Prof. D. N. Singh

SUCHIT DATTATRAYA GUMASTE

Ph. D.
Indian Institute of Technology Bombay, Powai, India suchitgd@rediffmail.com

DETERMINATION OF FABRIC OF FINE-GRAINED SOILS

Efforts have been made in this study to determine fabric (i.e., arrangement of soil particles and distribution of pores) of fine-grained soils that influences their engineering properties. For this purpose, a novel methodology based on impedance spectroscopy, which can be employed to measure electrical conductivity of the soil specimens, in their undisturbed, remolded and sedimented states that too in two orthogonal directions, has been developed. The directional dependency of electrical conductivity, defined as electrical anisotropy, has been expressed as 'anisotropy coefficient' and its utility and importance in defining the fabric anisotropy has been demonstrated. The results obtained from this methodology have been critically evaluated vis-a-vis those obtained by employing Scanning Electron Microscopy and Mercury Intrusion Porosimetry, which yield the fabric and the pore-size distribution of these specimens, respectively. It has been demonstrated that the proposed methodology, which is a non-destructive and non-invasive technique to determine soil fabric, is quite efficient and yields results easily and quickly. Further, by employing this methodology a classification scheme for defining the fabric of the fine-grained soils has been developed. It has also been demonstrated that based on various parameters such as particle size distribution, Liquid to Solid ratio, mineralogical composition of the soil, the pore fluid chemistry, self weight consolidation and thermal energy, different fabrics (flocculated to dispersed) get developed, which can be quantified in terms of anisotropy coefficient and the mean pore diameter.