Load bearing and settlement characteristics of Geosynthetic Encased Columns under seismic loads

Ordinary stone columns and Geosynthetic Encased Stone columns are used in remediation of soft soils with low bearing capacities. Primary objective of granular columns is to provide structural support to the overlying foundation layers. Given that the granular columns implemented in soft soil conditions support a large portion of the surcharge pressure, developing an understanding of settlement response and pressure bearing characteristics of granular columns under seismic loading conditions is of paramount importance. This study aims to present experimental findings of granular column load bearing response under simulated seismic loads and the effects of lateral boundary conditions on column behavior. In order to mimic the seismic behavior of columns supporting a sustained surcharge load, two different large-scale experimental assemblies are used in 1-g shaking table tests. The assemblies used were a laminar box and a rigid box which were intended as physical analogies for free-field and rigid boundary conditions. The reinforcement strains, pressure concentration on column heads, and settlement of the unit cells enhanced with granular columns with varying reinforcement stiffnesses are studied. The relationship between unit cell settlement and two important earthquake intensity measures namely, Arias Intensity and Shaking Intensity Rate, are also investigated.