ULTRASONIC CONVERGENCE MEASUREMENTS.

被引：0

作者：

McVey, James R.

机构：

来源：

Report of Investigations - United States, Bureau of Mines | 1984年

关键词：

ULTRASONIC TRANSDUCERS - Applications;

D O I：

暂无

中图分类号：

学科分类号：

摘要：

Tests during pillar robbing, longwall operations, and other mining activities indicate that roof-floor convergence rates can be used as an indicator of imminent roof failure. New instruments provide nonobstructing measurements up to 35 ft away. The ultrasonic transducers can be attached to a roof bolt, placed in an unsupported area (by means of a toss basket), or handheld.

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