Crushing characteristics of soil particles under high pressure cyclic loads

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K06575
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Building structures/Materials
• Research Institution: Hiroshima University
• Principal Investigator: YAMAMOTO HARUYUKI 広島大学, 国際協力研究科, 特任教授 (60158293)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 粒子破砕 / せん断強度 / 三主応力制御型高圧圧縮試験機 / 繰返し載荷 / 応力経路 / 粒子破砕量 / 塑性仕事量 / 杭先端支持力

Outline of Final Research Achievements

In practice, it may be important that the behavior of volume shrinkage and decreasing of shear strength due to particle crushing around pile tip in crushable sandy soils. The　particle crushing of sandy soils are reasons of the rapid increasing of settlements and the decreasing of pile tip bearing capacity. The repeated forces acting on the pile tip of high-rise building foundations are large by the cyclic additional load on pile head and decreasing effect of pile skin frictional resistance due to seismic rocking of superstructure.
In this study, the fundamental features of particle crushing under the cyclic high-stress conditions are found by the results of particle crushing tests with the high pressure true tri-axial compression apparatus. The experimental results are used for the designs and simulations of pile foundations under considering the particle crushing of soils.

Free Research Field

地盤・基礎工学

Academic Significance and Societal Importance of the Research Achievements

本研究成果の学術的意義は、高圧拘束下における地盤の変形強度特性を表す構成関係を土粒子の破砕現象そのものを基に構築する場合に土粒子の破砕に伴う地盤の体積収縮傾向や土粒子の微細化に伴う内部摩擦角の急激な減少傾向を定量的に説明するための基礎データとなるということである。
高圧拘束下の粒子破砕現象を考慮した地盤の変形や破壊現象が合理的に推定できるようになれば、破砕性地盤中の杭先端部近傍地盤の変形・支持力の推定精度が向上し、さらに繰返し効果をも考慮すれば地震時の杭先端支持力問題にも応用できるものと考えられ、より安全で合理的な設計根拠となる点に社会的な意義がある。