ABSTRACT
Urban mass transportation system in India requires huge investment and a massive upgradation. With the exponential rise in population and metro cities being center of attraction for working population of the far flung rural areas in the vicinity, a cost effective, scheduled and comfort mode of public transport was a need to meet the requirement of masses. Metro Rail Transportation System proves to be a boon to the society and cater the mobility of urban India. Underground metro projects aligned beneath the ground, require deep excavations in the order of 25–40 m in depth in urban populated areas which impose many challenges, especially, predicting the ground behavior.
This paper showcases a case study of an ongoing underground metro project construction covering the detailed site investigations proposed depending upon the outcome of preliminary investigations. It also presents how geological variations can occur within shaft excavation and further provides guidelines on fixing a geotechnical testing program for ground predictions and to decide upon secant pile termination depths in hard rock. Estimated ground conditions during investigations and actual conditions during piling were in close agreement thus allowing timely and cost-effective completion of secant piling job.
