Earth Pressure on an Excavation Wall in Rock Mass

In this study, the earth pressure on an excavation wall in rock mass is investigated under various conditions (type of rock, angle of join inclination, shear strength of joint, groundwater, permeability of wall, and earth pressure coefficient at rest). Based on the results of a physical model test of an excavation wall in joined rock mass, extended parametric study is performed considering the rock-structure interaction based on the discrete element method. The study results suggest that the earth pressure is strongly influenced by the condition of groundwater as well as the condition of wall and rock mass. The effect of groundwater on the earth pressure in a jointed rock mass different depending on rock type, the earth pressure coefficient at rest, wall permeability, and joint inclination angle. The groundwater effect was greatest under an impermeable wall condition and a vertical joint acted as an impermeable wall. Under inclined joint and groundwater conditions, the earth pressure in a permeable wall increased when compared with no groundwater condition and the increase was more evident when the earth pressure coefficient was smaller. As the rock and joint conditions were deteriorated further, the earth pressure increased and the influence of groundwater decreased. The study results also showed that for hard rock and good joint conditions, the influence of groundwater was more significant as the earth pressure coefficient increased, but as rock and joint weathered, the influence of groundwater was more significant as the earth pressure coefficient decreased.