Earthquake damage in underground roadways

Abstract

Earthquake damage in underground roadways and mine workings is considered, with particular application to the mines operated by Solid Energy NZ Ltd., on the West Coast of New Zealand’s South Island. The scenario considered is the effect on the mine workings of an earthquake, of moment magnitude eight, being generated by a rupture of the Alpine fault.

An empirical relation from the seismology literature is used to relate earthquake magnitude, distance from the epicentre and the peak ground acceleration resulting from the seismic waves. This relation is used to estimate the likely damage at the mine site. Also, the decay scale for Rayleigh (surface) waves is calculated and the implications for the mine workings considered.

The two-dimensional scattering of shear (SH) seismic waves from the mine workings is considered. Analytical solutions relevant to various mine tunnel geometries are presented with the stress and displacement amplification, due to scattering from the mine workings, calculated and discussed.