Effect of uncertainty in soil parameters on dynamic response of the ground using random field theory

ABSTRACT Seismic waves caused by earthquakes undergo many changes when passing through different layers of soil, which can be due to the heterogeneity and spatial variability of soil parameters affecting the seismic response of the earth. The parameters in a heterogeneous soil layer are affected by a set of uncertainties. In this study, the inherent variability of the soil shear modulus parameter on the soil dynamic response has been investigated. In this research, using the random field theory method and finite difference method in the framework of Monte Carlo simulations, the effect of two-dimensional spatial variability of soil shear modulus parameter on the peak ground acceleration amplification factor and surface acceleration response spectrum has been investigated. In conventional certainty analysis, only a constant value of the mean shear modulus is considered in the dynamic model, but in stochastic analysis, the soil shear modulus parameter is considered as a random variable, which in the random field theory method, this variability is considered in two dimensions. The results obtained from the analysis show that with increasing heterogeneity and changes in the soil shear modulus, the values of the peak ground acceleration amplification factor decrease. Also, by increasing the coefficient of variation of soil shear modulus and thus increasing the heterogeneity of soil profiles, the acceleration response spectrum of the soil profile resulting from random analysis decreases.