Laboratory and numerical analysis of geogrid encased stone columns

Abstract

Improvement of weak base soils under low-rise buildings, storage tanks, bridge piers, and also the treatment of soft foundations of factories and embankments can be achieved by using stone columns. This technique represents an economical method for the improvement of soft and compressible soils. Moreover, because of their environmental compatibility, low cost, and ease of implementation, they have been used for the improvement of weak soils around the world. This paper has investigated the effects of the dimensions, length and main related parameters on the strain–stress behavior of encased and unreinforced (uncased) stone columns. Settlement assessment, the effects of bulging on efficiency, and also geogrid-capped stone columns have been studied. The experimental results have been compared using parametric finite element modeling software. These results showed that short stone columns, even under small stresses, punched into soft soil. In that case, stress concentration occurred along the columns and they punched into the soft soil instead of resisting against wedge rupture formation below the overlying structure. Stone columns at least doubled the bearing capacity of the soft soils and decreased the differential and total settlements if designed according to appropriate conditions, and even if short in length.