Correlation between degree of saturation and soil shear strength of eluvial deluvial soil slopes along National road 49, Thua Thien Hue province, Vietnam

Abstract

Landslides are common in the mountainous regions of Thua Thien Hue province (Vietnam) during rainy seasons, especially along National Road 49. The shear strength of soil is an essential parameter for landslide susceptibility assessment. This study aims to investigate the relationship between the degree of saturation and the shear strength by using the unconfined compression test for the eluvial deluvial soil slopes in the weathering crusts of Long Dai formation, Ben Giang – Que Son complex and Dai Loc complex, along National Road 49. The soil shear strength in [five] areas where slope landslides occur varies from 0.56 to 0.17 kG/cm² when the degree of saturation increases from 58.5 to 97.4%. At the same time, the results also show that the shear strength and the degree of saturation are correlated from strong to very strong degrees (R > 0.7). The results are a useful reference, helping to clarify the characteristics of the shear strength according to the degree of saturation and making the assessment of slope stability along the studied road better in future.