Soil Improvement Technique to Mitigate Extreme Settlements on Deep Compressible Deposits in the Bogota Valley-Paper

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The study evaluated ground improvement for a large logistics park in Bogotá, Colombia, where warehouse loads would be placed over more than 50 m of very soft, highly compressible clay. The buildings’ floor loads and raised fill created an estimated surface load of about 7 t/m², making severe total and differential settlements likely. The authors cautioned that shallow rigid inclusions would not address consolidation in the deeper clay.<br /><br />A full-scale test section was built to reproduce stresses beneath the future warehouses, particularly at depths of 20–30 m. The 50 m by 35 m section was loaded with 7 m of surcharge and fitted with prefabricated vertical drains (wick drains) extending 30 m deep at 1.5 m spacing. Settlement plates and multi-level extensometers monitored movement during construction and for roughly two months after surcharge placement.<br /><br />The test recorded about 1.7 m of settlement at the center and 0.8 m at the corners, with substantial differential movement across the section. Approximately 90% of settlement occurred within 45–60 days of the start of filling. Extensometer readings confirmed that significant consolidation continued below 30 m, with settlements measured as deep as 40 m.<br /><br />Measured settlements closely matched the study’s initial estimates, but consolidation occurred faster than predicted. Updating the model using field results increased the estimated horizontal consolidation coefficient roughly fivefold, supporting the possibility of wider wick-drain spacing. The test also showed greater deep settlement than laboratory-based estimates had suggested.<br /><br />The authors conclude that full-scale testing is valuable for validating settlement predictions and optimizing drain design in Bogotá Valley soils. For heavily loaded, large-area developments over deep compressible deposits, deep wick drains combined with surcharge may provide better performance than shallow improvement methods.

Keywords

ground improvement

Bogotá Colombia

soft clay

prefabricated vertical drains

wick drains

surcharge loading

consolidation settlement

differential settlement

logistics park

full-scale field test