Dynamic Characterization of Settled Pond Ash Using Measured Shear Wave Velocity (Vs) and SPT-N Values: Correlation Between Vs & N

Reclamation of abandoned ash ponds for the construction of engineered facilities like gas based power plants, light weight structures, or parking lots often requires site specific response analysis to assess associated seismic hazards in seismically active areas. This requires dynamic site characterization of the ash ponds. In the present study, shear wave velocity measurements (Vs) from SASW technique are used for in-situ dynamic site characterization of the ash ponds. Measuring Vs on the ash ponds is difficult compared to the soils, as the ash deposited in the ponds is often in a very loose state and in swampy conditions. Shear wave velocities measured at three hydraulically deposited ash ponds in Delhi are presented. An empirical correlation between SPT (N) value and measured Vs is also developed. The authors observe that the developed correlation between N and Vs is significantly different than those reported for the soils, which signifies the importance of dynamic characterization of ash ponds using shear wave measurements rather than using empirical relations developed for soils.