Escavações com paredes rígidas com diferentes níveis de apoio um caso de obra

Abstract

The study of rigid walls for excavation support with various support levels is usually performed based on the classical methods of limit equilibrium design. For rigid walls with more than one support, it is common to calculate the resultant of the horizontal stresses by Rankine's theory and then to uniformize the Rankine diagram for the determination of the flexural moments and reaction forces at different support levels. Some authors consider the redistribution of horizontal stresses occurring since the initial stages, with only one level of support. This research intended to study this subject in more detail, verifying the suggestions from different authors and performing a sensitivity analysis incorporating different calculation tools in different excavation stages. These tools included those using simple manual calculation methods, programs focusing on resolution by classical methods, programs based on the elastic beam reaction and also numerical methods. In the case of numerical methods, two different constitutive soil models were compared in the Plaxis 2D program. In the sequence, a case study of an extensive subsoil executed in Rio de Janeiro was analyzed, including the monitoring of the horizontal displacements through inclinometer readings. The instrumentation aimed at controlling the behavior of the excavation during the whole execution. All available tools were used to predict the behavior of this excavation compared to the estimated behavior using the different calculation tools. Several conclusions were obtained by the author, who focused the advantages of the simple models, their limitations, as well as the comparison between the different models to predict the flow pattern. The expected results, compared to the instrumentation, allowed the confirmation of the excellent performance of the excavation site as well as the potential of the numerical analyzes and the ability of the simple and common tools still used in practice as guiding the initial excavation design.