Installation of steel pipe piles and steel pipe sheet pile for bridge foundation using vibratory inner-excavation method (NB SYSTEM)

Abstract

The NB System is an inner-excavation pile installation method for steel pipe pile and steel pipe sheet pile using vibration equipment. The NB System drastically increases pile installation speed, as the vibration motion temporarily reduces the frictional resistance between the surface of pile and the surrounding soil. The NB System can be used to load-bearing layers that include rocks and boulders and to soft rock layers; it can be used to a maximum depth of about 90 m. The advantages of the NB System include improved installation accuracy, since it has possibility of extracting/correcting of install errors. Furthermore, the NB System can be used in areas where have environmental limitations, since its low vibration and noise emissions, and vibro can be operated only when needed. The NB System has been used for more than 50 projects in Japan. In this paper, we report a construction case of steel pipe piles with a length of 87.5 m and steel pipe sheet piles with a length of 43.5 m both using the NB system in bridge foundation work.