Evaluating the influence of rate of undercutting on the stability of slopes

Cut slopes of alternating soft and hard layers along roads in Jordan are subject to differential weathering, erosion and human activities. This can result in undercutting, leading to rockfalls that endanger traffic. The factors affecting the rate of undercutting and the influence of this on the stability of ten selected road cuts along the Amman-Irbid highway in Jordan were determined. The depth of undercut was measured at selected points and the mean rate of undercutting found to vary from 10 to 73 mm/year. Grain density, bulk density, slake durability, Atterberg limits, porosity and grain size distribution were determined and correlated with the rate of undercut. A positive relationship was found between undercutting and the sand fraction and porosity values and a negative relationship with the slake durability index.