Development Characteristics And Formation Mechanism Of Karst Collapse Column In Zhangxie Mining Area

Karst collapse column is a kind of unique concealed structure developed in coal fields in North China.It has the function of water storage and water diversion,and poses a great threat to the safe mining of coal mines.Understanding the distribution characteristics of collapse columns and discussing the evolution process of collapse columns from the genetic mechanism not only provides a basic basis for the prevention and control of water damage of collapse columns,but also has certain scientific significance and practical value.Taking the collapse column in Zhangxie mining area as the object,based on the analysis of geological and hydrogeological conditions,combined with the data exposed and detected by drilling,geophysical prospecting and roadway construction,this paper analyzes the shape and distribution law of karst collapse column by using the methods of geological evolution,hydrogeological condition analysis and numerical simulation,and discusses the formation mechanism.The main results are as follows:(1)There are 5 proved collapse columns in Zhangxie mining area,most of which are nearly oval and strip-shaped in plane shape,cone or irregular geological body in section shape,and most of the internal rock strata collapse as a whole,develop high-angle fractures,and the internal rock strata bedding is clear.(2)The collapse column is mainly distributed along the direction of NNW structural collapse zone,and the fractures developed in the influence zone are the water outlet channel of overlying coal measure sandstone;Cambrian and Ordovician soluble rocks are the material basis for their development,while tectonic evolution is the controlling factor for the development of karst collapse columns,and paleogroundwater flow is the hydrodynamic condition for carbonate dissolution,scouring,collapse and collapse.(3)The karst collapse column in Zhangxie mining area is unevenly distributed in space.The top of the hidden karst collapse column is highly developed from the bedrock surface.From the bedrock outcrop along the inclined direction of the single inclined stratum,the buried depth of the top gradually increases.(4)The numerical simulation not only reflects the variation characteristics of roof displacement and stress in the collapse process,but also reflects the evolution process of four stages of collapse column:early stage,rapid collapse in the middle and early stage,slow collapse in the middle and late stage and filling and compaction in the late stage,and reveals the mechanism of roof collapse.(5)The karst collapse column in Zhangxie mining area has experienced weathering and denudation,sedimentary compaction of overlying strata,later magmatic hydrothermal action,groundwater erosion and mixing.Up to now,it has been in the state of gestation,occurrence and death.Figure[27]Table[11]Reference[82]...