Comparative Analysis of a Deep Excavation in a Clays Sequence in Bogota City, with an Emphasis on FEM and Auscultation from the View Point of the Soil-Structure Interaction

Abstract

This document presents the results of a geotechnical analysis in a deep excavation (11.25 m) in a sequence of lacustrine clays in the city of Bogota, Colombia, where it can be found clays of high plasticity and compressibility with void ratio (e) of 3 to 5, compression index (Cc) of 1.2 to 2.0, and young’s modulus E of elasticity under 1000 kPa with organic matter from medium to high. It will be analyzed the comparison of the projected measurement through the modeling of finite elements, as well as auscultated measurements of the deformation of the diaphragm walls, checked within the framework of the geological conditions studied for the execution of the project and the analysis of the soil - structure interaction used in the geotechnical design phase.

This study counts with the analysis of seven inclinometers installed in order to monitor the spatial displacements induced during the construction of three basements and piles of 40 m length to deep friction work under the structure of the building. Measurements lasted about sixteen months. In the research, it was found that the general behavior of predicted deformation is not consistent with the measured deformations. Mainly, due to the differences between the real contour conditions and the model, the wrong localization of the instrumentation, the measurement of the water table, the complex properties of rigidity of the materials, and the basic analysis of the soil - structure interaction of the project.