Elasto-plastic analysis of a circular opening considering material dilatancy and elasto-plastic coupling effects

Abstract

The deformation and fracture of a surrounding rock mass are important bases of underground engineering stability evaluation and bolting design. In this paper, an improved elastic-perfectly plastic-brittle model is employed to analyze the mechanical property weakening behavior of surrounding rock, including the elastic zone, plastic zone, and fracture zone. Examining a circular opening under hydrostatic pressure, material dilatancy, and elasto-plastic coupling were considered for an analytical study of stress and displacement of the surrounding rock. The influences of the supporting force, dilatancy, and elasto-plastic coupling were analyzed for a deep coal mine tunnel. It is shown that the supporting force cannot significantly change the state of the stress distribution, but it has an outstanding influence on the displacement of the surrounding rock. Dilatancy and elasto-plastic coupling can both cause a rapid increase of fractured zone deformation of the surrounding rock. Additionally, the majority of deformation within the surrounding rock was derived from expansion-related deformation of the fractured zone in a residual-strength state.

Keywords:

• Circular opening
• dilatancy
• elasto-plastic coupling
• analytical solution

Acknowledgments

The authors wish to acknowledge the financial supports of the National Basic Research Program of China (No. 2015CB057905) and the National Natural Science Foundation of China (No.51279202, No.91215301, No.51409263).