EVALUATION OF SUBSURFACE PROPERTIES USING RESISTIVITY DATA FOR _HILL ROADS

Abstract

The planning and construction of roads in hilly areas is an important. and difficult task due to rough terrain, scarce availability of desired type of construction material, stableside slop eetc. There are various locations in hilly areas which are prone to land slides and rock falls subsidence. If a road is constructed over these areas, it requires high maintenance cost throughout the year. High water table also causes many problems like settlement, frost action land slide and thus affects the stability of the payment. Therefore for efficent planning of hill roads evaluation of the subsurface properties is essential. It is also desirable that the method used for estimating the subsurface properties is optimal in terms of speed, economy and accuracy. Of the various geophysical methods electrical resistivity method, in which the electrical conductivity of a formation is measured, had found maximum applications in Highway Engineering. mainly because of its low cost, easy operation and speed. In the present study vertical electrical sounding (VES) has been carried out in a hill region between B.H.E.L. and siwaliks. V,E.S. data have been analysed to estimate resistivity and then after permeabitity. On the basis of laboratory experimentation a theoretical curve has been developed to estimate the field permeability from laboratory based resistivity of the soil.