Behavior of Reinforced Stone Column

Abstract

Rapid industrialization and large scale infrastructure development results in depletion of normal useful land and it simultaneously promotes the use of marginal and weak soil for infrastructure development. Some problematical soils like soft clay deposits, marine clays, recent fills, peat soils, etc. pose problems in construction because of very low bearing capacity, high compressibility and trend for lateral flow etc. These types of grounds need treatment to improve their engineering behavior as per design requirements of structure. One common technique for treating these soils is installation of stone columns. Stone columns derives its load carrying capacity from the confinement offered by the surrounding soil. Encasement of stone column has been extended the utilization of stone columns to soft clays. In present study, we provide two types of extra confinement externally and internally and these are circumferential encasement, circular horizontal strips and combination of two. An axisymmetric analysis was carried out using Mohr-Coulomb's criterion considering elastoplastic behaviour for soft clay and stone. Three type of surrounding is considered 7, 14, 30 kPa and the load carrying capacity of footings located over stone columns is compared with equal size of footings located on the virgin soil that is without a stone column underneath. Result shows that as strength of surrounding soil increases effect of extra confinement decreases. For low strength of surrounding soil full length of encasement is more effective but for high strength of surrounding soil partial length of encasement is sufficient.