Liquefaction and Post Liquefaction Response of Coal Ash Using Cyclic Simple Shear

This study explores the effect of relative compaction (RC) on liquefaction and post liquefaction response of coal ash simulating the conditions for highway/railway embankments and ash dykes in the disposal sites. Coal ash specimens were prepared at different relative compaction i.e., 86%, 90%, 92%, 95% and 100%. The specimens were firstly sheared under cyclic loading conditions to study the liquefaction response of coal ash, which then allowed to reconsolidate. After reconsolidation, the specimens were sheared under simple shear monotonic loading conditions to evaluate the post liquefaction response of coal ash. It was found that the specimens with lower RC liquified at the lower number of loading cycles. The shear modulus was found to decrease with the increase in the number of loading cycles for all the specimens. The shear modulus was also obtained to be lower for 86% RC specimens as compared to 100% RC specimens. The damping ratio was obtained to be almost constant with the increase in the number of loading cycles. Also, the variation in damping ratio for specimens with different RC was observed to be insignificant. Post liquefaction stress-strain behaviour of specimens indicated the significant change in shear stress response as compared to the specimens with no cyclic history. Post liquefaction pore water pressure response indicated a more dilative response as compared to pre liquified specimens.