Deformational Control in Excavating Unstable Slopes

Abstract

Rock bolting is not a commonly used tool for stabilizing rock slopes; however, its use in stabilizing large slopes in very poor rock is demonstrated here. During the excavation of double silos for a large pumped water storage hydroelectric scheme, multiple slope failures occur. Further excavation has been suspended until stabilization and excavation processes are determined. Extensive geological and numerical modeling, followed by sensitive monitoring with ongoing construction, is required. Deformations are predicted using a mechanistic finite element method. The installed monitoring system with predicted deformations is used to control construction and support requirements. If the measured deformations exceed the predicted deformations by more than 30% to 100%, depending on the class of rock, then reasons for these differences are determined before further excavations are performed.