Deliverable D3.1. Drainage to Excavations – State of the Art Report

Abstract

Ground works such as deep excavations and foundation works performed in soft clay can cause damage to neighbouring buildings and structures. Drainage causes pore pressure lowering, followed by consolidation settlements. The costs related to settlement damage can be substantial and there is a considerable potential for reducing these costs. The risk of settlement damage caused by drainage and pore pressure reduction can be reduced during the early design phase of a project by undertaking the correct type of investigations and understanding the hydrogeological conditions. Furthermore, one may select construction methods, which reduce risk of drainage. In case the selected construction solution yields an unacceptable risk for settlement damage to surrounding buildings and infrastructure, remedial measures may be designed to mitigate the effects, followed by implementation and monitoring during the construction phase. This report provides State-of-the-Art related to hydrogeological investigation methods, hydrogeological modelling and numerous measures to mitigate the effects of drainage to excavations. In addition, governing Norwegian rules and regulations are discussed, as well as the causes of drainage to excavations in Norwegian ground conditions.