Abstract:
Three groups of parallel rows of approximately 130ft long, 47in diameter pipe piles were installed at 118in on center to protect Japan’s HSR (High Speed Rail) bridge piers from landslides on a steep and sensitive slope. Each pile was rotated and simultaneously pressed into the non-sliding bedrock through the soil above, accomplishing non-vibratory and expedient installation all from the top of the previously installed piles. The slope’s geotechnical conditions were mostly colluvial soil and weathered sandy mudstone which were underlain by alternate layers of mudstone, tuff, and breccia of D to CM classes with as many as four landslide planes. The project’s planned landslide preventive measure was the installation of aligned pipe pile groups on the slopes above the bridge piers. The piles were placed with 71in gaps between them to allow ground water to freely migrate through. The Gyropress piling method, a variation of press-in piling, was adopted to rotate and simultaneously press pipe piles into the ground. A sacrificial cutting shoe was welded at the toe of each pile for fast pile installation even into hard soil, rock, or existing concrete. In order to deal with steep and unstable terrain at the project, a Clamp Crane, and Pile Runner were utilized in combination with the piling machine, so all the piling related activities were safely conducted from the top of previously installed piles without building a construction road on the unstable slope. This presentation will highlight the use of pressed-in pipe pile walls for prevention of landslides and debris flows with a couple of other projects.