针对高偏应力环境下层状顶板巷道冒顶事故频发、支护困难等问题,采用理论分析、数值模拟、现场探测和现场工程试验等综合研究方法,揭示了层状顶板巷道蝶叶塑性区的分布规律,阐明了蝶叶塑性区穿透分布致使巷道冒顶的力学机制,结果表明:蝶叶塑性区具有隔层穿透发育的特征,未发生塑性破坏岩层的存在不能阻断蝶叶塑性区在软弱岩层形成;顶板蝶叶塑性区穿透分布伴有强烈的变形压力,使软弱岩层塑性区下位未发生塑性破坏岩层受到持续巨大的"挤压"载荷,致使其发生断裂破坏,是巷道存在冒顶隐患的内在原因。据此提出了防止此类巷道冒顶的关键在于维护塑性区围岩稳定,需锚杆(索)长度大于塑性区边界,且具备可承受大变形而不破断的能力。基于以上研究,对神东保德矿81306二号回风巷进行了支护补强设计和试验,试验结果表明该支护对策能够有效维持巷道顶板稳定。
In this study,the problems of frequent roof fall accidents and support difficulties in the layered roof of roadway were investigated using theoretic analysis,numerical simulation,field detection and field engineering test,the distribution of the butterfly plastic zone of layered roof roadway was revealed,and the mechanical mechanism of roof fall due to butterfly plastic zone penetration was elucidated. The research shows that the butterfly plastic zone has the characteristic of penetrating across strata,and no plastic failure rock cannot block the formation of butterfly plastic zone in soft strata; The distribution of penetration of butterfly plastic zone in the roof is accompanied with strong deformation pressure,the lower no plastic failure rock under soft strata plastic zone is subjected to a continuous huge squeeze load which makes the no plastic failure rock fractured and failed,this is the intrinsic reason of roadway roof fall hazards.The key to prevent roof fall of the roadway is to keep the stability of plastic zone of surrounding rock,the length of rock bolts( or cables) should be longer than the plastic zone,and the rock bolts( or cables) should have the ability to withstand a large deformation without breaking. Based on the research,strengthening support and field test were con-ducted in the 81306-2 tailgate of Baode Colliery in Shendong,the field test shows that the support method proposed can maintain the stability of roadway roof effectively.