Case study of oval shaped foundation using the Gyropress Method under overhead restrictions

This paper describes the press-in piling method of steel pipe piles to form steel pipe foundations for the expansion of bridge piers to widen an existing bridge on the expressway. In this project, it was necessary to install steel pipes under girders/beams of a road bridge while keeping the bridge in service. It was also necessary to embed piles in a gravel layer having a maximum extrapolated SPT N-value of more than 70. The Gyropress Method using a type of machine capable of low headroom operation was adopted. In this method, steel pipe piles with pile toe ring bits are rotationally pressed-in to cope with hard ground and steel pipe piles can be pitched using a hoisting system for low headroom. By welding short segmental piles together in vertical position under overhead restrictions, it was possible to press in steel pipe piles until reaching the supporting layer.