WEP132  加速器土木、放射線防護  8月5日 小ホール 13:00 - 15:00
Major causes of girder deformation of SPring-8 storage ring and long-term variation of tunnel floor
○張 超(高輝度光科学研究センター),長谷川 誠,篠本 考秀,山本 浩司(SPring-8 Service Co. Ltd)
○Chao Zhang (JASRI), Makoto Hasagawa, Takahide Shinomoto, Hiroshi Yamamoto (SES)
Although the tunnel of SPring-8 storage ring is built on hard or artificial rock surrounding the hill of Miharakuri, the magnets on girders are observed have been displaced in certain degree, some far exceed the maximum permissible error of alignment. To investigate the cause, the shapes of girder surfaces were measured during the summer shutdown of 2013. And, the girder design was reconfirmed. On the other hand, since the operation of the storage ring in 1997, monitoring of the magnet alignments was executed in regular periods. We have 14 times of vertical surveys and 12 times of horizontal. Data of those are analyzed and summarized. As the result, deformation of girders could be divided to two phases, before and after the magnet alignment of 1995. The former needs further information to understand, while the latter is seen in close relation to girder support methods as well as the deformation of tunnel floor.