Study on the formation and expansion of subsurface cavity due to internal erosion and evaluation of potential risk of ground cave-in

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H02231
• 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: Kuwano Reiko 東京大学, 生産技術研究所, 教授 (80312974)
• Co-Investigator(Kenkyū-buntansha): 大坪 正英 東京大学, 生産技術研究所, 助教 (80804103)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 空洞 / 内部侵食 / 水みち / 陥没

Outline of Final Research Achievements

In order to prevent sinkholes and ground collapses, the underground cavities that cause cave-ins have to be detected and properly filled. However, due to a lack of knowledge in both cavity detection and countermeasures, road management practice is currently dominated by symptomatic countermeasures.
In this study, the mechanical behaviour of soil subjected to internal erosion and the generation and expansion mechanisms of underground cavities were investigated through laboratory soil tests and model experiments. A full-scale test road with artificial cavities was also constructed to develop a quantitative evaluation method for the risk of cave-in of cavities.

Free Research Field

地盤工学

Academic Significance and Societal Importance of the Research Achievements

陥没防止のためには、浅層部空洞に対しては地中レーダ探査によって探知することが可能であるものの、多数空洞が見つかる現状において対策の優先度を決めるために陥没危険度の評価が喫緊の課題であった。深層部空洞に関しては、地盤内部の侵食に伴う空洞生成・進展と陥没、および地下の水みち形成の過程と径路の把握について、これまで系統的な学術研究の事例が少なく知見の蓄積が進んでいない。本研究で、空洞の生成・拡大メカニズムを調べし深層部から浅層部に至る過程、および地表陥没に至る条件を明らかにした。