Resistência de juntas de rocha naturais e alteradas artificialmente

Abstract

The strength parameters of joints are fundamental in engineering design of fractured slopes. The shear and uniaxial compressive strengths of joints decrease over time, due to natural weathering, which may cause failures in the originally stable masses. The main objective of this research is to study the strength behavior of rock joints with different degrees of weathering by means of direct shear tests of specimens retrieved from boreholes in the Channel 1 area of interconnection and adduction to the AHE Simplício, located on the border of Minas Gerais and Rio de Janeiro states. Natural joints were subjected to artificial weathering in a special laboratory equipment in levels of up to 8300 hours (345 days) of continuous flow. The joints were characterized and classified by the roughness (JRC) and weathering level. Schmidt hammer tests were performed to obtain rebounds and uniaxial compressive strength. 26 shear tests were conducted directly in rough and smooth joints. The stress-displacement results have been analyzed for obtaining the direct shear strength parameters as a function of weathering level. The results indicate a reduction in the rebound and friction angle with increasing joint weathering.