Dynamic Response Analysis Of Shallow Foundation Resting On Coal Ash Deposit

Abstract

The current research presents an experimental investigation on coal ash samples (fly ash, bottom ash, and pond ash) collected from the NALCO thermal power plant and Talcher Thermal Power station, Odisha, India, and a numerical investigation on the dynamic response of shallow foundation on soil and pond ash deposit. Morphological, mineralogical, and geotechnical properties of coal ash (fly ash, bottom ash, and pond ash) samples were extensively investigated. The pond ash sample was chosen for further study because of its unique gradation of all collected samples. It was intended to determine the dynamic characteristics of pond ash subjected to dynamic excitation through laboratory tests and numerical analysis. A set of multiple cyclic triaxial tests were planned and performed on pond ash to examine the influence of test parameters like relative compaction, effective confining pressure, frequency, and shear strain. The properties obtained through the experimental tests were applied in the numerical analysis on pond ash subjected to different seismic excitations, i.e., the Nepal earthquake (Mw: 7.8) and Northeast India earthquake (Mw: 7.5). Liquefaction-induced deformation of pond ash was evaluated from the numerical analysis. newlineInitially, morphological, mineralogical, and geotechnical properties of coal ash (fly ash, bottom ash, and pond ash) were investigated. Then pond ash was subjected to dynamic loads using cyclic triaxial testing equipment. The factors influencing the liquefaction potential of pond ash were evaluated. At low frequency (0.3 Hz), the pond ash specimen takes 87 cycles to liquefy at its most densified state. Also, the maximum dynamic shear modulus was noticed at this stage, i.e., 6534.80 kPa, and the decay was observed at 87 cycles. In addition, the decay in dynamic shear modulus was rapid with the enhancement of cyclic shear strain. The presence of 50% fines and the highly compacted state of the pond ash specimen caused close packing of particles which offered more resistance to shear strain;