Proposal of seismic design technique of pile-foundation with the effect of irregular pile-supporting stratum

• Project/Area Number: 16K06565
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Building structures/Materials
• Research Institution: Yamagata University
• Principal Investigator: Mitsuji Kazuya 山形大学, 工学部, 教授 (90292250)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2018: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2017: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2016: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
• Keywords: 杭基礎建物 / 不整形地盤 / 東日本大震災 / 耐震設計 / 地震観測 / 常時微動観測 / 数値解析 / 有限要素法 / 建築構造・材料 / 耐震 / 構造工学・地震工学 / 地盤工学 / 防災

Outline of Final Research Achievements

Numerical simulation is carried out for the pile-foundation building with irregular pile-supporting stratum based on the damage investigation of the 2011 Tohoku earthquake. Pile length of the north side of this building is longer than south side by 10m in maximum. Numerical simulation model is organized to investigate dynamic behavior of the building for main shock of the 2011 Tohoku earthquake. Results indicate that seismic stress of short pile is larger than long pile due to rocking motion of super structure. This result shows good agreement with the report of damage investigation. General model of pile-foundation building is also organized and numerical simulation is conducted. The effect of the angle of the slope of pile-supporting stratum and seismic stress of the pile head is discussed and quantitatively estimated.

Academic Significance and Societal Importance of the Research Achievements

国土の広くない日本では、複雑な敷地条件に中高層建物を建設する例が数多く見られる。杭支持層が傾斜した建物では建物を支持する杭長が構面によって異なるため、杭頭部に発生する応力が複雑な状態となる。本研究では、杭支持層の傾斜に起因する杭長の違いにより、1）杭剛性の違いから杭応力に差が出ること、2) 建物の回転挙動が励起され、短い杭により大きな応力が生じること、を指摘した。これらの成果は、これまでの杭基礎の耐震設計には考慮されていなかった内容であるとともに、杭支持層が傾斜した建物の杭基礎設計や耐震改修を検討する際の有意義な基礎資料となる。

Research Products

• [Journal Article] Estimate of Local Site Effect with Irregular Seismic Bedrock for Earthquake Engineering Based on Microtremor Measurement (2018)
  • Author(s): Kazuya MITSUJI, Susumu OHNO, and Masato MOTOSAKA
  • Journal Title: 16th European Conference on Earthquake Engineering Volume: 1
  • Peer Reviewed
• [Journal Article] Dynamic behavior of a pile-foundation building with the effect of irregular pile-supporting stratum (2017)
  • Author(s): Kazuya Mitsuji, Masato Motosaka, Susumu Ohno, and Mai Tadokoro
  • Journal Title: 16th World Conference on Earthquake Engineering Volume: Paper No.1922
  • Peer Reviewed
• [Presentation] 山形盆地西部における地盤の常時微動観測 (2017)
  • Author(s): 三辻和弥、大野晋、源栄正人
  • Organizer: 日本建築学会東北支部研究報告集. 構造系
• [Presentation] 支持層の傾斜が杭基礎建物の地震時杭応力に及ぼす影響について (2017)
  • Author(s): 三辻和弥
  • Organizer: 第52回地盤工学研究発表会