Reliability Analysis on the Foundation Bearing Capacity in Ningbo Rail Transit Engineering

摘要

According to the first-stage geologic investigation reports of the line 1 and line 2 in Ningbo rail transit, the natural density (ρ) and the vane strength (Cu) probability distribution of the typical layers in Ningbo area were studied in this paper. Besides, the reliabilities of the typical layers foundation bearing capacity in Ningbo area were evaluated by the checking point method. It is found that (1) the natural densities of the typical layers in Ningbo area show good normal distribution as their corresponding variation coefficients (δ) are small. Unfortunately, the vane strengths of the typical soils in Ningbo area show poor normal distribution as their corresponding variation coefficients (δ) are large. (2) The soil parameters variation has significant influence on the reliability index β. Moreover, β is more sensitive to the variation of ρ than to the variation of Cu. (3) As the safety coefficient methods can not consider the influence of the soil parameters variation on the foundation stability, it is suggested that the foundation stability in Ningbo area should be evaluated by the reliability analysis method.