Collapse behavior of unsaturated remolded granitic residual soil

In the tropical area, most shallow foundations and embankments are involved in dealing with unsaturated soils. Any collapse or settlement in unsaturated soils is determined by two independent stress variables: the applied stress and suction. The massive collapse related to suction changes may lead to unrecoverable damages to compacted earth fills both economic and human loss while this collapse has not been seen in the design. The aim of this study was to investigate the influence of stress states and matric suction on collapse behavior of an unsaturated Malaysian granitic residual soil grade V. A suction-controlled double wall triaxial test was carried out to obtain the axial strain of the compacted specimen during loading and wetting collapse. In addition, there has been an attempt to predict the collapse behavior of the soil by using Rotational Multiple Yield Surface Framework (RMYSF). During loading in imposed suction, the axial strain increased as deviator stress increased. When the soil was inundated and the imposed suction was decreased step by step down to zero, the axial strain was very small at suction close to residual suction. It gradually increased as suction decreased. A massive settlement around 1.92% of the initial height was observed while the soil was nearly saturated. The findings also proved that the RMYSF model is able to predict the collapse behavior of the tested soil sufficiently.