煤岩体水力致裂弱化的理论与应用研究  

Research on theory and application of hydraulic fracture weakening for coal-rock mass

作　　者：黄炳香[1] 

机构地区：[1]中国矿业大学矿业工程学院,江苏徐州221116

出　　处：《煤炭学报》2010年第10期1765-1766,共2页Journal of China Coal Society

基　　金：国家重点基础研究发展计划(973)项目资助(2007CB209400);国家自然科学基金资助项目(50774079);中国矿业大学青年科学基金资助项目(2005A001)

摘　　要：以煤岩体强度弱化(结构改造)为工程背景,采用实验研究、理论分析、数值模拟和现场试验等研究方法对煤岩体水力致裂弱化的理论和技术进行了系统的研究,取得了以下主要成果:研制了4000kN真三轴岩体水力致裂模拟实验系统,在3个主应力条件下,能实现试块尺寸最大为500mm×500mm×500mm的模拟实验;设计了具有增压功能的油水加载转换器。应用真三轴水力致裂模拟实验系统及理论研究,开展了大尺寸煤岩体水力致裂裂缝扩展规律研究。研究了水力致裂裂缝前沿形态,孔底水压裂缝与主应力的关系,发现了中间主应力对孔底水压裂缝扩展的影响规律;分析了分叉水压裂缝扩展方向的特征,得出了原生裂隙等在渗透水压力作用下的结构破坏特征;在考虑渗透滤失引起的孔隙水压力(水力梯度)的基础上,得出了裂隙煤岩体水压裂缝扩张的水压力参数。实验结果表明,水力致裂裂缝的前沿为以钻孔致裂段为中心的椭圆形态,且椭圆的长短轴之比保持不变;分叉后水压裂缝破裂面的走向与σ3、σ2均垂直;煤体水力致裂破裂面的粗糙度明显比一般岩石材料要大。固液耦合作用下裂隙煤岩体结构破坏研究。在调查煤层裂隙分布规律的基础上,基于断裂力学得出了煤岩体内水压裂隙起裂的最小裂隙水压力与水压翼型分支裂纹的扩展长度。采用RFPA软件模拟了成组原生裂隙条件下,水力致裂弱化的结构改造形态。基于能量耗散损伤得出了裂隙煤岩体细观结构破坏与宏观力学性能弱化的关系。煤岩体水力致裂弱化的控制技术研究。结合水力割缝和水力致裂的优势,提出了预先水力割缝定向致裂技术。基于钻孔及钻孔水压力的叠加影响,通过多钻孔及其注液方式的组合来控制水压裂缝的扩展方向。结合水压爆破和水力致裂的优点,提出了水力爆破致裂弱化与增透方法,在水压控制爆�Based on the engineering background of coal-rock mass strength weakening（structure reformation）,researched on theory and technology of hydraulic fracture weakening for coal-rock mass systematically with research methods including experimental research,theoretical analysis,numerical simulation and field test.The main achievements were obtained as follows.True triaxial stimulation experiment system for rockseam hydraulic fracturing with 4 000 kN force was developed,which can complete the simulation experiment with the greatest size 500 mm × 500 mm × 500 mm under the condition of three principal stresses.And oil-water loading converter with pressurization function was designed.Applying true triaxial stimulation experiment system for rockseam hydraulic fracturing and theoretical study,research on crack propagation law of hydraulic fracturing for coal-rock mass with large size was carried out.Crack front shape of hydraulic fracturing and the relationship between hydraulic crack on the hole-bottom and principal stress were researched,and then the law of hydraulic crack propagation on the hole-bottom affected by intermediate principal stress was found.The characteristic of bifurcate hydraulic crack propagation direction was analyzed,and then structural failure characteristic of original crack affected by osmotic water pressure was got.Based on pore-water pressure（hydraulic gradient） caused by osmosis filtration,water pressure parameters of hydraulic crack propagation in fissured coal-rock mass were obtained.According to experimental results,the crack frontier of hydraulic fracturing is oval shape with the centre of borehole fracturing section.Besides,the ratio of long axis and short axis keeps unchanged.After bifurcation,the trend of hydraulic fracturing failure surface is vertical to both σ3 and σ2.The roughness of hydraulic fracturing failure surface is significantly greater than general rock material.Research on structural failure of fissured rock mass under the condition of solid-liquid coupling was made

关 键 词：煤岩体 水力致裂 裂缝扩展 细观结构 控制 

分 类 号：TD327.2[矿业工程—矿井建设]