Stone Column Treatment and Elaborate Load Tests Verification for Improving Subsoil Conditions on a Large-Scale Residential Development Project-Paper

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The project involved ground improvement for a 280-hectare residential and leisure development in Abu Dhabi, comprising 1,315 villas and townhouses, buildings, roads, tunnels and recreational facilities. Investigations across seven clusters identified alternating loose sands and soft silty clays susceptible to excessive settlement.<br /><br />Ground treatment combined vibro-replacement stone columns, Rapid Impact Compaction (RIC), and localized excavation and soil replacement, with a load-transfer platform. Stone columns were generally 1 m in diameter, installed to depths of 4–8 m on grids spaced 2.0–2.8 m apart. The works aimed to meet bearing-capacity and settlement limits and reduce liquefaction risk.<br /><br />Performance was checked through post-treatment cone penetration tests (CPTs), plate load tests (PLTs), and full-scale zone load tests (ZLTs). ZLTs applied up to 150% of allowable bearing pressure; the final load was maintained for 30 days to assess consolidation and long-term settlement. Eight trial tests helped calibrate the design, followed by additional testing during construction.<br /><br />The 30-day settlement records were analyzed using Asaoka’s observational method to estimate final settlement. The results were also back-analyzed to derive site-specific compression index (Cc) and consolidation coefficient (Cv), using a stone-column consolidation model. Although laboratory-based design values were Cc = 0.4 and Cv = 2 m²/year, trial-test back-analysis produced lower site-specific values: approximately Cc = 0.04–0.2 and Cv = 0.3–0.8 m²/year.<br /><br />The findings indicated that stone-column treatment reduced the clay layers’ effective consolidation parameters and associated long-term settlements. The authors report that this verification enabled optimization of the ground-improvement design, saving time, cost and aggregate.

Keywords

ground improvement

stone columns

Abu Dhabi

residential development

settlement control

Rapid Impact Compaction

cone penetration tests

plate load tests

Asaoka method

liquefaction risk