基于结构面网络模拟技术的边坡楔形体分析方法研究

山区高速公路的建设日益增多,岩质高边坡越来越多地出现于工程建设之中。对于完整性较好的岩质边坡,楔形体破坏是常见的边坡破坏类型之一。由于楔形体数量多,规模及稳定性都差别较大,位置也不固定,在勘探过程中难以确定,给边坡稳定性分析及设计带来很大不便。依据楔形体几何结构条件,将楔形体分成Ⅰ型(出现于坡肩,由两条相交的结构面与坡顶、坡面共同包围形成)和Ⅱ型(出现于坡面,由三条结构面与坡面共同包围形成),利用结构面三维网络模拟技术,对岩质边坡工程中楔形体进行随机分析和分步筛选,发展了搜索楔形体及其稳定性评价方法,用以指导边坡评价、设计和加固治理,并在厦沙高速的边坡稳定性分析中尝试应用。结果表明:对于岩质边坡,可根据楔形体的几何构成条件,利用楔形体分析方法,可以从岩体三维结构数字模型中抽取楔形体,并进行楔形体稳定性分析;通过Ⅰ型楔形体和Ⅱ型楔形体的对比,当边坡坡高较大时,Ⅱ型楔形体数量远远大于Ⅰ型楔形体,因此应更重视对Ⅱ型楔形体的研究。

Stability analysis of wedges of rock slopes based on 3D network simulation of structural surface

High rock slopes in mountainous areas are increasingly encounted with the construction of expressways. As one of frequently observed stablility issues of high rock slopes, wedge failure differs greatly in scale and stability as well as location distribution. Such characteristics cause significant difficulty in the slope stability analysis during exploration and the subsequent project design. According to their geometric structure, the wedges are divided into two types: I-type wedges on the slope shoulder and surrounded by two intersecting structural surfaces, top and slope surface, and II-type wedges on the slope surface and surrounded by three structural planes and slopes. By means of the three-dimensional network simulation technology of structural surface, the random analysis and step-by-step screening of wedges in rock slope engineering are carried out. The methods for searching wedges and evaluating their stability are developed to guide the evaluation, design and reinforcement of slopes. The applicability of this developed method is demonstrated by a case study, the practical application in Xiamen-Shaxian Expressway. The research results demonstrate that for the wedge analysis of rock slopes, it is possible to draw wedges from the 3D structural digital model for rock mass and analyze their stability based on the three-dimensional network simulation technology of structural surface. Comparison of I-type and II-type wedges indicates that when the slope is higher, the number of II-type wedges is far greater than that of I-type ones, therefore, the II-type wedges cannot be ignored in the slope projects.