Characterization and Geotechnical Properties of Penang Residual Soils with Emphasis on Landslides

The predominantly hilly terrain of Penang Island combined with average maximum daily temperatures ranging between 27-35°C and peak rainfall as high as 647 cm makes the overall area potentially susceptible to landslips. Over the recent past construction industry has shown a rapid growth mainly due to increase in the inflow of international tourists and other economic reasons. Eventually, the magnitude of disaster associated with landslides has also increased and that is one of the major concerns of engineering geologists and geotechnical engineers. With this background this paper attempts to characterize the largely granitic residual soils of Penang Island by discussing the nature, structural features, engineering behavior and field properties of soil samples extracted from 8 sites. These sites are distinctly chosen from a database of 31 sites for they are located over different prime geological formations. The mean values of various design properties at different depths are calculated and plotted to identify the property trend with depth and important behavioral features relevant to landslides are discussed. Similarly, compression index values are plotted against initial void ratio and liquid limit separately and resulting correlations are compared with the established ones. Correlations given by Azzous are found to hold good. Lastly, in the light of the lessons learnt from the past landslides and the current characterization results some improvements regarding slope instability problem are discussed.