Citation

Cássia de Brito Galvão T, Pereira AR, Parizzi M, Alves da Silva H. Nat. Hazards Rev. 2010; 11(2): 43-48.

Copyright

(Copyright © 2010, American Society of Civil Engineers)

DOI

10.1061/(ASCE)1527-6988(2010)11:2(43)

PMID

unavailable

Abstract

Slope failures in the tropics are directly related to the rainfall intensity. Refining techniques to prevent rain-induced slope failures play an important role, especially for the risky occupied areas close to big cities--the final destination from people who migrates from rural to urban areas. This paper presents the implementation of bioengineering associated with nailing techniques to control erosion and prevent rain-induced failures in a 35-m-high rocky slope (Ponteio Slope). The exposed phyllite rocks of this slope and the absence of a proper drainage system have been the identified as the trigger mechanism to the successive failures verified since 1953. In the past 15 years, berms and a concreted cover were built as attempts to stabilize this slope, but no drainage system was associated with those works. In December 2003, the implementation of bioengineering and soil nailing techniques in a total area of with a declivity, for the intact slope, of about 63° began. After the cleanup of the talus and the fissured concrete cover, the rocky mass was reinforced by connecting the superficial loose phyllites to the deeper and more resistant quartzite layer with 6-m steel reinforced bars, 130 in total. The subsequent operations carried out were seeding, rolling out the coconut fiber blankets and reinforced mat onto the slope surface, and finally, the placement of a metallic net anchored to the rods by bolts. The natural aesthetics of the whole bioengineering system adopted was improved as well as helping to improve the natural drainage system and avoiding the uplift pore pressures. The association of "soil nailing" and bioengineering techniques were cost-effective and succeeded in stabilizing the slope after several previous attempts. The slope was monitoring during the techniques implementation in 2003 and in the subsequent year, 2004. No failure occurred.