Experimental Evaluation of Building Settlements Founded on Liquefiable Soils-Paper

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The study uses 1-g shake-table experiments to investigate earthquake-induced settlement of shallow foundations on liquefiable soil and assess helical piles as a mitigation measure. A transparent soil box contained a loose, saturated sand layer over denser, non-liquefiable sand. Circular concrete footings representing low-rise buildings were tested at different widths and liquefiable-layer thicknesses. Accelerometers and pore-pressure sensors monitored ground response, while surface measurements compared settlement beneath the buildings with free-field settlement.<br /><br />Under shaking, pore-water pressures rose sharply, indicating liquefaction. Unsupported footings settled substantially more than the surrounding free field, supporting observations that building-induced settlement can exceed estimates based on conventional free-field, one-dimensional consolidation methods. The results showed that settlement is influenced by the foundation and soil configuration, and is more complex than those empirical methods capture.<br /><br />One exploratory test used a footing supported by four model helical piles embedded into the non-liquefiable layer. It showed a pronounced reduction in settlement compared with unsupported foundations. The authors conclude that helical piles may be a promising mitigation strategy for buildings on liquefiable soils.<br /><br />The experiments broadly aligned with settlement patterns reported in field observations and centrifuge studies. However, the helical-pile result came from a single preliminary test; pile installation was not representative of normal practice, and the test differed in scale and input motion from the unsupported-footing tests. Further testing is needed to evaluate pile embedment, helix dimensions, and scaling effects.

Keywords

shake-table experiments

liquefiable soil

shallow foundations

earthquake settlement

helical piles

soil liquefaction

pore-water pressure

free-field settlement

foundation mitigation

sand layer