Research progress of rock mechanics in deep mining

With the gradual development of coal mining into deep strata, the large deformation failure and strong dynamic impact disasters of surrounding rock caused by deep mining are becoming more and more serious. Under the complex geomechanical conditions including high ground stress, high ground temperature, high permeability, strong mining disturbance, strong rheology, and multi-field coupling, the stress field characteristics, rock fragmentation properties, strata movement and energy accumulation and release laws of deep mining areas are significantly different compared with those in shallow mining areas. In response to the rock mechanics issues in deep mining, this paper discusses the research progress made by the authors and team in three aspects: deep coal mining methods, failure mechanism and control of surrounding rock in deep roadway, and deep thermal disaster and geothermal utilization. The main results are as follows: ① the theory of balanced mining and the 110/N00 methodology for achieving balanced mining were proposed and applied in kilometer deep mines. ② The deep shaft construction mode with non-uniform pressure was proposed, and a SAP system to realize the stable lifting was developed. A mine construction method which can greatly reduce the roadway quantities and improve the coal recovery rate was invented. ③ Multiple experimental systems suitable for studying the macroscopic failure of deep soft rock under the effects of water, high temperature, high pressure, structural effects, multi-field coupling were developed. A supercomputing system capable of performing microscopic-level calculations was established. Based on the experimental results, the mechanism of large-scale deformation and failure of deep soft rock and its multi-scale mechanical properties were revealed. ④ An experimental system for simulating deep shock-type and strain-type rock bursts was built, and it was revealed that the rock burst is a nonlinear dynamic behavior in which energy is instantaneously released along the excavation-free surface. ⑤ The theory of excavation compensation support for deep roadway was proposed, and a NPR materials with extraordinary mechanical properties such as high constant resistance, high elongation, strong energy absorption, and impact resistance were invented. ⑥ A thermodynamic experimental system which can simulate deep high temperature, high humidity, and high-pressure environments was constructed, and a high temperature exchange machinery system (HEMS) for heat disaster treatment and heat source resource utilization was established. The above research achievements have been applied in the field of deep mining and can provide guidance for the complex rock mechanics problems faced by deep mining.