Rockbursts are dynamic failure processes of surrounding rock of tunnels. It is a great challenging task to simulate in detail the failure processes for both continuous approaches, e.g., FEM, and discontinuous approaches, e.g., DEM. The surrounding rock is generally hard and intact at the inception of rockburst. From the viewpoint of prevention and control of rockbursts, the driving forces at the inception of rockburst are much more important than the final failure modes. Based on the so-called deformation reinforcement theory developed by the authors, the inherent driving forces to failure for a continuous body are just the residual unbalanced forces of elasto-plastic FEM analysis. Residual unbalanced forces take place if the equilibrium and yield conditions cannot be satisfied simultaneously for the continuous body. The residual unbalanced forces can be used to determine directly the support parameters for the surrounding rock, and then be used as a proneness index of Rockburst. In this presentation, the influences of geological structures and ground stress on the residual unbalanced forces are addressed.

1 Introduction

Rockburst is a kind of sudden disaster that often occur in the deeply buried tunnel with brittle rock, high-stiffness rock, joint as well as faults. When its mechanical balance is destroyed, it releases the deformation potential energy of rock mass in a sharp form, which results in a special dynamic instability phenomenon.

The occurrence of rockburst will lead to serious consequences, resulting in mass casualties. Extreme rock burst occurs in the side arch, which may cause the death of workers and damage to the engineering equipment. For example, on November 28, 2009, extremely strong rockburst occurred in the drainage tunnel during the construction of Jinping secondary hydropower station. All the supporting systems along the shaft of the tunnel within 28m were destroyed, and the TBM head part was permanently buried, causing heavy casualties.

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