Influence of Weathering Depth and Fracture Intensity to Cut Slope Movement

: Various types of slope failure with different ground conditions were analyzed by detailed field investigation of 373 road-cuts along the national highways of Korea. The ground conditions, which are related to failure types and their triggering factors, are strongly dependent upon the weathering or soil depth and fracture intensity in cut slopes. We propose the soil depth ratio (SR) and block size ratio (BR) to define the ground conditions of the cut slopes and to evaluate their instability. SR, which is related to weathering conditions of the ground, is defined as the ratio of soil depth to that of slope height. When SR is greater than 0.4, sliding failure along discontinuities does not occur. BR is defined as the ratio of the block size index to that of slope height. When BR is less than 0.01, behavior of the rock slope shows characteristics of circular sliding even if SR is less than 0.4. Therefore, the ground conditions in cut slopes can be divided into 4 classes based on SR and BR: jointed rock mass (JRM), highly fractured rock mass (HRM), massive rock mass (MRM) and soil-like mass (SLM). This classification provides useful criteria to assess the instability of cut slope composed of various ground materials, and gives some simple rules about instability modes of the cut slopes. KCI Citation Count: 3