Study on pile group effect of belled conrete pile

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04777
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 23010:Building structures and materials-related
• Research Institution: Nihon University
• Principal Investigator: SHIMOMURA Shuichi 日本大学, 生産工学部, 准教授 (50443726)
• Co-Investigator(Kenkyū-buntansha): 新井 寿昭 西松建設株式会社(技術研究所), 技術研究所建築技術グループ, 主席研究員 (40511390)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 場所打ちコンクリート拡底杭 / 群杭効果 / 鉛直支持力 / 画像解析

Outline of Final Research Achievements

In this study, the mechanism of the group pile effect of belled piles and straight piles was analyzed based on model experiments and FEM analysis in order to obtain knowledge that contributes to the design considering the group pile effect of piles. As a result, it was clarified that the group pile effect was different due to pile bottom shape in the model tests. In response to this result, model tests were conducted to observe the behavior of the ground near the pile tip during vertical loading, and by the shear strain distribution obtained from the image analysis was confirmed that there was a difference in the ground behavior between the two piles. However, the mechanism of the group pile effect has not been fully explained by the ground behavior. On the other hand, it was confirmed that the current simple evaluation formula for the group pile effect can generally explain the experimental results.

Free Research Field

建築構造

Academic Significance and Societal Importance of the Research Achievements

拡底杭に関する群杭効果を考慮した設計法は確立されておらず，学術的背景のない根拠に基づき，設計者の裁量に委ねられた設計がされており，合理性の欠如，安全面のリスクが潜在している状況にある。本研究は最終的な設計法までには至っていないものの、実験データに基づき定量的に群杭効果を示すとともに、地盤挙動に基づく分析も行っている。また、現行の簡易な群杭効果の評価法との定量的な比較も行っている。簡易な設計法はニーズが高く、本研究では社会的要求に対応した設計法の確立に向けて有益な知見を得ている点でその意義は大きいと考えられる。