深部巷道围岩能量耗散与支护调控效应

Energy dissipation and supporting regulation effect of surrounding rock in deep roadway

煤岩破坏是能量驱动下的一种状态失稳现象,从能量角度描述围岩破坏特征是评价巷道稳定的有效方法之一。基于双向等压圆形巷道弹塑性解析,以时间为轴线,提出利用弹性和弹塑性变形时的应变能差量表征围岩耗散能,研究初始应力、开挖半径和围岩强度等因素对耗散能演化的影响规律,耗散能随围岩强度增加呈负指数衰减,高强度围岩耗散能小,大量弹性能积聚不利于动力灾害防控;相反,耗散能随初始应力和开挖半径增加呈近似指数关系增长,超过临界值后围岩耗散能急剧增加,从能量角度解释了煤矿巷道临界深度和断面尺寸的物理意义。依据锚杆支护预应力扩散原则,研究支护对围岩能量耗散的调控效应,得到耗散能随支护强度加大呈近似负指数关系衰减,其中,大部分耗散能由围岩破坏分担;在“支护-围岩”协同变形条件下,给出锚杆支护结构吸能和极限储能的表达式,建立支护调控围岩稳定的能量判据,反演巷道支护参数,成功应用于现场工程实践,取得良好控制效果。研究成果从调控围岩能量耗散角度给出巷道支护设计的一条新途径,具有较强的工程应用价值。

Coal-rock mass failure is the instable state driven by energy, and is one of the effective ways to evaluate the roadway stability with the failure characteristics of surrounding rock from the aspect of energy. By analysing circular roadway elastic-plastic equations based on equal pressure in double perpendicular direction, taking time as the axis, it proposes that the dissipated energy of surrounding rock(DESR) was indexed by the strain energy difference of completely elastic region and elastic-plastic region, by which revealed rules of initial stress, excavation radius and rock strength on the DESR evolution. The DESR decreased exponentially with the increase of surrounding rock strength. The DESR of high strength rock was small, which was not conducive to the prevention and control of dynamic disasters. Conversely, the DESR increased exponentially with the increase of initial stress and excavation radius. When exceeding the critical value, DESR increased dramatically. It explained the physical significance of the critical roadway depth and section size in coal mine. According to tension diffusion principle of bolting support, the supporting regulation effect on energy evolution of surrounding rock was studied, and DESR decayed exponentially with the increase of supporting intensity. The equations of absorbed and limit stored energy were derived under the condition of “support-surrounding rock” collaboration deformation. The energy criterion of supporting to control surrounding rock stability was established, inverting the roadway supporting parameters, which had been successfully applied to field engineering practice and achieved satisfying control effect. The research achievements yield insights into supporting design from the point of regulating DESR.