Investigation into effects of past earthquake histories on liquefaction properties of dense sandy ground and seismic behavior of superstructures resting on it

• Project/Area Number: 18H01531
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: The University of Tokyo
• Principal Investigator: Koseki Junichi 東京大学, 大学院工学系研究科(工学部), 教授 (30272511)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥17,680,000 (Direct Cost: ¥13,600,000、Indirect Cost: ¥4,080,000); Fiscal Year 2020: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000); Fiscal Year 2019: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000); Fiscal Year 2018: ¥10,140,000 (Direct Cost: ¥7,800,000、Indirect Cost: ¥2,340,000)
• Keywords: 地盤工学 / 液状化 / 振動台実験 / 室内土質試験

Outline of Final Research Achievements

Experimental investigations were conducted to study the increase of the liquefaction resistance of sandy soil deposits that undergo gradual densification due to many earthquake histories as well as to reveal its effect on the seismic performance of superstructures resting on such dense sandy soil deposits.
As a result, the liquefaction properties of dense sands were found not simply to depend on their overall relative density. The structural performance was largely affected by the past shaking histories under otherwise similar conditions of the dense subsoils, including their overall relative density. It was also demonstrated that the liquefaction resistance of dense sands could be more significantly raised by applying partial liquefaction histories repeatedly.

Academic Significance and Societal Importance of the Research Achievements

密な砂地盤の液状化特性が、平均的な相対密度だけでなく地震履歴の影響も受けることをを明らかにした点に学術的な意義がある。
実務においては密な砂地盤が重要構造物の支持地盤とされる場合が多いため、この研究成果は社会的にも意義も有する。
さらに、液状化しやすい砂地盤を締め固めて改良する際には、部分液状化履歴に相当する履歴を与えていくことで効果が高まると考えられることを示した点で、今後の応用研究の方向性も提示している。

Research Products

• [Journal Article] A procedure to reach high liquefaction resistance in laboratory testing on reconstituted sand specimens using hollow cylindrical torsional shear apparatus (2020)
  • Author(s): Liu Weichen、Koseki Junichi
  • Journal Title: Japanese Geotechnical Society Special Publication Volume: 8 Issue: 12 Pages: 476-479
  • DOI: 10.3208/jgssp.v08.j14
  • NAID: 130007908640
  • ISSN: 2188-8027
  • Year and Date: 2020-03-14
  • Peer Reviewed
• [Journal Article] Effects of compaction thickness on liquefaction properties of two kinds of sandy soils prepared by moist-tamping method (2020)
  • Author(s): Sasaki Tomoko、Kawamura Shima、Koseki Junichi
  • Journal Title: Japanese Geotechnical Society Special Publication Volume: 8 Issue: 9 Pages: 355-359
  • DOI: 10.3208/jgssp.v08.j12
  • NAID: 130007908673
  • ISSN: 2188-8027
  • Year and Date: 2020-03-14
• [Journal Article] Cyclic Bi-Axial Tests on Assembly of Metal Rods Under Constant-Volume Condition to Study Re-Liquefaction Behavior (2020)
  • Author(s): Koseki Junichi、Yokoyama Daichi、Morimoto Tokio
  • Journal Title: Transportation Infrastructure Geotechnology Volume: 7 Issue: 3 Pages: 478-495
  • DOI: 10.1007/s40515-020-00123-w
  • Peer Reviewed
• [Journal Article] Several challenges in advanced laboratory testing of geomaterials with emphasis on unconventional types of liquefaction tests (2019)
  • Author(s): Koseki Junichi
  • Journal Title: Geomechanics for Energy and the Environment Volume: 22 Pages: 100157-100157
  • DOI: 10.1016/j.gete.2019.100157
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Effects of induced anisotropy on multiple liquefaction properties of sand with initial static shear (2019)
  • Author(s): Morimoto, T., Aoyagi, Y. and Koseki, J.
  • Journal Title: Soils and Foundations Volume: 59 (5) Issue: 5 Pages: 1148-1159
  • DOI: 10.1016/j.sandf.2019.03.015
  • Peer Reviewed
• [Journal Article] Effects of small and large shear histories on multiple liquefaction properties of sand with initial static shear (2019)
  • Author(s): Morimoto, T., Aoyagi, Y. and Koseki, J.
  • Journal Title: Soils and Foundations Volume: 59 (6) Issue: 6 Pages: 2024-2035
  • DOI: 10.1016/j.sandf.2019.11.001
  • Peer Reviewed
• [Journal Article] Effects of compaction thickness and initial water content on liquefaction properties of compacted sand specimen (2018)
  • Author(s): SASAKI Tomoko、SATO Takeshi、ZHAO Chuang、KOSEKI Junichi
  • Journal Title: Japanese Geotechnical Journal Volume: 13 Issue: 4 Pages: 379-392
  • DOI: 10.3208/jgs.13.379
  • NAID: 130007541543
  • ISSN: 1880-6341
  • Year and Date: 2018-12-31
  • Peer Reviewed / Open Access
• [Journal Article] 締固め砂杭の施工が液状化強度特性に及ぼす影響に関する最近の知見 (2018)
  • Author(s): 古関潤一
  • Journal Title: 基礎工 Volume: 46（11） Pages: 2-5
• [Journal Article] Effect of past history on liquefaction resistance of level ground in shaking table test (2018)
  • Author(s): Teparaksa J.、Koseki J.
  • Journal Title: Geotechnique Letters Volume: 8 Issue: 4 Pages: 256-261
  • DOI: 10.1680/jgele.18.00085
  • Peer Reviewed / Open Access
• [Presentation] 二軸載荷試験装置を用いた再液状化試験および画像解析による微視的構造の変化に関する考察 (2020)
  • Author(s): 横山大智，森本時生，古関潤一
  • Organizer: 第55 回地盤工学研究発表会
• [Presentation] 締固め砂杭打設を模擬した水平地盤模型の振動台実験 (2020)
  • Author(s): 日下部真佑，古関潤一，原田健二
  • Organizer: 第55 回地盤工学研究発表会
• [Presentation] 砂締固め砂杭打設を模擬した水平地盤模型の振動台実験における応力ひずみ関係 (2020)
  • Author(s): 日下部真佑，古関潤一，原田健二
  • Organizer: 土木学会第75回年次学術講演会
• [Presentation] Analysis of repeated liquefaction behavior in shaking table test and triaxial test using energy approach (2019)
  • Author(s): Teparaksa, J. and Koseki, J.
  • Organizer: 16th Asian Reginal Conference on Soil Mechanics and Geotechnical Engineering
  • Int'l Joint Research
• [Presentation] Multiple-liquefaction behavior of sands in shaking table tests and cyclic stacked-ring shear tests (2019)
  • Author(s): Koseki, J., Aoyagi, Y., Morimoto, T., Wahyudi, S., Teparaksa, J. and Iqbal, M.S.
  • Organizer: 7th International Conference on Earthquake Geotechnical Engineering
  • Int'l Joint Research / Invited
• [Presentation] 1-g shaking table test study of the impact of repeated liquefactions (2019)
  • Author(s): Baboz, E., Watanabe, K. and Koseki, J.
  • Organizer: 7th International Conference on Earthquake Geotechnical Engineering
  • Int'l Joint Research
• [Presentation] The effect of strain amplitude on the repeated liquefactions of levelled ground in a model test (2019)
  • Author(s): Iqbal, M.S., Taparaksa, J. and Koseki, J.
  • Organizer: 9th Asian Young Geotechnical Engieer’s Conference
  • Int'l Joint Research
• [Presentation] Effects of pre-shear history on repeated liquefaction behavior of dense sand using hollow cylindrical torsional shear apparatus (2019)
  • Author(s): Liu, W. and Koseki, J.
  • Organizer: 土木学会第74回年次学術講演会
• [Presentation] 実験室で液状化強度が高い砂供試体を作る手法およびその複数回液状化挙動に関する研究 (2019)
  • Author(s): Liu, W., 古関潤一
  • Organizer: 第16回地盤工学会関東支部発表会
• [Remarks] Study of Pre-Shake Effects on Liquefaction
  • URL: http://geotle.t.u-tokyo.ac.jp/portfolio/study-of-pre-shake-effects-on-liquefaction-in-shake-table/
• [Remarks] Impact of Repeated Liquefaction on Superstructure
• [Remarks] Impact of the Repeated Liquefaction on Structure