Abstract Due to a stress redistribution after the excavation of an underground tunnel for radioactive waste disposal, an Ed/DZ (excavation disturbed/damaged zone) will be generated in the near field of the opening, resulting in significant changes in the hydraulic and mechanical properties of the rock mass in the zone. Initially more or less randomly distributed hydrocarbons at grain boundaries in rock salt, which sometimes can only be observed with ultraviolet light, can then be mobilised and migrate at a potentially significant rate towards the excavation. Within the international cooperative project DECOVALEX 2019, the migration mechanism of such fluid inclusions in rock salt is being studied intensively. A multi-scale modelling strategy has been developed. A macroscale coupled hydro-mechanical modelling of an underground excavation was performed to determine hydraulic and time-dependent deviatoric stress conditions, by taking into account the rock salt creep behaviour. Under the obtained macro-scale constraints, micro-scale modelling of a pathway dilation along halite grain boundaries was performed using different model strategies: a) coupled hydromechanical modelling with a consideration of hydraulic pressure-induced dilatant deformation, b) nonlinear dynamic model taking account of fluid migration, stress-dependent grain boundary wetting and shear-induced dilatancy of salt, and c) phase-field modelling of flow pathway propagation. The permeability increase resulting from the pathway dilation is estimated to be as high as two orders of magnitude. Based on the permeability determined, a series of pressure build-ups measured from a borehole with a high hydrocarbon release rate, a total of 430 build-ups within a monitoring time of 938 days, can be simulated with a macro-scale compressible flow model accounting for different zones around the opening.

中文翻译：

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岩盐中开挖应力重新分布导致油气释放的渗透率测定

摘要 由于放射性废物处理地下隧道开挖后的应力重新分布，在洞口近场会产生Ed/DZ（开挖扰动/破坏区），导致水力和力学性能发生显着变化。区域内的岩体。最初或多或少随机分布在岩盐晶界的碳氢化合物有时只能用紫外光观察到，然后可以移动并以潜在的显着速率向挖掘方向迁移。在国际合作项目DECOVALEX 2019中，正在深入研究岩盐中此类流体包裹体的运移机制。已开发出多尺度建模策略。通过考虑岩盐蠕变行为，对地下开挖进行了宏观耦合水力机械建模，以确定水力和时间相关的偏应力条件。在获得的宏观尺度约束下，使用不同的模型策略对沿岩盐晶界的通道膨胀进行微观尺度建模：a) 考虑液压引起的膨胀变形的耦合流体力学建模，b) 考虑非线性动力学模型流体迁移、应力依赖的晶界润湿和盐的剪切引起的剪胀，以及 c) 流动路径传播的相场建模。由通路扩张引起的渗透率增加估计高达两个数量级。根据确定的渗透率，