NON-LINEAR PERTURBATION STOCHASTIC FINITE ELEMENT METHOD FOR ANALYZING THE RELIABILITY OF VERTICAL LOADED PILE
单桩承载力可靠度的非线性摄动随机有限元分析

The algorithm of second-moment non-linear perturbation stochastic finite element method is studied and presented for the reliability analysis with the Duncan-Chang non-linear constitutive law of geotechnical engineering taken account into, and a corresponding computer program is also developed. The spatial soil properties are modeled as three-dimensional homogeneous random fields, and the criteria of modeled some soil properties as random fields. The technique of axisymmetric random fields' discretization by local average approaches is studied. The algorithm and the assembly method of covariance matrix are proposed. The first and second order partial derivatives of the elasticity matrix of axisymmetric case, and the assembly method of partial derivatives of the global stiffness matrix are obtained. The analytical model for estimating the first two probabilistic moments of pile's bearing capacity by stochastic finite element method is proposed. Both the uncertainty attached to the spatial soil properties and the uncertainty associated with load are considered for the influence of the reliability index. Application to a practical pile is given to demonstrate the suggested method. The results show that the non-linear stochastic finite element method is effective for analyzing the reliability of vertical loaded piling.