Prediction of closures and rock loads for tunnels in squeezing grounds : Sharma, V M; Ramamurthy, T; Sudhindra, C Proc 6th International Conference on Rock Mechanics, Montreal, 30 Aug–10 Sept 1987V2, P1227–1231. Publ Rotterdam: A A Balkema, 1987

Abstract

There are three main approaches namely analytical, observational and empirical, available for the design of support system of tunnels. The empirical approaches are based on rock mass classification systems, the observational approach basically represents a 'build as you go' philosophy, and the analytical solutions are mostly based on some simplifying assumptions about the ground behaviour. In the absence of any better technique being available, the designers mostly depend upon one empirical method or the other. Improvements in the design methods of tunnel supports and lining are obviously needed. It is necessary to understand the mechanism of behaviour of the system comprising support system and the surrounding medium, which, it is believed, can be achieved by a combination of theoretical considerations and studief of tunnel behaviour in the field. In this thesis, the convergence confinement method of ground-support interaction has been used as the basic technique to explain the phenomenon. The method of Brown et. al for calculating the radial convergence of a circular tunnel in a hydro-static stress field assuming the ground behaviour as elastic-strain softeningplastic using finite difference approach has been extended. Based on available experimental evidence, the relationship between two principal strains has been taken as non-linear. Finite difference approach has been replaced by part-integration and part numerical method. It is seen that the modified method converges faster and for