Effect of shaft rotation of driven spiral piles on vertical bearing capacity

Association for Disaster Prevention Research;et al.;Fukuoka Convention and Visitors Bureau;Japan Society for the Promotion of Science - Grant-in-Aid for Publication of Scientific Research Results;Kyushu Regional Planning Association;The Maeda Engineering Foundation15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015 -- 9 November 2015 through 13 November 2015 -- 121341This study explores the production of a new type of pile. This new spiral pile is made of a twisted steel plate, creating a continuous spiral shape. Before starting the large-scale production of these piles, it is necessary to experimentally determine their bearing qualities, which are related to installation method. It is also necessary to develop an analytical model to determine their bearing capacity. The purpose of this study is to determine the bearing qualities of the spiral pile and the behavior of the surrounding ground. Considering this, the first objective is to examine the incidence of the shape of the pile. The installation method and penetration resistances are thoroughly discussed on the basis of the results of static loading tests using model piles. The static penetration tests were conducted under various shaft rotary conditions at the model pile head. It was confirmed that the shaft rotary condition has a significant impact on the penetration resistance and vertical bearing capacity of the spiral pile. The second objective is to show the behavior of the ground before and during penetration using X-ray computerized tomography (CT). An industrial X-ray CT scanner was used to observe changes in the density of the sand surrounding the spiral piles before and during penetration. The disturbance area of the ground surrounding the spiral pile was observed using CT images; the images revealed that the disturbance area surrounding the spiral pile was significantly affected by shaft rotary conditions