Postearthquake Reconsolidation Settlement of Stone Column-Treated Liquefiable Sand

Abstract

Stone column is a convenient technique employed to enhance the liquefaction resistance of sandy soil subjected to seismic loading. After the end of an earthquake, the pore water pressures that generated during the earthquake commence to discharge through the stone column, which causes the progressive settlement of the soil surface. In the present paper, a generalized mathematical model is proposed to evaluate the postearthquake settlement of the stone column-treated liquefiable sand surface by adopting different factors such as well resistance, stiffness, smear, and clogging. The well-resistance effect is incorporated by taking into consideration the finite permeability of the column. The effect of stiffness is introduced by considering the difference between the volumetric compressibility of the stone column and soil. The parabolic distribution pattern of the radial permeability and compressibility of the soil within the smear zone are considered in order to quantify the smear effect that occurs during the construction of the column. The clogging effect of the stone column responsible for the gradual decrease in the permeability of the column due to the movement of fines into the pores of the column during dissipation of the pore pressure is also considered in the analysis. The model is verified by comparing its results with the existing field experimental data. It is observed that the postearthquake settlement of the soil is not significantly affected due to the change in the compressibility of the smeared soil. However, the permeability of the smeared soil significantly influences the postearthquake settlement. The rate of settlement significantly decreases because of the clogging of the stone column.