Vol18 No.9: 2486-2502
【Title】Effect of stress paths on failure mechanism and progressive damage of hard-brittle rock
【Author】CHENZi-quan1,2,3; HEChuan1; HU Xiong-yu1*; MA Chun-chi1,3
【Addresses】1 Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China; 2 Key Laboratory of Engineering Structures of Heavy Haul Railway, Ministry of Education, Central South University, Changsha 410075, China; 3 State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China
【Corresponding author】HU Xiong-yu
【Citation】Chen ZQ, He C, Hu XY, Ma CC (2021) Effect of stress paths on failure mechanism and progressive damage of hard-brittle rock. Journal of Mountain Science 18(9). https://doi.org/10.1007/s11629-020-6554-9
【Abstract】During deep buriedhard-brittle rock tunnel excavation, the surrounding rock experiences a complicated stress path and stress adjustment process. Once the adjusted stress exceeds the ultimate bearing capacity of rockmass, a rock failure mode defined as stress-cracking type will occur. In order to investigate the effect of stress paths on failure mechanism and progressive damage of deep-buried rockmass, the cyclic loading-unloading, loading-unloading, uniaxial, conventional and unloading triaxial compression tests on samples of hard-brittle sandstone were conducted. According to the experimental results, increase in the confining pressure was beneficial to improve the mechanical parameters of rock, but it will reduce the brittle failure features. Compared with conventional triaxial compression, the sandstone under unloading state had more remarkable stress drop and unstable failure characteristics. Meanwhile, it was found that the energy dissipation and energy release in the whole process of rock deformation were the internal power of driven rock progressive damage. With the increase of confining pressure, the energy hardening and energy accumulation features of rock were weakened, while the progressive damage evolution characteristics could be enhanced. In unloading state, more energy could be converted into elastic energy in the energy softening phase (σeb-σP), so that the pre-peak damage rate of rock was lower than that of conventional triaxial compression state. Thus, the energy dissipation rate of rock after peak strength decreased linearly with the increase of confining pressure under conventional triaxial compression state, while in unloading state it showed the opposite law.
【Keywords】Hard-brittle rock; Stress path; Confining pressure; Failure mechanism; Progressive damage