Energy Evolution Mechanism and Confining Pressure Effect of Granite under Triaxial Loading-Unloading Cycles

International Conference on Smart Engineering Materials 2018

Wang, Hao^1,2 ; Miao, Sheng-Jun^1,2

School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing

100083, China^1

Key Laboratory of High-Efficient Mining and Safety of Metal Mines(Ministry of Education of China, China^2

关键词: Confining pressure effect;    Confining pressures;    Dissipation energy;    Energy evolutions;    Internal crack;    Mechanical energies;    Strength limits;    Triaxial loading;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/362/1/012018/pdf
DOI  :  10.1088/1757-899X/362/1/012018

来源: IOP

【 摘 要 】

Rock mass undergoes some deformational failure under the action of external loads, a process known to be associated with energy dissipation and release. A triaxial loading-unloading cycle test was conducted on granite in order to investigate the energy evolution pattern of rock mass under the action of external loads. The study results demonstrated: (1) The stress peaks increased by 50% and 22% respectively and the pre-peak weakening became more apparent in the ascending process of the confining pressure from 10MPa to 30MPa; the area enclosed by the hysteresis loop corresponding to 30MPa diminished by nearly 60% than that corresponding to 10MPa, indicating a higher confining pressure prohibits rock mass from plastic deformation and shifts strain toward elastic deformation. (2) In the vicinity of the strength limit, the slope of dissipation energy increased to 1.6 from the original 0.7 and the dissipation energy grew at an accelerating rate, demonstrating stronger propagation and convergence of internal cracks. (3) At a pressure of 70% of the stress peak, the elastic energy of the granite accounted for 88% of its peak value, suggesting the rock mechanical energy from the outside mostly changes into the elastic energy inside the rock, with little energy loss.(4) Prior to test specimen failure, the axial bearing capacity dropped with a decreasing confining pressure in an essentially linear way, and the existence of confirming pressure played a role in stabilizing the axial bearing capacity.