Statistical Rainfall Risk Estimating Method for a Deep Collapse of a Cut Slope

Abstract

Embankment and cut slope collapses along railways sometimes occur under heavy rainfall caused by typhoon etc. and have influence on safe operation of the railroad trains. The risky locations along the railway must be identified in order to safely control operations for each railway line. For this purpose, a practical damage estimation method, which accurately predicts the hazard of slope collapse and can be used simply by railway workers, is a desirable development goal. This paper deals with a discriminant method between a surface and a deep collapse for cut slope collapses, and a critical rainfall prediction method for the deep cut slope collapse during heavy rainfall. The critical rainfall is given by a multiplying an accumulated rainfall by an hourly rainfall, which have the powers 0.4 and 0.2 respectively, using a multivariate analysis. The critical rainfall is then given by external variables such as geometrical and structural conditions for the cut slope, soil and rock, catchment and experiential rainfall conditions. This evaluation indicates that the accumulated rainfall has more influence than the hourly rainfall on the deep collapse of cut slopes. Since it was confirmed that the risk estimation standard proposed satisfied some observed values for deep collapses, it is considered that it can be used not only for planning the disaster mitigation procedures along railway right of way but also for predicting cut slope collapse due to concentrated rainfall.