Stone Column Performance in Clayey Soils: A Physical Modeling Assessment

Stone columns are widely used to improve the bearing capacity and consolidation characteristics of soils, the combined influence of confining pressure, column construction uniformity, and surrounding soil type specially soft cohesive clays remains poorly understood, particularly under controlled physical modeling conditions. To address this gap, a series of large-scale physical model tests was conducted using a triaxial apparatus to simulate realistic in-situ boundary conditions. The apparatus enabled the application of controlled confining pressures of ۱۰۰, ۲۰۰, and ۴۰۰ kPa to represent different overburden depths while monitoring the vertical stress– relative settlement (ratio of the settlement to the initial specimen height) response of specimens reinforced with a single stone column. Two clayey soils—classified as CL and CH according to the Unified Soil Classification System (USCS)—were used as the surrounding materials, and a sandy soil (SM) served as the column material. The effects of column preparation uniformity were examined by compacting the column material in one, two, and three layers. The results indicated that increasing the confining pressure significantly enhanced the load-bearing capacity of the specimens and that this effect was more pronounced in reinforced than in unreinforced soils. Columns compacted in multiple layers exhibited greater stiffness and strength due to improved particle interlocking and better bonding with the surrounding clay. Moreover, stone columns installed in CL soil provided higher bearing resistance compared with those in CH soil. The maximum vertical stress increased by ۱۳۵% and ۱۲۵% for CL and CH soils, respectively, when surrounding pressure increased from ۱۰۰ to ۴۰۰ kPa. Specimens with three-layer compaction exhibited up to ۶۶% to ۶۳% higher vertical stress compared to single-layer compaction under ۴۰۰ kPa.The experimental trends were consistent with dimensional analysis predictions, confirming the reliability of the adopted scaling approach. These findings provide valuable experimental data for improving the design of stone column–reinforced soft clayey soils.

کلیدواژه ها:

Stone Column ، Physical Modeling ، Confining Pressure ، Compaction uniformity ، Clayey soil ، Bearing Capacity