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Symmetry 2018, 10(9), 381; https://doi.org/10.3390/sym10090381

Time-Dependent Behavior of a Circular Symmetrical Tunnel Supported with Rockbolts

1
Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation, Shandong University of Science and Technology, Qingdao 266590, China
2
State Key Laboratory of Mining Disaster Prevention and Control Co-Founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266590, China
3
School of Environment and Resource, Southwest University of Science and Technology, Mianyang 621000, China
*
Author to whom correspondence should be addressed.
Received: 19 July 2018 / Revised: 15 August 2018 / Accepted: 28 August 2018 / Published: 4 September 2018
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Abstract

Under the effect of initial stress and excavation disturbance, there exists interaction between rock mass and rockbolt in deeply buried tunnels. In order to fully explore the mechanism of rock mass supported with rockbolts, this article studied the time-dependent behavior of the rock mass supported with discretely mechanically or frictionally coupled (DMFC) rockbolts. The interaction model elastic solutions under distributed force model were analyzed, then the viscoelastic analytical solutions were conducted to describe the rheological properties of the coupling model, and the solutions were acquired by setting the constitutive models of the rockbolt and rock mass in terms of a one-dimensional Kelvin model and a three-dimensional Burgers model based on material properties and dimension. Several examples were performed and the influence of initial stress σ0, the viscosity parameters η1 and η2 of the three-dimensional Burgers model as well as the pre-tension T0 on reinforcement effect were analyzed. According to the proposed model, the smaller η2 is or the larger the pre-tension T0 is, the more effective the support effect. However, when the pre-tension is too large, the support effect is no longer significantly enhanced. In addition, the early reinforcement effect is controlled by the first creep stage in the Burgers model while the ultimate support effect is mainly influenced by the viscosity coefficient of the second creep stage in the Burgers model. This research can provide an important theoretical reference to guide the parameter design of rockbolt reinforcement engineering in a circular symmetrical tunnel. View Full-Text
Keywords: time-dependent behavior; rockbolt support; viscoelastic solutions; circular symmetrical tunnel time-dependent behavior; rockbolt support; viscoelastic solutions; circular symmetrical tunnel
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Han, W.; Wang, G.; Liu, C.; Luan, H.; Wang, K. Time-Dependent Behavior of a Circular Symmetrical Tunnel Supported with Rockbolts. Symmetry 2018, 10, 381.

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