Static and Cyclic Resistance of Liquefiable Sands from the 2018 Lombok Earthquake: A Comprehensive Analysis With Particle Shape Considerations

This study evaluated the static and cyclic resistance of sands from the Pemenang site in North Lombok, an area that experienced widespread liquefaction during the 5 August 2018 earthquake. The assessment was conducted using a combination of field and laboratory investigations. Field testing using cone penetration tests (CPT) was employed to identify liquefiable layers and evaluate in situ conditions. The laboratory programme consisted of undrained static and cyclic triaxial tests performed under varying initial effective confining stresses and cyclic stress ratios. The particle shape was characterized in detail to investigate its influence on the sand’s liquefaction resistance. The CPT results revealed a loose silty sand to a sandy silt layer with a high liquefaction susceptibility. Static triaxial testing indicated non-flow behaviour and a relatively high critical-state friction angle, whereas cyclic tests showed significant cyclic mobility. The shape parameter analysis suggested that the angular and irregular shapes of Pemenang sand may contribute to its elevated static resistance. These findings provide essential data for site-specific seismic response analysis in the region and highlight the importance of incorporating particle morphology into assessments of liquefaction resistance.