泥化弱胶结软岩巷道底板变形破坏机理分析

Anslysis of deformation and failure mechanism of roadway in the mud weakly consolidated soft rock strata

煤矿软岩巷道极易发生变形破坏,底臌量大是其重要的特征.以新上海一号煤矿副井绕道巷道为工程背景,研究了泥化弱胶结软岩巷道底板的变形破坏机理.从现场选取岩样进行室内实验,研究发现围岩具有强度低、胶结程度差、遇水泥化软化、吸水膨胀等特殊的物理力学性质;结合现场监测数据和数值模拟结果,巷道底板变形速度快、持续时间长、总变形量大且不收敛,是以流变和膨胀为主的非线性大变形;底板破坏与变形增加的趋势一致,塑性区发展速度前期快,后期慢,但范围不断扩大;通过机理分析,巷道底板的变形破坏是在水和构造应力耦合作用下的恶性循环的结果,底臌为流动膨胀复合型,治理的关键是治水和加强支护.以上述理论为指导,对巷道支护方案进行了优化,监测数据显示底板变形破坏得到了有效控制.

Deformation and failure can easily happen in soft rock roadway of coal mine, and one of the most important features is large deformation of the floor. In order to study the deformation and failure mechanism of roadway in the mud weakly consolidated soft rock strata, the bypass roadway of auxiliary shaft in the new Shanghai No. 1 Coal Mine was taken as the engineering background. Through mechanics experiments to rock samples, special physical and mechanical property of surrounding rock were discovered, including low strength, poor cementation, muddying and swelling in the presence of water. Combining the results of situ monitoring and numerical simulation, deformation of floor of roadway was featured with fast speed, lasting long, large total volume and no convergence, and the deformation was large nolinear deformation mainly composed of flowing and swelling. Tendencies of failure and deformation were the same, expanding speed of plastic zone was faster in early stage than later stage, but the zone kept expanding. Through analyzing their mechanism, deformation and failure of the floor in roadway was the result of vicious circle under coupling effect of water and tectonic stress. As the floor heave was of the type which was integrated with flowing and swelling, water controlling and support reinforcing were key measures which were taken to deal with floor heave. Based on the study above, the support scheme of the bypass roadway of auxiliary shaft was optimized and the monitoring data showed that deformation and failure of the roadway were effectively controlled.