Mining stress full-cycle temporal and spatial evolution analysis on section coal pillar of fully-mechanized caving face
PANG Yihui1，2，ZHANG Guojun3，WANG Hongbo4，CHAI Hailong4
(1. Tiandi Science and Technology Co.，Ltd.，Beijing 100013，China；2. CCTEG Coal Mining Research Institute，Beijing 100013，China；3. State Key Laboratory of Water Resource Protection and Utilization in Coal Mining，National Institute of Clean and Low Carbon Energy，Beijing 102209，China；4. School of Energy and Mining Engineering，China University of Mining and Technology(Beijing)，Beijing 100083，China)
Abstract：The evolution process of the magnitude and direction of three-dimensional mining stress is the key to reveal the damage and failure mechanism of coal pillar. The coal pillar between the fully mechanized top-coal caving faces was divided into upper and lower areas. There were four stages：roadway excavation-right longwall face mining-left longwall face mining-mining stability. The 3DEC numerical simulation method was used to analyze the full-cycle temporal and spatial evolution law of three-dimensional mining stress of coal pillar in these stages. The mapping relationship between the fracture structure of overlying strata，mining stress and displacement of coal pillar was revealed. Based on the simulation analysis results，the Mohr-Coulomb strength criterion was used to analyze the transformation form of Mohr stress circle of coal pillar and the relationship between stress circle and strength envelope. The failure width of coal pillar was determined to be about 8m. The results show that longwall face mining causes the three-direction principal stress direction of coal pillar to rotate greatly. An obvious two-cluster or three-cluster rule was showed in the three-dimensional principal stress data of coal pillar. The division points of the data clusters correspond to the time when the right longwall face is advanced to the survey line and when the mining of right longwall face ends. The obvious asymmetry in overlying fracture structure of coal pillar was caused by the different mining sequences of longwall face. The fracture line of the overlying strata is biased towards the longwall face which is mined later. As a result，the horizontal displacement of the measuring point on the left side of coal pillar is significantly larger than that on the right side of coal pillar. The full-cycle temporal and spatial evolution law of coal pillar mining stress and the mapping relationship between the fracture structure of overlying strata，mining stress and displacement of coal pillar lay the foundation for revealing the damage mechanism of coal pillar.
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2023, Vol. 42 
