高地应力深切河谷卸荷响应及线路工程环境分析

Analysis of Unloading Response of Deep-incised Valley and Line Engineering Environment under High Geostress

为研究高地应力区域由河流深切引起的河谷谷坡岩石卸荷破坏,考虑在水平方向的构造应力,建立高地应力深切河谷计算模型,应用自上而下、逐步卸荷的方法对V形深切河谷进行数值模拟,研究谷坡在卸荷效应下的受剪破坏深度。基于Mohr-Coulomb原理提出剪应力发挥系数f概念,通过绘制f曲线来描述坡体内部剪力状态水平分布。分析结果表明:较之自重-卸荷模型,高地应力区的谷坡岩石卸荷效应更显著,即破坏深度更大;随着先期地应力量值增高,同一高程处的岩石卸荷破坏深度增大;同一量值高地应力作用下卸荷后,随高程降低岩石破坏深度增大,因此,在低高程区域的线路工程地质环境趋于恶劣。据此提出灾害预防措施与线路布置建议。

In order to study the rock unloading failure of valley slope caused by deep-incised river in the area of high geostress,the calculation model of deep-incised valley with high geostress was established by considering the tectonic stress in the horizontal direction.The shear failure depth of valley slope under unloading effect was studied by numerical simulation of V-shaped deep-incised valley with top-down and stepwise unloading method.Based on Mohr-Coulomb principle,the concept of shear stress play coefficient f was proposed and the horizontal distribution of shear force state inside the slope was described by drawing f curve.The results show that,compared with the deadweight-unloading model,the unloading effect of the valley slope rock in the high geostress zone is more significant,i.e.,the failure depth is larger.With the increase of the quantity value of initial geostress,the failure depth of rock unloading at the same elevation increases.After unloading under the action of high geostress of the same quantity value,the failure depth of rock increases with the decrease of elevation.Therefore,the engineering geological environment of the line tends to be bad in the low elevation area,based on which,some suggestions on disaster prevention measures and route layout are put forward.