GEOTECHNICAL RELIABILITY ANALYSIS OF A CANTILEVER PILE WALL
Numerical modeling, Python, Sandy Soil, ULS, SLS.
Geotechnical structures are subject to different uncertainties. These uncertainties are due to the natural variability of the soil properties, as well as because the limited knowledge of the several related events. The evaluation of these uncertainties is possible by the application of the reliability theory. Despite its adoption in international standards and the large number of scientific researches, the application of probabilistic theory in Brazil is still unusual, mainly in retaining structures. Accordingly, this work presents the development and application of calculation routines to analyze the geotechnical reliability of a cantilever pile wall. The first group of routines evaluates the reliability of the ultimate limit state (ULS) through FORM (First Order Reability Method) and Monte Carlo simulation. The second group of routines evaluates the reliability of the Service Limit State (SLS) using Monte Carlo simulation. The routines were developed using the Python language. Particularly for SLS evaluation, the Plaxis 2D finite element software was used to obtain the horizontal displacement values. A cantilever pile wall typically constructed in Natal/RN was used to apply the routines and to conduct the parametric study. It was verified that the most influential variable for the cantilever wall was the soil friction angle. The change in the coefficient of variation of the soil friction angle did not change the final reliability of the pile wall, because the embeddedment depth was oversized. Keeping the depth of excavation constant, the increase of the embedment depth has rapidly dropped to the failure probability and the design points of the FORM. For SLS, the increase in maximum horizontal displacement decreased the failure probability and increased the reliability index in a linear trend. The use of lognormal distribution reduces the failure probability in both ULS and SLS.