A G-PFEM Analysis of Cone Penetration Testing in Clay Considering Random Destructuration Fields

Understanding soil structure variability is crucial for geotechnical projects, especially in complex clay formations like London Clay. This study employs the Geotechnical-Particle Finite Element Method (G-PFEM), known for its ability to handle large deformations in insertion problems, while the material response is modeled using an enhanced structured Cam Clay model to investigate the effect of spatial variations in soil structure on cone penetration testing (CPTu) in stiff, overconsolidated London Clay. While it is conceptually recognized that clay structure affects the stress-strain response, our results show that the inherent structure of clay significantly influences the localized shear failure zone around the cone during penetrationparticularly in soils with structure variations. Using random field theory and Monte Carlo simulation, this study quantifies the spatial variability to refine the predictive accuracy of the G-PFEM model. A vertical scale of fluctuation (SoF) of 0.1/m was initially specified. However, analysis of the CPTu results shows that net cone resistance (q_net) maintains an autocorrelation length of approximately 0.1/m, whereas the porewater pressure exhibits a shorter autocorrelation length of about 0.05/m.By incorporating structural variability, the stochastic model effectively captures the inherent heterogeneity of the soil, uncovering spatial variations in stress and porewater pressure redistribution that remain unaccounted for in the deterministic approach. These findings highlight the importance of advanced numerical modeling to capture the complex behavior of clayey soils, thereby improving the interpretation of CPTu results.

Keywords: Probabilistic analysis, Random field, Structure variability, Geotechnical particle finite element method, Numerical analysis.