Early warning method for stability of double-inclined large-dip-angle fully mechanized caving face support

Abstract

The invention belongs to the technical field of coal mining equipment, and relates to a stability early warning method for a double-inclined large-dip-angle fully mechanized caving face support. Comprising the following steps: S1, establishing a support tendency instability model during normal stoping and weighting of a working face and in a roof caving area; s2, establishing a support trend instability model during normal stoping and weighting of the working face and in a roof caving area; s3, establishing a support tail torsion tendency instability model; s4, analyzing the critical working resistance under the critical condition of tendency slippage instability during normal recovery and weighting of the support and under the roof caving area condition; s5, analyzing the critical working resistance under the critical condition of trend slippage instability during normal recovery and weighting of the support and under the roof caving area condition; s6, analyzing the critical working resistance under the critical condition of inclination toppling instability during normal recovery and weighting of the support and under the roof caving area condition; s7, analyzing the critical working resistance under the critical condition of trend dumping instability during normal recovery and weighting of the support and under the roof caving area condition; and S8, analyzing the critical working resistance of the bracket under the torsion instability critical condition.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mining equipment and relates to a stability early warning method for a double-slope, large-angle fully mechanized caving working face support. Background Art

[0002] In the process of top coal caving in double-slope and high-angle fully mechanized caving working face, hydraulic support is a commonly used support equipment. It mainly relies on the hydraulic system to provide support force, controls the expansion and contraction of the support through the pressure change of hydraulic oil, adjusts the support force, and realizes the process of supporting the roof, isolating the roof goaf and mining the working face.

[0003] Since the initial pressure and periodic pressure of the high-angle working face are more complicated, the pressure on the hydraulic support is asymmetric. Therefore, the main reason affecting the instability of the support is the relationship between the critical working resistance and the inclination angle and the strike angle. There are three common instability modes of the support in the double-inclined high-angle comprehensive caving face: sliding instability, tipping instability and torsional instability. Among them, it is mainly caused by the friction force generated by the top and bottom plates on the top beam and base of the support being less than the gravity of the support itself. Most of them occur in the area with large water inflow on the working face, causing the top and bottom plates to be slippery. The tipping instability of the support is mainly due to the existence of the inclination component of the support along the working face, which makes the point of action of the combined force of the support deviate from the center of the support, resulting in the danger of the support tipping. In addition to the instability modes of sliding and tipping, the support of the high-angle comprehensive caving face sometimes suffers from tail torsional instability when working. The coal discharge port of the top coal caving support is located at the lower part of the tail beam of the support. During the coal discharge process, the support will be unevenly stressed, and the working resistance of the rear column of the support is less than that of the front column. This phenomenon is particularly serious in the fully-mechanized caving face with a large inclination angle. Due to the inclination angle of the working face, the coal flow along the inclination direction of the working face will exert lateral force on the tail beam during the coal caving process in the fully-mechanized caving face with a large inclination angle, which can easily cause lateral twisting of the support.

[0004] The instability and collapse of supports in fully mechanized caving working faces are extremely harmful, which not only threatens the lives of miners, but also may lead to the collapse of mine support systems, equipment damage, and reduced production efficiency. In view of the above problems, a support stability early warning method for fully mechanized caving working faces with double slopes and large dip angles is proposed, in order to timely detect the critical state of support collapse in fully mechanized caving faces with large dip angles and take timely anti-collapse measures. Summary of the invention

[0005] The present invention is an early warning system that needs to determine a suitable critical working resistance of a support so that the support can remain stable when the asymmetric stress on the support changes due to the continuous changes in the strike and dip angle of a double-inclined and large-angle coal seam fully mechanized caving working face.

[0006] The present invention adopts the following technical scheme: a double-slope large-angle fully-mechanized caving working face support stability early warning method, comprising: S1: Establish the support instability model for normal mining, pressure period and roof fall area of ​​the working face, where the instability is divided into sliding instability and tipping instability; S2: Establish instability models of support strike during normal mining, pressure period and roof fall area of ​​the working face, where instability is divided into sliding instability and tipping instability; S3: Establish the instability model of the stent tail torsional tendency; S4: Analyze the critical working resistance of the support under the critical conditions of instability due to inclination sliding in normal mining, pressure period and roof fall area; S5: Analyze the critical working resistance of the support under critical conditions of strike slip instability in normal mining, pressure period and roof fall area; S6: Analyze the critical working resistance of the support under the critical conditions of instability and tendency to collapse in normal mining, pressure period and roof fall area; S7: Analyze the critical working resistance of the support under the critical conditions of collapse and instability in normal mining, pressure period and roof fall area; S8: Analyze the critical working resistance of the bracket under critical conditions of torsional instability.

[0007] In some embodiments, in S4, when the inclination angle α is constant, the critical working resistance T of the bracket to maintain stability without slipping is 1 As the strike angle β increases, the critical working resistance T 1 It also gradually increases. Compared with the upward mining, it can be found that the critical working resistance T 1 It is larger than that in the overhead mining state, indicating that the support is more likely to slip along the inclination in the downward mining state. This is mainly due to the fact that the torsional force generated during the coal placement at the rear of the support in the fully mechanized caving face in the downward mining state is larger, which is more likely to cause the support to slip along the inclination. As the strike angle β increases, the critical working resistance T 1 It also gradually increases; as the inclination angle α increases, the critical working resistance of the support gradually increases, and the influence of the strike angle on the critical working resistance gradually decreases. By comparing the critical working resistance during normal mining and during pressure, it can be found that the critical working resistance of the support during pressure increases significantly, which is about 10 times that of the normal mining period; The strike angle β is an important factor affecting the stability of the support. As the strike angle β increases, the critical slip angle α gradually decreases, and slip becomes more likely to occur.

[0008] In some embodiments, in S5, as the inclination angle α and the strike angle β increase, the critical working resistance T required for the support to not collapse during the face mining is 1 Gradually increases, compared with the upward mining working face, it can be found that the critical working resistance T 1It is larger than that in the overturned mining state, which means that the support is more likely to fall down along the inclination in the overturned mining state. By comparing the critical working resistance required for sliding instability and overturning instability in the overturned mining state, it is found that the critical working resistance required for sliding instability is larger than that for overturning instability. Therefore, the support is more likely to fall down along the inclination. As the inclination angle α and the strike angle β increase, the critical working resistance T 1 Gradually increases. In summary, the critical working resistance of the support during the pressure period is much greater than that during the normal mining period, but the critical working resistance of sliding is still greater than the working resistance of dumping, indicating that the support is mainly unstable due to sliding along the inclination, and the critical working resistance in the downward mining state is greater than that in the upward mining state, indicating that sliding is more likely to occur in the downward mining state; The critical tipping angle of the bracket along the inclination is inversely proportional to the height h of the bracket, inversely proportional to the strike angle β, and directly proportional to the width b of the bracket. Therefore, the stability of the bracket can be increased by reducing the height of the bracket and increasing the width of the bracket. The relationship between the critical tipping angle of the bracket along the inclination and the strike angle is that as the strike angle β increases, the critical tipping angle of the bracket inclination becomes smaller and smaller, and the bracket is less likely to tip over and become unstable. When the inclination angle of the bracket is in the shaded area in the figure, the bracket will not tip over and become unstable.

[0009] In some embodiments, in S6, when the inclination angle is constant, the critical working resistance required for the support to not slip and become unstable when the working face is mining downward gradually increases with the increase of the inclination angle; when the inclination angle is 10°, the critical working resistance required for the support to not slip and become unstable when the working face is mining downward gradually increases with the increase of the inclination angle; when the inclination angle is 20°, the critical working resistance required for the support to not slip and become unstable when the working face is mining downward does not change much with the increase of the inclination angle, and basically remains at 970kN; when the inclination angle is 30°, the critical working resistance required for the support to not slip and become unstable when the working face is mining downward gradually decreases with the increase of the inclination angle; With the increase of the inclination angle α, the critical working resistance of the support gradually increases; with the increase of the strike angle β, the critical working resistance of the support also gradually increases, but when the inclination angle α gradually increases, the influence of the strike angle on the critical working resistance of the support gradually weakens; As the inclination angle increases, the critical slip angle β of the support along the strike in the free state gradually decreases. When α<12°, if the strike angle is in the shaded area in the figure, the support will not slip; if it is outside the shaded area, the support may slip. When α≥12°, the critical slip angle is 0, indicating that the support will definitely slip at this time.

[0010] In some embodiments, in S7, as the inclination angle and the strike angle increase, the critical working resistance required for the support to remain untied in the working face overturned mining state becomes larger and larger; when the strike angle β=10°, the coal seam inclination is less than 41°, the support will not tip over; when the strike angle β=20°, the coal seam inclination is less than 34°, the support will not tip over; when the strike angle β=30°, the coal seam inclination is less than 23°, the support will not tip over; With the increase of the inclination angle α, the critical working resistance of the support gradually increases; with the increase of the strike angle β, the critical working resistance of the support also gradually increases, but when the inclination angle α gradually increases, the influence of the strike angle on the critical working resistance of the support gradually weakens; As the inclination angle increases, the critical tipping angle of the support in the downward mining state of the working face gradually decreases; when the support strike angle is in the shaded area in the figure, the support will not tip over; when the support strike angle is outside the shaded area, there is a risk of tipping over.

[0011] In some embodiments, in S8, when the strike angle is constant, the critical working resistance gradually increases with the increase of the inclination angle of the bracket; when the inclination angle is less than 30°, the critical working resistance of the bracket also gradually increases with the increase of the inclination angle; but when the inclination angle is greater than 30°, there is no obvious regularity in the relationship between the working resistance of the bracket and the inclination angle.

[0012] Compared with the prior art, the present invention analyzes the critical conditions of slippage, tipping and torsional instability of the double-inclined and large-angle working face supports in three situations: normal mining, pressure period and roof fall area. It can derive the critical working resistance of different supports according to the changes in the inclination angles of different working faces, thereby providing early warning of the support stability, adjusting the support force of the support in time through the hydraulic device, maintaining normal working state, and ensuring the safety of the working face and normal advancement progress. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a support inclination slip instability model of the double-slope large-angle fully-mechanized caving face support in three situations: normal mining, pressure period and roof fall area; Figure 2 It is a model of the tilting and instability of the support of the double-slope large-angle fully-mechanized caving face support in three situations: normal mining, pressure period and roof fall area; Figure 3 It is a support strike slip instability model of the double-slope large-angle fully-mechanized caving face support in three situations: normal mining, pressure period and roof fall area; Figure 4 It is a model of the tilting and instability of the support of the double-slope large-angle fully-mechanized caving face support in three situations: normal mining, pressure period and roof fall area; Figure 5 It is the torsional instability model of the double-slope large-angle fully mechanized caving face support of the present invention; Figure 6 The critical conditions for the instability of the support of the double-slope large-angle fully-mechanized caving face support in three situations: normal mining, pressure period and roof fall area; Figure 7 The critical conditions for the tilting and instability of the support of the double-slope large-angle fully-mechanized caving face support of the present invention in three situations: normal mining, pressure period and roof fall area; Figure 8 The critical conditions for the sliding instability of the support strike of the double-slope large-angle fully mechanized caving face support of the present invention in three situations: normal mining, pressure period and roof fall area; Fig. 9 The double-slope large-angle fully-mechanized caving face support of the present invention is subjected to the critical conditions of collapse and instability of the support under three conditions: normal mining, pressure coming period and roof fall area; Fig.10 This is the critical condition for torsional instability of the double-inclined and large-angle fully mechanized caving face support of the present invention. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0015] The above-mentioned purpose of the present invention is achieved through the following technical solutions.

[0016] The invention provides a method for early warning of the stability of a support in a double-slope, high-angle fully-mechanized caving working face, which is based on the analysis of the critical working resistance of a hydraulic support working on a fully-mechanized caving working face with both a strike inclination angle and a tendency inclination angle. Compared with a horizontal or gently inclined working face, the hydraulic support is in a balanced state under the action of gravity, the support force of the bottom plate and the friction force of the bottom plate on the support, and the center of gravity and the center of the support base are in a vertical line, which is not easy to become unstable and fall; while the double-slope, high-angle working face has both a strike inclination angle and a strike inclination angle, and the center of gravity of the hydraulic support will deviate from the edge of the base due to the inclination, and the support is prone to be in an unstable state.

[0017] Depend on Figures 1 to 4The mechanical models of the support inclination sliding and falling, strike sliding and falling in the double-slope large-angle fully mechanized caving face support under three conditions, namely, normal mining, pressure period and roof fall area, are established respectively. During normal mining, the support is mainly subjected to roof pressure and the deadweight of falling coal gangue; during pressure period, when the basic roof breaks or during the fault period, the lateral thrust on the support along the inclination and strike increases, and the roof pressure on the support mainly comes from the deadweight generated by the top coal, direct roof and basic roof breaking; during the mining process of the working face, the roof in some areas is relatively broken and prone to roof fall. At this time, the support is equivalent to a free state and is only affected by its own gravity.

[0018] Depend on Figure 5 When the fully mechanized caving face supports caving top coal, the working resistance of the rear column of the supports will be less than that of the front column during the caving process, and the front and rear forces of the supports are uneven. The inclination and strike angle of the coal seam in the large-angle working face aggravate this uneven force. When the coal flow moves to the caving port of the support, it will generate lateral force on the tail beam of the support. If the torsion resistance of the support is not enough, the tail beam will swing sideways, thereby driving the support to twist.

[0019] Depend on Figure 6 (a) When the inclination angle α is constant, the critical working resistance T of the support to maintain stability without slipping 1 As the strike angle β increases, the critical working resistance T 1 Compared with overhead mining, it can be found that the critical working resistance T 1 It is larger than that in the overhead mining state, indicating that the support is more likely to slip along the inclination in the downward mining state. This is mainly because the torsional force generated during the coal release at the rear of the support in the comprehensive caving face in the downward mining state is larger, which is more likely to cause the support to slip along the inclination.

[0020] Depend on Figure 6 (b) As the strike angle β increases, the critical working resistance T of the support 1 The critical working resistance of the support also gradually increases with the increase of the inclination angle α, and the influence of the strike angle on the critical working resistance gradually decreases. Comparing the critical working resistance during normal mining and during pressure, it can be found that the critical working resistance of the support during pressure increases significantly, which is about 10 times that of the normal mining period.

[0021] Depend on Figure 6 (c) The strike angle β is an important factor affecting the stability of the support. As the strike angle β increases, the critical slip angle α gradually decreases, and slip becomes more likely to occur.

[0022] Depend on Figure 7 (a) As the inclination angle α and the strike angle β increase, the critical working resistance T required for the support to not collapse during face mining 1Compared with the upward mining face, it can be found that the critical working resistance T 1 It is larger than that in the upward mining state, which means that the support is more likely to fall along the inclination in the downward mining state. Comparing the critical working resistance required for sliding instability and toppling instability in the downward mining state, it is found that the critical working resistance required for sliding instability is larger than that for toppling instability. Therefore, the support is more likely to slide along the inclination.

[0023] Depend on Figure 7 (b) As the inclination angle α and the strike angle β increase, the critical working resistance T 1 In summary, the critical working resistance of the support during the pressure period is much greater than that during the normal mining period, but the critical working resistance of sliding is still greater than the working resistance of tipping, indicating that the support is mainly unstable due to sliding along the inclination, and the critical working resistance in the downward mining state is greater than that in the upward mining state, indicating that sliding is more likely to occur in the downward mining state.

[0024] Depend on Figure 7 (c), the critical tipping angle of the bracket along the inclination is inversely proportional to the height h of the bracket, inversely proportional to the strike angle β, and proportional to the width b of the bracket. Therefore, the stability of the bracket can be increased by reducing the height of the bracket and increasing the width of the bracket. The relationship between the critical tipping angle of the bracket along the inclination and the strike angle. As the strike angle β increases, the critical tipping angle of the bracket inclination becomes smaller and smaller, and the bracket is less likely to tip over and become unstable. When the inclination angle of the bracket is in the shaded area in the figure, the bracket will not tip over and become unstable.

[0025] Depend on Figure 8 (a), when the inclination angle is constant, the critical working resistance required for the support to not slip and become unstable when the working face is mining downwards gradually increases with the increase of the inclination angle; when the inclination angle is 10°, the critical working resistance required for the support to not slip and become unstable when the working face is mining downwards gradually increases with the increase of the inclination angle; when the inclination angle is 20°, the critical working resistance required for the support to not slip and become unstable when the working face is mining downwards does not change much with the increase of the inclination angle, and basically remains at 970kN; when the inclination angle is 30°, the critical working resistance required for the support to not slip and become unstable when the working face is mining downwards gradually decreases with the increase of the inclination angle.

[0026] Depend on Figure 8 (b) As the inclination angle α increases, the critical working resistance of the support gradually increases; as the strike angle β increases, the critical working resistance of the support also gradually increases, but when the inclination angle α gradually increases, the influence of the strike angle on the critical working resistance of the support gradually weakens.

[0027] Depend on Figure 8(c) As the inclination angle increases, the critical slip angle β of the support along the strike in the free state gradually decreases. When α<12°, if the strike angle is in the shaded area in the figure, the support will not slip; if it is outside the shaded area, the support may slip. When α≥12°, the critical slip angle is 0, indicating that the support will definitely slip at this time.

[0028] Depend on Fig. 9 (a), with the increase of inclination angle and strike angle, the critical working resistance required for the support to remain without tipping over in the working face overturning state becomes larger and larger; when the strike angle β=10°, the coal seam inclination is less than 41°, the support will not tip over; when the strike angle β=20°, the coal seam inclination is less than 34°, the support will not tip over; when the strike angle β=30°, the coal seam inclination is less than 23°, the support will not tip over.

[0029] Depend on Fig. 9 (b) As the inclination angle α increases, the critical working resistance of the support gradually increases; as the strike angle β increases, the critical working resistance of the support also gradually increases, but when the inclination angle α gradually increases, the influence of the strike angle on the critical working resistance of the support gradually weakens.

[0030] Depend on Fig. 9 (c) As the inclination angle increases, the critical tilting angle of the support in the downward mining state of the working face gradually decreases; when the support strike angle is in the shaded area in the figure, the support will not tilt; when the support strike angle is outside the shaded area, there is a risk of tilting.

[0031] Depend on Fig.10 When the strike angle is constant, the critical working resistance gradually increases with the increase of the inclination angle of the support; when the inclination angle is less than 30°, the critical working resistance of the support also gradually increases with the increase of the inclination angle; but when the inclination angle is greater than 30°, there is no obvious regularity in the relationship between the support working resistance and the inclination angle.

[0032] In summary, when the angle of the double-inclined large-angle working face changes, the early warning system based on the relationship between the above inclination change and the working resistance of the support can judge in advance what kind of unstable state the support is prone to, take protective measures in advance, and ensure normal and safe production of the working face.

Claims

1. A method for early warning of support stability in a double-slope, high-angle fully mechanized caving working face, characterized in that: include: S1: Establish the support instability model for normal mining, pressure period and roof fall area of ​​the working face, where the instability is divided into sliding instability and tipping instability; S2: Establish instability models of support strike during normal mining, pressure period and roof fall area of ​​the working face, where instability is divided into sliding instability and tipping instability; S3: Establish the instability model of the stent tail torsional tendency; S4: Analyze the critical working resistance of the support under the critical conditions of instability due to inclination sliding in normal mining, pressure period and roof fall area; S5: Analyze the critical working resistance of the support under critical conditions of strike slip instability in normal mining, pressure period and roof fall area; S6: Analyze the critical working resistance of the support under the critical conditions of instability and tendency to collapse in normal mining, pressure period and roof fall area; S7: Analyze the critical working resistance of the support under the critical conditions of collapse and instability in normal mining, pressure period and roof fall area; S8: Analyze the critical working resistance of the bracket under critical conditions of torsional instability.

2. The method for early warning of support stability in a double-slope, high-angle fully mechanized caving working face according to claim 1 is characterized in that: In S4, when the inclination angle α is constant, the critical working resistance T1 of the support to maintain stability without slipping increases with the increase of the strike angle β; but with the increase of the inclination angle α, the critical working resistance T1 also gradually increases. Compared with the overhead mining, it can be found that the critical working resistance T1 in the downward mining state is larger than that in the overhead mining state, indicating that the support is more likely to slip along the inclination in the downward mining state. This is mainly due to the large torsional force generated during the coal placement at the rear of the fully mechanized caving face support in the downward mining state, which is more likely to cause the support to slip along the inclination; As the strike angle β increases, the critical working resistance T1 of the support also gradually increases; as the inclination angle α increases, the critical working resistance of the support gradually increases, and the influence of the strike angle on the critical working resistance gradually decreases. By comparing the critical working resistance during normal mining and during pressure, it can be found that the critical working resistance of the support during pressure increases significantly, which is about 10 times that of the normal mining period. The strike angle β is an important factor affecting the stability of the support. As the strike angle β increases, the critical slip angle α gradually decreases, and slip becomes more likely to occur.

3. The method for early warning of support stability in a double-slope, high-angle fully mechanized caving working face according to claim 1 is characterized in that: In S5, as the inclination angle α and the strike angle β increase, the critical working resistance T1 required for the support to not tip over when the working face is mining downward gradually increases. Compared with the working face mining upward, it can be found that the critical working resistance T1 of the working face in the mining downward state is larger than that in the mining upward state, indicating that the support is more likely to tip over along the inclination in the mining downward state. By comparing the critical working resistance required for sliding instability and tipping instability in the mining downward state, it is found that the critical working resistance required for sliding instability is larger than that for tipping instability. Therefore, the support is more likely to slide along the instability; As the inclination angle α and the strike angle β increase, the critical working resistance T1 gradually increases. In summary, the critical working resistance of the support during the pressure period is much greater than that during the normal mining period, but the critical working resistance of sliding is still greater than the working resistance of dumping, indicating that the support is mainly unstable due to sliding along the inclination, and the critical working resistance in the downward mining state is greater than that in the upward mining state, indicating that sliding is more likely to occur in the downward mining state; The critical tipping angle of the bracket along the inclination is inversely proportional to the height h of the bracket, inversely proportional to the strike angle β, and directly proportional to the width b of the bracket. Therefore, the stability of the bracket can be increased by reducing the height of the bracket and increasing the width of the bracket. The relationship between the critical tipping angle of the bracket along the inclination and the strike angle is that as the strike angle β increases, the critical tipping angle of the bracket inclination becomes smaller and smaller, and the bracket is less likely to tip over and become unstable. When the inclination angle of the bracket is in the shaded area in the figure, the bracket will not tip over and become unstable.

4. The method for early warning of support stability in a double-slope, high-angle fully mechanized caving working face according to claim 1 is characterized in that: In S6, when the inclination angle is constant, the critical working resistance required for the support to not slip and become unstable when the working face is mining downward gradually increases with the increase of the inclination angle; when the inclination angle is 10°, the critical working resistance required for the support to not slip and become unstable when the working face is mining downward gradually increases with the increase of the inclination angle; when the inclination angle is 20°, the critical working resistance required for the support to not slip and become unstable when the working face is mining downward does not change much with the increase of the inclination angle, and basically remains at 970kN; when the inclination angle is 30°, the critical working resistance required for the support to not slip and become unstable when the working face is mining downward gradually decreases with the increase of the inclination angle; With the increase of the inclination angle α, the critical working resistance of the support gradually increases; with the increase of the strike angle β, the critical working resistance of the support also gradually increases, but when the inclination angle α gradually increases, the influence of the strike angle on the critical working resistance of the support gradually weakens; As the inclination angle increases, the critical slip angle β of the support along the strike in the free state gradually decreases. When α<12°, if the strike angle is in the shaded area in the figure, the support will not slip; if it is outside the shaded area, the support may slip. When α≥12°, the critical slip angle is 0, indicating that the support will definitely slip at this time.

5. The method for early warning of support stability in a double-slope, high-angle fully mechanized caving working face according to claim 1 is characterized in that: In S7, as the inclination angle and the strike angle increase, the critical working resistance required for the support to remain non-toppled in the working face overturned mining state becomes larger and larger; when the strike angle β=10°, the coal seam inclination is less than 41°, the support will not topple; when the strike angle β=20°, the coal seam inclination is less than 34°, the support will not topple; when the strike angle β=30°, the coal seam inclination is less than 23°, the support will not topple; With the increase of the inclination angle α, the critical working resistance of the support gradually increases; with the increase of the strike angle β, the critical working resistance of the support also gradually increases, but when the inclination angle α gradually increases, the influence of the strike angle on the critical working resistance of the support gradually weakens; As the inclination angle increases, the critical tipping angle of the support in the downward mining state of the working face gradually decreases; when the support strike angle is in the shaded area in the figure, the support will not tip over; when the support strike angle is outside the shaded area, there is a risk of tipping over.

6. The method for early warning of support stability in a double-slope, high-angle fully mechanized caving working face according to claim 1 is characterized in that: In S8, when the strike angle is constant, the critical working resistance gradually increases with the increase of the inclination angle of the bracket; when the inclination angle is less than 30°, the critical working resistance of the bracket also gradually increases with the increase of the inclination angle; but when the inclination angle is greater than 30°, there is no obvious regularity in the relationship between the bracket working resistance and the inclination angle.

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