Stress Distribution And Evolution Law Of Overburden Structure In Coal Seam Mining In Fold Region

With the deep development of coal mining in China,the rock burst is becoming more and more serious as a special strong ore pressure phenomenon,which poses a serious threat to the safety and efficient production of the mine.The research shows that the rock burst is the result of the comprehensive action of mining activity and regional tectonic stress field.It is particularly typical for the fold area mining under the influence of high horizontal tectonic stress.In the process of production,the strong mine earthquake often occurs,and the mining earthquake has long duration and great destructive,which further worsens the working environment of the working face.This paper studies the distribution of stress field,the characteristics of overlying rock fracture and the evolution law of the spatial structure of the fold tectonic zone by the combination of theoretical analysis,numerical simulation and field case analysis,taking the risk of induced shock in the fold tectonic zone as the research background.The basic types and components of fold structure are introduced in detail,and their distribution patterns are classified under the plane,vertical section and three-dimensional space,and the complexity of the fold structure of Huayan mining area and hujiahe coal mine is qualitatively and quantitatively analyzed.The FLAC³DD numerical calculation model is established based on the distribution pattern of fold structure in 2502 mining area of Yan Bei Coal Mine.The general rule of the distribution and evolution of the stress distribution and evolution under the condition of single working face mining is analyzed.The anticline pitching stage is obtained.The high stress concentration mainly occurs in the roof rock layer of the working face,and the horizontal stress is dominant.During the mining stage from anticline to syncline,the high stress concentration area is transferred from the roof to the floor rock stratum,and gradually dominates by vertical stress.The stress distribution characteristics during the mining stage from anticline to syncline are similar to that of the anticline mining stage.To establish a mechanical model of surrounding rock stress,the results showed that the high level of tectonic stress of surrounding rock in mining area is the main factors affecting the stability of vertical pressure?q?,lateral pressure coefficient??,cohesion of rock mass?C?and internal friction angle??,and the top floor of the factors to the sensitivity two sides of roadway,the lateral pressure coefficient is the main influencing factors.At the same time,the theoretical solution of the fracture step of the key strata overlying the working face is theoretically solved,which provides a theoretical basis for the quantitative prediction of the impact risk of the working face.Through the UDEC software on different stages of mining step,breaking the law,movement law of overlying strata spatial structure and spatial and temporal features of overburden rock fracture evolution,get fold anticline arch structure is conducive to the stability of the surrounding rock,the roof is not easy to collapse,and a downward movement of the syncline axis on both sides of the rock roof stratum trend.The fracture caused by overburden large range of caving,increasing direct roof pressure strength.The modeling method of large and complex fold tectonic area is proposed.Based on the measured data of in-situ stress and the characteristics of coal and rock strata in huayan coal mine and hujiahe coal mine,the FLAC^3D high simulation numerical model is constructed.The stress distribution and transfer characteristics of the stope are analyzed by large scale excavation simulation,and the working face is analyzed in the anticline and syncline axis.The spatial and temporal distribution characteristics and energy accumulation rules of mining tremor in mining process further reveal the stress distribution and overburden evolution characteristics of mining stope in fold structure area,and specific prevention and control methods are put forward for prevention and control of rock burst during mining in high tectonic stress area.