A Case Study on the in-situ Matrix Suction Monitoring and Undisturbed-Sample Laboratory Test for the Unsaturated Colluvium Slope

Abstract

ABSTRACT Huafan University is located on the slope of the Ta-Lun Mountain area. The slope surface in this area is a colluvium soil cover layer with loose non-uniform particles, with high permeability. Because it is situated above a rapidly changing water table, the pore water pressure varies dynamically, depending on the weather conditions. In the dry season, most of the topsoil behaves in the unsaturated condition such that the matrix suction in the soil increases its shearing strength. In contrast, when heavy rainfall occurs, the seepage by precipitation tends to destroy the existing matrix suction. This reduction in soil strength frequently results in slope failure. This study, focuses on the variation of matrix suction of the colluvium soil in different precipitation conditions with varying vegetation at the campus of Huafan University. The analysis of the in-situ monitoring results and the laboratory test results for the undisturbed specimens taken from the field, with shearing strength and matrix suction taken into account. It is expected the results to be a useful reference for disaster protection on slopes.