摘要
为深入探讨高瓦斯松软煤层、软硬复合煤层和突出煤层钻孔孔壁失稳问题,从而为钻孔成孔工艺提供参考与借鉴、提高部分高瓦斯和突出矿井的瓦斯治理效果,分析钻孔所处应力环境、煤体结构、孔隙压力、钻进速度等因素对孔壁稳定性影响。基于H-B准则、地质强度指标(GSI)与岩石断裂力学理论,建立Ⅰ类煤层钻孔孔壁失稳的力学判据,探讨Ⅱ-Ⅳ类煤层钻孔孔壁失稳的力学条件,并分析钻孔周围"三带(区)"内孔壁稳定性。研究表明:H-B准则可作为破坏准则来判定Ⅰ类煤层钻孔孔壁是否发生失稳破坏;而Ⅱ-Ⅳ类煤层钻孔孔壁需同时满足3个条件,即煤体发生强度破坏、裂纹在应力作用下逐步扩展和裂纹在瓦斯压力作用下继续扩展直至相互贯通,才会发生失稳破坏;此外,卸压带易垮孔,峰后应力集中带易喷孔、顶钻,峰前应力集中带的孔壁失稳破坏的概率较低。
In order to discuss the instability problem of borehole wall in high gas soft coal seam, hard and soft compound coal seam and outburst coal seam, provide reference for technology of drilling coalbed boreholes, and improve gas control effect in some gassy mine and outburst mine, influence factors of bore- hole wall stability, such as stress environment around borehole, coal structure, pore pressure and drilling speed, were analyzed. Based on H - B strength criterion, GSI and theory of rock fracture mechanics, a borehole wall instability mechanical criterion was established for coalbeds with structure I, mechanical con- ditions of borehole wall instability were discussed for coalbeds with structures II - IV, then stability of borehole wall in the three zones around borehole were analyzed. Research results show that H - B criterion can be used as instability criterion of borehole wall for coalbeds with structure I, that for the wall of boreh- des in coalbeds with structures II -IV, losing stability requires simultaneous three conditions： coal body strength failure, crack extends gradually under the action of stress, and cracks extend continuously until they connect each other under the action of gas pressure at last, that collapse of borehole wall always oc- curs in pressure released zone, gas blower and crown drill always occur in post-peak stress concentration zone, and that probability of losing stability of losing stability of borehole wall instability is lower in pre- peak stress concentration zone.
出处
《中国安全科学学报》
CAS
CSCD
北大核心
2014年第6期80-85,共6页
China Safety Science Journal
基金
河南省基础与前沿技术研究计划项目(132300410120)
河南省瓦斯地质与瓦斯治理重点实验室-省部共建国家重点实验室培育基地开放基金资助(WS2012A09)
河南省教育厅科学技术研究重点项目(14A440012)
河南理工大学博士基金资助(B2008-15
B2012-093)
河南理工大学青年骨干教师资助项目(649175)
