Risk assessment based selection of rock TBM for adverse geological conditions using Fuzzy-AHP

Uncertainty in geological and geotechnical parameters is inevitable as it is never possible to accurately determine every aspect of the ground conditions along the tunnel alignment during site investigations. As a consequence, there are many potential sources of geotechnical risk in both mechanized and conventional tunneling techniques. Problems such as encountering crushed and fault zones with running gouge, tunnel face and wall instabilities in blocky ground, large quantities of water inflow and converging tunnel sections are the principal geotechnical risks which affect the selection of an appropriate tunnel boring machine. The paper discusses the use of a fuzzy analytical hierarchy process as an efficient means of decision-making, which can take into account the different criteria pertinent to proper machine selection for anticipated ground conditions.