Grouting subsidence reduction method and system for mining without coal pillar or narrow coal pillar
By combining overburden separation grouting and goaf reinforcement, the problem of secondary development of separation in pillarless or narrow pillar mining was solved, achieving effective subsidence reduction and improving coal extraction rate and construction efficiency.
Patent Information
- Application Number
- CN202511746847.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-25
- Publication Date
- 2026-02-10
AI Technical Summary
When mining without or with narrow pillars, secondary delamination during the mining process of adjacent working faces makes it difficult to effectively control mining subsidence, leading to increased surface subsidence and affecting surface buildings and the ecological environment.
A dual settlement reduction measure is adopted, which combines grouting filling of overburden separation and grouting reinforcement of goaf. By constructing the first grouting borehole and reinforcement borehole on the mining face, a filling body and a support body are formed to control roof settlement and prevent surface collapse.
It effectively controlled the secondary development of delamination under pillarless or narrow pillar mining methods, slowed down surface subsidence, increased coal extraction rate, and reduced construction costs and difficulties.
Smart Images
Figure CN121497416A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of coal mining technology, and in particular to a grouting method and system for reducing sedimentation in coal pillar-less or narrow-pillar mining. Background Technology
[0002] With the continuous mining of coal resources, the coal pillar mining method leads to the waste of a large amount of coal resources and a low coal extraction rate. Although the coal pillarless mining can improve the coal extraction rate, the overlying strata above the goaf are prone to large-scale collapse, which leads to the aggravation of surface subsidence and causes serious damage to surface buildings, farmland, roads and other structures. Therefore, the overlying strata isolation grouting filling technology is usually used in coal pillarless (narrow) mining to reduce surface subsidence.
[0003] In related technologies, the overburden isolation grouting technology mainly forms a common load-bearing body with "separation zone filling body + key layer + zoned isolation coal pillar". Among them, the separation zone filling body shares part of the overburden load and reduces the load borne by the zoned isolation coal pillar. However, in the mining process of coal pillar-less or narrow coal pillar working faces, the isolation coal pillar of the overburden isolation grouting filling technology cannot form an isolation zone above the separation layer. During the mining process of adjacent working faces, the separation layer will develop again to form a new separation space, so it is difficult to effectively control mining subsidence. Summary of the Invention
[0004] The present invention aims to at least partially solve one of the technical problems in the related art.
[0005] To address this, one aspect of the present invention proposes a grouting method for reducing subsidence in pillarless or narrow-pillar mining. This method employs a dual subsidence reduction approach that combines grouting filling of overburden separation and grouting reinforcement of the goaf, thus solving the problem of difficulty in effectively controlling mining subsidence during the secondary development of separation in adjacent working faces under pillarless or narrow-pillar mining conditions.
[0006] Another embodiment of the present invention proposes a grouting and settling reduction system for pillarless or narrow pillar mining.
[0007] A method for reducing settling during pillarless or narrow pillar mining according to an embodiment of the present invention includes the following steps: Mining face division: The coal mining area is divided into multiple mining faces arranged in sequence; The first grouting borehole is constructed in the direction of the grouting layer from the topsoil layer at the mining face, wherein the grouting layer is located between the key overburden layer and the water-resistant layer. Grouting for sediment reduction involves injecting grout into the grouting layer through the first grouting borehole to form a filling body in the separation space. The reinforcement drilling construction involves constructing reinforcement boreholes on the surface soil layer towards the goaf after the coal is mined from the mining face to form a goaf. The reinforcement boreholes are at least two in number and are located on both sides of the first grouting borehole along the width of the mining face. The reinforcement boreholes are adjacent to the edge of the goaf. Grouting reinforcement involves injecting grout into the natural accumulation zone and load-affected zone of the goaf through the reinforcement boreholes to form a support structure. Repeat the first grouting drilling, the grouting settlement reduction, the reinforcement drilling, and the grouting reinforcement operation until the coal in all mining faces is mined in sequence.
[0008] According to the grouting and settlement reduction method for pillarless or narrow pillar mining according to embodiments of the present invention, the coal mining area is divided into multiple mining faces and mined sequentially. During mining, a first grouting borehole can be drilled on the corresponding mining face along the direction from the topsoil layer toward the grouting layer. Grouting is injected into the overburden separation layer through the first grouting borehole to form a filling body in the separation space. The filling body realizes grouting and settlement reduction during the mining process. After a goaf is formed on the corresponding mining face, reinforcement boreholes are drilled on the corresponding mining face along the direction from the topsoil layer toward the goaf. Grouting is performed in boreholes to reinforce the goaf, forming a goaf support structure. This support structure then serves to fill the goaf, control roof subsidence, and prevent surface collapse. By repeating the aforementioned process, grouting and subsidence reduction are completed for all mining faces in the coal mining area. Therefore, compared with related technologies, this invention adopts a dual subsidence reduction measure that combines overburden separation grouting and goaf grouting reinforcement. This solves the problem of difficulty in effectively controlling mining subsidence during the secondary development of separation in adjacent working faces under pillarless or narrow pillar mining methods.
[0009] In some embodiments, prior to the step of dividing the mining face, the method further includes: To determine the properties of the overlying rock, core samples are taken from the overlying strata of the coal mining area, and the mechanical parameters of the core samples are tested to determine the properties of the overlying rock. Design boreholes, determine the key layer position of the overburden and the grouting layer position based on the properties of the overburden rock, and determine the borehole data of each of the first grouting borehole and the reinforcement borehole on the mining face based on the surface construction conditions, wherein the borehole data includes the drilling method, number, borehole diameter, opening position and closing position.
[0010] In some embodiments, the construction of the first grouting borehole at the mining face is carried out simultaneously with coal mining to shorten the coal mining cycle and improve coal mining efficiency.
[0011] In some embodiments, there are multiple first grouting boreholes, and the multiple first grouting boreholes include at least one row of first grouting boreholes spaced apart along the width direction of the mining face, and each row of first grouting boreholes includes at least two first grouting boreholes spaced apart along the extension direction of the mining face. The distance between any two adjacent first grouting boreholes is less than or equal to the average diffusion range of the grouting slurry in the first grouting borehole.
[0012] In some embodiments, between the steps of constructing the first grouting borehole and the grouting settlement reduction operation, the method further includes: Water is injected intermittently into the first grouting borehole to clear it and open the separation space.
[0013] In some embodiments, the grouting and settling reduction operation specifically includes: Based on the water injection pressure of the first grouting borehole, determine whether the first grouting borehole meets the grouting conditions; Grout is injected into the grouting layer through the first grouting borehole at a set grouting pressure to form the filling body in the separation space. The set grouting pressure is not less than the natural ground pressure of the strata above the grouting layer.
[0014] In some embodiments, there are multiple reinforcing boreholes, and the multiple reinforcing boreholes include two rows of reinforcing boreholes spaced apart along the width direction of the mining face. The two rows of reinforcing boreholes are respectively located on both sides of the first grouting borehole along the width direction of the mining face. Each row of reinforcing boreholes includes at least two reinforcing boreholes spaced apart along the extension direction of the mining face. The distance between any two adjacent reinforced boreholes in each row of reinforced boreholes is less than or equal to the average diffusion range of the grouting fluid in the reinforced boreholes.
[0015] In some embodiments, during the reinforcement borehole construction operation, when a goaf is formed by mining coal from the mining face and the mining position of the mining face exceeds the design position, a reinforcement borehole is constructed on the mining face towards the topsoil layer in the direction of the goaf. The design position is 2-3 times the average diffusion range of the grouting slurry of the reinforcement borehole.
[0016] In some embodiments, after the grouting reinforcement operation, the method further includes: The second grouting borehole is formed by sealing the end of the reinforcement borehole adjacent to the next mining face to the top of the water-proof layer. At this time, during the grouting and settling reduction operation, grout is injected into the grouting layer through both the first grouting borehole and the second grouting borehole, so as to form a larger grouting area in the secondary development space of repeated mining and achieve filling and settling reduction of the grouting area.
[0017] In some embodiments, the first grouting borehole and the second grouting borehole are both used to inject grout into the grouting layer simultaneously with the mining of coal at the mining face.
[0018] In some embodiments, the reinforcement borehole includes a first borehole segment, a second borehole segment, a third borehole segment, and a fourth borehole segment connected sequentially from top to bottom, and the reinforcement borehole construction operation specifically includes: The first borehole section is constructed in the direction of the topsoil layer toward the goaf, so that the end of the first borehole section is located at the junction of the topsoil layer and the key overburden layer. The first casing is then installed and cemented. The second hole section is constructed from the end of the first hole section toward the key overburden layer and toward the goaf, so that the end of the second hole section is located at the junction of the key overburden layer and the grouting layer. The second casing is then installed and cemented. The third section is constructed from the end of the second section toward the grouting layer toward the goaf, so that the end of the third section is located at the junction of the grouting layer and the waterproof layer. The first grouting pipe is then lowered into the grouting layer, and the portion of the first grouting pipe located in the grouting layer is a grouting perforated pipe. A fourth section is constructed from the end of the third section toward the goaf, with the end of the fourth section located in the goaf. A second grouting pipe is then lowered into the goaf, with the portion of the second grouting pipe near the bottom of the goaf forming a grouting perforated pipe.
[0019] In some embodiments, during the grouting reinforcement operation, the second grouting pipe is used to grout the goaf and form the support structure; In the second grouting drilling operation, the fourth section of the reinforced borehole adjacent to the next mining face is sealed, and in the grouting and settling operation, the grouting layer is grouted by the first grouting pipe.
[0020] According to an embodiment of the present invention, a grouting and settlement reduction system for pillarless or narrow pillar mining is provided to implement the settlement reduction method described in any of the above embodiments. The system includes a mining face division module, a first grouting borehole construction module, a grouting and settlement reduction module, a reinforcement borehole construction module, and a grouting reinforcement module. The mining face division module is used to divide the coal mining area into multiple mining faces arranged in sequence. The first grouting borehole construction module is used to construct a first grouting borehole in the direction of the grouting layer from the topsoil layer at the mining face, wherein the grouting layer is located between the overburden key layer and the water-resistant layer; The grouting and settling reduction module is used to inject grout into the grouting layer through the first grouting borehole to form a filling body in the delamination space; The reinforcement borehole construction module is used to construct reinforcement boreholes on the surface soil layer towards the goaf after the goaf is formed by mining coal from the mining face. The reinforcement boreholes are at least two and are located on both sides of the first grouting borehole along the width of the mining face. The reinforcement boreholes are adjacent to the edge of the goaf. The grouting reinforcement module is used to inject grout into the natural accumulation area and load-affected area of the goaf through the reinforcement borehole to form a support structure.
[0021] The technical advantages of the grouting and settling reduction system for pillarless or narrow pillar mining according to the present invention are the same as those of the above-mentioned grouting and settling reduction method for pillarless or narrow pillar mining, and will not be repeated here.
[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0023] Figure 1 This is a schematic flowchart of a grouting method for reducing sedimentation in pillarless or narrow pillar mining according to an embodiment of the present invention.
[0024] Figure 2 This is a schematic diagram of the construction structure of the first grouting borehole and the reinforcement borehole on the mining face during the mining process of the grouting and settling reduction method for coal pillarless or narrow coal pillar mining according to an embodiment of the present invention.
[0025] Figure 3 This is a cross-sectional structural diagram of the first grouting borehole and the reinforcement borehole during the grouting and settling process of the mining face in the grouting method for coal pillarless or narrow coal pillar mining according to an embodiment of the present invention.
[0026] Figure 4 This is a schematic flowchart of a grouting method for reducing sedimentation in pillarless or narrow pillar mining according to another embodiment of the present invention.
[0027] Figure 5 This is a schematic flowchart of a grouting method for reducing sedimentation in pillarless or narrow pillar mining according to another embodiment of the present invention.
[0028] Figure 6 This is a schematic diagram of the reinforced borehole structure in the grouting and settling reduction method for coal pillarless or narrow coal pillar mining according to an embodiment of the present invention.
[0029] Figure 7 This is a schematic diagram of the grouting and settling reduction system for pillarless or narrow pillar mining according to an embodiment of the present invention.
[0030] Figure label: 1. Mining face; 11. Topsoil layer; 12. Grouting layer; 13. Key overburden layer; 14. Water-resistant layer; 15. Goaf; 2. First grouting borehole; 3. Filling body; 4. Reinforced borehole; 41. First borehole section; 42. Second borehole section; 43. Third borehole section; 44. Fourth borehole section; 45. First casing; 46. Second casing; 47. First grouting pipe; 48. Second grouting pipe; 5. Support structure. Detailed Implementation
[0031] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0032] It should be noted that the overburden isolation grouting and filling technology involves pumping slurry made from solid waste materials such as fly ash through ground boreholes at a ground slurry preparation station into the overburden separation area formed by mining at the working face to form a filling body, controlling the deformation and collapse of the overburden, and the grouting pressure forces the underlying broken rock mass to compact and form a support zone, thereby achieving the purpose of reducing surface subsidence.
[0033] Because there are no isolation pillars in the mining without (narrow) pillars, or the pillars left along the goaf are narrow and have low strength, it is difficult to form isolation zones in the delamination space during the mining process of adjacent working faces. The delamination develops again and forms new delamination spaces. The overburden delamination grouting and filling technology in related technologies does not fully consider the special mechanical structure and deformation characteristics of the overburden under the mining conditions without (narrow) pillars, so it is difficult to control mining subsidence.
[0034] Therefore, in response to the characteristics of secondary development of coal pillars or low-strength segregation layers and short segregation development window periods in the mining of multiple working faces without coal pillars or with narrow coal pillars in related technologies, this invention proposes a grouting method for reducing subsidence in mining without coal pillars or with narrow coal pillars. This method can simultaneously carry out grouting reinforcement of goaf and grouting filling of overlying segregation layers, in order to better solve the problems existing in related technologies.
[0035] like Figures 1 to 3 As shown in the figure, a method for reducing settling in pillarless or narrow pillar mining according to an embodiment of the present invention includes the following steps: Step S1, dividing the mining face 1, dividing the coal mining area into multiple mining faces 1 arranged in sequence; Step S2, the first grouting borehole 2 is constructed. The first grouting borehole 2 is constructed on the mining face 1 in the direction of the topsoil layer 11 toward the grouting layer 12, wherein the grouting layer 12 is located between the overburden key layer 13 and the water-proof layer 14. Step S3, grouting to reduce settlement, grouting is performed from the first grouting borehole 2 to the grouting layer 12 to form a filling body 3 in the separation space; Step S4, reinforcement borehole 4 construction: After the coal mining face 1 forms a goaf 15, reinforcement borehole 4 is constructed on the surface soil layer 11 of the mining face 1 towards the goaf 15. There are at least two reinforcement boreholes 4, which are located on both sides of the first grouting borehole 2 along the width direction of the mining face 1. The reinforcement borehole 4 is adjacent to the edge of the goaf 15. Step S5, grouting reinforcement, grouting is performed on the natural accumulation area and load-affected area of the goaf 15 through reinforcement borehole 4 to form support body 5; Repeat the construction of the first grouting borehole 2, the grouting and settlement reduction, the construction of the reinforcement borehole 4, and the grouting and reinforcement work until the coal of all mining faces 1 is mined in sequence.
[0036] According to the grouting and settlement reduction method for pillarless or narrow pillar mining according to an embodiment of the present invention, the coal mining area is divided into multiple mining faces 1 and mined sequentially. During mining, a first grouting borehole 2 can be drilled on the corresponding mining face 1 along the direction from the topsoil layer 11 toward the grouting layer 12. Grouting is injected and filled into the overburden separation layer through the first grouting borehole 2 to form a filling body 3 in the separation space. The filling body 3 realizes grouting and settlement reduction during the mining process. After the goaf 15 is formed on the corresponding mining face 1, a reinforcement borehole 4 is drilled on the corresponding mining face 1 along the direction from the topsoil layer 11 toward the goaf 15. By reinforcing the goaf 15 with grouting through the reinforced borehole 4, a goaf support 5 is formed. The support 5 then serves to fill the goaf 15, control roof settlement, and prevent surface collapse. By repeating the above process, grouting and settlement reduction are completed for all mining faces 1 in the coal mining area. Therefore, compared with related technologies, this invention adopts a dual settlement reduction measure that combines overburden separation grouting and filling with grouting reinforcement of the goaf 15. This solves the problem that it is difficult to effectively control mining settlement when secondary development of separation occurs during the mining of adjacent working faces in the case of no coal pillar or narrow coal pillar mining.
[0037] It is understandable that the entire mining process of this invention fully considers the special mechanical structure and deformation characteristics of the overburden under the condition of mining without (narrow) coal pillars. In response to the problems of difficulty in forming isolation coal pillars in goaf 15, low strength of artificial coal pillars and poor barrier effect when mining continuously without (narrow) coal pillars in multiple working faces, a dual subsidence reduction measure is adopted, which combines grouting reinforcement of goaf 15 and grouting filling of overburden separation layer. On the one hand, it can form a solidified body in goaf 15 to slow down the subsidence of overburden. On the other hand, the support body 5 formed by grouting reinforcement of goaf 15 will not form an isolation space for the above separation layer (when the surface or overburden subsides, the support body 5 will be compressed, and only plays the role of slowing down the subsidence of the surface and overburden, preventing excessive deformation of separation layer from causing the key layer to break). Therefore, the separation layer space can be developed again to form a larger grouting area, which can increase the grouting volume and thus effectively slow down the surface subsidence.
[0038] Specifically, multiple mining faces 1 can be arranged sequentially along the first direction shown in the figure. The first direction is consistent with the width direction of the mining face 1, and the first direction can be the orientation of the coal mining area. The mining face 1 can extend along the dip of the coal mining area. There may be no coal pillar between any two adjacent mining faces 1, or there may be a concrete wall or a narrow coal pillar. In other words, this invention is applicable to coal mining operations in both mining methods with no coal pillar between multiple working faces and mining methods with narrow coal pillars between multiple working faces. The key overburden layer 13 is also known as the stable bedrock layer.
[0039] In addition, existing technologies can be used to determine the "natural accumulation area and load-affected area of goaf 15". Generally speaking, the area around goaf 15 will have a large porosity due to the support of the coal body, but the central collapsed rock is compacted by the overlying strata and has a small porosity.
[0040] Furthermore, the grout concentration range of the first grouting borehole 2 is 50-75% to ensure grouting pressure. The grout concentration refers to the concentration of the grout prepared by grinding fly ash, coal gangue, construction waste and other solid waste into powder of appropriate particle size and mixing it with water in a certain proportion. The grout concentration is adjusted according to the water-ash ratio.
[0041] like Figure 4 As shown, in some embodiments, before step S1, the method further includes: Step S1': Determine the properties of the overlying rock by taking rock cores from the overlying strata of the coal mining area and testing the mechanical parameters of the rock cores to determine the properties of the overlying rock. Step S1”: Design the borehole, determine the key layer 13 and the grouting layer 12 of the overburden rock according to the properties of the overburden rock, and determine the borehole data of each of the first grouting borehole 2 and the reinforcement borehole 4 at the mining face 1 based on the surface construction conditions. The borehole data includes the drilling method, number, diameter, opening position and closing position (i.e. target point).
[0042] Understandably, determining the properties of the overburden rock and designing the drilling operations as described above can provide parameter basis for the subsequent construction of the first grouting borehole 2 and the reinforcement borehole 4.
[0043] Specifically, in step S1', the core sampling operation can be described as drilling a core borehole in the overlying strata or taking core samples; the mechanical parameters of the core may include deformation parameters (such as elastic modulus, Poisson's ratio, bulk modulus, shear modulus, etc.), strength parameters (such as tensile strength, shear strength, etc.), elastic parameters (such as elastic limit stress, elastic strain, etc.), and special parameters (such as brittleness index, fatigue strength).
[0044] In addition, in step S1", the surface construction conditions include the distribution of ground buildings and structures; the drilling method includes vertical drilling or directional drilling, which should be reasonably selected according to the surface construction conditions.
[0045] like Figures 1 to 4 As shown, in some embodiments, the construction of the first grouting borehole 2 at the mining face 1 is carried out simultaneously with the mining of coal. In other words, during the mining of coal at the mining face 1, the opening of the first grouting borehole 2 can be carried out at the same time to shorten the coal mining cycle and improve the coal mining efficiency.
[0046] like Figure 2 As shown, in some embodiments, there are multiple first grouting boreholes 2, and the multiple first grouting boreholes 2 include at least one row of first grouting boreholes spaced apart along the width direction of the mining face 1, and each row of first grouting boreholes includes at least two first grouting boreholes 2 spaced apart along the extension direction of the mining face 1.
[0047] The distance between any two adjacent first grouting boreholes 2 is less than or equal to the average diffusion range of the grouting slurry in the first grouting borehole 2.
[0048] It is understandable that, in combination with the above structure, during the mining process of mining face 1, one or more rows of first grouting boreholes can be arranged according to the length and width of mining face 1 to ensure the grouting and settlement reduction effect on the overburden separation layer. At the same time, the spacing between any two adjacent first grouting boreholes 2 is designed to be smaller than the average diffusion range of the grouting slurry of the first grouting borehole 2, which can ensure that when grouting is injected into the grouting layer 12 from multiple first grouting boreholes 2, a continuous filling body 3 structure can be formed in the separation layer space.
[0049] like Figure 4 As shown, in some embodiments, between step S2 and step S3, the method further includes: Step S2': Water is injected into the first grouting borehole 2 intermittently to clear the first grouting borehole 2 and open the separation space, laying the foundation for the smooth progress of subsequent grouting and settlement reduction operations.
[0050] like Figure 4 As shown, in some embodiments, step S3 specifically includes: Step S31: Based on the water injection pressure of the first grouting borehole 2, determine whether the first grouting borehole 2 meets the grouting conditions; In step S32, grout is injected into the grouting layer 12 through the first grouting borehole 2 at a set grouting pressure to form a filling body 3 in the separation space. The set grouting pressure is not less than the natural ground pressure of the strata above the grouting layer 12 to maintain surface stability.
[0051] like Figure 2 As shown, in some embodiments, there are multiple reinforcing boreholes 4, including two rows of reinforcing boreholes spaced apart along the width direction of the mining face 1. The two rows of reinforcing boreholes are located on both sides of the first grouting borehole 2 along the width direction of the mining face 1. Each row of reinforcing boreholes includes at least two reinforcing boreholes 4 spaced apart along the extension direction of the mining face 1.
[0052] The distance between any two adjacent reinforced boreholes 4 in each row of reinforced boreholes is less than or equal to the average diffusion range of the grout in the reinforced borehole 4.
[0053] Understandably, the opening of multiple reinforcement boreholes 4 can ensure that when the reinforcement is reinforced by grouting in the reinforcement boreholes 4 in the later stage, a reliable support effect can be formed on the natural accumulation area and load-affected area of the goaf 15. And by designing the spacing between any two adjacent reinforcement boreholes 4 to be less than the average diffusion range of the grouting slurry of the reinforcement boreholes 4, it is possible to form a continuous support structure 5 in the goaf 15 when multiple reinforcement boreholes 4 are grouted into the goaf 15.
[0054] like Figures 1 to 4 As shown, in some embodiments, in step S4, when a goaf is formed by mining coal from the mining face 1 and the mining position of the mining face 1 exceeds the design position, a reinforcement borehole 4 is constructed in the direction of the topsoil layer 11 from the mining face 1 toward the goaf 15. The design position is 2-3 times the average diffusion range of the grouting slurry of the reinforcement borehole 4.
[0055] like Figure 5 As shown, in some embodiments, after step S5, the method further includes: Step S6: The second grouting borehole is formed by sealing the end of the reinforcement borehole 4 adjacent to the next mining face 1 to the water-proof layer 14, thus forming the second grouting borehole. At this point, in step S3, grout is injected into the grouting layer 12 from both the first grouting borehole 2 and the second grouting borehole, so as to form a larger grouting area in the secondary development space of repeated mining and achieve filling and settlement reduction of the grouting area.
[0056] It is understandable that by sealing the end (or bottom) of the reinforcement borehole 4 adjacent to the next mining face 1 to the water-proof layer 14, a second grouting borehole can be formed. In the grouting and settling operation of the next mining face 1, the first grouting borehole 2 and the second grouting borehole can be used to grout the delamination space at the same time, which is conducive to the formation of a larger grouting area in the delamination space that is developed in the second stage of repeated mining.
[0057] Meanwhile, the present invention rationally arranges the grouting sequence, which can effectively reduce the number of boreholes and save construction costs. By adding reinforcement borehole 4, and sealing the lower part of reinforcement borehole 4 to the water-proof layer 14 after the reinforcement borehole 4 is used, the reinforcement borehole 4 can be used for delamination grouting, realizing one hole for two purposes. It is suitable for the "mining area 15 - delamination" composite disaster management scenario.
[0058] It should be noted that the average diffusion range of the grout in the reinforcement borehole 4 is smaller than that of the grout in the first grouting borehole 2 and the second grouting borehole. This is because the separation space formed during mining is relatively large, which facilitates grout diffusion. Therefore, the average diffusion range of the grout in the first grouting borehole 2 and the second grouting borehole is relatively large. However, when grouting the goaf 15, the goaf 15 is mostly composed of collapsed and broken rock. Small gaps are easily formed between the rocks, but it is difficult to form a large space. Moreover, the grout flow channel is easily blocked. As a result, the diffusion range of the grout in the reinforcement borehole 4 is smaller than that of the grout in the first grouting borehole 2 and the second grouting borehole when grouting the separation space.
[0059] In addition, during the mining of the previous mining face 1, the overlying strata move downwards, and the delamination develops for the first time. During the mining of the next mining face 1, due to the lack of supporting coal pillars or insufficient support strength of narrow coal pillars between the two mining faces 1, the overlying strata of the two mining faces 1 will continue to move downwards, so the delamination will develop a second time.
[0060] like Figure 5 As shown, in some embodiments, the first grouting borehole 2 and the second grouting borehole are both injected into the grouting layer 12 simultaneously with the mining face 1. In other words, during the mining process of coal at the mining face 1, grouting operations can be carried out simultaneously at the mining face 1 by the first grouting borehole 2 and the second grouting borehole into the grouting layer 12, so as to shorten the coal mining cycle and improve the coal mining efficiency.
[0061] like Figure 5 and Figure 6 As shown, in some embodiments, the reinforced borehole 4 includes a first borehole segment 41, a second borehole segment 42, a third borehole segment 43, and a fourth borehole segment 44 connected sequentially from top to bottom. Step S4 specifically involves: Step S41: Construct the first borehole section 41 in the direction of the topsoil layer 11 towards the goaf 15 on the mining face 1, so that the end of the first borehole section 41 is located at the junction of the topsoil layer 11 and the key overburden layer 13, and then run in the first casing 45 and cement it. Step S42: From the end of the first borehole section 41, construct the second borehole section 42 in the direction of the overburden key layer 13 toward the goaf 15, so that the end of the second borehole section 42 is located at the junction of the overburden key layer 13 and the grouting layer 12, and then run in the second casing 46 and cement it. Step S43: From the end of the second hole section 42, construct the third hole section 43 towards the goaf 15 from the grouting layer 12, so that the end of the third hole section 43 is located at the junction of the grouting layer 12 and the water-proof layer 14. Then, lower the first grouting pipe 47. The part of the first grouting pipe 47 located in the grouting layer 12 is a grouting perforated pipe to ensure the grouting effect and to prevent cementing. In step S44, the fourth section 44 is constructed from the end of the third section 43 towards the goaf 15, so that the end of the fourth section 44 is located in the goaf 15. The second grouting pipe 48 is then lowered into the goaf 15. The part of the second grouting pipe 48 near the bottom of the goaf 15 is a grouting perforated pipe to ensure the grouting effect and to prevent cementing.
[0062] It is understandable that the delamination grouting boreholes in related technologies usually adopt a three-section structure, while the present invention designs a "goaf 15 - delamination" composite grouting borehole, namely the reinforcement borehole 4. The reinforcement borehole 4 is a four-section structure for multi-purpose grouting, which can realize the delamination grouting after the goaf 15 is grouted.
[0063] During the grouting and settlement reduction process, the second grouting pipe 48 is used as the inner grouting pipe for the goaf 15, and the first grouting pipe 47 is used as the outer grouting pipe for the goaf 15. The inner and outer pipes are grouted simultaneously to reinforce both sides of the goaf 15. After the goaf 15 is reinforced, the lower part of the reinforced borehole 4 is sealed up to the height of the water-proof layer 14, that is, the fourth borehole section 44 is sealed. The first grouting pipe 47 is used as the inner grouting pipe for the separation grouting, and the second casing 46 is used as the outer grouting pipe for the separation grouting. The inner and outer pipes are grouted simultaneously to fill the separation space.
[0064] Specifically, the diameters of the first hole section 41, the second hole section 42, the third hole section 43, and the fourth hole section 44 decrease sequentially. A first sleeve 45 can be coaxially arranged in the first hole section 41. A second sleeve 46 can be coaxially arranged in the first hole section 41 and the second hole section 42, and the length of the second sleeve 46 is equal to the sum of the hole depths of the first hole section 41 and the second hole section 42. A first grouting pipe 47 can be coaxially arranged in the first hole section 41, the second hole section 42, and the third hole section 43, and the sum of the hole depths of the first hole section 41, the second hole section 42, and the third hole section 43 is equal to the length of the first grouting pipe 47. The portion of the first grouting pipe 47 located in the grouting layer 12 is a grouting perforated pipe. The second grouting pipe 48 can be coaxially arranged in the first hole section 41, the second hole section 42, the third hole section 43 and the fourth hole section 44. The sum of the hole depths of the first hole section 41, the second hole section 42, the third hole section 43 and the fourth hole section 44 is equal to the length of the second grouting pipe 48.
[0065] It should be noted that existing technologies in this field can be used for "cementing", which will not be elaborated here.
[0066] like Figure 5 and Figure 6 As shown, in some embodiments, in step S5, the goaf 15 is grouted by the second grouting pipe 48 to form a support body 5; In step S6, the fourth section 44 of the reinforcement borehole 4 adjacent to the next mining face 1 is sealed, and in the grouting and settling operation, the grouting layer 12 is grouted by the first grouting pipe 47.
[0067] In summary, in some embodiments of the present invention, the grouting and settling reduction method for pillarless or narrow-pillar mining includes steps S1, S2, S3, S4, and S5. Steps S2, S3, S4, and S5 can then be repeated until the sequential mining of all coal faces 1 is completed. In other embodiments, the grouting and settling reduction method for pillarless or narrow-pillar mining includes steps S1', S1", S1, S2, S3, S4, and S5. Steps S2, S3, S4, and S5 can then be repeated until the sequential mining of all coal faces 1 is completed. In still other embodiments... In some embodiments, the grouting method for reducing subsidence in pillarless or narrow-pillar mining includes steps S1', S1", S1, S2, S2', S3, S4, and S5. In other embodiments, the grouting method for reducing subsidence in pillarless or narrow-pillar mining includes steps S1', S1", S1, S2, S2', S3, S4, S5, and S6. It should be noted that in this embodiment, in step S3, grout is injected into the grouting layer 12 from both the first grouting borehole 2 and the second grouting borehole. Therefore, the grouting method for reducing subsidence in pillarless or narrow-pillar mining of the present invention can be any of the four methods described above.
[0068] Therefore, compared with related technologies, the present invention has the following advantages: 1) In terms of coal resource utilization, by adopting the coal pillar-free (narrow) coal pillar mining method combined with targeted grouting and sedimentation reduction technology, the coal extraction rate has been greatly improved. Compared with traditional coal pillar mining, the reduction or elimination of coal pillars allows more coal resources to be mined and utilized. 2) This invention targets the goaf and overburden separation by grouting, which enhances the stability of the overburden, inhibits the collapse and deformation of the overburden from being transmitted to the surface, and can effectively reduce the degree of surface subsidence. Therefore, it is of great significance for protecting the ecological environment around the mining area, ensuring the normal life of residents, and maintaining the stable development of the social economy. 3) In related technologies, the reinforcement of goaf and grouting after mining without (narrow) coal pillars often require separate drilling operations. This not only increases construction costs and time, but also, due to the complexity of the drilling layout and construction, can easily cause more disturbance to the geological structure, affecting the overall stability. At the same time, the construction technology and parameters of boreholes with different functions may differ, requiring separate design and operation, which increases construction difficulty and management costs. However, the multi-purpose drilling method proposed in this invention optimizes the borehole design and construction technology, and proposes a "goaf-separation" composite grouting borehole. This allows the same borehole to be used for both goaf grouting reinforcement and separation grouting filling, which can effectively reduce construction difficulty and construction costs.
[0069] The present invention will be further illustrated by specific embodiments below.
[0070] Example 1 A method for reducing settling during grouting in pillarless or narrow pillar mining includes the following steps: 1) Drill core holes in the overlying strata of the coal mining area to obtain rock cores and test their physical and mechanical parameters; 2) Based on the analysis of the properties of the overburden rock, the key overburden layer 13 and the grouting layer 12 were analyzed. Based on the distribution of ground buildings and structures, the drilling opening locations and target points were designed. 3) Select vertical or directional drilling according to the surface construction conditions, so that the first grouting borehole 2 is drilled to the grouting layer 12 and the reinforcement borehole 4 is drilled to the goaf 15. The aforementioned borehole spacing is generally less than the grout diffusion range, and the number of the aforementioned boreholes can be set according to the width of the mining face 1. 4) After the first grouting borehole 2 is completed, water is intermittently injected to keep the grouting channel unobstructed and promote the opening of the delamination layer; 5) Determine whether the first grouting borehole 2 meets the grouting conditions based on the water injection pressure. After grouting begins, control the grouting concentration between 50% and 75% to maintain the grouting pressure. 6) Start grouting and reduce settlement in the first grouting borehole 2. After the mining face 1 has been pushed past the design position of the reinforcement borehole 4 by 2-3 times the grout diffusion range, start grouting and reinforcing the strip-shaped area with high porosity in the goaf 15 using the reinforcement borehole 4 to form a support body 5. This body serves to fill the goaf 15, control roof settlement, and prevent surface collapse, laying a good foundation for subsequent grouting between the two working layers using the reinforcement borehole 4 in the goaf 15. 7) After the grouting reinforcement of the goaf 15 is completed, the bottom of the reinforcement borehole 4 near the next mining face 1 is sealed up to the water-proof layer 14, which serves as the separation grouting borehole of the next mining face 1, that is, the second grouting borehole. 8) The next mining face 1 is mined, and the first grouting borehole 2 is laid out in the next mining face 1 so that both the first grouting borehole 2 and the second grouting borehole fill the separation space with grout. 9) Repeat steps 3) to 8) above to complete the grouting reinforcement and overburden separation grouting filling of the goaf 15 of the subsequent mining face 1.
[0071] like Figure 7 As shown in the figure, an embodiment of the present invention provides a grouting and settlement reduction system for pillarless or narrow pillar mining, used to implement the settlement reduction method of any of the above embodiments. The system includes a mining face 1 division module, a first grouting borehole 2 construction module, a grouting and settlement reduction module, a reinforcement borehole 4 construction module, and a grouting and reinforcement module, wherein... The mining face 1 division module is used to divide the coal mining area into multiple mining faces 1 arranged in sequence; The first grouting borehole 2 construction module is used to construct the first grouting borehole 2 in the direction of the topsoil layer 11 toward the grouting layer 12 at the mining face 1, wherein the grouting layer 12 is located between the overburden key layer 13 and the water-proof layer 14. The grouting and settling reduction module is used to inject grout from the first grouting borehole 2 into the grouting layer 12 to form a filling body 3 in the separation space; The reinforcement borehole 4 construction module is used to construct reinforcement borehole 4 on the surface soil layer 11 of the mining face 1 towards the goaf 15 after the mining face 1 has formed a goaf 15 by mining coal. The reinforcement borehole 4 consists of at least two holes and is located on both sides of the first grouting borehole 2 along the width of the mining face 1. The reinforcement borehole 4 is adjacent to the edge of the goaf 15. The grouting reinforcement module is used to grout the natural accumulation area and load-affected area of the goaf 15 through the reinforcement borehole 4 to form the support body 5.
[0072] The technical advantages of the grouting and settling reduction system for pillarless or narrow pillar mining according to the present invention are the same as those of the above-mentioned grouting and settling reduction method for pillarless or narrow pillar mining, and will not be repeated here.
[0073] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0074] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0075] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0076] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.
[0077] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the 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 one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0078] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.
Claims
1. A method for reducing settling during pillarless or narrow pillar mining, characterized in that, Includes the following steps: Mining face division: The coal mining area is divided into multiple mining faces arranged in sequence; The first grouting borehole is constructed in the direction of the grouting layer from the topsoil layer at the mining face, wherein the grouting layer is located between the key overburden layer and the water-resistant layer. Grouting for sediment reduction involves injecting grout into the grouting layer through the first grouting borehole to form a filling body in the separation space. The reinforcement drilling construction involves constructing reinforcement boreholes on the surface soil layer towards the goaf after the coal is mined from the mining face to form a goaf. The reinforcement boreholes are at least two in number and are located on both sides of the first grouting borehole along the width of the mining face. The reinforcement boreholes are adjacent to the edge of the goaf. Grouting reinforcement involves injecting grout into the natural accumulation zone and load-affected zone of the goaf through the reinforcement boreholes to form a support structure. Repeat the first grouting drilling, the grouting settlement reduction, the reinforcement drilling, and the grouting reinforcement operation until the coal in all mining faces is mined in sequence.
2. The grouting method for reducing settling in pillarless or narrow pillar mining according to claim 1, characterized in that, Prior to the step of dividing the mining face, the method further includes: To determine the properties of the overlying rock, core samples are taken from the overlying strata of the coal mining area, and the mechanical parameters of the core samples are tested to determine the properties of the overlying rock. Design boreholes, determine the key layer position of the overburden and the grouting layer position based on the properties of the overburden rock, and determine the borehole data of each of the first grouting borehole and the reinforcement borehole on the mining face based on the surface construction conditions, wherein the borehole data includes the drilling method, number, borehole diameter, opening position and closing position.
3. The grouting method for reducing settling in pillarless or narrow pillar mining according to claim 1, characterized in that, The construction of the first grouting borehole at the mining face is carried out simultaneously with the mining of coal.
4. The grouting method for reducing settling in pillarless or narrow pillar mining according to claim 1, characterized in that, There are multiple first grouting boreholes, and the multiple first grouting boreholes include at least one row of first grouting boreholes arranged at intervals along the width direction of the mining face, and each row of first grouting boreholes includes at least two first grouting boreholes arranged at intervals along the extension direction of the mining face. The distance between any two adjacent first grouting boreholes is less than or equal to the average diffusion range of the grouting slurry in the first grouting borehole.
5. The grouting method for reducing settling in pillarless or narrow pillar mining according to claim 1, characterized in that, Between the steps of the first grouting borehole construction and the grouting settlement reduction operation, the method further includes: Water is injected intermittently into the first grouting borehole to clear it and open the separation space.
6. The grouting method for reducing settling in pillarless or narrow pillar mining according to claim 1, characterized in that, In the reinforcement drilling operation, when a goaf is formed by mining coal from the mining face and the mining position of the mining face exceeds the design position, reinforcement boreholes are constructed on the mining face towards the goaf from the topsoil layer. The design position is 2-3 times the average diffusion range of the grouting slurry of the reinforcement borehole.
7. The grouting method for reducing settling in pillarless or narrow pillar mining according to any one of claims 1-6, characterized in that, After the grouting reinforcement operation, the method further includes: The second grouting borehole is formed by sealing the end of the reinforcement borehole adjacent to the next mining face to the top of the water-proof layer. At this time, during the grouting and settling reduction operation, grout is injected into the grouting layer through both the first grouting borehole and the second grouting borehole, so as to form a larger grouting area in the secondary development space of repeated mining and achieve filling and settling reduction of the grouting area.
8. The grouting method for reducing settling in pillarless or narrow pillar mining according to claim 7, characterized in that, Both the first grouting borehole and the second grouting borehole inject grout into the grouting layer simultaneously with the coal mining at the mining face.
9. The grouting method for reducing settling in pillarless or narrow pillar mining according to claim 7, characterized in that, The reinforcement borehole comprises a first borehole segment, a second borehole segment, a third borehole segment, and a fourth borehole segment connected sequentially from top to bottom. The reinforcement borehole construction operation specifically involves: The first borehole section is constructed in the direction of the topsoil layer toward the goaf, so that the end of the first borehole section is located at the junction of the topsoil layer and the key overburden layer. The first casing is then installed and cemented. The second hole section is constructed from the end of the first hole section toward the key overburden layer and toward the goaf, so that the end of the second hole section is located at the junction of the key overburden layer and the grouting layer. The second casing is then installed and cemented. The third section is constructed from the end of the second section toward the grouting layer toward the goaf, so that the end of the third section is located at the junction of the grouting layer and the waterproof layer. The first grouting pipe is then lowered into the grouting layer, and the portion of the first grouting pipe located in the grouting layer is a grouting perforated pipe. A fourth section is constructed from the end of the third section toward the goaf, with the end of the fourth section located in the goaf. A second grouting pipe is then lowered into the goaf, with the portion of the second grouting pipe near the bottom of the goaf forming a grouting perforated pipe.
10. A grouting and settling reduction system for pillarless or narrow pillar mining, characterized in that, For implementing the settlement reduction method according to any one of claims 1-9, the system includes a mining face division module, a first grouting borehole construction module, a grouting settlement reduction module, a reinforcement borehole construction module, and a grouting reinforcement module, wherein... The mining face division module is used to divide the coal mining area into multiple mining faces arranged in sequence. The first grouting borehole construction module is used to construct a first grouting borehole in the direction of the grouting layer from the topsoil layer at the mining face, wherein the grouting layer is located between the overburden key layer and the water-resistant layer; The grouting and settling reduction module is used to inject grout into the grouting layer through the first grouting borehole to form a filling body in the delamination space; The reinforcement borehole construction module is used to construct reinforcement boreholes on the surface soil layer towards the goaf after the goaf is formed by mining coal from the mining face. The reinforcement boreholes are at least two and are located on both sides of the first grouting borehole along the width of the mining face. The reinforcement boreholes are adjacent to the edge of the goaf. The grouting reinforcement module is used to grout the natural accumulation area and load-affected area of the goaf through the reinforcement borehole to form a support structure.