Research on Evolution Characteristics of Unloading Energy in Excavation Face of High-Stress Pillar

Abstract

In the mining process of the stage empty field subsequent filling mining method, aiming at the problem of unloading failure and instability of the excavation face of the high-stress ore pillar, the theory of unloading stress component is introduced and combined with the energy release theory to explore the unloading failure mechanism of the excavation face of the ore pillar. The results show the following. (1) The degree of accumulation of strain energy in the pillar is related to the tangential stress. After the peak of the tangential stress, the energy changes from accumulation to release, indicating that energy release is the main cause of pillar damage. (2) In pillar unloading, there are 4 typical characteristic areas of stress during the loading process: crushing area, shaping area, elastic area, and original rock stress area. The energy accumulation area and the stress component area show good correspondence, and they all appear from the top to the bottom of the pillar. At 1/4, the starting point of unloading failure can be determined. (3) The mutation mechanism in the process of energy release is related to the time effect of tangential stress. On the contrary, the greater the tangential stress is, the longer the elastic zone lasts, and the more significant the energy accumulation is. Also, the increase in tangential stress will lead the energy release time becomes shorter, and a large amount of accumulated energy is released in a short time, causing local instability and destruction of the pillar, and eventually spreads to the whole.