Journal of Natural Disaster Science

CASE STUDY OF SLOPE STABILITY DURING RAINFALL

Minoru MATSUO
Professor, Department of Geotechnical Engineering, Nagoya University, Nagoya
and
Hisashi SUZUKI
Lecturer, Department of Civil Engineering, The University of Tokushima, Tokushima

(Received 1 April, 1988 and in revised form 26 July, 1988)

Abstract

We here discuss the method of slope stability analysis during rainfall applying the laboratory test results of soil samples from the site in a field. Detailed information on the seepage and the strength properties of partially saturated soils as well as the initial and boundary conditions for flow analysis are required if this method is to be applicable to engineering practice. The information and conditions used were obtained from site investigations and laboratory tests of soils that they are directly relevant to the accuracy of the evaluation of the slope failure mechanism when the finite element method is applied to actual case records.

A series of triaxial compression tests for partially saturated soils was made which clarified differences in soil strength produced by variations in exhaust and drainage conditions. The coefficient of permeability of partially saturated soil was estimated by Van Genuchten's Method based on data from the pF test. Analysis of slope stability that incorporated the detailed data referred to above was made of the case records of slope failure using actual rainfall observations. A sudden change in the safety factor of a slope with time was always observed at the very time of slope failure.

Key words

slope stability, triaxial compression test, partially saturated soils, rainfall, case history, seepage analysis