Analysis and Control of the Stability of Embankments on Soft Soils: Juturnaíba and others Experiences in Brazil

Abstract

Listen

Translate article

In the design and evaluation of the behavior of embankments on soft clay foundations, geotechnical characterization, along with instrumentation for measurements involving pore pressure and displacements (vertical and horizontal), are required in order to efficiently elaborate a construction. This paper presents the results of stability analysis, and stability control, with emphases on studies carried out by the Geotechnical Group (GEGEP) of the Federal University of Pernambuco, Brazil. Five Brazilian cases are presented: the Juturnaú­ba trial embankments and Juturnaú­ba Dam construction, located in Rio de Janeiro; the access embankments for the Jitituba River Bridge in Alagoas; the failure of an embankment alongside highway BR-101-PE in Recife, Pernambuco; and the Sarapuí­ trial embankment, located in Rio de Janeiro (Ortigão 1980; Ortigão et al. 1983). With the exception of the Juturnaíba trial embankment, all of the cases in the stability analysis concerned failure involving embankments on soft clays confirmed the need to apply the Bjerrum (1973) correction factor to field vane tests measuring undrained strength. Effective stress stability analysis utilizing a normally consolidated effective stress parameters for strength measurements, presented results that can be considered satisfactory. Stability control was carried out using measurements of displacements, deformations, and pore pressures. Proposals were presented and analyzed, especially for horizontal displacements, demonstrating good results, and the potential for practical application. Recommendations for use are presented in the paper. The joint results of stability analysis, and stability control, showed the importance of having an FS > 1.3 to guarantee adequate behavior and security.