Numerical Analysis of an Embedded Pile in Fractured Rock

Resumo

The determination of the load capacity of deep foundation elements is complex and requires the
definition of a good physical and mathematical model that expresses an adequate approximation of the installation
process, interaction mechanisms and the failure mode. In particular, piles embedded in rocks add difficulty to
predictions due to scarcity of specimen tests of the rock to define appropriate stress-strain relations, and
information about rock integrity in field. To overcome these issues, the Brazilian national practice of deep
foundations uses semi-empirical methods to predict load capacity validated with loading tests. In this context, the
present work presents a load capacity analysis of a deep foundation element embedded in rock using finite element
approach which is directly compared with axial compression static loading test, and semi-empirical predictions.
The pile was modeled considering elastic behavior, soil layers and fractured rocks were modeled considering the
elastoplastic model of Mohr Coulomb. Interaction mechanisms were modeled considering a normal rigid contact
behavior and penalty for tangential behavior. Results of two analyzes were presented in the paper: an analysis
defined considering a set of parameters derived based on in situ investigation (Standard Penetration Test - SPT
and Cone test - CPT) and; a parametric analysis to investigate the influence of the interaction coefficient. The
results presented contribute to the understanding of the behavior of embedded piles in situ and aims to help in the
definition of suitable models for prediction in future works.