Abstract
Deep high static loading roadway is extremely prone to rock burst under dynamic load disturbance. The “force-energy criterion” for the failure of surrounding rock in such deep roadways and the “energy criterion” for the rock burst was established by considering the stress and energy evolution characteristics of rock burst under this circumstance. Under the engineering background of the main roadway in No.1 mining area of Gaojiapu Coal Mine in Binchang Mining Area, Shaanxi Province, China, the partial stress field and distortion energy field of surrounding rock in the main roadway and the spatial-temporal evolution laws under dynamic load disturbance were simulated and analyzed by using a built-in dynamic module of FLAC3D. Results show that after the dynamic load disturbance, the partial stress and distortion energy are concentrated in the shallow part at two walls of the roadway in the early phase. With the continuous propagation of dynamic load stress wave, the partial stress and distortion energy are transferred to the deep part. The sudden high-energy release occurred in the peak zone of partial stress, leading to the plastic failure of coal and rock mass. Subsequently, the distortion energy was fully accumulated in the original plastic zone and transferred from shallow surrounding rocks to the deep surrounding rocks in the roadway, where the partial stress and distortion energy of coal and rock mass reached the yield conditions. Thus, the original plastic zone was sharply expanded, thereby forming a new plastic zone. The coal and rock mass experienced an approximately static failure when no residual energy (ΔU) was found in it. When ΔU > 0, the rock mass experienced dynamic failure, and ΔU was mainly the volume transformation energy, which is approximately one-half of the total elastic strain energy. ΔU was transformed into the initial kinetic energy of broken coal and rock mass. Thus, the coal and rock mass are burst out. In severe cases, this condition was manifested by the rock burst in the main roadway. An optimization scheme of prevention and control measures for rock burst was proposed on the basis of the above conclusions. The microseismic activity laws before and after the unloading were compared, and a good effect was achieved. The research results can lay a theoretical foundation for predicting and preventing rock bursts in coal mines by actively regulating the disaster-pregnant environment and mitigating the disaster-inducing conditions.
Highlights
Since the 21st century, China’s coal mining has entered the space of the second depth (500–2000 m) [1]
The stress stress of ofcoal coaland androck rockmass masshas hasaalinear linearrelationship relationshipwith withdepth, depth,and andthe thestored stored elastic strain energy of coal and rock mass has a quadratic relationship with depth
Elastic strain energy of coal and rock mass has a quadratic relationship with depth.The
Summary
Since the 21st century, China’s coal mining has entered the space of the second depth (500–2000 m) [1]. With the increase in mining depth, the geological conditions become increasingly complicated, and the occurrence frequency of rock burst-induced dynamic disasters and death toll present a gradual rising trend. On 20 October 2018, a rock burst accident occurred on Longyun Coal Industry of Shandong Energy Group, leading to a death toll of 21. The rock burst accident in Longjiabao Coal Mine of Jilin Coal Industry. The underground rock burst accident of Tangshan Mining Industry, a branch of Kailuan Limited Liability Corporation, resulted in seven deaths on 2 August 2019. On 22 February 2020, four people died from a rock burst accident in the Longgu Coal Mine of Shandong New Julong Energy Co., Ltd. Studying and preventing rock bursts are of great importance for ensuring the safe and efficient mining of deep coal resources
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