Analysis and design of plain and jacketed stone column in clays

Abstract

A novel approach on the analysis and design methods and" newly envisaged jacketed stone columns in clay presented in this thesis. It considers nonlinear for plain media is mechanical behaviour of the constituent materials as well as compatibility of deformation amongst these. To characterise the nonlinear mechanical behaviour of the constituent materials, the hyperbolic model forwarded by Kondner (1963) was used. The cavity expansion theory presented by Ladanyi (1963) is used here to formulate the desired equations for prediction of lateral resistance mobilized in the clay media. A new suction triaxial test was developed to characterise the mechanical behaviour of the aggregates which was proved to be very beneficial especially in case of large size specimens. As a part of these studies a literature review is presented to depict the state of the art as well as to identify the limitations of the existing design methods. To depict the applicability of the proposed analysis and design methods, illustration examples are presented. In the examples, the constituent materials include stone aggregates, a geogrid jacket liner and a soft clay from the south-east region of Bangladesh. A comparative study revealed that the existing methods may lead to unsafe designs. Moreover, the jacketed column was seen to provide a considerably stiffer foundation than its plain counterpart.