Effect of Shaking Pattern on Reliquefaction Potential of Solani Sand

Abstract

Due to occurrence of reliquefaction in saturated silty sands during successive earthquakes, severe damage to structures is caused, e.g. during 2011 Tohoku, Japan earthquake. In this paper, a study on evaluation of reliquefaction potential with different shaking pattern for Solani river sand (Roorkee) is reported. Application of successive acceleration loading was selected with reference to recent earthquake swarms (e.g. main-shock associated with foreshocks/aftershocks), i.e. 2010–2011 Christchurch earthquakes. Tests were performed with 1 g uniaxial shaking table on sand deposit in saturated condition at 25% density on tank having dimensions 1050 mm × 600 mm × 600 mm. Two sets of four sinusoidal successive shaking events were adopted and applied in both increasing (0.1–0.4 g) and decreasing pattern (0.4–0.1 g) with an equal interval of 0.1 g. Applied shaking sequence represent 2015 Nepal earthquake and 2011 Tohoku, Japan earthquake, respectively. All shaking events were carried out at 2 Hz frequency and for 1 min duration. Successive shakings were applied only after the complete dissipation of EPWP generated from previous shaking. For measuring EPWP, pore pressure transducers were connected to the model tank at three different depths. EPWP was evaluated and compared based on the shaking pattern. It is concluded that the reliquefaction resistance of sand decreases with the increase in acceleration amplitude despite overall sand densification. From the experimental observations, shaking pattern was found critical in influencing the reliquefaction potential of sands.KeywordsReliquefactionUniaxial shaking tableShaking patternSand densification