Quantitative Weathering Assessment of Rock Slope using CIELAB Color Space and Image Analysis Technique

Quantitative weathering assessment using color changes is one of the new tools for slope stability assessment. In many other engineering field, CIELAB color space and image analytical tools have aided in enhancing the conventional method or inaccuracy due to the subjective and qualitative nature of visual assessment. This study focuses on the granitic rock slope surface assessment because of the predominant rock formation of granite in Malaysia. The 3D model of the rock slope was analyzed to extract the geological planes using compass plugin in Cloud Compare software and verified by manual compass mapping via scanline survey. Findings show that the a* and b* values increased with an increase in weathering results. This study focuses on the 50 points of measurement of rock slope and indicated a positive correlation of a* and b* with R2=0.9027. The image analysis result of the rock slope shows that major zoning (74%) is susceptible to failure due to structural control whilst another 26% are controlled by significant weathering in the grade IV-VI. This outcome is strongly verified via a geomechanical test, geological structure, and mineralogical assessment. The aforementioned mechanism is recommended in any geotechnical and technical purpose in enhancing the method of weathering assessment because image analysis provides reliable measurements in addition to the manual visual inspection.