Influence of partial saturation on liquefaction resistance of soil: a case study at Yogyakarta - Bawen toll road

Abstract Liquefaction occurs in saturated granular soils. It is common practice in liquefaction assessments to assume soil located below the groundwater table to be fully saturated. However, numerous studies have shown many instances of soil below the water table were only partially saturated. A decrease in the saturation, even in small amounts, can significantly increase the liquefaction resistance of soil. This means that ignoring partial saturation in a liquefaction assessment may lead to an underestimation of liquefaction resistance. This research aims to investigate the degree of soil saturation on the field and its effects on liquefaction resistance at the Yogyakarta - Bawen toll road. The influence of partial saturation in a simplified liquefaction potential evaluation was calculated using the K S correction factor proposed by Hossain et al. Additionally, soil saturation on the field was measured using P-wave velocity ( V P ) measurements with seismic refraction method. Liquefaction potentials without considering the effect of partial saturation were calculated for three sites at the Yogyakarta - Bawen toll road. The results indicated the presence of potentially liquefiable layers at all investigation sites. Compressional wave velocity tomograms showed soil layers situated below the water table were only partially saturated. Taking this into account, liquefaction potentials were recalculated with partial saturation correction factor applied. The recalculation produced an increased liquefaction resistance and, consequently, an improved liquefaction safety factor above 1.00 for all layers. These results demonstrated the influence of partial saturation on liquefaction resistance and highlighted the importance of partial saturation investigation in liquefaction potential studies.