Effect of particle crushing on cyclic shear under high-pressure conditions

2019 Fiscal Year Final Research Report

• Project/Area Number: 19K21090
• Project/Area Number (Other): 18H05921 (2018)
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund (2019); Single-year Grants (2018)
• Review Section: 0303:Civil engineering, social systems engineering, safety engineering, disaster prevention engineering, and related fields
• Research Institution: Tokyo University of Science
• Principal Investigator: Noda Shohei 東京理科大学, 理工学部土木工学科, 助教 (30749289)
• Project Period (FY): 2018-08-24 – 2020-03-31
• Keywords: 海底地盤 / 粒子破砕 / 粒子画像 / 繰返しせん断 / 高圧

Outline of Final Research Achievements

Under high-pressure conditions, particle crushing becomes a problem. However, since load stress is small during cyclic shearing, particle crushing was not confirmed in the particle size distribution based on mass. In this study, we focused on the particle size distribution according to the number of particles. We examined the effect of particle crushing due to repeated shearing under high-pressure conditions. It was confirmed that the particles with smaller particle diameter increased as the result of extracting the particles after shearing, obtaining the respective diameters from the image of several thousand particles, and evaluating the particle size distribution by the number of particles confining pressure increased. Cyclic shear tests were performed on samples containing fines. The cyclic shear strength was lower than that of Toyoura sand, but the effect of confining pressure was similar to that of Toyoura sand.

Free Research Field

地盤工学

Academic Significance and Societal Importance of the Research Achievements

高圧条件では、粒子破砕が問題となるが、繰返しせん断時は載荷応力が小さいため、粒子破砕は発生していないと考えられていた。しかし、これまでの手法では微小な粒子破砕は評価できないため実際に破砕しているか確認することができなかった。本研究ではその微小な粒子破砕を評価する手法を検討するものである。微小な粒子破砕の評価は、間隙構造やミクロな浸透・ダイレイタンシーの理解にも役立つものと考えている。さらに、近年研究例が増えている個別要素法（DEM）といった粒状体解析にも重要なパラメータとなる。本研究により得られる成果がこれらに大きく貢献できると考えられる。