@Article{cmes.2021.014808,
AUTHOR = {Tantan Zhu, Da Huang, Jianxun Chen, Yanbin Luo, Longfei Xu},
TITLE = {Experimental and Numerical Study on the Shear Strength and Strain Energy of Rock Under Constant Shear Stress and Unloading Normal Stress},
JOURNAL = {Computer Modeling in Engineering \& Sciences},
VOLUME = {127},
YEAR = {2021},
NUMBER = {1},
PAGES = {79--97},
URL = {http://www.techscience.com/CMES/v127n1/41943},
ISSN = {1526-1506},
ABSTRACT = {Excavation and earth surface processes (e.g., river incision) always induce the unloading of stress, which can
cause the failure of rocks. To study the shear mechanical behavior of a rock sample under unloading normal
stress conditions, a new stress path for direct shear tests was proposed to model the unloading of stress caused
by excavation and other processes. The effects of the initial stresses (i.e., the normal stress and shear stress before
unloading) on the shear behavior and energy conversion were investigated using laboratory tests and numerical
simulations. The shear strength of a rock under constant stress or under unloading normal stress conforms to the
Mohr Coulomb criterion. As the initial normal stress increases, the cohesion decreases linearly and the tangent of
the internal friction angle increases linearly. Compared with the results of the tests under constant normal stress,
the cohesions of the rock samples under unloading normal stress are smaller and their internal friction angles are
larger. A strength envelope surface can be used to describe the relationship between the initial stresses and the
failure normal stress. Shear dilatancy can decrease the total energy of the direct shear test under constant normal
stress or unloading normal stress, particularly when the stress levels (the initial stresses in the test under unloading
normal stress or the normal stress in the test under constant normal stress) are high. The ratio of the dissipated
energy to the total energy at the moment failure occurs decreases exponentially with increasing initial stresses. The
direct shear test under constant normal stress can be considered to be a special case of a direct shear test under
unloading normal stress with an unloading amount of zero.},
DOI = {10.32604/cmes.2021.014808}
}