Computer aided planning for tunnel construction

Tunnels are subterranean conveyance systems. Historically tunnelling projects have suffered significant cost and time overrun on account of variation in geological formation. Variation in strata may lead to various problems like tunnel caving in, water seepage etc. An attempt has been made to extend the Q-system of rock mass classification for reliable prediction of these tunnelling problems. For the purpose tunnelling problems have been identified and classified. A computer tool has been developed to aid the process. Also simulation as an aid for time planning while tunnelling under such varying geological conditions has been investigated. Reliable estimates of tunnelling problems and effect of geological variations on the project schedule will help the project management in informed decision making as regards issues like resource requirement. This paper describes the compilation and classification of tunnelling problems, matching problems to the Q-system parameters and the simulation model developed.