Settlement behavior of piled raft foundation supporting a 300 m tall building in Japan constructed by top-down method

Abstract

This paper offers a case history of the tallest building in Japan, 300 m in height above the ground level, located in Osaka, constructed by top-down method. The foundation of the building is a piled raft foundation which consists of a raft foundation with its bottom depth of 30.5 m below the ground surface and cast-in-place concrete piles embedded in very dense gravel layer below a depth of 70 m. The top-down method enables to make deep excavation safely in consideration of the surrounding environment and construct upper and basement floors simultaneously. Field monitoring were performed on the settlement and the load sharing of the piled raft. It was found that the measured settlements and load sharing between the piles and the raft roughly agreed with the design values.