40 Performance of an experimental tunnel subjected to stresses ranging from 50 MPa to 230 MPa

For seismic research purposes a tunnel was driven into the region ahead of a longwall stope in a deep gold mine. This provided an opportunity to study the problems of tunnelling in very highly stressed ground and of designing support to resist severe stress changes and large stress transients.

The results of elastic stress analyses showed that the observed behaviour could be quantitatively explained in terms of criteria based on the principal stress difference. Support that was both stiff and compliant, comprising grouted tendons, lacing and mesh proved to be very effective in withstanding seismic forces.

• INTRODUCTION

• DESCRIPTION OF THE TUNNEL

• OBSERVATIONS

• STRESS AND FAILURE ANALYSIS

• CONCLUSIONS

• ACKNOWLEDGEMENTS

• REFERENCES