Characteristics of weathering zones of granitic rocks in Malaysia for geotechnical engineering design

Abstract

Tropical climatic conditions cause severe weathering to rock masses resulting in thick weathering profiles consisting of different weathering zones with complex characteristics. Feasible geotechnical engineering design requires a detailed understanding of the characteristics of each weathering zone. A typical weathering profile is usually characterized by field-scale observation and geological study. This paper presents the characteristics of weathering zones of various granitic rocks in the south of Malaysia. This region has a tropical climatic condition. The study was carried out in four active quarries located in Johor province, Malaysia, and forty sections were investigated in the study areas. A typical granitic weathering profile was characterized based on the geological and structural parameters (i.e. joint characteristics, corestone occurrence, rock/soil ratio, mass homogeneity, color of rock, and discoloration at joints' surfaces). The profile includes common zones ranging from fresh to residual soil; however, two subzones are introduced based on corestone (boulder) occurrence in the highly weathered and completely weathered zones. This study, based on detailed field observations at the mentioned quarries followed by analysis, presents an amalgamated picture of weathering zones in granitic profiles of a tropical region like Malaysia. Moreover, it is believed that the characterization of the typical weathering profile allows further classification of generally complex weathered rock masses for a specific geotechnical engineering design.