1887

Abstract

ters. Described sequence of materials imposes great difficulties in geotechnical and civil engineering investigations and site characterisation. The absence of any geological logic in covering materials together with sharp lateral variations, necessitates enormous amount of drilling, trenching and other standard geotechnical investigations. In order to reduce the amount of the standard exploration techniques it is inevitable to apply the appropriate geophysical methods for detecting and properly defining the subsurface structure. After testing several methods it was decided to use the combination of the electrical scanning and GPR techniques although the application of GPR remained questionable regarding it’s usefulness at the depth levels corresponding to the low resistivity garbage due to signal attenuation. The combined investigations were projected in such a way that the maximum depth of investigation of electrical scanning method amounts about 15 meters and that of GPR about 5 meters. It was expected to achieve the best possible horizontal and vertical resolution with shallow GPR investigations by using antenna frequencies of 500 MHz and 300 MHz depending on the dielectric and resistivity properties of the material deposited over garbage. Electrical scanning method employed 35 to 51 equispaced electrodes (4 meters apart) at six depth levels. The maximum depth of investigation of about 12 meters was sufficient to rich natural soil, consisting of marl and the horizontal resolution was excellent in delineating sharp lateral resistivity variations. Vertical resolution was in accordance with the limitation of resistivity method. In Fig. 1. the results obtained by electrical scanning method show the excellent coleration with the results of the standard geotechnical methods of investigation.

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/content/papers/10.3997/2214-4609.201406536
1999-09-06
2020-03-29
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