Review of the Use of Engineering Geological Information and Design Methods in Underground Rock Construction

Rapport, 2013

One of the main concerns in underground rock construction is the complexity and uncertainty of the ground conditions at the project site. Detailed knowledge of the actual ground conditions cannot be determined until they are revealed at excavation, and the risk of preparing insufficient design alternatives must be balanced against the cost of investigating the ground before construction. The handling of engineering geological information and the preparation of design alternatives of various construction measures consequently need careful consideration throughout the construction process. The ground conditions are generally established by collecting and characterising data, creating geological models of the site and grouping material with similar engineering characteristics. Various design methods are employed to solve the engineering issues, e.g. numerical modelling, use of experiences from similar cases and the evaluation of observations carried out during construction. There are, however, problems associated with the handling of engineering geological information and implementation of design methods which are not always considered in the construction process. This study aims at identifying some of the most common problems associated with information handling in rock engineering design and explore some viewpoints on how these problems can be mitigated. The following areas are reviewed within this study: •The framework of the underground construction process •The investigation, conceptualisation and characterisation of ground conditions as a part of the handling of engineering geological information •The concept of uncertainties and risks within rock engineering and how these are dealt with during the construction process •Design methods commonly employed in rock engineering, with focus on empirical rock mass classification systems and the observational method •Two design issues, rock support and grouting, and how the observational method is suggested to be applied in the design of these