Study on Dynamic Disaster Mechanisms of Thick Hard Roof Induced by Hydraulic Fracturing in Surface Vertical Well

Abstract

With the increase in mining depth and the deterioration of mining conditions, thick and hard overburden movement frequently induces mine earthquakes and rock bursts. Some mines are expected to prevent and control super thick hard rock mine earthquakes through vertical ground well water fracturing technology. However, the dynamic underground disaster appears more intense. Taking the '11.30' mine earthquake in a mine in Shandong Province as the engineering background, the dynamic disaster mechanism of an extraordinarily thick and hard roof induced by hydraulic fracturing of vertical wells on the ground was studied utilizing field investigation, accident case analysis, similar material simulation test, and theoretical analysis. The main conclusions are as follows: (1) After hydraulic fracturing vertical wells on the ground, the movement mode of thick and hard roofs changed from layer-by-layer to overall sliding movement; (2) The influence range of the advanced abutment pressure of the working face is reduced by the hydraulic fracturing of the vertical shaft, and the peak value of the advanced abutment pressure increases. Furthermore, the advanced abutment pressure's peak is far from the coal wall; (3) The hydraulic fracturing technology of cross-arranged vertical surface deep and shallow wells and the hydraulic fracturing technology of cross-perforated surface multi-branch horizontal wells are proposed to avoid the dynamic disaster of overall sliding movement of an extremely thick hard roof induced by surface hydraulic fracturing. Therefore, these research results provide significance for preventing and controlling mine earthquakes and rock bursts in super thick hard roof mines.

Simulation Study and Engineering Application of Weakening Mine Pressure Behavior in Stope through Ground Fracturing Thick and Hard Rock Strata

“…Gao et al explored the weakening impact of ground hydraulic fracturing technology on a high-key stratum through in situ monitoring and numerical simulation [14,15]. Adequate research on the breaking laws of hard roof, structure morphology formed by the broken blocks [16][17][18][19], factors affecting the stability of the structure [20][21][22][23][24][25], the blasting and hydraulic fracturing methods of the hard roof [26][27][28][29][30], expansion characteristics and influence factors of hydraulic fracturing fractures [31][32][33][34], a quantitative description method for crack propagation law [35][36][37], movement characteristics of key strata after fracturing and the influence of fracturing cracks morphology on structural stability [38][39][40][41] etc., have been conducted.…”

Study on the Mechanism and Prevention of Frequent Mine Seismic Events in Goaf Mining under a Multi-Layer Thick Hard Roof: A Case Study

“…On the basis of mine seismic prevention and control, Zhu et al [31] and Shang et al [32,33] established the energy prediction model of rooftop mine seismic events based on the "movement state of key strata", with the calculation of rooftop mine energy, and proposed a method for preventing and controlling mine seismicity in the massive and thick hard rock by hydraulic fracturing in vertical wells. Cui et al [34] studied the distribution characteristics of microseismic large-energy events on the mining face under solid coal and goaf and determined the relationship between microseismic large-energy events and the distribution law of mine pressure.…”