Structure stability analysis of rock masses is essential for forecasting catastrophic structure failure in coal seam mining. Steeply dipping thick coal seams （SDTCS） are common in the Urumqi coalfield, and some dyna...Structure stability analysis of rock masses is essential for forecasting catastrophic structure failure in coal seam mining. Steeply dipping thick coal seams （SDTCS） are common in the Urumqi coalfield, and some dynamical hazards such as roof collapse and mining-induced seismicity occur frequently in the coal mines. The cause of these events is mainly structure instability in giant rock pillars sand- wiched between SDTCS. Developing methods to predict these events is important for safe mining in such a complex environment. This study focuses on understanding the structural mechanics model of a giant rock pillar and presents a viewpoint of the stability of a trend sphenoid fractured beam （TSFB）. Some stability index parameters such as failure surface dips were measured, and most dips were observed to be between 46° and 51°. We used a digital panoramic borehole monitoring system to measure the TSFB＇s height （△H）, which varied from 56.37 to 60.50 m. Next, FLAC^3D was used to model the distribution and evolution of vertical displacement in the giant rock pillars; the results confirmed the existence of a TSFB structure. Finally, we investigated the acoustic emission （AE） energy accumulation rate and observed that the rate commonly ranged from 20 to 40 kJ/min. The AE energy accumulation rate could be used to anticipate impeding seismic events related to structure failure. The results presented provide a useful approach for forecasting catastrophic events related to structure instability and for developing hazard prevention technology for mining in SDTCS.展开更多
Steeply dipping seam group, which has complex occurrence conditions, belongs to the steeply dipping seam. The research on the strata movement around the coal face not only improves safe production technology in practi...Steeply dipping seam group, which has complex occurrence conditions, belongs to the steeply dipping seam. The research on the strata movement around the coal face not only improves safe production technology in practice, but also develops the mining theory. By using physical simulation experiments, numerical simulation and site test, the deformation, failure and movement of surrounding rock in Iongwall working face were analyzed. According to the analysis, characteristics of the seam group were formed which is different from the single seam. Asymmetry mechanics, sequential changes and imbalance of strata movement along the tendency working face were summarized. Furthermore the features of upper and lower seams were different. The mining of the lower seam induced more complex strata movement along the strike. Multi-section mining disturbed surrounding rocks in larger areas than the single section mining did, which had an impact on and dynamic loading function to the support when mining the lower seam, and produced a great influence on the stability of support-rock system.展开更多
基金financially supported by the Key National Basic Research Program of China (Nos.2014CB260404 and 2015CB251602)the Key National Natural Science Foundation of China (No.U13612030)+1 种基金Shaanxi Innovation Team Program (No.2013KCT-16)the High Technology Development Program of Xin Jiang Municipality (No.201432102)
文摘Structure stability analysis of rock masses is essential for forecasting catastrophic structure failure in coal seam mining. Steeply dipping thick coal seams （SDTCS） are common in the Urumqi coalfield, and some dynamical hazards such as roof collapse and mining-induced seismicity occur frequently in the coal mines. The cause of these events is mainly structure instability in giant rock pillars sand- wiched between SDTCS. Developing methods to predict these events is important for safe mining in such a complex environment. This study focuses on understanding the structural mechanics model of a giant rock pillar and presents a viewpoint of the stability of a trend sphenoid fractured beam （TSFB）. Some stability index parameters such as failure surface dips were measured, and most dips were observed to be between 46° and 51°. We used a digital panoramic borehole monitoring system to measure the TSFB＇s height （△H）, which varied from 56.37 to 60.50 m. Next, FLAC^3D was used to model the distribution and evolution of vertical displacement in the giant rock pillars; the results confirmed the existence of a TSFB structure. Finally, we investigated the acoustic emission （AE） energy accumulation rate and observed that the rate commonly ranged from 20 to 40 kJ/min. The AE energy accumulation rate could be used to anticipate impeding seismic events related to structure failure. The results presented provide a useful approach for forecasting catastrophic events related to structure instability and for developing hazard prevention technology for mining in SDTCS.
基金the New Century Excellent Talents in University of China(NCET-04-972)
文摘Steeply dipping seam group, which has complex occurrence conditions, belongs to the steeply dipping seam. The research on the strata movement around the coal face not only improves safe production technology in practice, but also develops the mining theory. By using physical simulation experiments, numerical simulation and site test, the deformation, failure and movement of surrounding rock in Iongwall working face were analyzed. According to the analysis, characteristics of the seam group were formed which is different from the single seam. Asymmetry mechanics, sequential changes and imbalance of strata movement along the tendency working face were summarized. Furthermore the features of upper and lower seams were different. The mining of the lower seam induced more complex strata movement along the strike. Multi-section mining disturbed surrounding rocks in larger areas than the single section mining did, which had an impact on and dynamic loading function to the support when mining the lower seam, and produced a great influence on the stability of support-rock system.
