Analysis and management of financial risks arising from ground conditions

摘要

Engineering works that involve subsurface construction or operations are vulnerable to problems that arise from unforeseen ground conditions. If foreseeable, such problems can be avoided by undertaking effective geotechnical investigations. Clients, consultants and contractors expose themselves to high levels of uncertainty and financial risk unless ground conditions are well defined by thorough, good-quality investigation. The financial benefits of adequate site investigation can be demonstrated by risk modelling, and such an approach is described for a tunnelling scheme. Two models are outlined in the case study: the first analyses the effect of uncertainty in ground conditions on planning estimates of project cost and duration; and the second models the financial consequences of encountering unforeseen conditions during construction. Both models indicate the financial benefits that can be obtained from good levels of investigation, and the results are shown to be realistic when compared to the prototype event. A strategy is proposed for the management of ground risk that relates the level of investigation to the complexity and degree of risk in a project.