Analysis of time-dependent deformations of openings in salt media

Abstract

An analysis of the time-dependent deformations of openings in salt media is described. The procedure involves (1) deriving three-dimensional constitutive equations for a Carlsbad potash material by means of laboratory tests; (2) developing a method of analysis capable of handling these constitutive equations and the geometries encountered in mining structures; (3) application of the method to particular field problems for which data are available. From results of uniaxial compression tests of potash specimens carried out in this investigation, and data obtained by other investigators from multiaxial testing of a similar material (rock salt), a three-dimensional viscoelastic-viscoplastic model is postulated. The finite-element method is chosen to handle the constitutive equations of this material model in the analysis of plane strain and axisymmetric problems. Good comparison with existing closed-form solutions is demonstrated for this approximate finite-element analysis, which is then used to calculate the deformations around a horizontal circular opening in an underground mine. The predictions are compared with field measurements. © 1972.