Pore Pressures in Debris Failure Initation

摘要

Soil filled bedrock depressions, or soil wedges, with typical dimensions of less than 10 x 10 x 2 meters, have been identified as major initiation locations for debris of failures in the Pacific Northwest. The ultimate stability of a soil wedge is determined by the pore-water pressures generated during rain storms by the convergence of shallow ground-water flow into the bedrock depressions. Analysis of the flow convergence is complicated by two factors, which are that the convergence is intrinsically three-dimensional which dictates a numerical approach to the analysis, and that the flow into a depression does not constitute an isolated system, but is only a small element of the overall hill-slope hydrology.