Fracture analysis of multi-hard roofs based on microseismic monitoring and control techniques for induced rock burst: a
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ORIGINAL PAPER
Fracture analysis of multi-hard roofs based on microseismic monitoring and control techniques for induced rock burst: a case study Wenlong Zhang 1 & Xiaocheng Qu 2 & Chen Li 1 & Xu Xu 3 & Songlin Zhang 3 & Guodong Jin 2 & Yanliang Wang 2 Received: 27 May 2019 / Accepted: 18 November 2019 # Saudi Society for Geosciences 2019
Abstract The fracture and behavior of multi-hard and thick roofs differ from those of other types of overlying strata. Therefore, abnormal rock pressure problems, such as gateway instability, rock burst, and hydraulic cylinder damage, will be encountered as a result of the instantaneous fracture of roofs. The key to controlling the behavior of the strata is to obtain the movement and fracture patterns of multi-hard and thick roofs. The periodical characteristics and occurrence zones of microseismic (MS) events of M mine with multi-hard and thick roofs were analyzed in the case study. Then the mining-induced fracturing and movement of the roofs were investigated. Anti-burst measures, including the “ultra-deep hole pre-split blasting measure,” the “stronger largediameter boreholes pressure relief measure,” and the “reducing advancing speed measure,” were implemented according to the conclusions from MS monitoring. Finally, the aim of “there were earthquakes, but there were no accidents” was achieved through these measures. Keywords Multi-hard roofs . Fracture analysis . Microseismic monitoring . Rock burst . Strata control
Introduction Hujierte coalfield is located in the southwest of the Inner Mongolia Autonomous Region in China; it includes seven minefields, two exploration areas, and one prospect area (Weng and Wang 2018) and has just begun to be mined in recent years. The mineable coal seams have three characteristics: buried approximately 630 m deep, typically covered by several hard strata, and experience strong rock burst tendencies. Some studies have shown that hard strata tend to form large cantilever beams after mining, which increases the stress concentration in mining-disturbed zones. Yang et al. (2018b) obtained that seismic waves can introduce a surprisingly high Responsible Editor: Zeynal Abiddin Erguler * Wenlong Zhang [email protected] 1
School of Energy and Mining Engineering, China University of Mining and Technology (Beijing), Beijing 10083, China
2
Beijing Anke Xingye Technology Co., Ltd, Beijing 10083, China
3
Beijing Anke Xingye Mine Research Institute Co., Ltd, Beijing 10083, China
level of stress on the coal for an instant. Ning et al. (2017c) discovered that numerous problems are encountered as a result of the instantaneous fracture of hard and thick main roofs. During the non-weighting period, the behavior of the hard rock strata and the instability of the gateway may not be apparent (Ning et al. 2017c). However, during special periods, such as weighting periods or square periods (mechanical mechanism and types of square will be introduced in the “Mechanical mechanism and types of square” section), the overlying hard rock strata may instantaneou
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