Finding the Relationship between RQD and Fracture Frequency in the Different Ok Tedilithologies

Rock Quality Designation, RQD, is based on core recovery procedure which, in turn, is based indirectly on the number of fractures and amount of softening or alteration in the rock mass as observed in the rock cores. Many researches have been conducted to relate RQD and rock mass fracture. Along with many other parameters, RQD and fractures contribute greatly to the classification of a rock mass, which affect practical engineering practice and design such as pit slopes in mining. Setbacks in accurate judgement of the strength of the different rock types at one of the major open pit mine in Papua New Guinea was observed. Series of practical examinations using RQD data and scan line mapping of fractures has been conducted in four main section of the pit slope. Variation of RQD with scan line mapping of structures was observed to be as high as 24% in the horizontal bench face. In addition, the range of possible variation of RQD with scan line length was analyzed with four different models including two new models introduced in this case study for the first time. It is shown that at least 4 m of scan line length is required to maintain a reliable value for the RQD in the models.