Valuation of Rock Mass Classification and Rockfall Geohazard in Abandoned Limestone Quarry for Reclamation

Abstract The land reclamation of an area classified as geohazard-prone requires a comprehensive geological input before deciding on implementing sustainable and efficient development. The assessment of rock slope for quarry reclamation is crucial because quarry sites are exposed to geohazard events, particularly slope failure and rockfalls. Therefore, this study was conducted to assess the stability and potential failure of three rock slopes, namely GG1, GG2, and GG3, at an abandoned limestone quarry site in Kinta Valley, Malaysia. The Rock Mass Rating (RMR) and Slope Mass Rating (SMR) systems were utilised to assess the rock mass classification, while the rockfall analysis was performed to analyse the trajectory of the rock block. The slope kinematic analysis was also carried out to determine the potential mode of failure. The rockfall scenarios were simulated based on the input data of rock material properties to evaluate the safety aspect of the site for future urban development. The RMR system indicated that the quality of the rock mass was good and very good, while the SMR ranging from moderate to very good. The kinematic stability analysis for three slopes indicated the potential of a wedge, planar, and toppling failure. The analysis of the rockfall trajectory showed that the maximum rolling distance of the rock block was up to 5 m from the toe of the slope. Thus, the study proposed the construction of a buffer zone at least 20 m from the rock slope as a mitigation approach to avoid potential rockfall geohazard.