基于激光扫描的巷道不规则围岩表面对喷射混凝土支护特性影响分析

Analyzing Effects of Uneven Rock Surface on Performance of Shotcrete Support in Roadway Based on Laser Scanning

为研究钻爆法施工巷道围岩表面形状特征对喷射混凝土支护特性的影响,以贵州锦丰金矿为工程背景,采用三维激光扫描仪对巷道围岩表面进行扫描,建立巷道三维模型,使用三维软件剖取巷道实际断面形状,对断面的几何特征进行分析。对标准断面和实测断面分别建立数值模型,对比分析了喷射混凝土的内力变化及其对围岩的支护效果,结果表明,巷道不规则围岩表面导致喷射混凝土剪力和弯矩明显增大,而对轴力的影响相对较小;巷道围岩凹坑部位多为负弯矩极值点,凸起部位多为正弯矩极值点;在轴力和弯矩共同作用下,凸起部位的喷射混凝土安全系数明显降低,对围岩的支护作用减弱,围岩容易出现拉伸破坏。

Guizhou Jinfeng Gold Mine was taken as an engineering example for investigating effect of geometric features of rock surface on the performance of shotcrete support in the roadway constructed by drilling and blasting.The rock surface of the roadway was scanned by using a 3D laser scanner,and a 3D geometric model was established for the roadway.The actual shape of cross⁃sections was created by slicing the geometric model with a 3D software for analyzing the geometric features.With numerical models respectively established for the designed and actual sections,the variation in internal forces of the shotcrete and its supporting effect for the surrounding rock were analyzed.The results show that uneven rock surface of a roadway can lead to significant increase in the shear force and bending moment of shotcrete,but relatively small effect on the axial force.It is found that concave part of surrounding rock in a roadway is subjected to maximum negative bending moment,while convex part is mostly subjected to maximum positive bending moment.Under the interaction of axial force and bending moment,the shotcrete on convex part has an obvious lower safety factor,leading to weakened support to the surrounding rock,thus tensile failure is prone to occur.