Research status and prospect on cultivated land damage at surface subsidence basin due to longwall mining in thecentral coal grain compound area

As a large coal and grain producing province in Central China,the contradiction between safe and efficient coal mining and cultivated land protection,grain production is more prominent in Henan Province. How to re- pair the damaged farmland due to coal mining,protect the undamaged farmland in the mining area,and stabilize the coal production capacity is one of the major problems facing the central coal grain compound area. Based on the analysis of the typical characteristics and the bottleneck problems of the central coal grain compound area,this paper analyzes the research and development progress of mining subsidence and farmland damage from four aspects:mining overburden and aquifer damage,surface subsidence law and soil degradation,mining farmland damage and crop growth,source subsid- ence control and land damage repair technology. It includes the failure of aquifer and structural instability,the definition and criterion of full mining,the overall response behavior of surface subsidence and overburden failure,the impact of sur- face subsidence on soil degradation and cultivated land damage,the identification of cultivated land damage and crop growth monitoring in subsidence area,and the remediation technology of coal mining damaged land. Based on the a- nalysis of the current investigations,four development directions of mining subsidence and cultivated land damage in the central mine grain complex area are presented:the transmission mechanism of overburden strata structure instabili- ty and aquifer damage caused by mining,the law of mining induced surface subsidence and the mechanism of land dam- age,temporal and spatial evolution law of cultivated land damage and crop growth in mining area,and the efficient col- laborative restoration technology for controlling overburden failure and reducing surface subsidence from the source. These four directions will help to obtain the transmission coupling mechanism of ‘overburden failure-surface subsid- ence-cultivated land damage-crop responses’. Finally,the paper will present an efficient collaborative rehabilita- tion technological system for mining subsidence and cultivated land damage in central coal grain compound area. It will provide theoretical and technical supports for green coal mining and food security.