Tunnel Closure for Nonlinear Mohr-Coulomb Functions

by Timothy C. Kennedy, Dept. of Mech. Engrg., Oregon State Univ., Corvallis, Oreg.; formerly, Research Engr., SRI International, Menlo Park, Calif.,
Herbert E. Lindberg, Staff Scientist; SRI International, Menlo Park, Calif.,

Serial Information: Journal of the Engineering Mechanics Division, 1978, Vol. 104, Issue 6, Pg. 1313-1326

Document Type: Journal Paper

Discussion: Smart John D. (See full record)
Closure: (See full record)

Abstract: A closed-form analysis for elastic-plastic response of a cylindrical tunnel in rock under axisymmetric loading at infinity shows the effect of yielding according to a nonlinear Mohr-Coulomb-type function in which the angle of internal friction decreases with increasing mean normal stress. Explicit expressions for stresses and deformation are obtained by approximating the nonlinear function by a series of straight line segments. Comparisons of tunnel closures calculated with nonlinear functions with those from single straight line approximations show that tunnel closure is sensitive to plastic behavior nearest the tunnel. This means that the low-stress part of the yield function, where nonlinearity is usually greatest, should be modeled as accurately as possible.

Subject Headings: Tunnels | Elastic analysis | Stress analysis | Deformation (mechanics) | Model accuracy | Closed form solutions | Rocks | Axisymmetry |

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