ANALYSIS OF LATERALLY LOADED PILE USING MONTE CARLO METHOD

Abstract

Laterally loaded pile is a deep foundation; usually these are analyzed under subgrade reaction approach. Conventional methods of analysis and design of foundations employ the values of soil parameters as average values emanating from multiple tests conducted for this purpose. Pile is considered as a vertical beam supported on elastic foundation. Surrounding soil is modeled by Winkler's hypothesis in which it is replaced by infinitely closed spaced independent elastic spring. However, due to inherent variability in the soil strata, the soil properties cannot be considered as deterministic quantities. Further, consideration of mean value of any soil property leads to the use of quite high values of the factor of safety in the analysis. In view of these, it is more appropriate to consider the soil parameters as random variables. In the present work, the analysis of a laterally loaded pile has been carried out considering the soil parameters as a random variables using Monte Carlo simulation. The probabilistic approach used for this purpose employs modulus of elasticity as the soil parameter, which has been considered as random variable having normal and lognormal distribution. Influence of various parameters like pile length, no. of element, corresponding maximum bending moment, factor of safety studied by means of a detailed parametric study. Factors of safety with respect to bending moment, reliability index and mean value of factor of safety have been determined and these were related to coefficient of variation and correlation coefficient of the random variable. A detailed parametric study revealed that for a given risk level, the factors of safety can be expressed in terms of the coefficient of variation of bending moment and only mildly upon other geometric parameters of the soil —pile system. Results are presented in the form of reliability index and factor of safety.