A thesis submitted in partial fulfilment of the requirements for the degree of Master of Engineering, School of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 1987

The support requirements of a section of the Central tunnel (Part of the South Link Railway Project in Taiwan, R.O.C.) are evaluated using the New Austrian tunneling method. The analysis is firstly conducted using four empirical methods the Geomechanics Classification (RMR method), BIENIAWSKI (1973), the NGI-Q system, BARTON et al., (1974), Rock Structure Rating (RSR concept), WICKHAM et. al. (1974) and Rock Quality Designation (RQD), DEERE et al. (1969). Then the carrying capacity of a modified support system based on an observational approach in the tunnel is checked by the s hear failure theory of the NAHL An analytical method, rock-support interaction analysis, is used to determine support requirements for induced stress conditions. These predictions are compared in order to investigate the applicability and flexibility of the modified support systems to the rock conditions encountered. A valuation, comparison and correlation of design methods, recommend support works and geological parameters involved is carried out. A cost analysis of the support systems provides a comparative evaluation of the predicted support in terms of economy. The results of the analysis indicate that the rock mass qualities investigated range from fair to very poor and the corresponding actual supports used can be reduced to 28% and 8% in cost for fair and poor rock condition, but should be increased to 10% for very poor rock condition. The modified support systems are generally more conservative than those recommended by the four empirical methods; however, t:hey are less conservative than those of a rock-support interaction analysis