Deformation characteristics and influential factors of a toppling rock slope based on the grey relational analysis

This paper explores the deformation behaviour of 1(#) toppling rock slope, located on the right bank of the Lancang River upstream of Huangdeng Hydropower Station in China. Field monitoring data show that the surficial and deep displacements of the toppling rock slope increase greatly during the second stage of the impoundment period. The deformation of the toppling rock slope in the lower part is generally larger than that in the higher part, and the displacement near the dam side is larger than that farther from dam. Furthermore, the horizontal deep displacement decreases with increasing depth of the slope. Based on the measured displacements of the toppling rock slope, the grey relational analysis (GRA) method is used to explore the correlations between the slope displacement rate and the relevant influencing factors, including rainfall, water level fluctuation, time and air temperature. The results show that the main control factors influencing the slope displacement rate are the water level fluctuation followed by rainfall. The findings may suggest that the 1(#) toppling rock slope has the potential of hydrodynamic instability, and the water level fluctuation caused by the reservoir operation should be fully concerned to avoid the instability of the toppling rock slope.