Abstract

This study discusses the characterization of rock slopes along the 54 km road from Ranau to Tambunan (RTM), Sabah, Malaysia. Along this stretch, seven slopes were assessed, with two (B20 and B35) located in the Crocker Formation and the others (B4, B5, B7, B13 and B16) in the Trusmadi Formation. The Geological Strength Index (GSI) technique was used to characterize the weathering condition and rock structures of the slopes. These two parameters are used to assign a GSI value that will indicate the quality of the rock masses. From the finding, it was found that slopes located in the Trusmadi Formation have lower GSI values and poorer surface conditions compared to those in the Crocker Formation. Based on field observations, the slopes in the Trusmadi Formation are sheared, highly weathered and folded. The weathering grade for these slopes range from moderate to high and the GSI values range from 20-35. In comparison, the two slopes (B20 and B35) in the Crocker Formation exhibit lower weathering grades, fewer intersecting joints and GSI values from 60-80. Apart from the GSI assessment, rock specimens were tested using the Point Load Index (PLI) test for strength measurement. The value from this test was later converted to UCS for strength classification. The lithologies tested are quartzite, meta-sandstone, sandstone and phyllite. Quartzite and meta-sandstone exhibit higher strength values than the other rock types. The rocks strength as observed in this study was influenced by the type of lithology, failure mode and by the weathering condition.

Keywords:

Discontinuity, GSI, rock mass condition, rock slope, rock strength, weathering,

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