LIMESTONE AND CHALK CHARACTERISTIC IN BUKIT PECATU, BADUNG, BALI

Limestones and chalks are unique forms of sedimentary rock which posses high compression strength but easily weathered and eroded when expose to the surface process. Subsurface investigation such as coring, sampling and laboratory testing are required to establish the rock characteristics. In general, rock characteristic indicators are unconfined compression strength, rock quality designation (RQD), fracture spacing, fracture conditions, ground water state and fracture orientation. These indicators are very practical in classification of rock mass rating (RMR) system. The aim of this research is to analyse the characteristic of limestone and chalk in Bukit Pecatu. The samples from three sites in Pecatu Heights Peninsula, Badung Regency, Bali are characterized in this study. The sites are selected to represent the west, central and east parts of the peninsula. The study findings on the strength parameters are as follow, unit weight varies from 20 - 22 kN/m3 , ultimate bearing pressure (UBP) 2 - 16 MPa, safe bearing pressure (SBP) 1 - 2 MPa and natural cut slope angle 45 - 55o to horizontal. The RMR value of the west part of the peninsula reveals higher value than the two other parts. Categorized as Fair Rock for west part with RMR score 52 and Poor Rock for central and east parts of the peninsula with RMR scores 37 and 29, respectively