考虑土性参数空间变异性的桩基可靠度分析

The inherent spatial variability has been considered as a major source of uncertainties in soil properties. It significantly affects the performance of geotechnical structures. However,most of the current studies use the implicit model of indirect approximation to simulate it,and there are few studies using a direct explicit method to model. This paper integrates a Monte Carlo simulation-based Reliability-Based Design( RBD) approach with the random field theory to establish a reliability analysis method for pile foundation based on random field theory and simulate the spatial variability by random field method directly and explicitly. Then,the effect of spatial variability of soil on the RBD of pile foundations is analyzed based on a drilled shaft example. The results show that the spatial variability of soil affects feasible designs of drilled shafts significantly. Ignoring spatial variability leads to conservative designs. The spatial variability has a greater impact on the design of small diameter drilled shafts. In addition,the paper also uses the equivalent variance reduction method to model,indirectly and approximately,the spatial variability of soil parameters. It is found that the indirect modeling using the equivalent variance reduction method with the simplified form of variance reduction function in RBD might lead to relatively conservative designs.