ABSTRACT
This paper presents the foundation design (mixed solution: barrettes and foundation slab), and the design and back analysis of the diaphragm wall forming the basement retaining wall of a major commercial development in Bogota, Colombia. The development consists of 4 eleven-story office towers each, and 4 basements for car parking use, occupying the entire venue area (18,000 m2 per basement). The design considers a permanent structural diaphragm wall, 60 cm thick, 40 m in depth, a substructure built with a Top-Down construction sequence, using basements slabs as horizontal elements of support. The Maximum Excavation Level is −15.0 m to enable the construction of the slab foundation with Finished Floor Level at −13.5 m. The ground profile consists mainly of very soft clay with natural water content up to 200%. The water table was detected at 4 m depth. An important number of in-situ shear vane tests and laboratory tests were performed as part of an additional ground investigation in order to have more accuracy in the undrained shear strength of the clays. The project is heavily instrumented with inclinometers, piezometers, extensometers and topographical survey. The excavation is complete and the theoretical results obtained during the design stage are compared with the instrumentation measurements. This back analysis was used in the form of adjusted sets of soil parameters for traditional elasto-plastic modelling and finite element modelling of the excavation sequence.
