Study on the effect of hydro‐chemical dissolution on shear properties of rock fractures using the improved discontinuous deformation analysis

• Published in: International journal for numerical and analytical methods in geomechanics 2023-06, Vol.47 (8), p.1457-1480
• Main Authors: Gao, Jingyao, Chen, Guangqi, Mitani, Yasuhiro, Gong, Shilin, Feng, Chaofan
• Format: Article
• Language: English
• Subjects: Acidity; Analysis; Chemical damage; Chemical degradation; Constitutive models; damage factor; Deformation; Deformation analysis; Deformation effects; Degradation; Discontinuity; discontinuous deformation analysis; Dissolution; Dissolving; Fractures; Homogeneity; hydro‐chemical effect; Normal stress; Numerical analysis; Rock; Rock masses; Rock properties; Rocks; Shear properties; Shear strength; Shearing; Synchronism
• ISSN: 0363-9061; 1096-9853
• DOI: 10.1002/nag.3523

Hydro‐chemical erosion has critical effects on the short‐ and long‐term stability of fractured rock masses in subsurface engineering. Attempts have been made to study this water‐rock interaction process using numerical approaches. However, the majority of the existing approaches quantify the degradation based on the homogeneity hypothesis, which leads to unrealistic results in the case of rock mass with discontinuities. In this study, the hydro‐chemical degradation is represented through geometrical variation of a single crack and reflected in the modified bilinear constitutive model by introducing the hydro‐chemical damage factor. Then, discontinuous deformation analysis (DDA) method embedded in such improvements is chosen to implement the direct shearing process of the rock fracture after hydro‐chemical erosion. The results reveal that the peak shear strength decrease with the increase in the acidity solutions, and a logarithmic relation is found between the decreasing percentage of shear properties and soaking time, which are consistent with the laboratory results. Besides, based on the proposed method, the change in peak shear strength presents synchronism with the variation in the mineral ion and H+${H}^ + $ concentration, shown to be in good agreement with the basic understanding of the dissolution process. In addition, the failure patterns of the sheared samples under different normal stress are studied. This research provides an effective tool to quantify the hydro‐chemical damage from the microscale and will be a significant complement to the coupled numerical analysis of the water‐rock interaction process.