Study on Blast-induced Cumulative Damage of Tunnel Surrounding Rock and Its Application in Determining Allowed Safety Distance

摘要

The seismic wave derived from multiple blasts in a longspan tunnel will in all probability induce cumulative damage of surrounding rock, and affects surrounding rock's stability and even cause wall rock to collapse. In this study, international advanced apparatus, Blastmate III, was applied to monitor surrounding rock's response to blast vibration. Blast vibration signals are analyzed both in time and frequency using Hilbert-Huang Transform (HHT) method, which has excellent ability in time-frequency analysis of non-stationary random signals. The nonlinear characteristics of surrounding rock's cumulative damage are also analyzed using this method. The study uses UTEP to indicate the evolutionary process of cumulative damage in surrounding rock. The author puts forward a new thinking to determine the allowed safety distance by cumulative damage. This study is instructive and meaningful to wall rock supporting and reducing blast vibration in longspan tunnel.