Abstract
Abstract This paper deals with a deep circular tunnel excavated in infinite homogeneous and isotropic elasto-viscoplastic rock mass subjected to a hydrostatic initial stresses. The tunnel is divided into the initial plastic, viscoplastic, and elastic zones. By combining the generalized Bingham model with Mohr-Coulomb yield criteria, analytical solutions of the circular tunnel are derived with the consideration of non-associated flow rule and elasto-viscoplasticity. The initial plastic zone is defined as the instantaneous change of rock mass excavation. Based on the initial plastic zone, the stresses in viscoplastic zone are transferred to the deep surrounding rock with time due to the initial earth stresses. The results are compared with the elastic-brittle solution at static conditions, and the solutions of this paper are validated. Moreover, the presented results shows that the stress and displacement of the surrounding rock varies with time, and the solutions can be obtained at different instants of time.
Highlights
Many coal mines and metal mines have reached a mining depth of more than one kilometer
Fritz [25] used the viscoplastic constitutive relation of the surrounding rock in a manner similar to the form of the linear elastic Hooke's law, and the elastic–viscoplastic analysis was carried out by ensuring that the stress and strain satisfy the basic equations of the problem and the stress intensity condition
This study was based on the generalized Bingham model in accordance to the correspondence principle that has been extensively adopted in plastic and viscoelastic mechanics
Summary
Many coal mines and metal mines have reached a mining depth of more than one kilometer. Sulem [21], Ladanyi [22], Gill [23], and Wang [24] et al, analyzed the stress and strain of the surrounding rock of the roadway based on the viscoelastic model, but neglected the plastic mechanical properties. This led to the overestimation of the support pressure in the support design. Its three-dimensional elastic–viscoplastic constitutive equation is established by rigorous mechanical analyses, and the stress and deformation solutions of elastic–viscoplastic surrounding rock are obtained in circular roadways. The variation law of stress and displacement of the surrounding rock was analyzed at different times given its significance for roadway engineering design and construction
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