Report No. : GEO Report No. 100

Report Title : Methods of Assessment and Monitoring of the Effects of Gas Pressures on Stability of Rock Cuts due to Blasting in the Near-field (2000), 55 p.

Author : Blastronics Pty Ltd.

Abstract

This GEO Report presents a succinct review of the current state of knowledge on gas pressure effects on the stability of rock cuts due to blasting.

The main objectives of this study are: (1) to summarise the state-of-the-art methods for assessment and monitoring of the effects of gas pressure on stability of rock cuts and excavations due to blasting within close distances; (2) to determine, if possible, the extent of no-blast zones to be imposed, and (3) to recommend practical measures to be carried out, for eliminating adverse blasting effects on nearby rock cuts and excavation under the Hong Kong geological conditions and urban environment.

The study has included a comprehensive search and review of relevant papers published in the international literature dealing with gas pressure from blasting and a detailed examination of five cases of field gas pressure measurement. It was found that none of the published papers addresses the effects of gas pressure on rock slope stability. The report concludes that specification of safe no-blast zones around excavations will continue to have to be largely based on engineering judgement and experience, due to the shortage of reliable field data and lack of reliable methodology for assessment. The information presented in this Report could serve as a useful reference.

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