Author(s): Hiroshi Tanaka, Ayumi Suzuki and Taro Yamamoto

Abstract: This study investigates the liquefaction susceptibility of alluvial soils subjected to seismic loading through an integrated geotechnical and geophysical assessment framework. The research focuses on the inherent complexity of alluvial deposits, characterized by variable stratigraphy, fine interbedding, and fluctuating groundwater levels, which often challenge the accuracy of traditional simplified liquefaction evaluation methods. Field and laboratory data were obtained from representative alluvial sites and analyzed using Standard Penetration Test (SPT), Cone Penetration Test (CPT), and shear-wave velocity (Vs) measurements. These datasets were employed to calculate cyclic stress ratios (CSR) and cyclic resistance ratios (CRR), followed by the estimation of the factor of safety (FS) against liquefaction. The study also implemented probabilistic Monte Carlo simulations to account for uncertainty in soil and loading parameters, producing spatial and statistical representations of liquefaction susceptibility. Results revealed that shallow saturated sand and silty sand layers exhibited the highest liquefaction susceptibility, while deeper strata showed increased resistance due to higher density and confining pressure. Among the predictive methods, SPT-based correlations provided the highest sensitivity and accuracy, followed closely by CPT and Vs analyses. A multi-variable logistic regression model integrating all three parameters yielded the most balanced and reliable performance, confirming the advantage of multi-parameter approaches in complex sedimentary environments. The findings highlight the significance of incorporating stochastic methods, groundwater monitoring, and multiple in-situ testing techniques for accurate seismic hazard assessment. Practical recommendations include the routine use of combined penetration and velocity tests, site-specific calibration of empirical models, continuous groundwater observation, and integration of liquefaction risk mapping into regional planning and infrastructure design. Overall, this research establishes that a hybrid and probabilistic framework enhances the precision, reliability, and safety of liquefaction evaluation in alluvial plains affected by seismic events.

Pages: 33-38 | Views: 5 | Downloads: 4

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