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Geomechanics and Engineering Volume 20, Number 1, January10 2020 , pages 29-41 DOI: https://doi.org/10.12989/gae.2020.20.1.029 |
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Evolution of sandstone shear strength parameters and its mesoscopic mechanism |
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Hao Shi, Houquan Zhang and Lei Song
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| Abstract | ||
| It is extremely important to obtain rock strength parameters for geological engineering. In this paper, the evolution of sandstone cohesion and internal friction angle with plastic shear strain was obtained by simulating the cyclic loading and unloading tests under different confining pressures using Particle Flow Code software. By which and combined with the micro-crack propagation process, the mesoscopic mechanism of parameter evolution was studied. The results show that with the increase of plastic shear strain, the sandstone cohesion decreases first and then tends to be stable, while the internal friction angle increases first, then decreases, and finally maintains unchanged. The evolution of sandstone shear strength parameters is closely related to the whole process of crack formation, propagation and coalescence. When the internal micro-cracks are less and distributed randomly and dispersedly, and the rock shear strength parameters (cohesion, internal friction angle) are considered to have not been fully mobilized. As the directional development of the internal micro-fractures as well as the gradual formation of macroscopic shear plane, the rock cohesion reduces continuously and the internal friction angle is in the rise stage. As the formation of the macroscopic shear plane, both the rock cohesion and internal friction angle continuously decrease to a certain residual level. | ||
| Key Words | ||
| strength parameter evolution; plastic shear strain; mesoscopic mechanism; numerical study;sandstone | ||
| Address | ||
| Hao Shi: 1.) State Key Laboratory for Geomechanics & Deep Underground Engineering, School of Mechanics & Civil Engineering, China University of Mining and Technology, Xuzhou, 221116, People\'s Republic of China 2.) GeoEnergy Research Centre, University of Nottingham, Nottingham NG7 2RD, U.K Houquan Zhang and Lei Song: State Key Laboratory for Geomechanics & Deep Underground Engineering, School of Mechanics & Civil Engineering, China University of Mining and Technology, Xuzhou, 221116, People\'s Republic of China | ||