Overlying Strata Movement Law And Control Of Underground Mining In End Slope

A large amount of coal in end slope is left during open pit mining,it not only wastes a considerable amount of resource,but also results in safety problems,such as coal spontaneous combustion and slope failure,underground mining is an effective method to solve the above problems.Strata behavior of underground mining in end slope is different from that of traditional underground mining,and the disturbance of underground mining may lead to landslide,it is important in both theory and engineering to study the overlying strata movement law and control of underground mining in end slope.Methods such as theoretical analysis,physical simulation,numerical simulation and field monitoring are adopted to study the following aspects during underground mining in end slope,the structure and mechanical behavior of overlying strata,damage evolution mechanism of slope induced by overlying strata movement,stability and evaluation method of slope,control of overlying strata movement and slope deformation,the following main innovations can be drawn:(1)A mechanical model “voussoir beam” of overlying strata of underground mining in end slope is established,geometric movement,mechanics characteristic and stability of broken rock block in “voussoir beam” structure are analyzed.The roof is treated as plate structure,thus obtaining the deformation estimating formula and breaking behavior.“Voussoir beam-plate-slip surface” structure model analyzing the slope failure caused by overlying strata movement is established,modified Sarma method studying the stability of disturbed slope is proposed,and solving algorithm of safety factor is shown.(2)The linkage damage process of overlying strata and disturbed slope of underground mining in end slope is revealed by physical simulation,dynamic evolution law of “voussoir beam-plate-slip surface” structure is obtained,the evolution mechanism of “L” and arc fracture of disturbed slope is revealed,the failure of disturbed slope surface is obtained,including transverse fracture,longitudinal fracture and step slipping,and “transverse four zones” in disturbed slope is proposed.(3)Strength reduction numerical calculation model of slope stability considering the disturbance of underground mining is established,deformation distribution law of disturbed slope is analyzed,evolution law of position and shape of critical slip surface is tracked through plastic shear strain and deformation distribution,the effect of working face advancing on safety factor of disturbed slope is obtained,thus offering basis for choosing reasonable stop line of working face.(4)Control mechanism of overlying strata movement and disturbed slope deformation through adjusting the overburden load of disturbed slope and controlling the slipping of weak plane is revealed,control technology for different zones of disturbed slope of underground mining in end slope is proposed,including pressing the bottom,reducing slope weight and using anti-slide pile,the research achievements are successfully applied in Pingshuo mining area.There are 106 figures,13 tables and 203 references in this dissertation.