Structural Evolution And Rock Pressure Activity Regularity Of Weakly Cemented Strata Of The Large Mining Height Work Face In Western China

With the rapid developing of China's Western development,recently,a large number of western coal mine which focus on the resource of weakly cemented strata will be completed and put into operation in succession.Due to the natural endowment conditions of weakly cemented strata,its physical and mechanical properties are obvious different from rock of Middle East.The rock pressure activity regularity of large mining height work face in weakly cemented strata is also different from the properties in Middle East according to the mining experiences.Because the properties of weakly cemented strata and rock pressure activity regularity of work face were not known clearly,the accidents often happen,such as large area roof caving,sidestepped subsidence,water inrush and sand inrush,supports damage and so on.The problems of structural evolution regularity and the distribution of three zones in coal mine and support choice and so on must be solved.The engineering background of this thesis is the large mining height work face of weakly cemented strata in Hongqinghe coal mine.According to the laboratory experiment,numerical simulation,similar material simulation,theoretical analysis,in-situ test and other methods,the different physical mechanical properties between weakly cemented strata and rock in middle east were studied,the geographic distribution of weakly cemented strata were statistics,the deformation regularity of goaf rock of broken and caving and filling and disintegration and compaction and consolidation were analyzed,the strata structure evolution model of large mining height work face of weakly cemented strata was builded,the distribution characteristics of caving zone and the evolution regularity of fracture zone in large mining height work face of weakly cemented strata were revealed,the mechanism between surrounding rock and supports were studied,the calculation method of working resistance of supports in large mining height work face of weakly cemented strata was obtained.The following research results were obtained.(1)The weakly cemented rocks have the characteristics of low strength,poor cementation,and mudding,easy disintegration and so on.The weakly cemented strata distributes in the Xinjiang,Shendong,Mengdong,Ning Dong and Sanxi,based on the mechanical parameters,physical parameters,rock-forming age and other reasons,the variability of the weakly cemented strata was evaluated.(2)Aiming at the different property of broken expand and disintegration between weakly cemented rock and rock in Middle East.According to the the broken rock compression experiment and rock disintegration experiment,the property of initial broken expand and the residual broken expand and the characteristics of resistant disintegration were studied,the characteristics of strong broken expand and easy disintegration were revealed.(3)According to the different physical mechanical properties between weakly cemented rock in western and the rock of Middle East,based on the experiment and theoretical analysis,the characteristics of deformation and broken and caving and disintegration and compaction and consolidation were analyzed under the mining disturbance.The rock deformation regularity of broken and caving and filling and disintegration and broken again and compaction and consolidation was studied.The deformation evolution mechanism of weakly cemented strata filling body was revealed for the weakly cemented rock.(4)Based on the engineering background of 3-1 work face in Hongqinghe coal mine,according to the similar material simulation and numerical simulation and theoretical analysis.The regularity of strata movement and stress distribution of weakly cemented strata of the large mining height work face were studied,the characteristics of layer upon layer caving from bottom to top about overlying strata was obtained,the failure mechanism of overlying strata during crack initiation and development and cutting through was revealed.(5)Based on the mechanics of weakly cemented strata and the deformation mechanics of filling body,through the similar material simulation and theoretical analysis,the deformation of overlying strata and regularity of movement in large mining height work face of weakly cemented strata was analyzed,the evolution model of strata fracture of large mining height work face of weakly cemented strata was builded,the distribution characteristics of caving zones of three types roof structures were studied in large mining height work face.The distribution regularity of caving zone of large mining height work face of weakly cemented strata was obtained,the coordination evolution mechanism of caving zone and fracture zone is revealed.(6)Based on the foundation of distribution characteristics and evolution regularity of three zones in large mining height work face of weakly cemented strata.The regularity of rock pressure activity was studied in large mining height work face of weakly cemented strata,the mechanism of action between supports and surrounding rock were analyzed.The calculation method of working resistance of supports was obtained in large mining height work face of weakly cemented strata,the rationality and practicability of the method was verified by the field test data.This paper preliminarily explored the physical mechanics property of weakly cemented strata and the evolution regularity of overlying strata structure and the distribution regularity of three zones in large mining height work face.However,because of the influence of complex geological conditions in western,it is necessary to study on the physical mechanics of weakly cemented strata further and a large number of rock pressure monitoring data,the rock pressure activity regularity of large mining height work face of weakly cemented strata in western would be revealed further.