Abstract:

How to determine the mechanical behavior of the elastoplastic deformation and stress redistribution in rock mass without supporting reaction after tunnel excavation is the important research problem all the time. The insufficiency and defect existed in the solution of Kastner equation are as follows: (1) there are drawbacks in the mechanical treatment of supporting reaction, which has no practical meaning; (2) in the solution of plastic zone stresses, it takes no advantage of the plastic constitutive relation given by perfect elastoplastic materials; (3) in the solution of plastic zone stresses, the influence of axial stress along tunnel is not taken into account. The perfect elastoplastic solution based on the incremental constitutive relation of plastic mechanics, namely Levy-Mises relationship and D-P yield criterion, is addressed. The present solution is studied with calculation results by Kastner equation and numerical computation. It has more theoretical meaning and practical value, for the present solution, it is able to account for three problems neglected in the solution of Kastner equation.

Key words: axisymmetric circular openings, incremental Levy-Mises constitutive relation, D-P yield criterion, perfect elastoplastic solution