Book Description

This report describes solutions to a class of dynamic elastoplastic problems that model some of the salient features of the response of hardened underground facilities in rock. The theoretical model consisted of multilayered concentric cylinders of elastoplastic materials with time-dependent loads applied to the exterior boundary. Each element in the cross section was assumed to be incompressible and its yield governed by a Mohr-Coulomb failure criterion. The number of elements within the cross section was not limited. Solutions of the theoretical model were cast in the general form normally used in structural dynamics: Mass x Acceleration = External applied load - Internal resistance. The resulting equations can be quickly and inexpensively evaluated on a digital computer. To extend the range of validity of the exact theory, a first-order correction factor was developed to account for the compressibility of the materials, and a simple method to treat backpacked structures was introduced. The theory was verified by comparing calculated values with experimental measurements from small-scale static and explosively driven tunnel collapse studies. Good agreement was noted for all cases considered. (Author).