Stress redistribution and formation of the pressure arch above underground excavation in rock mass

Abstract

Pressure arch utilises the self-stabilizing capacity of surrounding rock and is benefit to the roof stability of underground excavations. The analysis of it provides a new stability assessment tool for underground engineering. In this paper, a series of numerical simulations were carried out to investigate the formation and properties of pressure arch and the self-stabilisation mechanism of surrounding rock. It is found that stress redistribution results in the formation of the pressure arch. The inner and outer boundary of arching area are determined as the principal stress trajectories through the inflection points of the principle stress-depth curves on the centre line of caverns. Furthermore, parametric analysis illustrates that in situ stress ratio and excavation size have more significant effect on the inner and outer boundaries and the arch thickness than roof shape and overburden depth. Finally, it can be observed that the various trends of the inner boundary height with different influence factors are same with the displacement of the crown, and it could be used as an indicator for stability assessment. Based on the observed phenomena, a design scheme is proposed to determine the maximum size of the underground openings cross-section without support in agreement with the geomechanical conditions.

Keywords:

• Pressure arch
• underground excavation
• roof stability
• numerical simulation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors would like to thank the funds provided by China National Key Basic Research Program under Grant No. 2014CB046904 and Key Program of National Natural Science Foundation of China under Grant No. 41130742.