Design of underground caverns - An overview

Design of large caverns such as Power House Cavern is a challenging task and various approaches have been devised to face this challenge. With the experience of increasing number of such caverns. these approaches have been modified and even new methods have came up Traditionally. the support system of such caverns was designed based on empirical approaches which were mainly based on experience with more: emphasis in passive supports. With the passage of time. the role of the rocks around excavation as supporting structure itself was given increasing importance and this awareness led to development of more scientific and sophisticated methods to study thc behaviour of rock mass around excavation. This paper describes briefly various traditional design approaches. the recent developments and their respective merits and demerits. These approaches have been weighted against the aim of design in terms of their practical suitability. The role of orientation of cavern and the effect of quality of construction & time of installaltion of supports on stability of the structure has also been discussed. Various precautions required to be taken using the recently developed design techniques have been emphasised.