大采深巷道底板软弱夹层对底鼓影响数值分析

Simulation analysis of influence of floor weak interlayer on floor heave in deep mining roadway

为研究巷道底板围岩中软弱夹层对巷道底鼓的影响,采用理论分析和数值模拟施相结合的方法,依据底板夹层不同分布位置及个数构建了8种模型,对比分析了夹层对巷道底鼓量、底板塑性区、应力分布规律的影响。结果表明:1)随着夹层数量的增加,巷道底鼓量逐渐增大,当底板中存在3层夹层时巷道底鼓量是无夹层时的1.88倍;当存在相同个数夹层时,浅部夹层和深部夹层对底鼓影响较大,中深部夹层次之。2)浅部夹层弱化了底板围岩强度,使底板拉破坏深度增大;中深部及深部夹层吸收了不平衡能量,在其层面下附近围岩中形成一定的原岩区;深部夹层较浅部夹层有减小围岩塑性区的作用。3)随着夹层数量增加、夹层距离巷道底板表面增大,底板围岩中应力集中区范围缩小。4)夹层阻隔了地应力均匀分布,致使深部夹层附近形成一定程度应力集中。结合数值模拟结果可知针对底板含弱夹层巷道,需加固底板以控制底鼓。

In order to analyze the influence of floor weak interlayer on floor heave in roadway sur-rounding, eight models based on different position and number of weak interlayer in the floor have been constructed by combining numerical simulation with theoretical calculations. The influence of interlayer on floor heave deformation, plastic area and stress distribution law has been analyzed. The simulation results show that：1） The volume of roadway floor heave increases gradually with the increase of inter-layer number, and when there are 3 interlayers in the coal floor, the volume of roadway floor heave is 1.88 times than the volume without interlayer, while when there are the same number of interlayer, shallow part and deep interlayer have greater influence on the floor heave in deep level than mid-dle-deep interlayer. 2） The strength of floor surrounding rock is weakened by partial shallow interlayer, which causes the increase in the tensile failure depth of floor. Unbalance energy is absorbed by middle-deep and deep interlayer, so that the original rocks area form in the vicinity of the level of surrounding rock. Deep interlayer can decrease plastic area compared with shallow part interlayer. 3） The stress concentration zone decreases gradually in floor surrounding rock with increase of interlayer number and distance between interlayer and surface of roadway floor. 4） Stress uniform distribution is separated by interlayer, and stress concentration near deep interlayer, in a manner, are formed. According to the sim-ulation results, it is concluded that the roadway with weak interlayer in the floor must be reinforced in order to control floor heave.