Abstract
Fluid transmission in geothermal reservoirs is significantly affected by foliated metamorphic rocks, which exhibit high anisotropy and heterogeneity. Coupled with hydromechanical analysis, we used discrete element-based software, which adopt the anisotropic properties of rock mass to investigate areas affected by hydraulic stimulation at geothermal sites. The proposed model was first validated using an existing benchmark problem concerning geothermal analysis under isotropic conditions. The analysis further considers the foliation-orientation-dependent shear behavior. The results indicate that the model with anisotropic angle \(\alpha =45^\circ\) predicts the greatest increase in fracture aperture when accounting for the contributions of both shear dilation and joint normal stress drop. The analysis also examined the influence of anisotropy on the rock mass failure patterns. The zone of shear failure is highly affected by two factors: angle \(\alpha\) and the stress state acting on the foliation plane. The case where \(\alpha =90^\circ\) demonstrates an evident stress concentration area near the fracture end tips, thereby facilitating shear failure in the zone. The results demonstrate that the proposed model can reasonably simulate the anisotropic hydromechanical coupling behavior of metamorphic rock masses.
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Funding
This research was financially supported by the Industrial Technology Research Institute, and Ministry of Science and Technology, Taiwan under Contract MOST 108–2628-E-009–004-MY3 and MOST 109–2623-E-009–001-NU.
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Shiu, WJ., Weng, MC., Chiu, CC. et al. Evaluating coupled hydromechanical behavior of anisotropic rock mass using DEM. Bull Eng Geol Environ 81, 98 (2022). https://doi.org/10.1007/s10064-022-02605-2
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DOI: https://doi.org/10.1007/s10064-022-02605-2