Comparative Bearing Capacity Assessment of Bored Pile and Driven Pile Foundations under Complex Geotechnical Conditions in a Volcanic-Tectonic Region

Abstract

Foundation performance in heterogeneous volcanic–tectonic ground is strongly influenced by variations in soil resistance, lithology, and rock-mass quality. This study compares the allowable axial capacity of 0.40 m diameter bored and driven piles under complex soil–rock conditions at Mebongo Village, North Gorontalo, Indonesia. The analysis was based on borehole logs, corrected Standard Penetration Test (SPT) resistance, groundwater conditions, and Rock Quality Designation (RQD) obtained from three boreholes investigated to a depth of 10 m. Allowable pile capacities were evaluated using established analytical approaches for bored and driven piles and subsequently compared at different embedment depths. The results demonstrate a depth-dependent reversal in the relative performance of the two foundation systems. At shallow embedment, driven piles provide higher calculated allowable capacities; however, the trend reverses as embedment depth increases. At 10 m depth, the bored-pile capacities reach 178.21, 188.01, and 186.86 tons at BH-01, BH-02, and BH-03, respectively, compared with 129.08 tons for the driven pile at all three locations. Consequently, bored piles provide capacity increases of 38.06%, 45.65%, and 44.80%, respectively. The investigated ground exhibits substantial heterogeneity, with SPT resistance ranging from 11 blows to values exceeding 60 and RQD ranging from 14.5% to 100%. The results indicate that the comparative performance of pile foundations is governed by the interaction between embedment depth, soil resistance, lithological variability, and rock-mass quality. Bored piles are therefore considered more suitable where deep penetration through interbedded soil and fractured basaltic rock is required. The findings highlight the importance of integrating geological and geotechnical variability into foundation selection rather than relying solely on pile type or nominal dimensions.