Application of cohesive soil flow limit and slope critical flow angle

Abstract

This study investigates the relationship between moisture content in cohesive soils and critical slope failure angles during spontaneous liquefaction. We adapted the liquid limit test apparatus, originally developed by A. Atterberg in 1911, into a liquid-flow limit test apparatus. Soils from three actual cases of slope failures were used in experiments. The moisture content at which soils undergo spontaneous liquefaction was designated as the flow limit (FL), corresponding to the downslope angle of circular failure. This value represents the critical sliding angle due to soil saturation and the maximum slope angle for exposed mudrock or clay slopes. Beyond this critical FL angle, all vegetation is susceptible to loss due to soil liquefaction. The consistent test results observed reaffirm that different soils exhibit similar spontaneous liquefaction angles and FL behaviour.