Browsing by Author "Teli, Sujay"

The present experimental study evaluates the overburden correction factor (Kσ) of different pond ash samples under earthquake loading for liquefaction analysis. A series of 54 stress-controlled cyclic simple shear tests was conducted on pond ash specimens at different overburden pressures and cyclic stress ratios. Cyclic resistance ratio (CRR) was evaluated for each pond ash sample at different overburden pressures using two criteria based on maximum excess pore water pressure and double amplitude shear strain to evaluate the Kσ. The Kσ values obtained for the pond ash were compared with the Kσ values for natural soils (clean sand and sand-silt mixtures). The cyclic resistance ratio (CRR) and Kσ values were observed to decrease with an increase in overburden pressure from 50 kPa to 100 kPa, and a further increase in overburden pressure to 150 kPa led to an increase in CRR and Kσ values for pond ash specimens with fine particles dominated matrix. However, an opposite trend was observed for pond ash specimens with coarse particles-dominated matrix. The unique response of Kσ values for pond ash was found to be significantly different from the already available Kσ response for natural cohesionless soil (clean sand and sand-silt mixtures) as it unavoidably included the effect of OCR and void ratio along with the vertical overburden pressure.

The deposition process of ash slurry in the disposal site results in segregation of bottom ash and fly ash particles. Pond ash collected from different locations of the same disposal site can have varying proportions of bottom ash and fly ash particles. The present study evaluates the effect of varying bottom ash content on the liquefaction response of pond ash. A series of stress-controlled cyclic simple shear (CSS) tests were performed on pond ash with varying bottom ash content (0%, 20%, 40%, and 50%). The loading cycles were applied in the sinusoidal form at 1 Hz frequency and 0.12 cyclic stress ratio (CSR) under 100 kPa vertical overburden stress. All the specimens were prepared at their respective 95% maximum dry density (MDD) and optimum moisture content (OMC). The number of loading cycles required to liquefy the specimen was evaluated based on two criteria: i) Excess pore water pressure ratio, ru≥0.9, and ii) Double amplitude shear strain, γDA≥7.5%. Dynamic properties such as shear modulus (G) and damping ratio (D) were also evaluated for pond ash with varying bottom ash content. It was observed that the liquefaction resistance increased with an increase in bottom ash content. The generation of shear strain with the number of loading cycles was found to be more gradual with an increase in bottom ash content. The specimen with 0% bottom ash content showed a sharp decrease in shear modulus with an increasing number of loading cycles as compared to the specimen with 50% bottom ash content.