Geotechnical synthesis of 2D-Electrical resistivity tomography of geomaterial – laboratory model study / Zainab Mohamed and Nurbaiyah Mohamad Noh

In this paper, a laboratory scale model study was conducted on interbeded geomaterial using electrical resistivity instrument. The electrical resistivity value of individual material was determined and modeled as mass scale. The tank was filled with composite geomaterial constituted of interbedding of cement mortar as hard layer and residual sedimentary soil. Forty-one copper electrodes of 15 cm long were used and installed at 4 cm spacing in the tank. The composite geomaterials were labeled as Model 1, Model 2 and
Model 3, where they were referred respectively to interbedding of hard layer and layers of residual soil at natural dry state and wet state. The electrical resistivity terrameter was used to obtain the georesistivity pseudo-section by adopting Werner protocol. The georesistivity pseudo-sections were derived from 3 models simulated the subsurface of rock mass in humid tropic environment.The objective was to synthesize the composite georesistivity
pseudo-section based on geo-engineering principle. It was observed that
the pseudo-section of the composite geomaterial was represented by
range of colors with range of georesistivity values. The horizontal bands
of color differentiated the georesistivity of models vertically but constant
in horizontal direction. The georesistivity value at material scale was
comparable to the range of georesistivity values derived from the 2D
electrical resistivity pseudo-sections. The contrasts in the conductivity of clay
fraction, silica and electrolytes have differentiated the electrical resistivity
pseudo-section of sandy soil mass and cement mortar hard material.