Design and Field Comparison of Ground Improvement and Bored Piles for Large Diameter Steel Water Tanks-Technical Paper Upload

Technical Paper Upload

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The paper compares ground improvement and bored pile foundations for large steel water tanks, emphasizing that the best solution depends on site-specific soil conditions and settlement requirements.<br /><br />At a Saudi Arabian terminal station, a 50 m diameter, 50,000 m³ tank was founded on stone columns extending 17 m deep. Weak soils extended to about 15 m, underlain by denser sand. The design used a 19% area replacement ratio, with denser column spacing beneath the ring beam. Zone load tests and plate load tests produced settlements close to or below predictions, supporting the design assumptions.<br /><br />At the nearby pumping station, a 41 m diameter, 25,000 m³ tank faced soft, weak soils extending much deeper—potentially to 45 m. Ground improvement was considered unsuitable, so the tank was supported on 138 bored piles, each 1 m in diameter and up to 42.5 m deep.<br /><br />A second case covered three 106 m diameter, 170,000 m³ tanks on generally granular soils. Stone columns, 800 mm in diameter and 8.5 m deep, were designed to meet settlement, differential settlement, and seismic liquefaction criteria. A zone load test recorded less settlement than predicted, while post-treatment CPT results showed increased soil resistance.<br /><br />The cases demonstrate that ground improvement can provide a cost-effective and potentially more sustainable alternative to deep foundations where soil conditions permit. Reliable soil investigations, realistic foundation pressure estimates, and field verification tests are essential to confirm performance and protect tank serviceability.

Keywords

ground improvement

bored pile foundations

stone columns

water tanks

settlement control

soil investigation

liquefaction resistance

Saudi Arabia

plate load tests

foundation design