Laserfiche WebLink
:~ <br /> <br />ai <br />i <br />-~ <br /> <br />Response of Pressurized Pipelines to Production- <br />Size Mine Dlasting <br />by <br />David E. Siskind <br />and <br />Mark S. Stagg <br />U. S. Bureau of t4ines <br />Twin Cities Research Center, Minneapolis, h1M <br />ABSTRACT <br />The mining industry occasionally blasts near- pressurized transmission <br />pipelines and has requested guidance on safe vibration levels and setback <br />distances. The Bureau of Ftines and the Indiana Department of Matural <br />Resources cooperated with Ah1AX Coal Comirany on a study of coal mine overburden <br />blasting. Five buried and pressurized 250-ft pipeline sections were <br />specifically installed on the Minnelralra Ftine Iriglrwall near Sullivan, 1P1 for <br />testing to failure. Four welded steel pipes ranging from 6- to 20-in diameter <br />and one 8-in PVC water supply pipe were monitor-ecl for vibration, strain, and <br />internal pressure for a period of 6 months while production blasting advanced <br />up to the pipeline field, In contrast to previous studies of small-scale <br />blasting representing construction activities, these tests involved overburden <br />blasts of up to 2100 lb per delay in 12-1/4-in diameter holes. <br />Initial analyses found low strains and calculated stresses from even <br />large blasts, a result consistent with previous tests of small-scale blasting. <br />Ground vibrations of 5 in/s produced worst case (circumferential) strain <br />levels about 25 pct of those resulting from pipeline pressurization and <br />calculated stresses of only about ]0-]6 pct of the ultimate tensile strength. <br />Mu pressurization failures occurred at the vibration amplitudes reached, over <br />20 in/s. These results suggest that buried pipelines are relatively resistant <br />to blast vibrations. <br />illustrations and tables follow text <br />129 <br />I~~ <br />