Soil Properties and Behaviour Studies using Joint-interpretation of 4-D Electrical Resistivity Tomography and Soil Mechanics Methods in Penang, Malaysia

Summary The paper presents the integration of geophysics and soil mechanics methods in investigate the properties and behaviour of clayey sand soil properties for slope study from March until April. The geophysical method used in this study is 4-D electrical resistivity tomography (ERT), meanwhile soil mechanics used several laboratory tests, namely direct shear, moisture content, porosity, plastic limit and liquid limit. The infield survey using 4-D ERT was conducted for three different months and soil samples were collected along the survey line. The model resistivity with topography obtained showed all the ERT results gave a good results with RMS error between 2.4 - 2.4 %. Based on the model resistivity results, the subsurface of slope area can be divided into two main zone, dry clayey sand soil (100 - 550 ohm.m) and clayey sand soil (550 - 1300 ohm.m). The model resistivity results showed there are changes in electrical properties of soil, which associated with the moisture content, porosity and structure of soil itself during the three months of investigation period. In conclusion, the integration of both ERT and soil mechanics methods are capable to investigate the clayey sand soil’s properties and its behaviour during three months period.