State of the Art Ground Improvement Technique for A Residential Complex: Case Study-Paper

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The paper presents a ground-improvement solution for a 198-unit residential complex in Chennai, built on variable, weak silty and sandy clay deposits extending to about 6–8 m. Deep foundations were initially the conventional option, but their cost, six-month construction schedule, noise and vibration made them unsuitable for the urban setting.<br /><br />Following geotechnical assessment, the project used a raft foundation supported by vibro stone columns installed with Keller’s dry bottom-feed method. The columns improve soil strength and stiffness and provide drainage paths that accelerate consolidation. Installation uses displacement rather than soil removal or water jetting, and automated equipment records compaction data for quality control. The design was based on Priebe’s methodology and independently reviewed.<br /><br />Ground improvement was completed in six weeks. Plate-load tests showed acceptable performance under the design loading, and settlement was monitored at 14 points on the raft during construction and afterward. Measured settlements were substantially below analytical predictions and within the allowable range for raft foundations on clayey soils, demonstrating the effectiveness of the system.<br /><br />The case study concludes that dry bottom-feed vibro stone columns provided a technically effective and cleaner alternative to piles, while significantly reducing construction time. The faster foundation work helped the residential project finish ahead of schedule, benefiting the developer, suppliers, bankers and eventual residents.

Keywords

ground improvement

vibro stone columns

raft foundation

geotechnical assessment

Chennai residential complex

silty clay deposits

dry bottom-feed method

settlement monitoring

plate-load tests

Priebe methodology