Stability of Colluvial Slopes

这项研究计划研究建立在堆积层上的天然和人造斜坡的不稳定性。(冰川由残留土壤和运输土壤的混合物组成)当这种材料是斜坡的一部分时，由于重力引起的持续下坡运动，混合物持续处于接近破坏的状态。由于崩塌是一种非常常见的地表沉积物，这种破坏模式对建立在这种材料上的大量天然和人造斜坡的建立、运行和/或扩展具有重要的影响。这种不稳定的例子包括1996年3月俄亥俄州135英亩的垃圾填埋场的斜坡崩塌--城市固体废物填埋场有史以来最大的斜坡崩塌--以及1981年9月圣路易斯大坝的上游斜坡崩塌。基于这些和其他最近的案例，似乎天然和人造斜坡下面的粘性崩塌材料中可以调动耗尽的残余抗剪强度，不利的影响是需要一个平坦得多的斜坡来设计以抵御破坏。这导致天然斜坡上可供开发的区域较小，通过限制扩展或要求从扩展区域和/或现有废物下昂贵地挖掘堆积物，减少了填埋场的空域或容量。该项目包括实地案例研究以及分析和实验技术的结合。这项计划的目标之一，是为建造/扩建天然及人造斜坡而制订设计建议。

This research program addresses the instability of natural and man-made slopes founded on colluvium. (Colluvium consists of a mixture of residual and transported soils.) When this material is part of a slope, the mixture is continually in a near-failure state because of constant downslope movement caused by gravity. Since colluvium is a very common surficial deposit, this failure mode has important implications for the creation, operation, and/or expansion of the large number of natural and man-made slopes that are founded on this material.Examples of such instability include the March 1996 slope failure of a 135-acre landfill in Ohio -- the largest slope failure ever in a municipal solid waste landfill -- and the upstream slope failure of the San Luis Dam in September 1981.Based on these and other recent case histories, it appears that a drained residual shear strength can be mobilized in cohesive colluvial materials underlying natural and man-made slopes, with the adverse effect that a much flatter slope is required to design against failure. This results in a smaller area for development in natural slopes and reduced airspace or capacity in landfills, either by limiting the expansion or requiring the expensive excavation of colluvium from the expansion area and/or from under the existing waste.The project includes a study of field case histories and a combination of analytical and experimental techniques. A goal of this project is to develop design recommendations for the construction/expansion of natural and man-made slopes founded on colluvium.