Prof. D. N. Singh

HANUMANTHA RAO B

Ph. D.
Indian Institute of Technology Bombay, Powai, India hanuma_bendadi@iitb.ac.in

DETERMINATION OF HYDRAULIC CONDUCTIVITY OF UNSATURATED SOILS

Various in-situ and laboratory techniques, empirical relationships and Pedo-transfer functions (PTFs), have been developed by earlier researchers to establish soil-water characteristic curve (SWCC). However, most of these techniques are elaborate, cumbersome, time consuming, employ expensive experimental setups and resort to destructive and invasive methods of determining soil moisture content. Also, though the SWCC so obtained can be employed for estimating hydraulic conductivity of unsaturated soils, which is an indirect method, and they are soil specific. This calls for development of techniques that can be employed for direct determination of hydraulic conductivity of unsaturated soils, under laboratory and field conditions.
? With this in view, efforts were made to create unsaturated state of the soil mass by (i) employing a geotechnical centrifuge, (ii) imposing thermal flux and (iii) employing a pressure membrane extractor (PME). And, for determining the instantaneous moisture content of the soil mass electrical measurements (i.e., voltage across two points in the soil mass) were conducted. The utility of these techniques for establishing the SWCC, quite easily and rapidly, and that too in a non-destructive and non-invasive manner has been demonstrated very clearly. In addition, attempts have been made to determine hydraulic conductivity of the soil mass in its in-situ state by conducting lysimetric studies.