Bearing capacity of spatially variable unsaturated fly ash deposit using random field theory

The aim of the present study is to examine the bearing capacity of a spatially variable, unsaturated fly ash deposit, based on finite element limit analyses. Strength nonlinearity of fly ash, arising due to partial saturation, has been modelled based on the well-known van Genuchten (vG) fitting parameters, obtained from the water retention characteristics curve (WRCC). For the probabilistic study, WRCC fitting parameters and angle of internal friction of the fly ash deposit have been considered as stationary Gaussian random fields within a practicable range of coefficient of variation and anisotropic correlation lengths. Random field has been generated based on the Karhunen–Loeve expansion method. Adequate numbers of Monte-Carlo simulations have been executed to evaluate the probabilistic distribution of the bearing capacity, considering strength nonlinearity as well as the random distribution of the input parameters. Influence of stationary spatial variation of WRCC fitting parameters and friction angle on the probability of failure of a footing resting on the fly ash deposit is presented and observations are duly explained. The results of this study would be useful for practising engineers to design a safe fly ash fill and therefore offer a sustainable solution for the bulk utilization of fly ash in geotechnical engineering applications.