Cooperative control method for large-mining-height fully mechanized coal mining face coal wall caving

Abstract

The invention provides a large-mining-height fully mechanized coal mining face coal wall caving cooperative control method which comprises the following steps: before mining of a working face, performing regional fracturing on a hard roof in a target layer by adopting an underground large-flow horizontal long hole regional fracturing mode; according to the mining height of the large-mining-height working face, proper supporting strength of a hydraulic support and a face guard plate form are selected; the large-mining-height fully-mechanized coal mining hydraulic support is of a face protection structure with multiple stages of face protection plates and is used for protecting coal wall caving generated on a coal face when the coal face below a hard top plate is subjected to stoping. By means of the method, the problems of large-mining-height working face strong mine pressure appearance and coal wall caving roof caving are effectively solved, and the treatment effect of large-mining-height working face coal wall caving is improved.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to a method for collaboratively controlling coal wall spalling in a fully mechanized mining face with a large mining height. Background Art

[0002] The technology of fully mechanized large-scale mining and full-height mining at one time is one of the main mining processes for thick and extra-thick coal seams in my country. At present, the maximum one-time mining height has reached 10m. With the increase of mining height, the difficulty of controlling the surrounding rock of the working face has increased significantly. The problem of coal wall spalling at the working face has become increasingly prominent, becoming the main geological disaster threatening the safe production of large-scale mining faces. Large pieces of spalled coal will hinder the normal passage of coal mining machines. When large-scale spalling occurs in a short period of time, it is easy to cause the scraper conveyor to overload or the transfer port to be congested, resulting in shutdown of the working face and easily inducing roof collapse at the end face. In addition, the coal blocks ejected at high speed by the spalling of the coal wall also pose a certain threat to the safety of fully mechanized mining equipment such as hydraulic supports and operators.

[0003] At present, the area with super-large mining height working face with mining height above 6.0m has the characteristics of stable coal seam occurrence conditions, brittle coal quality, and undeveloped fissures. In addition, the presence of hard roof and high mining intensity of working face cause strong mining pressure in the large mining height working face in this area. The mining pressure during mining is an important reason for the instability of coal wall spalling in the large mining height working face in this area. In order to solve the surrounding rock control problem of large mining height fully-mechanized mining working face with coal wall spalling as the core, high-resistance hydraulic supports are generally used in coal mines in these areas. At present, the maximum working resistance of hydraulic supports has reached 29000kN, but the simple strong resistance support cannot fundamentally solve the surrounding rock control problem caused by strong mining pressure, and brings new problems such as large equipment investment and continuous upgrading of equipment tonnage. In addition, measures for grouting reinforcement have also been proposed to address the problem of coal wall spalling, but for hard coal seams with undeveloped fissures in these areas, the treatment effect is not significant, and it will interfere with the normal production operation of the working face and slow down the advancement of the working face, which is inconsistent with the current situation of large-scale mining intensity and high-speed advancement in large mines in this area. Summary of the invention

[0004] The present invention provides a method for coordinated control of coal wall spalling in a fully mechanized mining face with large mining height, which effectively alleviates the problems of strong mine pressure and coal wall spalling and roof collapse in the working face with large mining height, and improves the control effect of coal wall spalling in the working face with large mining height.

[0005] The present invention provides a method for collaboratively controlling coal wall spalling in a fully mechanized mining face with a large mining height, the method comprising the following steps: Before mining at a high-mining fully-mechanized mining face, when unloading and weakening the thick hard rock layer above the hard roof, a large-flow horizontal long-hole regional fracturing method is used to regionally fractur the hard roof; According to the mining height of the large mining height fully mechanized mining working face, the large mining height fully mechanized mining hydraulic support is reasonably selected. The large mining height fully mechanized mining hydraulic support is used to support the hard roof when the large mining height fully mechanized mining working face is mined. The large mining height fully mechanized mining hydraulic support adopts a side guard structure of a multi-level side guard plate. The side guard structure of the multi-level side guard plate is used to protect the coal wall fragments generated by the large mining height fully mechanized mining working face under the hard roof when the large mining height fully mechanized mining working face is mined.

[0006] In some embodiments, the method further comprises: The target layer for regional fracturing of the hard roof is determined according to the height range of the thick hard rock layer, and the process of determining the height range of the thick hard rock layer includes: Determine the average expansion coefficient in the hard roof collapse space of the goaf; The height range of thick hard rock formations is calculated according to the following formula: Among them, M represents the mining height of the fully mechanized mining face with large mining height, Represents the average expansion coefficient.

[0007] In some embodiments, the construction project of regional fracturing of the hard roof is carried out outside the influence range of the advance support pressure of the large mining height fully mechanized mining face.

[0008] Furthermore, the influence range of the advance support pressure is the distance between the starting point and the installation position of the borehole stress gauge, and the judgment criterion of the starting point is the position point when the drilling stress rise value reaches 5% of the initial stress.

[0009] In some embodiments, the downhole high-flow horizontal long-hole regional fracturing method adopts a retreat-type staged composite fracturing process, and corresponding fracturing process parameters are designed.

[0010] In some embodiments, the method of reasonably selecting the large mining height fully-mechanized mining hydraulic support according to the mining height of the large mining height fully-mechanized mining working face includes: For large mining height fully mechanized mining working faces with mining height above 3.5m, two-column shielding hydraulic supports are preferred as large mining height fully mechanized mining hydraulic supports.

[0011] Furthermore, the support strength that the large mining height fully mechanized hydraulic support needs to meet is , M represents the mining height of the large mining height fully mechanized mining face.

[0012] In some embodiments, the method further comprises: When mining the fully mechanized mining face with large mining height, the mine pressure monitoring system is used to monitor the initial support force of the fully mechanized hydraulic support with large mining height and the pressure status of the fully mechanized mining face with large mining height in real time; Dynamically adjust the initial support force of the hydraulic support for large mining height comprehensive mining according to the pressure state of the large mining height comprehensive mining working face; Among them, when the large mining height fully mechanized mining working face is in a non-pressure state, the initial support force requirement of the large mining height fully mechanized mining hydraulic support is set to no less than 80% of the rated initial support force; When the large mining height fully mechanized mining working face is under pressure, start the booster pump installed on the large mining height fully mechanized mining hydraulic support, and set the initial support force requirement of the large mining height fully mechanized mining hydraulic support to not less than 90% of the rated initial support force.

[0013] In some embodiments, when mining is performed on a fully mechanized mining face with a large mining height, it also includes: When the pressure of the fully mechanized mining face with a large mining height is less than the preset pressure threshold, the number of multi-level side guards to be retracted in groups is set to no more than 5; When the pressure of the fully mechanized mining face with a large mining height is greater than the preset pressure threshold, the number of racks for retracting the multi-level side guard plates in groups is set to 2 or 3.

[0014] Furthermore, the retracting method of the multi-level guard plate includes: When the depth of the coal wall spalling in the fully mechanized mining face with large mining height is greater than 0.8m, the multi-level wall protection plate is recovered in two steps; Wherein, before the upper cutting drum of the coal mining machine passes through, the recovery degree of the multi-stage side guard plate is set to be 45 degrees to the horizontal ground; When the coal mining machine passes through the current large-mining-height fully-mechanized hydraulic support, the multi-level side guard plates at a 45-degree angle to the horizontal ground will be fully retracted into place.

[0015] The method for collaboratively controlling the spalling of coal wall in a fully-mechanized mining face with large mining height provided by the present invention adopts an underground large-flow horizontal long-hole regional fracturing method to perform regional fracturing on the hard roof, and adopts a fully-mechanized mining hydraulic support with large mining height to protect the hard roof during regional fracturing, and the hydraulic support adopts a multi-level side protection plate to mutually support the coal wall during mining. Thus, the pressure relief of fracturing and the supporting force of the support are coordinated, and the side protection structure is adopted to control the side spalling, so as to realize scientific control of the roof and coal wall, effectively alleviate the problems of strong mine pressure and spalling of coal wall in the working face with large mining height, and greatly improve the spalling control effect of coal wall in the working face with large mining height compared with the traditional method. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced one by one below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a flow chart of the method for collaboratively controlling coal wall spalling in a fully mechanized mining face with a large mining height provided by the present invention.

[0018] Figure 2 It is a schematic diagram of the target layer of the regional fracturing provided by the present invention.

[0019] Figure 3 It is a schematic diagram of the relationship between the mining height and the support strength provided by the present invention.

[0020] Figure 4 It is one of the schematic diagrams of the side guard of the multi-level side guard plate provided by the present invention.

[0021] Figure 5 This is the second side guard schematic diagram of the multi-level side guard plate provided by the present invention.

[0022] Figure 6 This is the third side guard schematic diagram of the multi-level side guard plate provided by the present invention.

[0023] Reference numerals: 1: Support top beam; 2: Upper telescopic beam; 3: Lower telescopic beam; 4: First-level guard plate; 5: Second-level guard plate; 6: Third-level guard plate; 7: Upper cutting drum of coal mining machine. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The following describes the method for coordinated control of coal wall spalling in a fully mechanized mining face with large mining height according to the present invention in conjunction with the accompanying drawings. Figure 1 The figure is a flow chart of the method for controlling the coal wall spalling in a fully mechanized mining face with large mining height provided by the present invention. Figure 1 As shown, the method includes the following steps 101 to 102.

[0026] Step 101, before mining at the high-mining height fully-mechanized mining face, when unloading and weakening the thick hard rock layer on the upper layer of the hard roof, regional fracturing of the hard roof is performed using an underground large-flow horizontal long-hole regional fracturing method.

[0027] In coal mining operations, before mining at the high-mining fully-mechanized mining face, it is necessary to survey the thick hard rock layer of the hard roof above the coal mine and perform pressure relief and weakening. Pressure relief and weakening are generally achieved by regional fracturing of the thick hard rock layer, reducing the hanging length of the hard roof, and promoting effective filling of the goaf after the roof collapses. In the embodiment of the present invention, a large-flow horizontal long-hole regional fracturing method is used underground to perform regional fracturing on the hard roof, so as to achieve pressure relief and weakening of the thick hard rock layer on the upper layer of the hard roof. The fracturing process and fracturing process parameters of the underground large-flow horizontal long-hole regional fracturing method are generally determined according to the maximum horizontal principal stress distribution of the hard rock layer above the hard roof, the uniaxial compressive strength of the hard roof and other parameters. By means of underground large-flow horizontal long-hole regional fracturing, the stress environment of the mining field is improved, and the dynamic load impact of the breaking and instability of multiple hard roofs on the coal wall working face is reduced.

[0028] Step 102. According to the mining height of the large mining height fully mechanized mining working face, the large mining height fully mechanized mining hydraulic support is reasonably selected. The large mining height fully mechanized mining hydraulic support is used to support the hard roof when the large mining height fully mechanized mining working face is being mined. The large mining height fully mechanized mining hydraulic support adopts a side guard structure of a multi-level side guard plate. The side guard structure of the multi-level side guard plate is used to protect the coal wall fragments generated by the large mining height fully mechanized mining working face under the hard roof when the large mining height fully mechanized mining working face is being mined.

[0029] When unloading and weakening the thick and hard rock layer on the upper layer of the hard roof, hydraulic supports are required to protect the hard roof in the working area of ​​the large mining height fully-mechanized mining face. Therefore, a reasonable selection of large mining height fully-mechanized mining hydraulic supports is required. Including reasonable support types, support strength and support forms of hydraulic supports. The selection of hydraulic supports is determined according to the mining height M of the large mining height fully-mechanized mining face. Because for large mining height fully-mechanized mining faces with different collection heights, the initial support force level and support strength of large mining height fully-mechanized mining hydraulic supports are different. The higher the collection height, the higher the initial support force level and support strength of the hydraulic supports. The large mining height fully mechanized mining hydraulic support is used to support the hard roof during mining in the large mining height fully mechanized mining working face. The ultra-high support resistance of the hydraulic support is used to suppress the sinking and delamination of the near-field hard roof, and to improve the overall stiffness of the support-surrounding rock system. By acting on the ultra-high cutting force on the hard roof, the cutting line of the hard roof is moved backward, the broken position and the suspended roof state near the hard roof are changed, and the pressure of the hard roof rotation on the coal wall is reduced.

[0030] In addition, the large mining height fully mechanized mining hydraulic support adopts a protection structure of multi-level protection plates, which is used to protect the coal wall spalling generated on the working face when the large mining height fully mechanized mining face under the hard roof is mined. In the embodiment of the present invention, the selected large mining height fully mechanized mining hydraulic support is designed with a protection structure of multi-level protection plates. This protection structure of multi-level protection plates is used to protect the working face of large mining height fully mechanized mining, that is, to protect the coal wall when the coal wall spalling occurs in the fully mechanized mining working face of large mining height, and to prevent the flying coal blocks of the coal wall spalling from hitting the hydraulic support or the operating personnel. By optimizing the protection structure, the protection area of ​​the coal wall is increased, the protection force and the timeliness of the protection response are improved, and the deformation and damage of the coal wall and the sliding of spalled coal are suppressed.

[0031] The present invention adopts an underground large-flow horizontal long-hole regional fracturing method to regionally fractur the hard roof before mining in the large-mining height fully-mechanized mining working face, and adopts a large-mining height fully-mechanized mining hydraulic support to protect the hard roof during mining, and the hydraulic support adopts a multi-level side protection plate to protect the coal wall during mining. Thus, the pressure relief of fracturing and the supporting force of the support are coordinated, and the side protection structure is used to control the side spalling, so as to realize the scientific control of the roof and the coal wall, effectively alleviate the problems of strong mine pressure and coal wall spalling and roof caving in the large-mining height working face, and greatly improve the effect of coal wall spalling control in the large-mining height working face compared with the traditional method.

[0032] In some embodiments, before regional fracturing of the hard roof using the underground high-flow horizontal long-hole regional fracturing method, it is necessary to determine the target layer for regional fracturing of the hard roof based on the height range of the thick hard rock layer. Because after the large-mining height fully-mechanized mining face is mined, it is necessary to determine the height range of the roof rock layer that causes a significant impact, and then determine the target layer for regional fracturing. The height range of the thick hard rock layer is calculated based on the mining height M of the large-mining height fully-mechanized mining face of the coal mine. The following describes the process of determining the height range of the thick hard rock layer.

[0033] In order to reduce the effect of hard roof pressure on the coal wall, it is necessary to reduce the hanging length of the hard roof and promote the effective filling of the goaf after the hard roof collapses. Therefore, the target layer of regional fracturing should be determined for this purpose. First, determine the average crushing expansion coefficient in the collapse space of the hard roof in the goaf. This coefficient can be estimated by actually measuring the rock formation data. The average crushing expansion coefficient is generally between 1.15 and 1.2, and then the height range of the thick hard rock layer is calculated according to the following formula: Among them, M represents the mining height of the fully mechanized mining face with large mining height, It represents the average expansion coefficient. According to the above formula, the rock layer height range can be calculated to be 5M or 6M.

[0034] After calculating the range of rock layer heights that will be significantly affected by mining at the large-height fully-mechanized mining face, regional fracturing is then carried out on the target layer within the range of rock layer heights. Specifically, fracturing is carried out on the target layer surface of the hard roof with a thickness of more than 10m and a uniaxial compressive strength of more than 30MPa. When the number of target layers to be fractured is more than one, the vertical spacing between the target layers for fracturing shall not be less than 10m, and the vertical spacing between the lowest fracturing layer and the coal seam shall not be less than 10m.

[0035] For example, Figure 2 As shown in the figure, taking the geological drilling hole 58 of the fully mechanized mining face of a coal mine in a certain area as an example, according to the analysis of the hard roof conditions of the coal seam, within the range of 50m above the coal seam of the working face, the thick hard rock layers from bottom to top are 22.64m thick medium-grained sandstone and 12.9m thick siltstone. Therefore, it is determined that the target rock layers to be regionally fractured and weakened in this area of ​​the working face are 2 layers, and the target layers of regional fracturing are determined to be 15m and 35m respectively.

[0036] The embodiment of the present invention performs regional fracturing within the range of rock layer heights that are significantly affected by mining in a fully-mechanized mining face with a large mining height, thereby reducing the effect of hard roof pressure on the coal wall and promoting effective filling of the goaf after the hard roof collapses.

[0037] In order to reduce the impact of fracturing construction on the production of coal wall working face, the construction project of regional fracturing of hard roof is carried out outside the influence range of the advance support pressure of the fully mechanized mining face with large mining height. The influence range of the advance support pressure is obtained based on the actual measurement of the borehole stress gauge during fracturing or determined based on coal mine production experience.

[0038] In some embodiments, the influence range of the advance support pressure is the distance between the starting point and the installation position of the drilling stress gauge, and the judgment criterion of the starting point is the position point when the drilling stress rise value reaches 5% of the initial stress. This position point is recorded as P1, then the distance between point P1 and the installation position of the drilling stress gauge is the influence range of the advance support pressure.

[0039] Taking the actual implementation situation of a coal mine in a certain area as an example, the measured influence range of the advanced support pressure of the working face is about 100m, that is, the distance between the starting point and the installation position of the borehole stress gauge is 100m. In order to reduce the impact of fracturing construction on the production operations of the working face, the construction project of regional fracturing of the hard roof can be set to be carried out 200 meters away from the advanced large-mining height comprehensive mining working face.

[0040] According to the embodiment of the present invention, the advance distance of the regional fracturing construction is determined to be a distance outside the influence range according to the influence range of the advance support pressure of the working face, which can effectively reduce the influence of the fracturing construction on the production operation of the coal wall working face.

[0041] In some embodiments, the specific implementation process of regional fracturing can be determined by the mechanical properties of the hard rock formation to be fractured, specifically selected according to the in-situ stress test and roof rock mechanical parameter test results of the actual mining area. Here, the underground large-flow horizontal long-hole regional fracturing method is adopted, and the retreat-type segmented composite fracturing process is adopted, and the corresponding fracturing process parameters are designed. The process parameters of regional fracturing include: crack radius, borehole diameter, hole depth of fracturing borehole, horizontal hole depth, horizontal spacing of boreholes, etc. In order to achieve a good fracturing pressure relief effect, these fracturing process parameters must be reasonably designed according to the mechanical properties of the rock formation to be fractured.

[0042] Taking the actual implementation of a coal mine in a certain area as an example, according to the results of stress in-situ tests and roof rock mechanics parameter tests, the maximum horizontal principal stress of the sandstone roof of the 2-2 coal seam in the mining area is distributed in 3.3~20.5MPa, the average uniaxial compressive strength of the hard sandstone roof is about 50MPa, and the maximum tensile strength is 3.12MPa. It is calculated that the fracture pressure of the hard roof rock layer is not less than 15MPa, and the required pumping pressure is 15~32MPa. Based on this, the retreat-type staged composite fracturing process is adopted, and the process parameters of regional fracturing are set as follows: single pump flow is 1.5m³ / min; pump station pressure is 70MPa; fracture radius is greater than 40M; borehole diameter is 120mm; the depth of the fracturing borehole does not exceed 800m; the horizontal hole depth is 400m~650m, and the horizontal spacing of the borehole is 80m.

[0043] The embodiment of the present invention adopts underground large-flow horizontal long-hole regional fracturing to achieve active pressure relief and weakening of the hard roof above the coal wall. The process parameters of the regional fracturing are determined according to the actual stress data of the rock strata in the mining area. This can effectively improve the stress environment of the mining area, reduce the dynamic load impact on the coal wall caused by the breaking and instability of multiple layers of thick and hard roof, and achieve a good fracturing pressure relief effect.

[0044] In some embodiments, when regional fracturing is performed, it is necessary to select a reasonable large mining height fully-mechanized mining hydraulic support to achieve top and side protection. Here, it is necessary to select a large mining height fully-mechanized mining hydraulic support with multi-level side protection plates according to the actual mining height M of the large mining height fully-mechanized mining working face. When selecting a hydraulic support in an embodiment of the present invention, the hydraulic support is selected according to the support type, support strength and side protection form, which is described in detail below.

[0045] Generally speaking, working faces with higher mining heights are prone to coal wall spalling problems. Here, for large-mining-height fully-mechanized mining working faces with a mining height of more than 3.5m, two-column shielding hydraulic supports are preferred as large-mining-height fully-mechanized mining hydraulic supports.

[0046] In a certain coal mining area, when the mining height of the large mining height fully mechanized mining face reaches 10m, a two-column shielding hydraulic support is selected as the large mining height fully mechanized mining hydraulic support. The specific hydraulic support model that can be selected is ZY29000 / 45 / 100D hydraulic support with a rated working resistance of 29000kN.

[0047] Regarding support strength, it is necessary to ensure that the support strength of the large mining height fully-mechanized mining hydraulic support is not less than 1.8Mpa, and the rated initial support force is 37.5Mpa, thereby ensuring that the hydraulic support has sufficient initial support force level.

[0048] In terms of the side protection form, the side protection structure of the large mining height comprehensive mining hydraulic support is set as a multi-level side protection plate, specifically a three-level side protection plate. The total length of the three-level side protection plate is 5.5m. Flexible protective wings are set between the frame side protection plates of each large mining height comprehensive mining hydraulic support to prevent coal wall collapse blocks from rushing out from between the frames.

[0049] The embodiment of the present invention takes the mining height as the basis, reasonably selects the large mining height comprehensive mining hydraulic support from the perspective of support type, support strength and side protection form, and selects a two-column shielding hydraulic support for side and top protection during working face mining. The ultra-high support resistance of the hydraulic support suppresses the sinking and separation of the near-field roof, and improves the overall stiffness of the support-surrounding rock system. The ultra-high cutting force acting on the roof causes the roof cutting line to move backward, changes the broken position and suspended roof state of the near-field roof, and effectively reduces the pressure of the roof rotation on the coal wall.

[0050] In some embodiments, the specific support strength of the large mining height fully-mechanized mining hydraulic support can be reasonably and accurately set according to the mining height of the large mining height fully-mechanized mining working face. The embodiment of the present invention adopts an empirical formula method to determine the reasonable support strength of the large mining height fully-mechanized mining hydraulic support. By collecting the statistical results of the support strength and mining height of the large mining height working face hydraulic support, it is determined that the support strength is positively correlated with the mining height (referred to as mining height), such as Figure 3 As shown, Figure 3 The positive correlation coordinate diagram between support strength (unit: MPa) and mining height (unit: m) is shown. After fitting this positive correlation, the fitting straight line is obtained. , and then we can determine that the support strength that the large mining height fully mechanized hydraulic support needs to meet is , M represents the mining height of the fully mechanized mining face with large mining height. Therefore, according to the actual mining height in a coal mining area, it can be determined that the support strength of the two-column shield hydraulic support is 1.88~1.95MPa.

[0051] The embodiment of the present invention can accurately calculate the support strength of the large mining height fully mechanized hydraulic support by mining height, thereby improving the support effect of the support in actual mining operations and providing a good working environment for controlling the risk of coal wall spalling in actual mining operations.

[0052] In some embodiments, when mining a large mining height fully mechanized mining face, a mine pressure monitoring system is used to monitor the initial support force of the large mining height fully mechanized mining hydraulic support and the pressure state of the large mining height fully mechanized mining face in real time. Therefore, during mining, the hard roof above the large mining height fully mechanized mining face will produce periodic pressure, causing the large mining height fully mechanized mining face to produce periodic pressure. Here, the periodic pressure of the large mining height fully mechanized mining face refers to the periodic mine pressure caused by the periodic breaking of the hard roof on the coal mining face. By monitoring this periodic pressure state and issuing an early warning. In this way, the initial support force of the large mining height fully mechanized mining hydraulic support can be dynamically adjusted according to the pressure state of the large mining height fully mechanized mining face.

[0053] When the large mining height comprehensive mining working face is in a non-pressure state, the initial support force requirement of the large mining height comprehensive mining hydraulic support shall be set to not less than 80% of the rated initial support force. When the large mining height comprehensive mining working face is in a pressure state, the booster pump installed on the large mining height comprehensive mining hydraulic support shall be started, and the initial support force requirement of the large mining height comprehensive mining hydraulic support shall be set to not less than 90% of the rated initial support force.

[0054] For example, the rated initial support force of a large mining height comprehensive mining hydraulic support is 37.5Mpa. When the large mining height comprehensive mining working face is in a non-pressure state, the initial support force of the large mining height comprehensive mining hydraulic support is set to not less than 30Mpa. When the large mining height comprehensive mining working face is in a pressure state, the booster pump installed in the large mining height comprehensive mining hydraulic support is started to increase the initial support force of the large mining height comprehensive mining hydraulic support to more than 34Mpa to relieve the hard roof pressure of the large mining height comprehensive mining working face.

[0055] According to the embodiment of the present invention, when mining in a large mining height fully mechanized mining face, by real-time monitoring the initial support force of the large mining height fully mechanized mining hydraulic support and the pressure state of the large mining height fully mechanized mining face, the initial support force level of the support can be adjusted in real time according to the pressure state of the large mining height fully mechanized mining face, thereby achieving accurate control of the pressure of the large mining height fully mechanized mining face and ensuring the normal and safe progress of the mining operation process.

[0056] In some embodiments, after cutting coal on a large mining height working face, the telescopic beam and the side guard plate of the large mining height fully-mechanized hydraulic support are controlled, and the multi-level side guard plate is extended to protect the coal wall from spalling. Here, when mining a large mining height working face, the operator operates the coal mining machine to cut coal on the working face. After cutting coal, the working face may have coal wall spalling, and the pressure of the hard roof on the working face will also change. At this time, the telescopic beam of the large mining height fully-mechanized hydraulic support is controlled, and the multi-level side guard plate is extended in time to protect the roof and side guard.

[0057] like Figure 4 As shown, Figure 4The schematic diagram of the normal protection of multi-level sidewall plates during mining at a large mining height working face is shown. During mining at a large mining height fully-mechanized mining working face, an upper telescopic beam 2 and a lower telescopic beam 3 are extended and retracted from the support top beam 1 of the large mining height fully-mechanized mining hydraulic support. The lower telescopic beam 3 is connected to three-level sidewall plates, specifically, a first-level sidewall plate 4, a second-level sidewall plate 5, and a third-level sidewall plate 6. After mining and cutting the coal on the working face, the lower telescopic beam 3 of the large mining height fully-mechanized mining hydraulic support is controlled to extend and retract the multi-level sidewall plates to protect the coal wall of the working face.

[0058] When mining in a fully-mechanized mining face with a large mining height, serious coal wall spalling may occur. In order to be able to control it in time, the embodiment of the present invention monitors the depth of the coal wall spalling in real time. When the depth of the coal wall spalling is detected to be greater than 0.8m, it means that the coal wall spalling is serious, and the fully-mechanized mining hydraulic support with a large mining height is advanced. Because in the case of serious spalling in the working face with a large mining height, in order to prevent roof collapse, the empty top area of ​​the end roof should be reduced as much as possible, and the support should be advanced in time.

[0059] In the embodiment of the present invention, after cutting coal on a fully-mechanized mining face with a large mining height, the telescopic beam of the fully-mechanized mining hydraulic support with a large mining height is controlled to extend and retract the multi-level sidewall protection plate to protect the sidewall, and when the coal wall is severely spalled, the fully-mechanized mining hydraulic support with a large mining height is advanced to pull the support. Thus, the reasonable operation of the support and the multi-level sidewall protection plate can effectively control the spalling of the coal wall, avoid the serious damage to the mining equipment and operators caused by the spalling of the coal wall, and improve the safety of the coal cutting operation.

[0060] Furthermore, when mining the large mining height working face, the large mining height fully-mechanized mining hydraulic support extends and retracts multi-level side guard plates for side guarding. In order to ensure that the coal mining machine can cut coal, the multi-level side guard plates need to be recovered. Since the side guard plates between the large mining height fully-mechanized mining hydraulic supports are all provided with flexible protective wings, it is impossible to recover the multi-level side guard plates of a large mining height fully-mechanized mining hydraulic support alone. The recovery of the multi-level side guard plates is recovered in groups according to the number of large mining height fully-mechanized mining hydraulic supports. Since the large mining height fully-mechanized mining hydraulic supports play the role of protecting the top and side guards of the hard roof and large mining height fully-mechanized mining working face in real time, it is necessary to reasonably set the number of recovered frames according to the pressure borne by the hydraulic supports and the working face.

[0061] Coal cutting can only be carried out after the guard plates of the large mining height comprehensive mining hydraulic support are recovered. The number of recovered frames is determined according to the pressure of the hydraulic support of the working face. The mine pressure monitoring system can be used to monitor the pressure status of the large mining height comprehensive mining working face, and the pressure of the hydraulic support of the working face can be measured, that is, the pressure of the large mining height comprehensive mining working face.

[0062] When the pressure of the large-mining height comprehensive mining working face is lower than the preset pressure threshold, the number of multi-level side guards for group retracting shall be set to no more than 5; when the pressure of the large-mining height comprehensive mining working face is higher than the preset pressure threshold, the number of multi-level side guards for group retracting shall be set to 2 or 3.

[0063] Here, when the pressure of the working face support is less than the preset pressure threshold, it means that the mine pressure of the working face is weak at this time, and the number of racks for group-retracting multi-level side guards is set to no more than 5, that is, the number of large-mining height comprehensive mining hydraulic supports for group-recovering side guards is no more than 5. When the pressure of the working face support is greater than the preset pressure threshold, it means that the mine pressure of the working face is strong, and it is still necessary to ensure that there are a certain number of side guards to protect part of the working face coal wall, then the number of racks for group-retracting multi-level side guards is set to 2 or 3, that is, the number of large-mining height comprehensive mining hydraulic supports for group-recovering side guards is 2 or 3, and the remaining unrecovered side guards in the large-mining height comprehensive mining hydraulic supports continue to cling to the coal wall to prevent the coal wall from being flaked after the coal is cut on the part of the working face coal wall where the side guards have been recovered.

[0064] In addition, in order to ensure that the coal mining machine can cut coal, when the operating personnel operate the guard plates of the two large-mining height comprehensive mining hydraulic supports behind the coal mining machine, the large-mining height comprehensive mining hydraulic supports extend the multi-level guard plates to ensure that the guard plates are close to the coal wall, and then the corresponding number of guard plates are recovered according to the pressure of the hydraulic supports on the working face.

[0065] According to the embodiments of the present invention, when the pressure on the working face is relatively low, the recovery speed of the multi-stage side guards can be accelerated by reasonably controlling the number of multi-stage side guards that are recovered in groups, thereby ensuring that the coal mining machine can pass through in time to cut coal. When the pressure on the working face is relatively high, in order to avoid serious coal wall spalling on the working face where the side guards have been recovered, a part of the side guards are retained and only a certain number of side guards are recovered, thereby ensuring the safe passage of operators operating the coal mining machine.

[0066] In some embodiments, after the coal is cut on the working face, the corresponding number of multi-level side guards need to be recovered in groups, but the way to recover the side guards needs to be selected according to the actual situation, and they cannot be recovered all at once. Here, when the coal wall spalling is serious in the fully mechanized mining working face with large mining height, the multi-level side guards are recovered in two times.

[0067] Generally speaking, when the depth of coal wall spalling in a fully mechanized mining face with a large mining height is greater than 0.8m, it indicates that the coal wall spalling is serious, otherwise it is minor. Therefore, the embodiment of the present invention selects the method of recovering the side guard plate according to this standard. The following describes the process of recovering the multi-level side guard plates twice when the depth of coal wall spalling is greater than 0.8m.

[0068] First, before the upper drum of the coal mining machine passes through, the recovery degree of the multi-level side guard plates is set to a 45-degree angle with the horizontal ground. This is the first recovery. When the coal mining machine passes through the current large-mining height comprehensive mining hydraulic support, the multi-level side guard plates at a 45-degree angle with the horizontal ground will be completely recovered into place.

[0069] like Figure 5 As shown, before the upper cutting drum of the coal mining machine passes, the recovery degree of the multi-level side guard plate is set to be 45 degrees to the horizontal ground. Because when the multi-level side guard plate is close to the coal wall, since the working surface of the coal wall is in the vertical direction, the main body of the multi-level side guard plate is almost perpendicular to the ground. Before the upper cutting drum of the coal mining machine passes, the first stage of recovery is carried out, and the recovery degree of the multi-level side guard plate is set to be 45 degrees to the horizontal ground.

[0070] like Figure 6 As shown, when the shearer passes through the current large-mining height fully-mechanized hydraulic support, the upper cutting drum 7 of the shearer has already cut the coal of the hydraulic support, and the multi-level side guard plates at an angle of 45 degrees to the horizontal ground are completely recovered. Because when the upper cutting drum 7 of the shearer passes through the hydraulic support, the coal cutting on the working face is completed, and the second stage of recovery is performed, and the multi-level side guard plates at an angle of 45 degrees to the horizontal ground after the first stage of recovery are completely recovered.

[0071] In the embodiment of the present invention, the movement of the coal mining machine can perform two-stage recovery of the multi-level wall guard plates, which can effectively block the flying of coal blocks from the coal wall spalling, prevent the coal blocks from entering the large feet of the large mining height comprehensive mining hydraulic support, and greatly reduce the risk of workers in the support being hit by the spalled coal. This improves the control effect of the coal wall spalling in the working face with large mining height and ensures the mining safety of the working face with large mining height.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for collaboratively controlling coal wall spalling in a fully mechanized mining face with large mining height, characterized in that: The method comprises: Before mining at a high-mining fully-mechanized mining face, when unloading and weakening the thick hard rock layer above the hard roof, a large-flow horizontal long-hole regional fracturing method is used to regionally fractur the hard roof; According to the mining height of the large mining height fully mechanized mining working face, the large mining height fully mechanized mining hydraulic support is reasonably selected. The large mining height fully mechanized mining hydraulic support is used to support the hard roof when the large mining height fully mechanized mining working face is mined. The large mining height fully mechanized mining hydraulic support adopts a side guard structure of a multi-level side guard plate. The side guard structure of the multi-level side guard plate is used to protect the coal wall fragments generated by the large mining height fully mechanized mining working face under the hard roof when the large mining height fully mechanized mining working face is mined.

2. The method for controlling the coal wall spalling in a fully mechanized mining face with a large mining height according to claim 1 is characterized in that: The method further comprises: The target layer for regional fracturing of the hard roof is determined according to the height range of the thick hard rock layer, and the process of determining the height range of the thick hard rock layer includes: Determine the average expansion coefficient in the hard roof collapse space of the goaf; The height range of thick hard rock formations is calculated according to the following formula: Among them, M represents the mining height of the fully mechanized mining face with large mining height, Represents the average expansion coefficient.

3. The method for controlling the coal wall spalling in a fully mechanized mining face with a large mining height according to claim 1 is characterized in that: The construction project of regional fracturing of the hard roof is carried out outside the influence range of the advance support pressure of the large mining height fully mechanized mining face.

4. The method for controlling the coal wall spalling in a fully mechanized mining face with a large mining height according to claim 3 is characterized in that: The influence range of the advance support pressure is the distance between the starting point and the installation position of the drilling stress gauge, and the judgment standard of the starting point is the position point when the drilling stress rise value reaches 5% of the initial stress.

5. The method for controlling the coal wall spalling in a fully mechanized mining face with a large mining height according to claim 1 is characterized in that: The underground large flow horizontal long hole regional fracturing method adopts a retreat-type staged composite fracturing process, and designs corresponding fracturing process parameters.

6. The method for controlling the coal wall spalling in a fully mechanized mining face with a large mining height according to claim 1 is characterized in that: According to the mining height of the large mining height fully mechanized mining working face, the large mining height fully mechanized mining hydraulic support is reasonably selected, including: For large mining height fully mechanized mining working faces with mining height above 3.5m, two-column shielding hydraulic supports are preferred as large mining height fully mechanized mining hydraulic supports.

7. The method for controlling the coal wall spalling in a fully mechanized mining face with a large mining height according to claim 6 is characterized in that: The support strength that the large mining height fully mechanized hydraulic support needs to meet is , M represents the mining height of the large mining height fully mechanized mining face.

8. The method for controlling the coal wall spalling in a fully mechanized mining face with a large mining height according to claim 1 is characterized in that: The method further comprises: When mining the fully mechanized mining face with large mining height, the mine pressure monitoring system is used to monitor the initial support force of the fully mechanized hydraulic support with large mining height and the pressure status of the fully mechanized mining face with large mining height in real time; Dynamically adjust the initial support force of the hydraulic support for large mining height comprehensive mining according to the pressure state of the large mining height comprehensive mining working face; Among them, when the large mining height fully mechanized mining working face is in a non-pressure state, the initial support force requirement of the large mining height fully mechanized mining hydraulic support is set to no less than 80% of the rated initial support force; When the large mining height fully mechanized mining working face is under pressure, start the booster pump installed on the large mining height fully mechanized mining hydraulic support, and set the initial support force requirement of the large mining height fully mechanized mining hydraulic support to not less than 90% of the rated initial support force.

9. The method for controlling the coal wall spalling in a fully mechanized mining face with a large mining height according to claim 8 is characterized in that: When mining is carried out on a fully mechanized mining face with a large mining height, the method further comprises: When the pressure of the fully mechanized mining face with a large mining height is less than the preset pressure threshold, the number of multi-level side guards to be retracted in groups is set to no more than 5; When the pressure of the fully mechanized mining face with a large mining height is greater than the preset pressure threshold, the number of racks for retracting the multi-level side guard plates in groups is set to 2 or 3.

10. The method for controlling coal wall spalling in a fully mechanized mining face with large mining height according to claim 9, characterized in that: The retracting method of the multi-level guard plate includes: When the depth of the coal wall spalling in the fully mechanized mining face with large mining height is greater than 0.8m, the multi-level wall protection plate is recovered in two steps; Wherein, before the upper cutting drum of the coal mining machine passes through, the recovery degree of the multi-stage side guard plate is set to be 45 degrees to the horizontal ground; When the coal mining machine passes through the current large-mining-height fully-mechanized hydraulic support, the multi-level side guard plates at a 45-degree angle to the horizontal ground will be fully retracted into place.

Images