某倾倒边坡开挖下的变形特征及加固措施分析

以皖南某高速公路一个反倾边坡为例,在详细地质调查基础上分析了边坡以倾倒-滑移为主要特征的倾倒变形力学机理。调查结果显示在边坡原有倾倒变形的基础上,开挖爆破等工程扰动首先使开挖面顶部出现倾倒变形并伴有后缘拉裂隙,同时坡体内部断续结构面逐渐贯通,最下级台阶面出现外鼓等。上述现象的出现显示出边坡具有整体失稳破坏的趋势。在上述地质概念模型基础上,应用离散单元法对边坡变形全过程进行模拟,验证上述变形破坏机理,并揭示了边坡在深度方向上的变形分区现象,即倾倒-折断区、强烈倾倒区、倾倒影响区和正常岩层区。

On the deformation characteristics and reinforcement measures of a toppling slope under excavation

Based on geologic investigation on an anti-dip slope of an expressway in southern Anhui Province,the mechanism of toppling deformation was analyzed for the slope characterized by toppling-sliding deformation.The evidences showed that toppling deformation firstly happened on the top of the excavated surface with tensile cracks,which arose from excavation disturbance and developed along the old toppling deformation patterns.Meanwhile,inner discontinuities were connected together step by step,and the lowest part of the slope swelled outwards.The whole slope showed a tendency of toppling-sliding failure.According to the above geologic conceptual model,the whole deformation process of the slope was simulated with discrete element method,which reappeared the phenomena and mechanism mentioned above.It also reveals that the deformation can be divided into four zones,that is,toppling-fracturing zone,intense toppling zone,toppling influencing zone and normal rock zone.Countermeasures were made according to above model and the results of numerical simulation.