This study attempts to investigate the effect of mining speed on the activation characteristics of normal faults. Taking the working face 8302 of the Xinjulong Coal Mine as the engineering background, this study explores the activation mechanism under the disturbance caused by hanging wall mining of normal faults. We investigated the effect of mining speed and the distance from the working face to the fault on the activation tendency of the fault through numerical simulation. Results show that the high-level stratum of normal fault is a high-risk area for fault plane activation, and its activation tendency index T_s is influenced by fault inclination θ and mining speed v of the working face. The fault activation in the mining process of the hanging wall working face can therefore be divided into 2 stages: quasi-static and activation. With the increase of v, the peak stress of surrounding rock decreases first and then increases. When v is 3 m/d, the peak stress reaches its minimum of 28.12 MPa. This could alleviate the stress concentration of surrounding rock. When the distance between the working face and the fault is less than 30 m, the risk of fault plane activation increases significantly. However, with a mining speed of 3 m/d, the activation tendency of fault plane reaches its minimum, and the distance causing fault activation is reduced to 40 m, outperforming those with other mining speeds.

This study aims to tackle the problem of frequent coal-rock dynamic events caused by local stress concentration in deep mining working face under high static stress environment. Specifically, by taking the deep working face of Hongqinghe Mine located in Xinjie Mining Area as an example for analysisthis paper investigates the geological conditions of No. 3^-1coal seam that are affected by the mining method and the coal rock dynamic disaster events occurred during mining; utilizes numerical simulation to simulate the mining stress field and energy field of the stope; analyzes the potential coal burst instability area and mechanism of coal burst gestation and catastrophe in the stope during the mining of the No. 3^-1103 working face; probes into the sources of catastrophic stress and influencing factors of coal-rock disasters in dangerous areas, puts forward targeted prevention and control measures. Results show that: ① the roof strata structure, goaf and coal pillar are the key factors influencing coal burst in the stope during the mining of the No. 3^-1103 working face; ② the simulation results indicatethe location and characteristics of the coal burst instability area in the stope of the No. 3^-1103 working faces, as well as the simulation outlines 5 strong coal burst areas and 11 medium coal burst areas presented in the stope; ③ Measures are proposed for coal burst during mining from the perspective of cutting off the dynamic load source, reducing static load stress concentration, and blocking the transmission of high concentration stress. Detailed measures include implementing multi-source prevention and control in areas with high static or high static+dynamic loads, implement pre-pressure off-load measures prior to mining, and local risk relief and coal burst prevention and reduction treatments during mining.

Making clear the vibration response law of buildings(structures)due to blasting is of great significance both engineeringly and the economically. By conducting blasting experiment at subway station entrance A, the vibration signal of building NO.2 was analyzed through Hilbert-Huang transform. Results indicate that as height increases, the three-vector peak vibration velocity attenuate sharply, and then shows a wave-shaped change in the middle and amplify on the top floor, which was divided into attenuation area(0~26.15 m], fluctuation area(26.15~71.75 m]and amplification area(71.75~94.55 m]. The shape of the Hilbert spectrum gradually changes from three-peak to single-peak, the dominant frequency band attenuates from 75~125 Hz to 10~40 Hz and the energy amplitude decreases. This demonstrates that the lower vibration frequency of the floor in the amplification area could easily cause resonance. Based on the composition of the top-level energy spectrum fitted by the ground measuring points, it is verified that the essence of the top-level amplification effect is to selectively amplify the energy close to the natural frequency of the building in the blasting seismic wave.