The Interaction Mechanism Of "Support-surrounding Rock" In Steeply Dipping Coal Seam With Large Mining Height

Due to the inclination of the large mining height in the steeply dipping seam,the roof caving filling process and the collapse backward sliding filling will have different effects on the working face "support-surrounding rock“,so it is easy to cause the support to fall and slip,which can affect the working safety conditions.Therefore,the paper studies the interaction mechanism of "support-surrounding rock" under the condition of large mining height caving roof and rolling filling in steeply dipping seam.Clarifying the interaction of”support-surrounding rock“in different areas of working face,revealing the instability mechanism of "support-surrounding rock" system along the face of the working surface and inclination direction,and strengthening the fully mechanized mining face with large dip angle in coal seam.The stability of the system of support-surrounding rock,and the design of the sub-regional control scheme of the "support-surrounding rock" system,the development and perfection of the long wall mining theory of large inclined seam has certain significance.In this paper,the method of field measurement,physical similarity material simulation,numerical simulation,theoretical analysis and so on,is applied to the law of roof movement of longwall longwall mining in the steeply dipping seam.And the relationship between the support and roof under the roof caving,the influence of the roof caving on the force of the support and the movement state of each area of the face under the condition of the direct roof caving and gangue filling,the stress and strain characteristics of surrounding rock are studied preliminarily,the main conclusions are as follows:During the fracture stage of roof strata the roof tensile stress effect is obvious in the upper and middle part of the working face in the steeply dipping coal seam,and the subsidence of the basic roof strata reaches the maximum value,and the fracture of the mined-out area first occurs in the upper part of the working face.The load of the support will suddenly increase when the roof strata collapse in the steeply dipping coal seam face.As the front caving angle of the roof strata is changed periodically,at the same time,the cantilever length of the cantilever beam on the top of the support will change periodically,and the maximum length of the cantilever beam will decrease with the roof caving height increasing,and the length of the roof cantilever beam will reach the maximum after the maximum of the top caving angle.With the rise of roof caving height,the probability of the roof cutting is increased.Under the condition of the different enrichment rate of the roof of the steeply dipping coal seam,with the increase of the enrichment rate,the stress value of the roof of GOB is increasing,the stress value of the roof is decreased in the support area,and the support pressure decreases with the support area of the coal wall in front of the support.Under the condition of different enrichment rate,the pressure of support column,shield beam and top beam increases with the development of working face.Under the condition of large dip seam roof caving and gangue filling,the working resistance of the support is low in the rolling and filling area,but the working resistance of the support varies greatly and the stability of the stent is lower in the filling area and the non filling area,and the working resistance is significantly higher than the lower filling area in the backfill area.In the upper part of the working surface,the working resistance reaches the maximum of the working resistance of the work face support,the area support is very unstable.Based on the analysis of the relationship between the support and surrounding rock in different areas of the working face,the stability conditions of the support under the roof integrity and the roof breaking condition as well as the support working resistance of the roof in different areas of the working face are obtained,and the reasons for the higher working resistance change are summarized.