ChaMod-HSSR - Characterization and modelling of hard soil / soft rock considering anisotropy and swelling

Transitional stratum, also termed hard soil / soft rock (HSSR), is geomechanically a challenge. It’s behaviour strongly depends on the state of stress, it alters rapidly in contact with water, and often conventional characterization and classification methods from rock and soil mechanics as well as numerical material models are often inadequate. HSSR can feature an inherent anisotropy and may be prone to swelling. Not only the numerical modelling of the swelling behaviour according to the state-of-the-art has deficits, but above all those of the anisotropic rock mass and system behaviour. The construction of the Angath Adit, Tirol (Austria), through the rock mass of the Unterangerberg begins in 2023. This rock mass comprises a large variety of HSSR. The ChaMod-HSSR research project seizes this rare opportunity and aims at a detailed characterization of HSSR as well as the further development and calibration of material models. In the Angath Adit, observations will be carried out and relevant information and data from experimental (in situ, laboratory) and measurement campaigns are included in the evaluations and modelling work. Among other things, the project will result in a detailed description of the essential material specifics in their natural variability, a pool of information and data of high quality, as well as recommendations for characterization and modelling of HSSR. In addition, it shall contribute to a clear and meaningful approach differentiating between rock, HSSR, and soil. The long-term goal of the project consortium is to reduce uncertainties in the planning and execution of structures on and in HSSR and to optimize them.