Improved nonlinear Burgers shear creep model based on the time-dependent shear strength for rock

• Published in: Environmental earth sciences Vol. 79; no. 6
• Main Authors: Lin, Hang, Zhang, Xing, Cao, Rihong, Wen, Zhijie
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2020; Springer Nature B.V
• Subjects: Biogeosciences; Connecting; Creep tests; Damage; Earth and Environmental Science; Earth Sciences; Environmental Science and Engineering; Geochemistry; Geology; Hydrology/Water Resources; Mechanical properties; Original Article; Rheological properties; Rheology; Rock mechanics; Rock properties; Rocks; Shear creep; Shear strength; Shear tests; Solifluction; Terrestrial Pollution; Time dependence; Shear strength; Creep; Nonlinear viscoplastic element; Damage
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-020-8896-6

Shear strength is an important mechanical index of rock. The adjustment and reorganization of rock structure can be reflected by the variation of shear strength. During rock rheology, the shear strength decreases with time due to rock damage. Therefore, from the point of difference of shear strength, the mechanical properties of rock can be effectively studied. In this paper, for the state of direct shear test, the Kachanov creep damage law was adopted to describe the time characteristics of the rock shear strength during the accelerated creep stage. A nonlinear viscoplastic element on the basis of time-dependent shear strength was established by connecting the plastic element representing shear strength with the viscous element in parallel. After introducing the nonlinear viscoplastic element into the classic Burgers model, the rationality of the model was verified by the shear creep test results of rock discontinuity. Results showed that the modified Burgers model can reflect the mechanical properties of rock in three creep stages. In addition, the model parameter δ can also reflect the evolution of internal cracks in rock during creep.