| In Japan、 pile foundations constructed on volcanic ash ground are usually designed based on specifications for sandy soil ground. However、 the mechanical characteristics of volcanic ash soil、 such as friability against confining pressure、 differ from those of sandy soil. Vertical loading and electric cone penetration tests were therefore conducted for foundation piles of bridges constructed on volcanic ash soil at 14 sites to confirm the vertical bearing mechanism of piles in volcanic ash soil.[*]Volcanic ash soil in Hokkaido can be roughly divided into pyroclastic fall deposit and pyroclastic flow deposit based on the type of eruption. Testing and verification showed that the skin friction f of piles in pyroclastic fall deposit developed in a manner equivalent to that of sandy soil、 but that in pyroclastic flow deposit it tended to decrease compared with that of sandy soil. A certain level of correlation was observed between the skin friction f of piles and cone-end resistance qt、 indicating potential application to design and construction management in the future. |
