Investigating stone column effectiveness for sabkha soil improvement: field tests and numerical model

Abstract

This study explores the application of stone columns to improve the bearing capacity of sabkha soil for the construction of a Lattice Communication Tower foundation in the Eastern Province of Saudi Arabia. Geotechnical investigation report, an on-site footing loading test to evaluate the foundation's bearing capacity and settlement behavior following stone column installation, and post-cone penetration tests (CPT) to assess soil densification are all part of the study data. The uppermost 4 m of the soil profile comprise a medium to dense layer of sand with silt, followed by a 12-m layer of weak sabkha soil (SPT, N less than 4). Below the sabkha layer, the strata exhibit varying densities, ranging from medium to dense and very dense layers, extending to the maximum depth of investigation. The comparison of Pre- and Post-CPT data revealed significant improvements in the sand and silt layer above the sabkha layer, as well as moderate improvements in the upper portion of the sabkha layer. However, the majority of the sabkha soils and underlying soil layers did not show significant improvement. Plaxis 3D numerical models were employed to provide insights into the performance of the composite area encompassing stone columns and the surrounding soil. Comparing field tests and numerical models showed that neglecting stone column installation effects in numerical models led to overestimating settlements. However, when examining the field data and numerical results with a raised coefficient of lateral earth pressure when of K∘=2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${K}_{^\\circ }=2$$\\end{document}, a distinct alignment between settlement values consistent with those derived from field testing. The findings highlight the importance of including site-specific conditions and installation effects in numerical modeling to accurately predict the behavior of stone columns in sabkha soils.