Fundamental study on the accuracy of performance evaluation tests of basecourse and subgrade soil and their relationship to each other.

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K14805
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 22010:Civil engineering material, execution and construction management-related
• Research Institution: Nihon University
• Principal Investigator: YAMANAKA Kohichi 日本大学, 理工学部, 助教 (80733287)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 路床・路盤材 / 性能照査型設計 / 性能指標 / 測定精度 / レジリエントモデュラス / 小型FWD

Outline of Final Research Achievements

In this study, we focused on subgrade soil and carried out (1) a study on the measurement accuracy of performance indicators obtained from indoor tests, (2) a study on the measurement accuracy of performance indicators obtained from on-site measurement tests, and (3) an investigation on the correlation between each performance indicator. As a result, it was shown that Mr test could obtain more accurate measurement results than CBR test in indoor tests, and in on-site tests, the test using a portable FWD could measure subgrade soil more accurately than the plate loading test. In addition, this study also showed the correlation between each indicator based on the results obtained. Furthermore, it was shown that the deflection obtained from the portable FWD and that obtained from the multi-layered elastic theory using Mr test match by applying a coefficient β that takes into account the influence of loading speed and analysis of the distribution of ground contact pressure to the model

Free Research Field

舗装工学

Academic Significance and Societal Importance of the Research Achievements

道路舗装においても性能照査型に移行したにもかかわらずその普及は進んでいないのが現状であり，その要因である路床・路盤材の的確な評価方法の確立に加え，従来の仕様規定型と性能照査型で用いる評価指標の関連性を解明していく必要が求められている。
本研究は，性能照査型を進める上でも，各試験の精度および関係性を，本研究を行うことで明らかとなった問題点を踏まえて新たな知見を提示した研究であると考える。