Rock mass classification system of the Crocker formation in Kota Kinabalu for rock slope engineering purpose, Sabah, Malaysia
This study aims to classify the rock mass of the interbedded Crocker Formation in Kota Kinabalu, Sabah. The rock cut slopes in CPSB Stone Quarry Sdn Bhd (slope B1, B2, B3 and B4) and Lakang Point (slope LP) in Tamparuli, Tuaran Hospital (slope TH) in Tuaran and Telipok-Sulaman by-pass (slope TS1 eas...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2011
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| Subjects: | |
| Online Access: | https://eprints.ums.edu.my/id/eprint/39146/1/24%20PAGES.pdf https://eprints.ums.edu.my/id/eprint/39146/2/FULLTEXT.pdf |
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| Summary: | This study aims to classify the rock mass of the interbedded Crocker Formation in Kota Kinabalu, Sabah. The rock cut slopes in CPSB Stone Quarry Sdn Bhd (slope B1, B2, B3 and B4) and Lakang Point (slope LP) in Tamparuli, Tuaran Hospital (slope TH) in Tuaran and Telipok-Sulaman by-pass (slope TS1 east, TS1 west, TS2 east and TS2 west of Telipok) in Telipok were selected for this study. The facies types in the study area are very thick-bedded sandstone unit (facies B), thick to medium-bedded sandstone unit (facies C), thin-bedded sandstone unit (facies D), thin-bedded siltstone and/or sandstone unit (facies E) and thick-bedded shale unit (facies F) which form the channel, channel-lobe, lobe prograding and basin plain facies associations. Application and evaluation of four selected existing rock mass classification system contribute to the formulation of Modified Slope Mass Rating (M-SMR) system for classifying the Crocker Formation rock mass. The M-SMR is obtained from basic Rock Mass Rating (RMRbasic) by adding an adjustment factor (discontinuity orientation parameter). The M-SMR parameter calculation for interbedded Crocker Formation rock mass quality are lithological unit thickness (LUT) approaches, classical RQD calculation method, weighted averaged of discontinuity set, weighted averaged, normal condition and new adjustment factor (NAF) for UCS, RQD, discontinuity spacing, discontinuity condition, water flow and discontinuity orientation parameters, respectively. For the safety of rock slope design, the weighted averaged of worst discontinuity set spacing, worst rating of discontinuity condition and worst condition of water flow are recommended. The M-SMR system is divided into class I (very low risk, very stable) to class VI (extremely risky, extremely unstable). Slope TS1 east, TS2 west and LP representing class II, slope B3 class III, slope B4, TS1 west and TS2 east class IV, slope B1 and B2 class V and slope TH class VI in the study area. The M-SMR system was formulate in order to propose the rock cut slope design in term of rock cut slope stabilization and protection measure, design model review and slope remapping and optimal slope angle for the interbedded Crocker Formation in the study area. Suggested risk mitigation measure for Crocker Formation are slope re-excavation for ‘extremely risky’ slope TH and only some scaling for ‘low risk’ slope LP, TS1 east and TS2 west. Detailed design model review (DMR) and slope remapping by expert and experienced engineering geologists or geotechnical engineers is highly recommended for class VI and V and IV of M-SMR in slope TH and slope B1 and B2 and slope B4, TS2 east and TS1 west, respectively. Slope TS1 east, TS2 west and LP of stable class II is only recommended for DMR and slope remapping by engineering geologist or geotechnical engineer. The range of optimum slope angle for less than 50m height slope of the Crocker Formation in the study area is between 65o to 70o and 40o to 45o for class II and IV of M-SMR system, respectively. Correlation between the Modified Slope Mass Rating (M-SMR) with geomechanical characteristics of the Crocker Formation such as facies characteristic, orientation of bedding planes with respect to slopes face, rate of weathering and degree of deformation and mode of rock slope failure is also produced. The diagonal orientation of bedding plane with respect to slope face of the channel, channel-lobe, migrating lobe and basin plain facies has been representing class II, class III to V (depending to channel and lobe facies ratio), class IV and class VI, respectively in the study area. |
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