A method for dynamic control of the roof in the gob-side entry retaining with roof cutting

Abstract

The present invention provides a method for dynamic control of the roof in gob-side entry retaining, which relates to the technical field of coal mining. The method specifically includes: dividing the strata behavior zoning of the roof in gob-side entry retaining, respectively determining the support schemes for the advanced dynamic pressure influence area, the mining and excavation dynamic load action area, and the stable area of the roadway formed after mining, and determining the specifications and models of single hydraulic props and π-shaped beams according to the roof conditions of the roadway, the roadway section size, etc.; determining the permanent support scheme during the one-time roadway formation period and the permanent support scheme during the secondary reuse period, specifically the setting of the number of bolts and their pre-tightening force, the setting of the number of cable bolts and their pre-tightening force, etc. The method determines the support method and support parameters according to the zonal failure characteristics of the roof in gob-side entry retaining, restricts the plastic failure of the roof through multiple roof reinforcements, and additionally sets permanent support schemes at different stages of the one-time roadway formation and the secondary reuse. The method effectively controls the roof in zones and at different times, realizing the safety of the gob-side entry.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mining, and in particular to a method for dynamic control of the roof of a roof-cutting and roadway-retaining system. Background Art

[0002] Non-pillar mining has been widely used due to its advantages such as high recovery rate and low driving volume. As an important passage in the non-pillar mining and excavation system, roof-cutting and roadway-retaining shoulders important functions such as transportation and pedestrian passage. The roof failure of roof-cutting and roadway-retaining experiences a primary roadway formation stage and a secondary reuse stage, with obvious spatio-temporal characteristics. The time-sharing characteristics are manifested in that during the primary roadway formation, the stress field of the roadway surrounding rock is redistributed, and the roof failure of roof-cutting and roadway-retaining is mainly affected by the superposition of the redistribution of the original rock stress and the roof-cutting pre-splitting detonation. During the secondary reuse, the mining of adjacent working faces further damages the roof, and the roof structure moves again, causing secondary disturbance to the roof of roof-cutting and roadway-retaining. The zoning characteristics are manifested in that due to different influence ranges of mining and excavation disturbances on the roof of roof-cutting and roadway-retaining, the mine pressure manifestations of the roofs in each area are significantly different, and the roof deformations have their own characteristics.

[0003] In the prior art, corresponding support methods have been proposed based on the uniformity of the roof failure of roof-cutting and roadway-retaining, but the spatio-temporal failure characteristics of the roof of roof-cutting and roadway-retaining have not been considered from a dynamic perspective, which results in poor applicability, low matching degree and poor support effect of the corresponding support methods. In on-site applications, phenomena such as roof subsidence in the advanced support section, shallow roof fracture, and deterioration and failure of the support structure have occurred on the roof of roof-cutting and roadway-retaining, seriously threatening the long-term safety of roof-cutting and roadway-retaining. Summary of the Invention

[0004] On the premise of fully considering the spatio-temporal failure characteristics of the roof of roof-cutting and roadway-retaining, in order to effectively control the roof during the roof-cutting and roadway-retaining process, ensure the safety of mine mining, dynamically adapt to the change of the roof failure state, and realize the dynamic support of the roof in different zones, the present invention provides a method for dynamic control of the roof of roof-cutting and roadway-retaining, and the specific technical solutions are as follows.

[0005] A method for dynamic control of the roof of roof-cutting and roadway-retaining, the steps include:

[0006] A. Divide the mine pressure manifestation zones of the roof of roof-cutting and roadway-retaining according to the roof monitoring data, and respectively determine the ranges of the advanced dynamic pressure influence zone, the mining dynamic load action zone, and the post-mining roadway formation stable zone;

[0007] B. Determine the roadway support scheme according to the roadway roof conditions and roadway section dimensions of the mine pressure manifestation zones, including the specification models of single hydraulic props and π-shaped beams;

[0008] C. Determine the permanent support scheme during the primary roadway formation period and the permanent support scheme during the secondary reuse period, including the setting of the number of bolts and their pre-tightening forces, and the setting of the number of cable bolts and their pre-tightening forces.

[0009] Preferably, step A includes:

[0010] A1. Monitoring the approaching amount of the roadway roof and floor;

[0011] A2. Plotting the change curves of the approaching amounts of the roof and floor, and dividing the advanced dynamic pressure influence area, the mining dynamic load action area, and the post-mining roadway stability area according to the magnitudes and rates of the approaching amounts of the roof and floor.

[0012] More preferably, the monitoring of the approaching amounts of the roadway roof and floor is specifically carried out at the positions ahead of and behind the advancing face of the working face, setting monitoring intervals, and arranging multiple monitoring sections respectively.

[0013] More preferably, the monitoring interval is less than or equal to 20 m, the range ahead of the working face is less than or equal to 100 m, the range behind the working face is less than or equal to 600 m, and the monitoring period is less than 90 days.

[0014] More preferably, the approaching amounts of the roof and floor in the advanced dynamic pressure influence area are greater than 200 mm, the approaching amounts of the roof and floor in the mining dynamic load action area are 50 - 200 mm, and the approaching amounts of the roof and floor in the post-mining roadway stability area are less than 50 mm.

[0015] Preferably, step B includes:

[0016] B1. In the advanced dynamic pressure influence area, determining the support strength of the single hydraulic prop, adopting the support method of combining the single hydraulic prop and the π-shaped beam, arranging the single hydraulic prop and the π-shaped beam respectively from the roadway center line to the roof cutting side of the roadway and from the roadway center line to the solid coal side of the roadway, and setting the spacing to be 0.8 - 1.2 m;

[0017] B2. In the mining dynamic load action area, determining the support strength of the single hydraulic prop, adopting the support method of combining the single hydraulic prop and the π-shaped beam, and arranging them perpendicular to and parallel to the roadway trend in the roadway; among them, the spacing on the side close to the roof cutting side is set to be 0.5 - 0.8 m; the spacing on the roadway center line and on the side close to the solid coal side is set to be 0.8 - 1.2 m, and the spacing in the direction perpendicular to the roadway trend is 0.6 - 1 m; the combination of the single hydraulic prop and the π-shaped beam parallel to the roadway trend is arranged continuously and aligned without intervals;

[0018] B3. In the post-mining roadway stability area, determining the support strength of the single hydraulic prop, adopting the support method of combining the single hydraulic prop and the π-shaped beam, and arranging the single hydraulic prop and the π-shaped beam from the roadway center line to the roof cutting side of the roadway, and the spacing in the direction perpendicular to the roadway trend is 0.5 - 0.8 m.

[0019] More preferably, the support strength of the single hydraulic prop in the advanced dynamic pressure influence area is greater than or equal to 400 kN / m 2 , and the support strength of the single hydraulic prop in the mining dynamic load action area is greater than or equal to 600 kN / m2 ; the support strength of the single hydraulic prop in the post-mining roadway formation and stability area is greater than or equal to 100 kN / m 2 .

[0020] Preferably, step C includes:

[0021] C1. During the first roadway formation, determine the support parameters of the bolt according to the roadway geological conditions, roadway width, and bolt model;

[0022] C2. The bolts are respectively arranged from the roadway center line to the roof cutting side and the solid coal side of the roadway. The distance between adjacent bolts is 0.6 - 1 m. The bolts are connected by a steel strip and a pre-tightening force is applied;

[0023] C3. Determine the support parameters of the cable bolt according to the bolt support setting;

[0024] C4. The cable bolts are respectively arranged from the roadway center to the roof cutting side and the solid coal side of the roadway. The distance between adjacent cable bolts is 1.2 - 1.6 m. The cable bolts are arranged perpendicular to the roadway roof. The cable bolts are connected by a steel strip and a pre-tightening force is applied;

[0025] C5. During the secondary reuse period, additional cable bolts are driven on the roof cutting side of the roadway, and the distance between the cable bolts is set to 0.8 - 1.2 m.

[0026] More preferably, the pre-tightening force of the bolt is greater than or equal to 120 kN. The inclination angle of the inclined bolt is 10° - 20°, and the inclination angle of the inclined cable bolt is 10° - 20°.

[0027] More preferably, the tray of the cable bolt is a laminated energy-absorbing base. The laminated energy-absorbing base includes isoprene rubber and steel plate, and the isoprene rubber and the steel plate are bonded by a heat vulcanization process.

[0028] A method for the dynamic control of the roof of a roof-cutting and gob-side entry retaining provided by the present invention mainly solves the problems that the existing support scheme does not consider the spatio-temporal failure characteristics of the roof of the roof-cutting and gob-side entry retaining, and the existing support methods have poor applicability, low matching degree, and poor support effect. Based on the zonal characteristics of the abutment pressure manifestation of the roof of the roof-cutting and gob-side entry retaining and the time-sharing characteristics of the first roadway formation stage and the secondary reuse stage, the present invention proposes a zonal dynamic support scheme, a first roadway formation support scheme, and a secondary reuse support scheme. The three complement each other and jointly constitute a "dynamic control method" that changes with the failure state of the roof of the roof-cutting and gob-side entry retaining. This method can dynamically adapt to the change of the roof failure state and realizes the zonal dynamic support of the roof. Its beneficial effects also include:

[0029] (1) According to the zonal failure characteristics of the roof in gob-side entry retaining with roof cutting, the gob-side entry retaining with roof cutting is divided into the advanced dynamic pressure influence area, the mining and excavation dynamic load action area, and the gob-side entry stability area after mining. Furthermore, according to the zonal strata pressure manifestation characteristics, a zonal support scheme based on the parameters and layout methods of single props, bolts and cables is formulated. According to the strata pressure manifestation characteristics of the roof and floor, a support structure composed of single hydraulic props and π-shaped beams is set up, and the roof of the roadway is reinforced multiple times, restricting the plastic failure of the roof and forming a dynamic control method adaptable to the dynamic changes of the roof in gob-side entry retaining with roof cutting.

[0030] (2) According to the time-sharing failure characteristics of the roof in gob-side entry retaining with roof cutting, the gob-side entry retaining with roof cutting is divided into the primary roadway formation stage and the secondary reuse stage, and time-sharing support schemes for bolts and cables and their layout methods are formulated respectively. The support in the primary roadway formation stage realizes the initial reinforcement of the roof in gob-side entry retaining with roof cutting, and the secondary reuse support scheme realizes the later strengthening control of the roof in gob-side entry retaining with roof cutting. The two cooperate with each other, realizing both roof protection in the early stage and roof fixation in the later stage.

[0031] This method also has the advantages of good applicability, high matching degree, good support effect, etc. Especially in on-site applications, the roof in gob-side entry retaining with roof cutting avoids problems such as severe subsidence of the roof in the advanced support section, fracture of the shallow roof, and deterioration of the support structure body, realizing the safety of the gob-side entry with roof cutting. Description of the Drawings

[0032] Figure 1 It is a schematic diagram of the zonal strata pressure manifestation in gob-side entry retaining with roof cutting.

[0033] Figure 2 It is a schematic diagram during the primary roadway formation stage of gob-side entry retaining with roof cutting.

[0034] Figure 3 It is a schematic diagram during the secondary reuse stage of gob-side entry retaining with roof cutting.

[0035] Figure 4 It is a top view of the temporary support for the roof in the advanced dynamic pressure influence area of gob-side entry retaining with roof cutting.

[0036] Figure 5 It is Figure 4 The I-I sectional view of the temporary support for the roof in the advanced dynamic pressure influence area of gob-side entry retaining with roof cutting in

[0037] Figure 6 It is a top view of the temporary support for the roof in the mining and excavation dynamic load action area of gob-side entry retaining with roof cutting.

[0038] Figure 7 It is Figure 6 The I-I sectional view of the temporary support for the roof in the mining and excavation dynamic load action area of gob-side entry retaining with roof cutting in

[0039] Figure 8 It is a top view of the temporary support for the roof in the gob-side entry stability area after mining of gob-side entry retaining with roof cutting.

[0040] Figure 9Yes Figure 8 Cross-section view I-I of the temporary support for the roof in the stable area of the roadway formed after roof cutting and roadway retaining in the middle

[0041] Figure 10 Is the top view of the roof support in the stage of forming the roadway in one pass with roof cutting and roadway retaining

[0042] Figure 11 Yes Figure 10 Cross-section view I-I of the roof support in the stage of forming the roadway in one pass with roof cutting and roadway retaining in

[0043] Figure 12 Yes Figure 10 Cross-section view II-II of the roof support in the stage of forming the roadway in one pass with roof cutting and roadway retaining in the middle

[0044] Figure 13 Is the top view of the roof support in the secondary reuse stage of roof cutting and roadway retaining

[0045] Figure 14 Yes Figure 13 Cross-section view I-I of the roof support in the secondary reuse stage of roof cutting and roadway retaining in the middle

[0046] Figure 15 Yes Figure 13 Cross-section view II-II of the roof support in the secondary reuse stage of roof cutting and roadway retaining in the middle

[0047] Figure 16 Is the front view of the laminated energy-absorbing base

[0048] In the figure: 1 - this working face, 2 - adjacent working face, 3 - roof cutting and roadway retaining, 4 - stable area of the roadway formed after mining, 5 - area affected by mining dynamic load, 6 - area affected by advanced dynamic pressure, 7 - roof cutting side, 8 - solid coal side, 9 - isoprene rubber layer, 10 - steel plate. Specific implementation manners

[0049] Combined with Figures 1 to 16 As shown, the specific implementation manners of a method for dynamic control of the roof in roof cutting and roadway retaining provided by the present invention are described.

[0050] Example 1

[0051] Based on the zonal characteristics of the mine pressure manifestation of the roof in roof cutting and roadway retaining, and the time-sharing characteristics of the stages of forming the roadway in one pass and secondary reuse, in order to solve the problems such as poor applicability, low matching degree, and poor support effect in support, a method for dynamic control of the roof in roof cutting and roadway retaining is proposed. The control roadway serves the present working face and the adjacent working face. The specific steps include:

[0052] A. Divide the zones of the mine pressure manifestation of the roof in roof cutting and roadway retaining.

[0053] Divide the strata behavior zoning of the roof of the gob-side entry retaining by the roof monitoring data, and determine the scopes of the advanced dynamic pressure influence area, the mining and excavation dynamic load action area, and the post-mining roadway stability area respectively.

[0054] Step A includes:

[0055] A1. Monitor the convergence of the roadway roof and floor.

[0056] A2. Draw the curves of the convergence change of the roof and floor, and divide the advanced dynamic pressure influence area, the mining and excavation dynamic load action area, and the post-mining roadway stability area according to the magnitude and rate of the convergence of the roof and floor. The convergence of the roof and floor in the advanced dynamic pressure influence area is greater than 200 mm, the convergence of the roof and floor in the mining and excavation dynamic load action area is 50 - 200 mm, and the convergence of the roof and floor in the post-mining roadway stability area is less than 50 mm. According to the on-site measured values, compare with the roof and floor convergence indexes to divide the advanced dynamic pressure influence area, the mining and excavation dynamic load action area, and the post-mining roadway stability area; the specific zoning can be shown in the following table.

[0057]

[0058] Among them, the monitoring of the convergence of the roadway roof and floor is specifically carried out at the advanced position and the lagged position of the working face advancement. Set the monitoring interval and arrange multiple monitoring sections respectively.

[0059] The monitoring interval is less than or equal to 20 m, the range in front of the working face is less than or equal to 100 m, the range behind the working face is less than or equal to 600 m, and the monitoring period is less than 90 days. Specifically, in the range of 0 - a m in front of the working face advancement position, take a ≤ 100 m; in the range of 0 - b m behind the working face advancement position, take b ≤ 200 m; in the range of b - c m behind the working face advancement position, take c ≤ 400 m. The monitoring interval l, take l ≤ 20 m. Arrange i sections, take i ≤ 20; monitor for n days, take n ≤ 90 days.

[0060] B. Determine the dynamic support plan for the zoning.

[0061] Determine the roadway support plan according to the roadway roof conditions and roadway section dimensions in the strata behavior zoning, including the specification models of single hydraulic props and π-shaped beams. After determining the roadway support plan, determine the layout plan of "single hydraulic props and π-shaped beams" based on the theoretical calculation formula. The support strength calculation of the single hydraulic prop is as follows:

[0062]

[0063] In the formula, Q is the support strength provided by the single hydraulic prop, kN / m 2 ; γ d is the average unit weight of the roof rock mass, 25 kN / m 3; Z is the buried depth of the roadway, in m; a is the width of the roadway, in m; h is the height of the roadway, in m; is the internal friction angle, in °; C is the cohesion, in MPa.

[0064] Step B includes:

[0065] B1. In the area affected by advanced dynamic pressure, determine the support strength of the single hydraulic prop, adopt the support method of combining single hydraulic props and π-shaped beams, arrange single hydraulic props and π-shaped beams separately from the roadway center line to the gob-side of the roadway and from the roadway center line to the solid coal side of the roadway, and set the spacing to be 0.8 - 1.2 m.

[0066] B2. In the area affected by mining dynamic load, determine the support strength of the single hydraulic prop, adopt the support method of combining single hydraulic props and π-shaped beams, and arrange them perpendicular and parallel to the roadway strike in the roadway; among them, the spacing on the side close to the gob-side is set to be 0.5 - 0.8 m; the spacing on the roadway center line and the side close to the solid coal side is set to be 0.8 - 1.2 m, and the spacing in the direction perpendicular to the roadway strike is 0.6 - 1 m; the single hydraulic props and π-shaped beams combined parallel to the roadway strike are arranged in a continuous and aligned manner without intervals.

[0067] B3. In the stable area of the roadway formed after mining, determine the support strength of the single hydraulic prop, adopt the support method of combining single hydraulic props and π-shaped beams, and arrange single hydraulic props and π-shaped beams from the roadway center line to the gob-side of the roadway, and the spacing in the direction perpendicular to the roadway strike is 0.5 - 0.8 m.

[0068] Among them, the support strength of the single hydraulic prop in the area affected by advanced dynamic pressure is greater than or equal to 400 kN / m 2 , the support strength of the single hydraulic prop in the area affected by mining dynamic load is greater than or equal to 600 kN / m 2 ; the support strength of the single hydraulic prop in the stable area of the roadway formed after mining is greater than or equal to 100 kN / m 2 .

[0069] C. Determine the time-sharing permanent support plan.

[0070] Determine the permanent support plan during the one-time roadway formation period and the permanent support plan during the secondary reuse period, including the setting of the number of bolts and their pre-tightening force, and the setting of the number of cables and their pre-tightening force.

[0071] Step C includes:

[0072] C_{1}. During the one-time roadway formation period, determine the support parameters of the bolts according to the roadway geological conditions, roadway width and bolt model.

[0073] Among them, determine the bolt layout plan based on the theoretical calculation formula so that the strength after support is not lower than 0.35 MPa. The bolt support strength calculation formula is as follows:

[0074]

[0075] Wherein, P is the strength after bolt support, MPa; γ is the average unit weight of the roof rock mass, 25 kN / m 3 ; λ is the coefficient of lateral pressure; a is the roadway width, m; h is the roadway height, m; is the angle of internal friction, °; θ is

[0076] According to the geological conditions of roadway driving, a numerical calculation model is established to check the roof stress state and roof subsidence under different bolt layout schemes, and the bolt layout scheme is determined accordingly.

[0077] C2. The bolts are respectively arranged from the roadway center line to the roof cutting side and the solid coal side of the roadway. The adjacent bolt spacing is 0.6 - 1 m. The bolts are connected by a steel strip and a pre-tightening force is applied.

[0078] C3. Determine the support parameters of the cable bolts according to the bolt support settings.

[0079] C4. The cable bolts are respectively arranged from the roadway center to the roof cutting side and the solid coal side of the roadway. The adjacent cable bolt spacing is 1.2 - 1.6 m. The cable bolts are arranged perpendicular to the roadway roof. The cable bolts are connected by a steel strip and a pre-tightening force is applied.

[0080] C5. During the secondary reuse period, additional cable bolts are installed on the roof cutting side of the roadway, and the cable bolt spacing is set to 0.8 - 1.2 m.

[0081] Among them, the steel strip connection structure is a mine-used W-shaped steel strip, with a structural width of 220 mm ≤ B0 ≤ 280 mm, a thickness of 2.2 mm ≤ T ≤ 3.0 mm, and a length of L = b(i + 2) + 300 mm. There are round holes on the steel strip for the bolts to pass through. The hole spacing is 600 - 1000 mm, and the diameter of the round hole is 28 mm ≤ k ≤ 34 mm. The pre-tightening force of the bolts is greater than or equal to 120 kN. The inclination angle of the inclined bolts is 10° - 20°, and the inclination angle of the inclined cable bolts is 10° - 20°.

[0082] The tray of the cable bolt is a laminated energy-absorbing base. The laminated energy-absorbing base includes isoprene rubber and steel plates, and the isoprene rubber and the steel plates are bonded by a hot vulcanization process. For the laminated energy-absorbing base, the thickness of the isoprene rubber is 5 mm ≤ T ≤ 8 mm, the thickness of the steel plate is 5 mm ≤ T ≤ 8 mm, the width of the isoprene rubber is 260 mm ≤ B0 ≤ 300 mm, the width of the steel plate is 260 mm ≤ B0 ≤ 300 mm, the number of layers of the isoprene rubber is 3 ≤ i ≤ 6, and the number of layers of the steel plate is 3 ≤ j ≤ 6. The diameter of the cable bolt hole is 28 mm ≤ k ≤ 34 mm.

[0083] The dynamic control method for the roof of gob-side entry retaining mainly aims to solve the problems that the existing support schemes do not consider the spatio-temporal failure characteristics of the roof of gob-side entry retaining, and the existing support methods have poor applicability, low matching degree and unsatisfactory support effect. Based on the zonal characteristics of the abutment pressure manifestation of the roof of gob-side entry retaining and the time-sharing characteristics of the first roadway forming stage and the second reuse stage, the invention proposes a zonal dynamic support scheme, a first roadway forming support scheme and a support scheme for the second reuse. The three complement each other and jointly constitute the "dynamic control method" that changes with the failure state of the roof of gob-side entry retaining. This method can dynamically adapt to the change of the roof failure state and realizes the zonal dynamic support of the roof.

[0084] Embodiment 2

[0085] As shown in the accompanying drawings of the specification, taking a certain mine as an example, a dynamic control method for the roof of gob-side entry retaining is specifically described. The specific steps of using this method to support the roadway include:

[0086] Step A. Divide the abutment pressure manifestation zones of the roof of gob-side entry retaining according to the roof monitoring data, and respectively determine the ranges of the advanced dynamic pressure influence zone, the mining dynamic load action zone and the post-mining roadway stability zone.

[0087] Monitor the roof-to-floor convergence of the roadway. In the range of 0 - a m ahead of the working face advancement position, the range of 0 - b m behind the working face advancement position, and the range of b - c m behind the working face advancement position, arrange 1 monitoring section every 1 m, with a total of i sections arranged, and monitor for 90 days. According to the monitoring data, draw the curves of the roof-to-floor convergence change. According to the magnitude and rate of the roof-to-floor convergence, divide the gob-side entry into the advanced dynamic pressure influence zone, the mining dynamic load action zone and the post-mining roadway stability zone.

[0088] Step B. Determine the roadway support scheme according to the roof conditions of the roadway in the abutment pressure manifestation zones and the roadway section size, including the specification models of the single hydraulic props and the π-shaped beams.

[0089] Determine the dynamic support scheme for the advanced dynamic pressure influence zone. Specifically, according to the roof conditions of the roadway, the roadway section size, the specification models of the single hydraulic props and the π-shaped beams, determine the layout scheme of "single hydraulic prop + π-shaped beam" based on the theoretical calculation formula. The support strength provided by the single hydraulic prop is 400 kN / m 2 . According to the geological conditions of the roadway driving, establish a numerical calculation model, check the roof stress state and roof subsidence under different layout schemes of single hydraulic props and π-shaped beams, and determine the layout scheme accordingly. Starting from the roadway center line and towards the gob-side cutting of the roadway, the single hydraulic props and the π-shaped beams are named D1, D2, D3 ······ D i and towards the solid coal side of the roadway, the single hydraulic props and the π-shaped beams are named D′1, D′2, D′3 ······ D′ i, the adjacent single hydraulic props and π-shaped beams are arranged perpendicular to the roadway alignment with a spacing of 800 - 1200 mm. Here, i is the number of "single hydraulic props + π-shaped beams" on one side of the roadway, and i ≤ 3.

[0090] Determine the dynamic support plan for the mining-induced dynamic load action area. According to the determined layout plan of single hydraulic props and π-shaped beams, starting from the roadway centerline and towards the roof cutting side of the roadway, the single hydraulic props and π-shaped beams are named C1, C2, C3 ······ C i , where C1, C i are arranged perpendicular to the roadway alignment, and between C1 and C i , C is arranged t , C t is arranged parallel to the roadway alignment. C1 is arranged with a spacing of 800 - 1200 mm, C i is arranged with a spacing of 500 - 800 mm close to the roof cutting side, and C t is arranged without spacing and in continuous alignment in a row. Among them, the distance between C1, C t , and C i is 600 - 1000 mm. Towards the solid coal side of the roadway, the single hydraulic props and π-shaped beams are named C1′, C′2, C′3 ······ C′ i , and the adjacent "single hydraulic props + π-shaped beams" are arranged perpendicular to the roadway alignment with a spacing of 800 - 1200 mm. i is the number of "single hydraulic props + π-shaped beams" on one side of the roadway, where i ≤ 3, and t = 1.

[0091] Determine the dynamic support plan for the post-mining roadway stabilization area. According to the determined layout plan of single hydraulic props and π-shaped beams, the support strength provided by the single hydraulic props is 100 kN / m 2 . According to the determined layout plan of the combination of single hydraulic props and π-shaped beams, starting from the roadway centerline and towards the roof cutting side of the roadway, the layout of the single hydraulic props and π-shaped beams is named W1, W2, W3 ······ W i , and the adjacent single hydraulic props and π-shaped beams are arranged perpendicular to the roadway alignment with a spacing of 500 - 800 mm. Towards the solid coal side of the roadway, there is no need to arrange single hydraulic props and π-shaped beams. i is the number of "single hydraulic props + π-shaped beams" on the roof cutting side of the roadway, where i = 1.

[0092] Step C. Determine the permanent support plan during the one-time roadway formation period and the permanent support plan during the secondary reuse period, including the setting of the number of bolts and their pre-tightening force, and the setting of the number of cables and their pre-tightening force.

[0093] The permanent support plan during the one-time roadway formation period means that during the one-time roadway formation period, the first bolt system and the second cable system are arranged alternately along the roadway driving direction until the roadway driving is completed.

[0094] Arrange the first bolt system M1. The bolts are high-strength left-handed non-ribbed threaded steel bolts with a diameter of 20 - 22 mm and a length of 2200 - 2500 mm, and the pre-tightening force ≥ 120 kN. According to the geological conditions of roadway excavation, roadway width and bolt specification models, determine the bolt arrangement plan based on the theoretical calculation formula so that the strength after support is not less than 0.35 MPa. According to the geological conditions of roadway excavation, establish a numerical calculation model to check the roof stress state and roof subsidence under different bolt arrangement plans, and determine the bolt arrangement plan accordingly. According to the determined bolt arrangement plan, starting from the roadway center line and towards the roof cutting side of the roadway, the bolts are sequentially named G1, G2, G3 ··· G i . Towards the solid coal side of the roadway, the bolts are sequentially named G′1, G′2, G′3 ····· G′ i . i is the number of bolts on one side of the roadway, and the spacing between adjacent bolts is 600 - 1000 mm. In the same vertical plane of the roadway roof, use a bolter to drive bolts into the roof. Bolt G i tilts at a certain angle towards the roof cutting side of the roof, and bolt G′ i tilts at a certain angle towards the solid coal side of the roof, and the remaining bolts are arranged perpendicular to the roof. Connect the bolts through a steel strip structure and apply a pre-tightening force to form the first bolt system M1. Among them, the number of bolts i of the first bolt system M1 ≤ 3, and the angles at which bolts G i , G′ i tilt towards the roof cutting side of the roof and the solid coal side of the roof are 10° ≤ α ≤ 20°.

[0095] Arrange the second cable bolt system M2. After forming the first bolt system M1, determine the cable bolt arrangement plan so that the strength after cable bolt support is not less than 0.35 MPa. According to the determined cable bolt arrangement plan, starting from the roadway center, towards the roof cutting side of the roadway, the cable bolts are sequentially named S1, S2, S3 ······ S i . Towards the solid coal side of the roadway, the cable bolts are sequentially named S′1, S′2, S′3 ······ S′ i . i is the number of cable bolts on one side of the roadway. The spacing between adjacent cable bolts is 1200 - 1600 mm. In the same vertical plane of the roadway roof, use a cable bolter to drive cable bolts into the roof, and all cable bolts are arranged perpendicular to the roof. Connect the cable bolts through a steel strip structure and apply a pre-tightening force to form the second cable bolt system M2. The number of cable bolts i of the second cable bolt system M2 ≤ 2, and the angles at which cable bolts S1 and S′1 tilt towards the roof cutting side of the roof and the solid coal side of the roof are 10° ≤ α ≤ 20°. The cable bolts are steel strands with a diameter of 21.6 mm, a length of 7300 - 9300 mm, and a pre-tightening force ≥ 120 kN.

[0096] During the secondary reuse, a third cable bolt system M3 is arranged on the basis of the original support setting. On the side of the roof cutting of the roadway, cable bolts are additionally drilled at a distance of d m from the roof of the cutting side of the roadway, parallel to the roadway alignment direction. Along the direction towards the roadway exit, the cable bolts are successively named BS1, BS2, BS3... BS i . i is the number of additionally drilled cable bolts. The spacing between adjacent cable bolts is 800 - 1200 mm. In the same vertical plane of the roadway roof, a cable bolt drill is used to drill cable bolts into the roof. The cable bolts BS1, BS2, BS3... BS i are arranged at a certain angle towards the upper roof on the cutting side. The cable bolts are connected through a steel strip structure and a pre-tightening force is applied. The steel strip structures are arranged in alignment in columns. The third cable bolt system M3 is formed. The number of cable bolts i of the third cable bolt system M3 = 1, and the cable bolt BS i is inclined at an angle of 10° ≤ α ≤ 20° towards the roof on the cutting side. The cable bolts of the third cable bolt system M3 are made of steel strands with a diameter of 21.6 mm, with a length of 9300 - 12300 mm, and the pre-tightening force ≥ 120 kN.

[0097] Certainly, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the essence of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for controlling the roof state of roof cutting and gob-side entry retaining, characterized in that the steps Including: A. Divide the strata behavior zones of the roof of the gob-side entry retaining by the roof monitoring data, and respectively determine the scopes of the advanced dynamic pressure influence zone, the mining and excavation dynamic load action zone, and the post-mining roadway stability zone; B. Determine the roadway support scheme according to the roadway roof conditions and roadway section dimensions in the strata behavior zones, including the specifications and models of single hydraulic props and π-shaped beams; C. Determine the permanent support scheme during the first-pass roadway formation and the permanent support scheme during the secondary reuse, including the setting of the number of bolts and their pre-tightening forces, and the setting of the number of cable bolts and their pre-tightening forces; The step A includes: A1. Monitor the convergence of the roadway roof and floor; A2. Draw the curve of the roof and floor convergence change, and divide the advanced dynamic pressure influence zone, the mining and excavation dynamic load action zone, and the post-mining roadway stability zone according to the magnitude and rate of the roof and floor convergence; The monitoring of the roadway roof and floor convergence is specifically carried out at the positions ahead of and behind the working face advancement. Set the monitoring intervals and arrange multiple monitoring sections respectively; The step B includes: B1. In the advanced dynamic pressure influence zone, determine the support strength of the single hydraulic prop, adopt the support method of combining single hydraulic props and π-shaped beams, arrange single hydraulic props and π-shaped beams respectively from the roadway center line to the gob-side of the roadway and from the roadway center line to the solid coal side of the roadway, and set the spacing to be 0.8 - 1.2 m; B2. In the mining and excavation dynamic load action zone, determine the support strength of the single hydraulic prop, adopt the support method of combining single hydraulic props and π-shaped beams, and arrange them perpendicular to and parallel to the roadway alignment in the roadway; among them, the spacing on the side close to the gob-side is set to be 0.5 - 0.8 m; the spacing on the roadway center line and the side close to the solid coal side is set to be 0.8 - 1.2 m, and the spacing in the direction perpendicular to the roadway alignment is 0.6 - 1 m; the single hydraulic props and π-shaped beams combined in the direction parallel to the roadway alignment are arranged in a continuous and aligned manner without intervals; B3. In the post-mining roadway stability zone, determine the support strength of the single hydraulic prop, adopt the support method of combining single hydraulic props and π-shaped beams, and arrange single hydraulic props and π-shaped beams from the roadway center line to the gob-side of the roadway, and the spacing in the direction perpendicular to the roadway alignment is 0.5 - 0.8 m; The step C includes: C1. During the first-pass roadway formation, determine the support parameters of the bolts according to the roadway geological conditions, roadway width and bolt models; C2. The bolts are respectively set from the roadway center line to the gob-side and the solid coal side of the roadway, the adjacent bolt spacing is 0.6 - 1 m, and the bolts are connected by steel straps and pre-tightening forces are applied; C3. Determine the support parameters of the cable bolts according to the bolt support settings; C4. The cable bolts are respectively set from the roadway center to the gob-side and the solid coal side of the roadway, the adjacent cable bolt spacing is 1.2 - 1.6 m, the cable bolts are arranged perpendicular to the roadway roof, and the cable bolts are connected by steel straps and pre-tightening forces are applied; C5. During the secondary reuse, additional cable bolts are driven on the gob-side of the roadway, and the cable bolt spacing is set to be 0.8 - 1.2 m.

2. The method for controlling the roof of a cut-top roadway following the state according to claim 1, characterized in that The monitoring interval is less than or equal to 20 m, the range ahead of the working face is less than or equal to 100 m, the range behind the working face is less than or equal to 600 m, and the monitoring period is less than 90 days.

3. A method for the dynamic control of the roof of the roadway with roof cutting and gob-side entry retaining according to claim 1, characterized in that, The roof and floor convergence in the advanced dynamic pressure influence area is greater than 200 mm, the roof and floor convergence in the mining dynamic load action area is 50 - 200 mm, and the roof and floor convergence in the roadway formation stable area after mining is less than 50 mm.

4. A method for the dynamic control of the roof of the roadway left by roof cutting according to claim 1, characterized in that, The supporting strength of the single hydraulic prop in the advanced dynamic pressure influence area is greater than or equal to 400 kN / m 2 , and the supporting strength of the single hydraulic prop in the mining and excavation dynamic load action area is greater than or equal to 600 kN / m 2 ; the supporting strength of the single hydraulic prop in the roadway stability area after mining is greater than or equal to 100 kN / m 2 .

5. The method for the dynamic control of the roof of the roadway retained by roof cutting according to claim 1, characterized in that, The pre-tightening force of the bolt is greater than or equal to 120 kN, the inclination angle of the inclined bolt is 10° - 20°, and the inclination angle of the inclined cable bolt is 10° - 20°.

6. A method for the dynamic control of the roof of the roadway left by roof cutting according to claim 5, characterized in that, The tray of the cable bolt is a laminated energy-absorbing base, and the laminated energy-absorbing base includes isoprene rubber and steel plates, and the isoprene rubber and the steel plates are bonded by a heat vulcanization process.

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