Current status and prospect of coal mining technology under buildings,water bodies and linear structure,and above confined water in China

China has a large amount of coal resources that are difficult to mine due to buildings,water bodies,linear structure and confined water.Mining under building,water bodies and linear structure,and above confined water is an effective measure for resource exhausted mines to increase the resource recovery rate,extend the service life of the mines and achieve sustainable development in China.Based on the analysis of the current status of coal mining under buildings and structure,the source-controlled subsidence and damage mining method are expounded,including the filling mining,partial mining,coordinated mining,the measures to reduce deformation of buildings by grouting bed separation.By analyzing the transfer process of overburden failure caused by longwall mining,the criterion of the full mining degree of overburden failure based on the transfer process of overburden failure and its height calculation method are proposed,which reveals the formation mechanism of the height of overburden failure.The surface borehole observation method and coordinated mining have successfully applied to coal mining under water bodies in different geological mining conditions.In addition,the magnetotelluric detection were carried out to detect the destruction characteristics of loose aquifers in high-intensity mining,the destruction characteristics of loose aquifers under the influence of mining were analyzed,which revealed the destruction mechanism of loose aquifer and verified the feasibility of magnetotelluric method for detecting the damage of aquifers.Coal mining technology and safety measures of mining under buildings,water bodies and linear structure,and above confined water were summarized.Finally,the study forecasts that the development of coal mining technology under buildings,water bodies and linear structure,and above confined water in China's coal mines will be mainly based on source-controlled subsidence anddamage mining methods,overburden damage control technology.Underground in-situ protection coal mining technology will be the future trend of mining under buildings,structure and water bodies in China.