弱胶结软岩巷道围岩应力与位移分布规律及支护技术

Distribution law of stress and displacement of surrounding rock in shallow-buried weak-cemented soft rock roadway and its support practice

针对西部浅埋弱胶结软岩巷道的复杂地质条件,基于X射线衍射试验、电镜扫描、岩石力学物理试验与现场监测,揭示了西部浅埋弱胶结软岩巷道围岩变形破坏失稳机理。根据巷道围岩大变形破坏特征,建立了FLAC3D数值模型,模拟演化了弱胶结软岩巷道的围岩应力位移分布规律和塑性区范围,研究结果表明:弱胶结软岩巷道围岩最大主应力决定了巷道围岩的破坏深度,且随围岩深度近似呈"へ"形分布;巷道围岩不同方向深部变形s与巷道表面距离h呈负指数衰减变化的关系。通过对比分析,数值模拟塑性区范围和地质雷达探测松动圈厚度基本一致,从而为弱胶结软岩巷道围岩稳定性分析及支护加固方案设计提供了科学指导。最后针对弱胶结软岩巷道塑性区范围,提出了"锚网喷主动支护+36U型钢支架+全断面锚注"的联合支护技术,现场监测结果表明改进的支护方案可以有效控制巷道围岩变形及塑性区的扩展,保证了巷道的长期稳定及安全。

Based on the geological conditions in shallow-buried,weak-cemented soft rock in Western China,the failure mechanism of mine roadway is revealed by the X-ray diffraction,electron microscopy,rock mechanics test and on-site monitoring;FLAC3 Dnumerical simulation model is established to simulate the stress distribution, surrounding rock displacement and range of plastic zone in mine roadway according to the large deformation theory of mine roadway. The results show that the maximum principal stress of the surrounding rock of weak cemented soft rock roadway determines the failure depth of the surrounding rock,which is approximately distributed with the depth of the surrounding rock in the shape of "へ". The relationship between the deep deformation s in different directions of the surrounding rock and the surface distance h of the roadway is negative exponential decay. The accord of plastic zone range in mine roadway is proved true by comparing the FLAC3 Dsimulation and GPR exploration,giving a guide for the stability analysis,design of supporting and reinforcement scheme of the roadway surrounding rock in weak-cemented rock. Finally,according to the range of the plastic zone in weakcemented rock roadway,the technology of combining support of anchor net spray active support +36 U steel support+full section anchor injection is proposed to determine the plastic zone range of mine roadway in weak-cemented rock,which can control the surrounding rock deformation and the plastic zone expansion.