ABSTRACT
This chapter reviews the major methodologies that used for investigating the rock mass stability around underground excavations. The strengths and limitations of each method are discussed. For instance, the rock mass classification systems are normally preferred by the engineers to evaluate the overall rock mass quality, to provide preliminary support guidelines, and to estimate the rock mass properties at an early stage of a rock engineering project. However, they have limited capabilities to provide ultimate support designs or to predict the accurate rock mass behavior and the intrinsic rock failure mechanisms. The analytical methods may be applicable for simple underground problems but difficult to apply for those with complex geologies and engineering disturbances. Field instruments are generally installed to record the rock mass response during and after excavation. Major concerns are probably the continuity and reliability of the field monitoring data. On the other hand, the recorded information can be used for the back-analysis of in-situ parameters or to validate the existing analysis. Numerical modeling is a capable tool of tackling complicated rock engineering problems. This method should be applied wisely and in conjunction with other methods, such as the empirical methods and the field instrumentations, for the purpose of developing an adequate model.
