Analytical Model for Deep Tunnel with an Adaptive Support System in a Viscoelastic-Burger's Rock

This paper presents an exact closed-form solution for the mechanical behavior of a linear viscoelastic Burger's rock around a circular tunnel supported by an adaptive support system. The tunnel consists of a bilayer concrete/stress-control element. The stress-control element is achieved with a hydraulic system deforming at constant pressure to a maximum displacement and becoming practically rigid after the initial deformation phase. Analytical equations are provided for the tunnel boundary displacement and the pressure exerted by the rock on the concrete liner. Results obtained from the analytical solution are validated by comparing them to numerical modeling results. A parametric study is performed to investigate the effects of installation time, yield strength of the stress-control element, and support deformation capacity on the tunnel response. Based on the closed-form solution, the yield capacity of the bilayer concrete/stress-control element is compared to that of the traditionally used bilayer concrete/compressible grout. The results show that the variation of tunnel response with installation time, yield strength, and deformation capacity of the yielding support are not monotonic. There is an optimal thickness of the yielding layer for given yield strength, beyond which the yield efficiency will not further increase. Notably, the results highlight the greater yield efficiency of the bilayer concrete/stress-control element than the bilayer concrete/compressible grout, particularly in tunnels with a relatively thin annulus void and using a yielding layer with relatively low yield strength.

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  • English

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  • Accession Number: 01851268
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 14 2022 9:25AM