Análisis del comportamiento de dos excavaciones profundas en suelos blandos de la ciudad de Bogotá D.C.

Abstract

The three-dimensional models using finite elements more accurately model the behavior of an excavation and the deformations of the retaining system. The present work evaluates the behavior of the deformations and stresses in two deep excavations carried out in soft soils in Bogotá, during their different construction stages, for which a three-dimensional modeling using finite elements was carried out (RS3, Rock and Three-dimensional soil analysis program from Rocscience), based on instrumentation readings, as well as geotechnical parameters defined in soil studies. Several numerical simulations were performed based on the undrained geotechnical parameters defined in the soil studies, the position of the water table, and the instrumentation readings. The constitutive model used was Mohr Coulomb given its versatility and simplicity. For the calibration of the model it was necessary to adjust the geotechnical parameters defined in the soil studies. The results of the calibrated modeling were compared with the classical theories of Rankine (1857), semiempirical method of Zapata (2007), and with a two-dimensional analysis using the Phase 2 (RS2) program. As a result, an approximation was reached between the values obtained from the model and the values of the instrumentation, as follows: in project A, the undrained shear strength was reduced between 13% and 52%, the elastic moduli were reduced on average by 52%, while the reduction in Poisson's ratios was 14%; Regarding project B, the reduction in shear strength and modulus of elasticity on average were of the order of 73% and 52% respectively, and it was not necessary to modify the Poisson's ratios.