Determination of Extent of Excavated Damage Zone Around Mined Tunnels using Pre and Post Construction Pore-Water Pressure Response

将核废料封存在深部地质储存库（DGR）是全球长期处置乏核燃料的首选方法。DGR的好处是工程和地质屏障的存在，将储存库与周围的地质环境隔离开来。所面临的挑战;然而，与任何地下开挖一样，在坑道开挖过程中，围岩也会受到破坏，称为开挖损伤区（EDZ）。随着与围岩距离的增加，裂缝强度逐渐减小，损伤起裂和裂缝扩展发生，直接影响围岩的原位渗透率。目前，通过数值模拟和在可进行实地试验的全尺寸地下实验室对经济开发区内的即时和时间变化进行评估。这些地下实验室依靠开挖试验坑道后对宿主岩石进行物理取样以及非破坏性的地球物理方法。这两种方法的总体效果都有一定的局限性。这些方法都不能在测试设备的整个生命周期内实时地完全表征EDZ的时间地质力学特性。

The containment of nuclear waste in deep geological repositories (DGR) is the preferred method for long-term disposal of spent nuclear fuel globally. The benefit of a DGR is the presence of both engineered and geological barriers that isolate the repository from the surrounding geological environment. The challenge; however, is that like any underground excavation, the surrounding host rock will be damaged during adit excavation known as the excavated damage zone (EDZ). Damage initiation and fracture propagation occurs with the crack intensity decreasing with distance from the tunnel wall, which has a direct influence on the in situ permeability of the host rock. Currently, assessment of the immediate and temporal changes within the EDZ is carried out through numerical simulation and in full-scale underground laboratories where field tests can be conducted. These underground laboratories rely on physical sampling of the host rock following excavation of test adits as well as non-destructive geophysical methods. Both of these methods have some limitations in their overall efficacy. None of these methods can fully characterize the temporal geomechanical properties of the EDZ on a real-time basis throughout the life of the test facility.