Sub-surface profiling using electrical resistivity tomography (ERT) with complement from peat sampler

Abstract

The pre-construction works include the geotechnical investigation which comprises the surface and subsurface exploration. Sub-surface exploration often causes several difficulties such as high cost, time consuming, localized investigation and intrusive. Furthermore, investigation on soft soil such as peat often raises several additional problems such as high risk of sample disturbance, difficult access for heavy equipment and inconsistent data due to the heterogeneity of peat. The advancement of geophysical method such as Electrical Resistivity Tomography (ERT) allows the determination of soil profile in time-efficient manner, economic, larger volume of investigation and non-intrusive. This study focused on the determination of soil profile, particularly peat layer using ERT method with complement from peat sampler data. The study was conducted at Parit Nipah, Johor. The results revealed a high accuracy profile delineated by the ERT method with only less than 8% percentage of error as compared to peat sampler profile. The comparison between Schlumberger and Wenner array showed that; the Schlumberger showed superior depth of penetration, with almost 3 times deeper penetration relative to Wenner. The Schlumberger array is also able to delineate lateral variation within the peat layer. Finally, the resistivity value of peat obtained ranged from 100.8 to 139.5 ohm.m with both arrays having consistent results.