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The detailed design for slope stabilization of the “Duas Pedras” Hill, at “Córrego D’Antas”, Nova Friburgo, State of Rio de Janeiro, arose from the need to establish a set of works and interventions in the location upon the occurrence of the “”Megadesastre” in the Mountain Region of the Rio de Janeiro State” (occurred on January 2011) and considered one of the biggest events of widespread mass movements in Brazil, triggered by extreme weather conditions. Officially, it caused 947 casualties, 300 missing persons, over 50 thousand homeless and affected almost 1 million people.

The project was undertaken by COBA Brazil and involved the specialities of geology, geotechnics, hydraulics and structures.

The slope stabilization techniques of the “Duas Pedras” Hill at “Córrego D’Antas” included the following:

fix the blocks or chippings, preventing them from sliding - fixing with bolting and/or anchoring, with or without buttresses, fixing with anchored grid, use of counterforts or beam with anchor bolts/ anchored beam and “spider” systems made of high-tensile steel wire;

fragmentation and removal of blocks - removal of small loose blocks or breakdown of larger blocks;

enable the safe fall of blocks and flow of debris, without causing damage - flexible and/or rigid barriers against falling blocks and debris flow.

The design of the drainage system took into account the need to divert the flows resulting from rainfall of the urban area at the bottom of the “Duas Pedras” Hill. For such, two subsystems were designed and executed, which flow into the “D'Antas” stream.

One of the major challenges of the implementation of this project was related to the logistics and complexity of the construction process, due to the gradient of the rocky hillside a set of movable “inclined planes” was adopted.




Lx, 29 Feb 2016