SAFENET-2 – fracture evolution in crystalline rocks (from lab to in situ scale)

Abstract. The DECOVALEX Task SAFENET is dedicated to advancing the understanding of fracture nucleation and evolution processes in crystalline rocks, with applications in nuclear waste management and geothermal reservoir engineering. Further improvements to fracture mechanics models are required in two distinct areas. Firstly, there is a need to enhance numerical methods for fracture mechanics under varying thermo-hydro-mechanical (THM) conditions. Secondly, there is a requirement to develop applied tools for performance and safety assessment in the context of nuclear waste management, as well as for reservoir optimisation in geothermal applications. Building on the achievements of SAFENET, which concentrated on benchmarking fracture models and experimental laboratory analyses, SAFENET-2 is dedicated to extending and validating models from the laboratory to the field scale. This paper gives a detailed description of the SAFENET-2 experimental programme work plan and modelling exercises. The experiments will be carried out at the rock mechanics laboratories of the University of Edinburgh and Chongqing University. For field data, the STIMTEC experiment at the Reiche Zeche teaching and research mine (Technische Universität Bergakademie Freiberg) is used. The individual steps of the Task are described in detail in this paper. As a result of SAFENET, the benchmark suite will be made available as interactive exercises via a web portal, thus promoting the concept of open science. The paper is a tool for teams to organise their work efficiently and is also an overview and insight for the community.