Influence of Tunnel Shape on the Shotcrete Lining Stress

Tunnel excavation is generally done using drill and blast method and the weak geology causes the over breaks of tunnel. The over breaks not only increases the cost and construction time but also it has influence on the stress on shotcrete lining. This paper presents the influence of shape of the tunnel on the shotcrete lining stress is studied using a numerical modelling with the case study of Kathmandu University Research Tunnel. The region of over breaks is taken as 0.15-0.30 m for weak rock mass [1].Two numerical models have been prepared and the obtain result shows that the stress on the shotcrete lining increases with increase in the over breaks and should be consider in the design of shotcrete lining if the shotcrete lining is to be used as final lining.