Hysteresis effects on shear strength of an unsaturated laterite soil
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Date
2019
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Publisher
Universiti Teknologi Malaysia
Abstract
Landslides are among the common problem encountered in tropical regions. Water content and suction basically have influence on the permeability and shear strength of unsaturated soils slope. This study investigated the relationship between the soil water characteristic curve and the shear strength of laterite soil with respect to matric suction. In additional, it also explored the shear strength of laterite soil with respect to hysteresis effect. The soil hydraulic parameters were then estimated by using data from both the infiltration and redistribution phases for cases in which hysteresis was considered but restricted to the simplifying assumption. Pressure plate is the most common method in soil water characteristic curve method to find the drying path but for wetting curve, the modified pressure plate is needed. Based on the result, it was found that the filter paper method is suitable than pressure plate method and can compose high matric suction until 43,021.94 kPa compared to pressure plate that is only limited until 1,500 kPa. The equilibrium times of the filter paper is dependent in suction source, contact condition and suction level. The differences in hysteresis curve and relationship results are also discussed. Hysteresis result between 702.63 kPa to 43,021.94 kPa is obtained for laterite soil, utilizing filter paper method with matric suction. The shear strength and factor of safety due to hysteresis for laterite soil have also been demonstrated, where the factor of safety for laterite soil range from 1.55 until 5.00. New equation for hysteresis also has been developed. The finding from this study indicates that filter paper method can be used to produce both drying and wetting curve which can be used for slope stability analysis.
Description
Thesis (PhD. (Civil Engineering))
Keywords
Shear strength of soils, Slopes (Soil mechanics)—Stability, Hysteresis