2017 年 5 巻 2 号 p. 1-4
Small diameter caisson type piles have been used for the foundations of the structures built in mountainous areas, such as bridges, power lines and so on. Therefore, those piles will continue to be important foundations of the structures built in mountainous area. The small diameter caisson type piles, however, have been constructed by manpower mostly under dangerous and terrible situations. For example, digging, assembling retaining wall, spraying shotcrete, assembling rebar, and compaction of placed concrete are all carried out by manpower at the bottom of the small diameter pile hole. Furthermore, the dug soil is conveyed from the pile hole to outside, retaining wall and rebar are carried into the pile hole, in the situation that the workers are working at the bottom of the pile hole. Due to the poor construction situation, decreasing the number of young workers who take care of the future construction of piles has been accelerating. Therefore, improving the construction situation of the small diameter caisson type pile is an urgent issue, which has to be solved rapidly. The authors have proposed an unmanned construction system for the small diameter caisson type pile, in which workers do not need to go into the pile hole during the pile construction. The applicability of the system has already confirmed from test constructions of three real piles, which were performed at the two construction sites of expressway. The applicability confirmed from the test constructions as well as the details of the proposed system are summarized in this paper.
