Influence of Weathering and Correlations Between Wave Propagation Velocity and Durability with Physical and Mechanical Parameters in Phyllites

Abstract

Ultrasonic longitudinal wave velocity (Vp) and durability are characteristics largely determined in geotechnical evaluations. These properties are useful in the analysis of weathered rocks because they usually have good relationships with physical and mechanical properties of rocks. Additionally, the tests to obtain these parameters are easy to perform. However, few studies have been performed specifically on low degree metamorphic rocks. The purpose of this study is to evaluate the influence of weathering on these parameters, as to propose correlations between Vp and some mechanical and physical parameters. This study was carried out using phyllites from three weathering profiles located along the highway BR-356, Minas Gerais, Brazil. The results reveal a clear influence of weathering on Vp and durability mainly due to increased porosity. However, as the variation of this parameter is heterogeneous, the relationship between Vp, durability, and weathering is not uniform, although they present general trends. The behavior shown by porosity reflects the complex role of chemical weathering on fractures. The non-uniform pattern of Vp and durability throughout the weathering classes is also a consequence of the heterogeneity and anisotropy intrinsic to these phyllites. The empirical relationships established exhibit good correlation coefficients.