A genetic-algorithm approach for assessing the liquefaction potential of sandy soils

The determination of liquefaction potential is required to take into account a large number of parameters, which creates a complex nonlinear structure of the liquefaction phenomenon. The conventional methods rely on simple statistical and empirical relations or charts. However, they cannot characterise these complexities. Genetic algorithms are suited to solve these types of problems. A genetic algorithm-based model has been developed to determine the liquefaction potential by confirming Cone Penetration Test datasets derived from case studies of sandy soils. Software has been developed that uses genetic algorithms for the parameter selection and assessment of liquefaction potential. Then several estimation functions for the assessment of a Liquefaction Index have been generated from the dataset. The generated Liquefaction Index estimation functions were evaluated by assessing the training and test data. The suggested formulation estimates the liquefaction occurrence with significant accuracy. Besides, the parametric study on the liquefaction index curves shows a good relation with the physical behaviour. The total number of misestimated cases was only 7.8% for the proposed method, which is quite low when compared to another commonly used method. Correspondence to: G. Sen ([email protected]) Nomenclature Abbreviation Explanation amax Maximum Ground Acceleration (g) CPT Cone Penetration Test SSSSR Site Seismic Shear Stress Ratio SSSR7.5 Seismic Shear Stress Ratio (corrected for M=7.5) Cq Correction coefficient of overburden stress for CPT resistance D50 Mean grain size (mm) FC Fines Content g Gravitational acceleration (g=9.81 m/s2) GA Genetic Algorithm GWT Groundwater Table depth (m) LI Liquefaction Index M Magnitude (Moment magnitude =Mw) qc1 Corrected tip resistance according to overburden stress (kPa) qc Measured CPT tip resistance (MPa) rd Stress reduction coefficient RMSE Root Mean Square Error F1, F2 Objective functions z CPT test depth from surface (m) σvo Total vertical overburden pressures (kPa) σ ′ vo Effective vertical overburden pressures (kPa) Published by Copernicus Publications on behalf of the European Geosciences Union. 686 G. Sen and E. Akyol: Assessing the liquefaction potential of sandy soils