Compaction Techniques on Heterogenous Ground to Achieve the Exacting Specification Requirements with Suitable Verification Testing Procedures-Paper

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The paper describes ground improvement for a 500,000 m² urban development in Abu Dhabi, where adoptable roads were planned over highly variable soils. Loose to medium-dense marine and wind-blown sands overlie silty and clayey deposits, stiff clay, and mudstone; groundwater lies about 2–3 m below ground level. The project required improved bearing capacity and stiffness, controlled settlement, dense granular soils, and reduced liquefaction risk.<br /><br />The site was divided into 2,000 m² control boxes. Pre-improvement cone penetration tests (CPTs), interpreted alongside boreholes and other tests, were used to characterize each box and select a suitable treatment. Robertson’s Soil Behavior Type Index helped distinguish granular soils from cohesive layers, allowing compaction to target the sands without unnecessarily treating competent underlying clay or mudstone.<br /><br />Three techniques were used according to required treatment depth: High Energy Impact Compaction (HEIC) to about 2.5 m, Rapid Impact Compaction (RIC) to about 4 m, and Dynamic Compaction (DC) to about 8 m. Site trials informed the work, and post-treatment CPTs, SPTs, laboratory testing, and zone load tests verified performance.<br /><br />Post-CPT results were assessed against specification requirements using established correlations for relative density, friction angle, elastic modulus, settlement, and liquefaction resistance. Settlement estimates used Schmertmann’s method. Eight zone load tests on 3 m × 3 m foundations recorded settlements of 2.59–5.18 mm at the working load and 6.74–14.44 mm at three times that load.<br /><br />The authors emphasize that successful compaction on heterogeneous ground depends on careful site characterization, appropriate selection of treatment methods, and verification procedures matched to the soil types and project specifications.

Keywords

ground improvement

Abu Dhabi

cone penetration test

high energy impact compaction

rapid impact compaction

dynamic compaction

liquefaction resistance

settlement control

Robertson soil behavior type index

zone load tests