Classification of heterogeneous granitic weathering in tropical regions: influence of weathering zones, joints, and boulder occurrences via statistical analysis.

Abstract

The classification of weathered rock masses in tropical regions is continuously revised to enhance the understanding of their complex behavior and characteristics, particularly in heterogeneous granitoid formations. However, the influence of in situ boulders and joint characteristics on the development of heterogeneous weathering zones remains poorly understood. This study examines the impact of boulder occurrence, degree of weathering, and joint characteristics on the formation of tropical heterogeneous granitic weathering zones. A total of 46 panels, spanning from the top to the base of slopes across five quarries in Johor, Malaysia, were systematically analyzed and classified based on boulder distribution and joint features across different weathering zones. The findings reveal that boulder occurrence contributes to the formation of 17 distinct weathering profiles, categorized into four dominant groups with six, five, four, and three weathering zones, occurring at frequencies of 35%, 20%, 27.5%, and 17.5%, respectively. Among these, five major weathering profiles classified as types I, II, III, IV, and V, were identified as the most prevalent, with occurrence rates of 17.5%, 15%, and 7.5% each for the latter three. The presence or absence of boulders, particularly in moderately to completely weathered (MW-CW) zones, plays a critical role in shaping weathering profiles, offering valuable insights for subsurface exploration and understand the subsurface ground models. These findings contribute to weathering classification, thereby improving environmental management and engineering practices in boulder-rich heterogeneous granite zones.