overlying rock mass within The rock expansion coefficient of each rock layer; The first The volume of a rock layer after crushing; The first The volume of the rock layer before it is broken. All of them are obtained by direct measurement after sampling the overlying rock mass.

[0079] Finally, according to the formula:

[0080]

[0081] Determine that the thickness of the rock layer in the overlying rock mass is greater than the thickness of the coal seam The average value of the rock expansion coefficient Where, The thickness of the rock layer in the overlying rock mass is greater than the thickness of the coal seam The total number of rock layers; , All are positive integers.

[0082] Then, according to the formula:

[0083]

[0084] Determine the height of the collapse zone Where, is the coal seam thickness; The thickness of the rock layer in the overlying rock mass is greater than the thickness of the coal seam The average value of the rock expansion coefficient; Coal seam inclination.

[0085] Step S102: Determine the maximum fracture zone height The rock layers within the overlying rock mass whose middle layer thickness is greater than the preset coal seam thickness and whose uniaxial compressive strength is greater than the preset strength threshold are effective key layers. According to the number of effective key layers, the effective key layers are divided into single-layer key layers and multi-layer key layers.

[0086] In this application, the maximum fracture zone height is calculated based on the mine geological histogram and test report. The inner layer thickness is greater than the coal seam thickness (5 meters) and the uniaxial compressive strength The rock layer is defined as an effective key layer. The effective key layer represents the rock layer whose vibration energy released during critical movement or fracture will have an effective impact on the working face. Generally speaking, the closer the effective key layer is to the working face, the thicker the coal seam is, and the higher the uniaxial compressive strength is, the greater the effective impact on the working face.

[0087] When the number of effective key layers is 1, it is defined as a single-layer key layer; when the number of effective key layers is greater than 1, it is defined as a multi-layer key layer. The key layers at different layers are classified and processed, different pre-cracking measures are taken, and the goaf is classified and filled. In other words, when the overburden on the working face contains only one effective key layer, the working face is only affected by one effective key layer, reflecting that the overburden environment on the working face is relatively clear; when the overburden on the working face contains more than one effective key layer, the working face is jointly affected by multiple effective key layers, and the working face needs to consider the mutual influence between the effective key layers, reflecting that the overburden environment on the working face is relatively complex.

[0088] Step S103: In response to the effective key layer being a single-layer key layer, based on the height of the collapsed zone in the goaf, The distance from the effective key layer closest to the coal top to the coal top , the roof is pre-cracked and the collapsed area is reinforced by grouting to fill the goaf; in response to the effective key layer being a multi-layer key layer, based on the height of the collapsed zone The rock formations are divided into zones, different zones are classified and pre-cracked, and the collapsed areas are reinforced by grouting to fill the mined-out areas.

[0089] For a single-layer key layer, first determine the distance from the effective key layer closest to the coal top (preferred key layer) to the coal top based on the drill hole histogram data. Specifically, the thickness and burial depth of each rock layer are clearly defined in the drill hole histogram, and based on this, the distance from the effective key layer (preferred key layer) closest to the coal top to the coal top can be determined.

[0090] When the distance from the key layer to the coal top is preferred Greater than the height of the collapse zone (Right now ) when the rock mass that falls with mining is reinforced by grouting to fill the goaf; when the distance from the key layer to the coal top is preferred Less than the height of the collapse zone (Right now ), determine the effective key layer located at the height of the collapse zone The rock layer within is the key layer. That is to say, the key layer must be an effective key layer, but the effective key layer is not necessarily the key layer. In a single layer of key layers, the only effective key layer must be the preferred key layer; when the only effective key layer is located at the height of the collapse zone When the value is within , the only valid key layer is the key key layer.

[0091] When the key layer is located at the height of the collapse zone Within, the key layer is fully pre-cracked and the collapsed area is reinforced by grouting to fill the goaf; when the key layer is located at the height of the collapsed zone Based on the hydraulic fracture expansion criterion, the key layers are located at the height of the collapse zone. The key layers are cut with hydraulic pressure in the part within the rock formation, and the part of the key layers that is located in the collapse zone is pre-cracked, and the collapse zone is reinforced with grouting to fill the goaf. When the key layers are cut with hydraulic pressure in the direction of hydraulic pressure, the cracks generated by the water pressure always start and expand in the direction perpendicular to the minimum principal stress. Continuous water injection can make the radial cracks extend forward continuously. The crack inclination angle is related to the original crack inclination in the rock formation, but it does not coincide with the fracture surface that can be formed in the end.

[0092] At the height of the collapse zone When the part within the tunnel is subjected to hydraulic directional cutting to separate the key layer, a drilling rig equipped with a drilling and cutting drill bit is used to drill a hole into the rock layer to the set position (the drilling level is based on the center line of the tunnel and extends to the edge of the key layer's hanging top, and the height distance is from the coal top upwards). ), and then input high-pressure water into the slotting drill bit, while rotating the drill pipe in place to cut the slots, forming radial cracks; and the drill bit can quickly retreat, then rotate in place to cut the slots, and then quickly retreat, repeating the rotation and retreat to the set position, and withdrawing the drill pipe, which can cause multiple radial cracks in the rock around the drill hole.

[0093] Alternatively, while inputting high-pressure water, slowly withdraw the drill rod outward until it reaches the set position, and then withdraw the drill rod to create an axial crack zone in the rock mass from the inside to the outside along the direction of the drill rod. Multiple axial crack zones can be formed by rotating at different angles. Under the influence of the water injection segmentation pressure and the gravity of the key layer itself, the rock layer is segmented.

[0094] For multi-layer key layers, the key layer is located at the height of the collapse zone. The rock strata within the area are divided into low-lying areas, and blasting pre-crack treatment is performed on the rock strata in the low-lying areas, and grouting reinforcement is performed on the collapsed areas to fill the mined-out areas. After blasting the rock strata in the low-lying areas, the rock fragmentation and expansion can be more effectively increased, so that the grouting effect of the same amount of rock strata is more sufficient, the filling effect is better, and the overlying rock strata that have not collapsed can be better supported.

[0095] The key layer is located at the height of the collapse zone Outside and located at the maximum fracture zone height The rock formation within the area is divided into the median zone, and the rock formation in the median zone is subjected to hydraulic fracturing treatment, and the collapsed area is reinforced by grouting to fill the mined-out area. Here, hydraulic fracturing treatment refers to the rock formation as a whole, which is to fracture the rock formation, making it looser and more prone to collapse.

[0096] A portion of the key layer is located at the height of the collapse zone Within, part of the collapse zone height The rock formations outside the composite area are divided into composite areas. The rock formations in the composite area are based on the expansion criterion after the hydraulic fractures encounter the surface layer. After the rock formation is cut by hydraulic directional cutting in the rock formation, it is classified and processed by the low-level area and the middle-level area method. Here, hydraulic directional cutting is carried out on a certain surface of the rock formation, aiming to split the rock formation into two parts.

[0097] Here, the rock strata in the high-position area are not the main body of the collapse and filling, and there is no need for large-scale collapse. By performing hydraulic fracturing treatment on the rock strata in the middle area, the accumulated elastic energy can be effectively reduced, and the large-scale collapse of the rock strata in the high-position area caused by blasting can be effectively solved. At the same time, it is avoided to provide favorable conditions for the sudden collapse of the adjacent rock strata (the blasting has a large impact area, which will provide favorable conditions for the sudden collapse of the adjacent rock strata).

[0098] Through hydraulic fracturing, the rock formation that needs to collapse is pre-cracked, which can effectively release the accumulated energy in the unbroken rock formation, effectively reducing its accumulated energy peak or even losing the accumulated energy. At the same time, it is easier to collapse and the overhang will not be too long. Then, grouting is used to reinforce the rock formation that has collapsed in the goaf, so that the collapsed rock mass has sufficient strength to support the overlying rock formation and to a certain extent prevent ground collapse.

[0099] In this application, when drilling and grouting to reinforce the collapsed area to fill the goaf, the preferred keyword is the distance from the coal layer to the top of the coal. Greater than the height of the collapse zone , or, the key layer is located at the height of the collapse zone Or, when the key layer of multiple layers is located in the low area or the middle area, according to the formula:

[0100]

[0101] Determine the height of the grouting borehole from the coal top Where, is the coal seam thickness.

[0102] When the key layer is located at the height edge of the collapse zone Or, if the key layer of the multi-layer is located in the composite area, according to the formula:

[0103]

[0104] Determine the height of the grouting borehole from the coal top .

[0105] When grouting drilling is carried out, a row of horizontal grouting holes is drilled from the drilling chamber, and according to the formula:

[0106]

[0107] Determine the total width of the grouting borehole and grouting drilling spacing Where, is the width of the goaf, is the effective diffusion radius of the grouting slurry, is the treatment length of the goaf, For coal mining efficiency.

[0108] In this application, whether it is a single key layer or multiple key layers, when filling the goaf, the formula is as follows:

[0109]

[0110] Determine the theoretical filling height of the goaf Where, is the coal seam thickness, For coal mining efficiency, is the average value of the coefficient of expansion, Coal seam inclination.

[0111] After the goaf is filled, according to the formula:

[0112]

[0113] Determine the evaluation index for grouting filling in goaf Where, is the actual filling height of the goaf, is the compressive strength of the breaking key layer, It is the sum of the self-load of the critical fracture layer and the uniformly distributed load transferred from the overlying rock layer; is the breaking step distance of the key layer, The thickness of the fractured butler layer. The fractured key layer refers to a single layer of rock that has been fully pre-cracked and hydraulically cut, or multiple layers of rock that have been pre-cracked, hydraulically fractured, or hydraulically cut.

[0114] When the rock layer is not broken, according to the formula:

[0115]

[0116] Determine the breaking step ;

[0117] When the rock layer breaks, according to the formula:

[0118]

[0119] Determine the breaking step Where, is the tensile strength of the breaking key layer, is the Poisson's ratio of the critical fracture layer.

[0120] In this application, when δ>1.2, the goaf is completely filled and the fracture zone is supported, with a good filling effect. When 1.0<δ<1.2, the goaf is completely filled, with a moderate filling effect. When δ<1.0, the goaf is not completely filled, with a poor filling effect. Blasting and fragmentation followed by grouting should be used for secondary filling of the goaf, i.e., blasting and fragmentation drilling and grouting should be used.

[0121] Specifically, a row of horizontal blasting and fragmentation drill holes is drilled from the chamber, according to the formula:

[0122]

[0123] Determine the total width of the blasting drill hole and height Where, is the width of the goaf, is the thickness of the coal seam. The range is 3~5 meters.

[0124] According to the formula:

[0125]

[0126] Determine the distance between two adjacent blasting and fragmentation drill holes; where, , are all positive integers, and , Indicates the number of blasting and fragmentation drill holes; is the thickness of the critical fracture layer, is the tensile strength of the breaking key layer, is the uniform load on the critical fracture layer. hour, , is the initial collapse step distance of the key layer; hour, is the periodic collapse step distance of the key layer.

[0127] Therefore, by classifying and treating the hard and thick roof overlying the coal rock, so that it can collapse in a timely and efficient manner, the collapsed and inner broken rock is promptly reinforced by in-situ grouting, an artificial in-situ modified filling area is formed, and the goaf is filled in a timely and efficient manner to achieve a "top-to-bottom" structure, realize the effect of supporting the overlying hard roof, avoid the sudden fracture of the hard roof with accumulated elastic energy to generate stress waves and induce impact ground pressure disasters, and maximize the protection of safe mining of the working face.

[0128] The embodiment of the present application also provides a hard roof classification pre-cracking in-situ grouting modification filling anti-collision system, such as Figure 5 As shown, the anti-collision system includes:

[0129] Collapse zone height unit 501 is configured to determine the maximum fracture zone height of the working face The thickness of the overlying rock mass within the range is greater than the thickness of the coal seam. The average value of the rock expansion coefficient , to determine the height of the collapse zone in the goaf ;

[0130] The layer division unit 502 is configured to determine the maximum fracture zone height The rock layers with a thickness greater than the preset coal seam thickness and a uniaxial compressive strength greater than the preset strength threshold are effective key layers, and according to the number of effective key layers, the effective key layers are divided into single-layer key layers and multi-layer key layers;

[0131] The pre-splitting grouting filling unit 503 is configured to respond to the effective key layer being a single layer key layer, based on the height of the collapse zone of the goaf. The distance from the effective key layer closest to the coal top to the coal top , pre-crack the roof in a classified manner, and reinforce the collapsed area with grouting to fill the goaf;

[0132] In response to the effective key layer being a multi-layer key layer, based on the collapse zone height The rock formation is divided into zones, different pre-cracking operations are taken for different zones, and grouting reinforcement is carried out on the collapsed areas to fill the mined-out areas.

[0133] The hard roof classification pre-cracking in-situ grouting modification filling anti-collision system provided in the embodiments of the present application can realize the steps and processes of the hard roof classification pre-cracking in-situ grouting modification filling anti-collision method of any of the above embodiments, and achieve the same technical effects, which will not be repeated here.

[0134] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0135] Throughout the present invention, terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0136] The foregoing description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are readily apparent to those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A hard roof classification pre-cracking in-situ grouting modification filling anti-scouring method, characterized in that: include: Step S101: according to the maximum fracture zone height of the working surface The thickness of the overlying rock mass within the range is greater than the thickness of the coal seam. The average value of the rock expansion coefficient , to determine the height of the collapse zone in the goaf ; Step S102: Determine the maximum fracture zone height The rock layers in the overlying rock mass within the range of 10 ... Step S103: In response to the effective key layer being the single-layer key layer, the height of the collapsed zone in the goaf is determined based on the and the distance from the effective key layer closest to the coal top to the coal top , pre-crack the roof in a classified manner, and reinforce the collapsed area with grouting to fill the goaf; In response to the effective key layer being the multi-layer key layer, based on the collapse zone height Divide the rock formation into zones, pre-crack different zones according to their classification, and reinforce the collapsed areas with grouting to fill the mined-out areas; Wherein, the effective key layer is the single layer key layer, based on the height of the collapse zone in the goaf. and the distance from the effective key layer closest to the coal top to the coal top , classify and pre-crack the roof, and reinforce the collapsed area with grouting to fill the goaf, including: Determine the distance from the preferred key layer to the coal top : The preferred key layer is the effective key layer closest to the coal top; In response to the distance from the preferred key layer to the coal top Greater than the height of the collapse zone , grouting reinforcement is carried out on the rock mass that falls during mining to fill the mined-out area; In response to the distance from the preferred key layer to the coal top Less than the height of the collapse zone , determine the effective key layer located at the height of the collapse zone The rock layers within are the key layers; The key layer is located at the height of the collapse zone as a whole Within, the key layers are fully pre-cracked and the collapsed areas are reinforced by grouting to fill the goaf; In response to the key layer portion being located at the collapse zone height Based on the expansion criterion of hydraulic fractures after encountering the layer, the key layer is located at the height of the collapse zone. Directional hydraulic fracturing is performed on the part within to divide the key layer, and pre-cracks are performed on the part of the key layer located in the collapse area after division, and grouting reinforcement is performed on the collapse area to fill the goaf.

2. The hard roof classification pre-cracking in-situ grouting modification filling anti-scouring method according to claim 1 is characterized in that: Step S101 includes: According to the formula: Determine the maximum fracture zone height of the working face ; Where, is the thickness of the coal seam; Maximum crack height for working surface The overlying rock mass within the range is sampled and the formula is used: Determine the maximum crack height of the working surface The expansion coefficient of each rock layer in the overlying rock mass within ; Where, The maximum crack height of the working surface The overlying rock mass within The rock expansion coefficient of each rock layer; The first The volume of a rock layer after crushing; The first The volume of a rock layer before it breaks down; According to the formula: Determine that the thickness of the rock layer in the overlying rock mass is greater than the thickness of the coal seam The average value of the rock expansion coefficient ; Where, The thickness of the rock layer in the overlying rock mass is greater than the thickness of the coal seam The total number of rock layers; , All are positive integers.

3. The hard roof classification pre-cracking in-situ grouting modification filling method according to claim 2 is characterized in that: In step S101, According to the formula: Determine the height of the collapse zone ;in, is the thickness of the coal seam; The thickness of the rock layer in the overlying rock mass is greater than the thickness of the coal seam The average value of the rock expansion coefficient; The inclination of the coal seam.

4. The hard roof classification pre-cracking in-situ grouting modification filling anti-scouring method according to claim 1 is characterized in that: In step S103, in response to the effective key layer being the multi-layer key layer, the rock layer is divided into zones based on the height of the collapse zone, different zones are classified and pre-cracked, and the collapse zone is grout-reinforced to fill the goaf, including: The whole will be located at the height of the collapse zone The rock strata within the area are divided into low-lying areas, the rock strata in the low-lying areas are subjected to blasting pre-cracking treatment, and the collapsed areas are reinforced by grouting to fill the mined-out areas; The whole will be located at the height of the collapse zone Outside and located at the maximum fracture zone height The rock formations within the middle zone are divided into the middle zone, the rock formations in the middle zone are subjected to hydraulic fracturing treatment, and the collapsed zone is reinforced by grouting to fill the mined-out zone; A portion of the whole is placed at the height of the collapse zone Within, part of the height of the collapse zone The rock formations outside the composite area are divided into composite areas, and the rock formations in the composite area are classified into composite areas based on the expansion criteria of the hydraulic fractures after encountering the surface layer. After hydraulic directional cutting of the rock formation within the range, the low-level area and the middle-level area methods are used for classification processing.

5. The hard roof classification pre-cracking in-situ grouting modification filling method according to claim 4 is characterized in that: In step S103, In response to the distance from the preferred key layer to the coal top Greater than the height of the collapse zone Or, the key layer is located at the height of the collapse zone as a whole. Or, the multi-layer key layer is located in the low area or the middle area, according to the formula: Determine the height of the grouting borehole from the coal top Where, is the thickness of the coal seam; In response to the key layer being located at the height of the collapse zone Or, the multi-layer key layer is located in the composite area, according to the formula: Determine the height of the grouting borehole from the coal top .

6. The hard roof splitting pre-cracking in-situ grouting modified filling anti-scouring method according to claim 1 is characterized in that: Step S103 further includes: According to the formula: Determine the total width of the grouting borehole and grouting drilling spacing Where, is the width of the goaf; is the effective diffusion radius of the grouting slurry; is the treatment length of the goaf; For coal mining efficiency.

7. The hard roof classification pre-cracking in-situ grouting modification filling anti-scouring method according to claim 1 is characterized in that: Also includes: According to the formula: Determine the theoretical filling height of the goaf ;in, is the thickness of the coal seam; For coal mining efficiency; is the average value of the expansion coefficient; is the coal seam inclination; According to the formula: Determine the evaluation index for grouting filling in goaf ; Where, is the actual filling height of the goaf, is the compressive strength of the breaking key layer; It is the sum of the self-load of the critical fracture layer and the uniformly distributed load transferred from the overlying rock layer; is the breaking step distance of the breaking key layer; is the thickness of the critical fracture layer; wherein the critical fracture layer is a rock layer that has been fully pre-cracked and hydraulically cut in the single-layer critical layer, or a rock layer that has been subjected to blasting pre-crack treatment, hydraulic fracturing treatment, and hydraulically cut in multiple layers of critical layers; When the rock layer is not broken, according to the formula: Determine the breaking step ; In response to the breaking of the rock formation, according to the formula: Determine the breaking step ; Where, is the tensile strength of the breaking key layer, is the Poisson's ratio of the critical fracture layer.

8. The hard roof classification pre-cracking in-situ grouting modification filling method according to claim 7 is characterized in that: Also includes: In response to , the goaf is filled with secondary grouting by blasting and drilling grouting, according to the formula: Determine the total width of the blasting drill hole and height Where, is the width of the goaf; is the thickness of the coal seam; According to the formula: Determining the distance between two adjacent blasting and fragmentation drill holes; Where, , are all positive integers, and , the number of drill holes for said blasting; is the thickness of the critical fracture layer; is the tensile strength of the breaking key layer; is the uniformly distributed load on the critical fracture layer.

9. A hard roof classification pre-cracking in-situ grouting modified filling anti-collision system, characterized by: In-situ grouting reinforcement is performed using the method according to any one of claims 1 to 8, wherein the system comprises: The collapse zone height unit is configured according to the maximum fracture zone height of the working face. The thickness of the overlying rock mass within the range is greater than the thickness of the coal seam. The average value of the rock expansion coefficient , to determine the height of the collapse zone in the goaf ; Horizontal division unit, configured to determine the maximum fracture zone height The rock layers within the overlying rock mass with a thickness greater than the preset coal seam thickness and a uniaxial compressive strength greater than the preset strength threshold are effective key layers, and according to the number of effective key layers, the effective key layers are divided into single-layer key layers and multi-layer key layers; The pre-splitting grouting filling unit is configured to respond to the effective key layer being a single-layer key layer and based on the height of the collapse zone in the goaf. and the distance from the effective key layer closest to the coal top to the coal top , pre-crack the roof in a classified manner, and reinforce the collapsed area with grouting to fill the goaf; In response to the effective key layer being a multi-layer key layer, based on the collapse zone height The rock formation is divided into zones, different pre-cracking operations are taken for different zones, and grouting reinforcement is carried out on the collapsed areas to fill the mined-out areas.

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