Masataka Tatsuta

Novel compound steel sheet pile for earth retaining works

This paper describes a new type of steel sheet pile that is applied to temporary earth retaining works for the construction of underground structures. The steel sheet pile system, so-called Hat+H pile, has higher rigidity, lighter weight as a wall and can be driven easier compared with conventional retaining walls. The section which consists of Hat-type sheet pile and H-shape are compounded by simple fillet welding. The sheet pile of 900 mm is the widest hot-rolled monopile in the world, so the number of piles can be reduced compared with conventional piles whose width is 400 mm. The H-shape provides high rigidity as a composite section. Therefore, Hat+H piles can attain rapid construction and high stability of retaining walls and their works, that is, they are a solution for enhancing safety and productivity, which is required in recent years because underground structures have become more complicated and deeper with expanding urbanisation. This paper presents the results of a structural test and driving test on full-scale Hat+H piles in order to verify the required performance as a member of temporary retaining walls. The results of the flexural test show that the Hat+H pile has high flexural capacity and can be evaluated as a composite section in design. In the driving test, Hat+H pile was previously fabricated in the yard and repeatedly installed and pulled out to simulate a situation of temporary use. As a result, it was verified that Hat+H piles have high robustness and drivability, and are appropriate members for temporary earth retaining walls.