Earthquake-induced fracture displacements and transmissivity changes in a 3D fracture network of crystalline rock for spent nuclear fuel disposal  

作　　者：Wenbo Pan Zixin Zhang Shuaifeng Wang Qinghua Lei 

机构地区：[1]Department of Geotechnical Engineering,College of Civil Engineering,Tongji University,Shanghai,China [2]Key Laboratory of Geotechnical and Underground Engineering,Ministry of Education,Tongji University,Shanghai,China [3]Department of Earth Sciences,ETH Zürich,Zürich,Switzerland [4]Department of Earth Sciences,Uppsala University,Uppsala,Sweden

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2023年第9期2313-2329,共17页岩石力学与岩土工程学报（英文版）

摘　　要：During the long service period of a nuclear waste repository in crystalline rock,large earthquake(s)may occur nearby the repository site and coseismically alter the local stress field around pre-existing fractures within the geological formation.The resulting fracture normal/shear displacements may lead to fracture opening and further promote the transport of leaked radionuclides into the groundwater system.Thus,it is of central importance to analyze the consequences of potential future earthquake(s)on the hydrogeological properties of a repository site for spent nuclear fuel disposal.Based on the detailed site characterization data of the repository site at Forsmark,Sweden,we conduct a three-dimensional(3D)seismo-hydro-mechanical simulation using the 3Dimensional Distinct Element Code(3DEC).We explicitly represent a primary seismogenic fault zone and its surrounding secondary fracture network associated with a power-law size scaling and a Fisher orientation distribution.An earthquake with a magnitude of M_(w)=5.6 caused by the reactivation of the primary fault zone is modeled by simulating its transient rupture propagating radially outwards from a predefined hypocenter at a specified rupture speed,with the faulting dynamics controlled by a strength weakening law.We model the coseismic response of the off-fault fracture network subject to both static and dynamic triggering effects.We further diagnose the distribution of fracture hydro-mechanical properties(e.g.mechanical/hydraulic aperture,hydraulic transmissivity)before and after the earthquake in order to quantify earthquakeinduced hydraulic changes in the fracture network.It is found that earthquake-induced fracture transmissivity changes tend to follow a power-law decay with the distance to the earthquake fault.Our simulation results and insights obtained have important implications for the long-term performance assessment of nuclear waste repositories in fractured crystalline rocks.

关 键 词：EARTHQUAKE Fracture network Aperture Fracture transmissivity Shear dilation Nuclear waste disposal 

分 类 号：TU452[建筑科学—岩土工程]