Estudo de caso da rotura de fundação de aterro sobre solo mole da rodovia RJ-099

Abstract

Soft soil deposits exhibit high compressibility, low shear strength, and low permeability, posing significant challenges to the stability of embankment construction, especially in highway engineering projects. This study aims to investigate the causes of the failure of an embankment constructed during the revitalization and expansion works of the RJ-099 highway, located in the city of Itaguaí, Rio de Janeiro, Brazil, through slope stability analyses and the evaluation of the safety factor throughout the construction stages. The local geotechnical profile consists of a layer of dark gray, slightly sandy organic silty clay, followed by a layer of fine to coarse sand and, at greater depths, a layer of sandy clayey silt. The undrained shear strength of the soil was determined using the method proposed by Mantaras et al.The analysis included simulations of embankment stability immediately after construction and after soil strength gain over time. For the latter condition, the consolidation theory proposed by Barron was adopted, considering a six-month period. The embankment was modeled with an initial height of 2.0 m and four surcharge stages of 1.0 m each. Five simulations were performed using the Slide software, considering successive surcharge increments until the embankment reached a total height of 6.0 m, according to the actual construction sequence. The results indicated an increase in the safety factor due to soil strength gain over time. Therefore, it was concluded that the premature execution of all embankment layers may have directly contributed to the observed failure.