Improved Model of Rock Mass Dilatation.
Abstract
This report documents the results of an investigation aimed at developing analytical models for calculating closure and failure resistance of deep tunnels, based on an improved dilatation model for the rock. The phenomenon of rock dilatancy is first reviewed, and an improved dilation model - in which the rate of dilation progressively vanishes with the plastic deformation - is described. The improved dilatation model involves the introduction of a single parameter: the maximum inelastic volume increase that the material can experience. The new dilatation model was then used for the development of two mathematical models of a deep cylindrical tunnel, one for hydrostatic, the other one for nonhydrostatic loading. For the hydrostatic loading, it was shown that closure of the tunnel requires the solution of a nonlinear ordinary differential equation and, for the nonhydrostatic loading, a system of nonlinear partial differential equations of the hyperbolic type is involved. In both cases, the numerical procedures are discussed in detail: Runge-Kutta for the hydrostatic loading, and the method of characteristics for the nonhydrostatic case. Model test experiments were then reviewed in an attempt to validate the improved dilatation model. Keywords: Rock dilatancy; Elastoplastic models; Hydrostatic loading; Nonhydrostatic loading; Laboratory experiments; Variable dilatancy.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 29, 1985
- Accession Number
- ADA166101
Entities
People
- Christopher St. John
- Emmanuel Detournay