| Summary: | Surface excavation of tropical weathered massive and bedded rock masses presents significant challenges to contractors and project owners due to indistinct zones of soil-rock boundaries. This study aims at identifying the factors that contribute to the inhomogeneities and unique characteristics of tropical weathered rock masses, which impact the surface excavation of the rocks. A series of geological, geotechnical and geophysical tests were carried out to determine the important variables for this study. Several rock material parameters and rock mass properties affecting excavation were identified. Data collection involved laboratory testing and fieldworks at 8 study sites; four (4) sites for the bedded rock mass at Aurora Central Nusajaya, Johor; Eco Botani, Nusajaya, Johor; Iskandar Puteri, Johor and Bentong, Pahang, while the four (4) sites at Ulu Kinta, Perak; Nilai, Negeri Sembilan; Kulai, Johor and Kota Tinggi, Johor for the massive rock mass. The field studies involved geological mapping, evaluation of weathering state, discontinuity studies, in-situ rock characterization and geophysical testing. Trial excavations were also carried out across different lithologies using hydraulic excavators of varying capacities and specifications. To determine the significance parameters, statistical analyses were conducted to increase the confidence and enhance the accuracy of the results. The significance key factors for the bedded rock mass are the moisture content, Point Load Index (Is(50)), seismic velocity and slake durability in the first cycle (SD1). As for the massive rock mass, the significant parameters are characterized by the dry density, Is(50), block volume, and slake durability in the first cycle SD1. A Weathering Index Chart and a grading system were established as significant parameters that influence the performance of surface excavation in both bedded and massive rock masses. The proposed classification and method offer a more effective approach in evaluating surface excavation in tropical weathered rock masses.
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