Effects of pore pressure cycling during earthquakes on fault reactivation

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K15092
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Asahina Daisuke 国立研究開発法人産業技術総合研究所, 地質調査総合センター, 主任研究員 (40738316)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 断層再活動 / 間隙水圧 / 三軸試験 / 透水係数 / 不連続面

Outline of Final Research Achievements

The purpose of this study is to investigate the effects of pore pressure-induced fault reactivation during earthquake. To achieve this objective, the effects of cyclic changes in pore water pressure on the hydraulic properties of fractured rock samples were investigated. We have also conducted a direct shear test using the true triaxial test apparatus to characterize the shear behavior of rock samples under various pore pressure and joint roughnesses. This study enables us to measure and evaluate the parameters of pore pressure as well as the mechanical changes in the fracture surface that have not been considered in previous studies.

Free Research Field

岩石力学，断層の力学，岩盤工学，コンクリート工学

Academic Significance and Societal Importance of the Research Achievements

本研究の特色は，地震動による間隙水圧の動的な変動と断層の水理・力学的な挙動を室内実験により再現し定量的に評価することにある．間隙水圧が断層の再活動に与えるメカニズムについて検討している研究は少なく，特に間隙水圧の変動と岩石破断面の力学的な伝播過程の定量的な評価に関する研究少ない．断層の再活動に伴う間隙水圧の動的な影響及びその伝播過程を明らかにすることは，地震発生メカニズムの解明といった防災学的な価値だけでなく，例えば，油ガス田開発における資源の生産性の向上というより工学的な目的に貢献することができる．