Tire Encasement and Granular Column Stability

Abstract

Abstract Granular columns derive their load capacity from the confinement offered by the surrounding soil. However, lateral support can be problematic in extremely soft soil. Granular columns, when embedded in very soft clay, may bulge because of a lack of confinement offered by the surrounding soil. To avoid these problems, additional confinement can be provided by using geogrid or geosynthetic encasement. This study investigates a method of encasement construction with the aim of using waste tires to build columns. Without any recycling pretreatment, waste tires were used as material for stone encasement. Tires were stacked vertically to form a column frame structure and were bonded together using infinite screws and tightened with bolts. The diameter of the stone columns was that of a nominal car tire in all tests. A similar geosynthetically encased stone column with identical geometrical properties was also tested. Load tests were performed on both geotextile and tire-encased columns in a clay bed medium under incremental surcharge loads. To measure the bucking deformations of the column section using photogrammetric methods, unconfined loading tests were conducted under the same loading conditions. Results obtained from small-scale laboratory tests show that tire encasement makes the stone columns stiffer and stronger than traditional geotextile-encased stone columns.