Analysis of influence of air-entry values to unsaturated soil properties

Abstract

Soil slope instability is a grave concern in regions with high annual precipitation, especially in tropical countries. The impact of soil instability on the economies of these countries is severe since it usually causes fatalities and property loss. The research and development of the systems to reduce the impact of soil slope failures by predicting slope failure, monitoring the slope, and early failure warning has made it possible to implement safety measures. Despite the considerable effort to implement these measures, the factors contributing to soil slope instability are complex and have not been explored extensively. The air-entry value (AEV), which is the matric suction, is a critical factor in predicting the risk of slope instability. This paper will analyze the interaction of the basic soil properties and the soil hydraulic properties, also known as AEV. The researchers collected natural undisturbed soil samples from several locations to determine their AEVs which obtained by plate pressure extractor apparatus. The basic soil properties, namely the natural moisture content, particle size distribution and bulk density were determined in the laboratory, and the values were used to determine the correlation between the basic soil properties and the soil AEV. The results show that the soil with higher coefficient of curvature and percentage of sand have lower air-entry values, which mean they could experience disastrous slope failure during heavy rainfalls. This strong correlation underscores the significance of soil hydraulic properties as the critical factor in soil slope instability.