Stone columns are constructed using stone aggregates of typical size ranging from 15 to 75 mm. Alternatively, building debris and shredded tyre chips can be used to replace the stone aggregates either partially or totally, which can be an environment-friendly solution to the disposal of solid waste materials. This paper presents the results of model tests on ordinary floating stone columns (OSC) and encased floating stone columns (ESC) constructed with a mixture of stone aggregates and shredded tyre chips. Tyre chips of 10 mm size, 2 to 3 mm thick after removing steel wires, were used in this study. Large size direct shear tests were also conducted for different mix proportions of tyre chips and stone aggregates to assess their shear strength properties. Model tests were conducted on ordinary and encased floating stone columns of diameter (d) 100 mm and l/d ratio of 4.5. Loading was applied through hydraulic jack and reaction loading frame. Model test results show that an ordinary stone column made of stone aggregates can be replaced by an encased stone column made of 100% tyre chips. This confirms the possibility of either partial or full replacement of stone aggregates with tyre chips in stone columns.

No abstract

The utility of construction of stone columns in soft soil like clay, marine soil in coastal regions as a ground improvement technique is widely acknowledged. This study presents a numerical analysis of behaviour of ordinary and encased columns, made of various mix proportions of shredded tyre chips and stone aggregates, through Finite Element modelling (with Plaxis 3D software). It is observed that encased columns exhibited remarkable decrease in bulging with respect to ordinary columns. This was true even for columns composed of high proportion of tyre chips (50-100% by volume) owing to generation of higher hoop strain in such columns. The development of hoop strain increased the tensile strength of encasement and hence the column stiffness. The study illustrates the variation of maximum lateral deformation and the corresponding depth with the amount of tyre chips in the mix proportion forming the column. A decrease in bulging along with bulging at greater depths was observed in encased columns, the bulging was negligible for columns wherein the tyre content varied between 0 and 30% by volume. The settlement reduced remarkably with the construction of encased columns irrespective of the mix proportions composing the columns. The study concludes that partial replacement (30-70% by volume) of stone aggregates with shredded tyre chips in encased columns in soft soil is feasible with encasement of significant stiffness.

No abstract

No abstract