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RESPONSE OF PRESSURIZED PIPELINES TO - PRODUCTION - SIZE MINE BLASTING by David E. Siskind and Mark S. Stagg U. S. Bureau of Mines Twin Cities Research Center. Minneapolis, MN ABSTRACT impacts on transmission pipelines as a key research need. Although The mining industry occasional- in a cooperative effort between some work has been done in the ly blasts near pressurized transmis AMAX Coal Company; Division of 1970's and S0's on blasting near siun pipelines and has requested Reclamation of the Indiana pipelines, none to the authors' guidance of safe vibration levels Department of Natural Resources knowledge, involved large-scale and setback distances. the Buretu (IDNR). Vibronics, Inc., New production mine blasting. of Mines and the Indiana Mexico Tech, and Ohio Valley Involved parties met for initial Department of Natural Resources Pipeline. Inc. AMAX has concerns planning in November 1991. cooperated with AMAX Coal about blasting near active pressur- Installation and monitoring began Company on a study of coal mine ized transmission pipelines at the in March 1992 allowing time to overburden blasting. Five buried Minnehaha Mine. nor Sullivan. IN procure needed supplies. equip- and pressurized 250-ft pipeline as well as at other mines. They ment, pipelines sections. etc., and sections were specifically installed approached the Bureau and other also insuring reasonable weather on the Minnehaha Mine highwall cooperators in the fall of 1991 for the difficult installation phas. near Sullivan, IN for testing to fail• about the feasibility of conduct- es. Monitoring locations were urc. Four welded steel pipes rang- ing such a stud); involving a vani- chosen so that the first vibrations ing from 6- to 20- in diameter and ety of test pipelines subjected to would be as high as 2 in/s (5 one 8- PVC water supply pipe full-scale overburden blasts at cm/s). Five total mining cycles of were monitored for vibration, one of their surface coal mines. roughly 30 days each were strain, and internal pressure for a The Bureau's role was to install expected to bring the blasting period of 6 months while product and operate monitoring equip- adjacent to the pipelines. Eight lion blasting advanced up to the ment for measuring strain and months actually would be pipeline field. In conirast,to previ- vibration and interpret the results required for the stud: otas studies of small-scale blasting of those measurements. Other This report describes the representing construction activi- cooperators had responsibilities results up to and including the ties. these tests involved overbur- for pipeline installation (Ohio penultimate cycle of mining den blasts of up to 2100 lb per Valley Pipeline), supplemental approaching the pipeline field, delay in 12-1/4-in diameter holes. vibration monitoring and eontinu• One additional pass is expected. Initial analysis found low ors monitoring of internal pros- which will likely include some strains and calculated stresses sures (Vibronics), and analysis, blasts that will be within the from even large blasts, a result interpretation. and monitoring inelastic zone of permanent consistent with previous tests of support (IDNR and New Mexico ground deformation. The authors small-scale blasting, Ground Tech). AMAX provided the site. expect to prepare a more corn- . vibrations of 5 in/s produced costs of pipeline installation,secu- prehensive report on this stud: worst case(circumferential)strain rity fence and other facility However, the high interest in this levels about 25 pct or those result- improvements, and shot coordi- work and its significance justified ing from pipeline pressurization nation. its earliest reporting. and calculated stresses of only This project provided an about 10-18 pct of the ultimate opportunity to study a problem BACKGROUND tensile strength. No pressurization previously identified as of wide- Some previous work on vibra- failures occurred at the vibration spread concern. Numerous amplitudes reached, over 20 in/s. requests for advice on blasting pipelines impacts on transmission These results suggest that buried near pipelines have been of earth exists. An examination pipelines are relatively resistant received b• the Bureau over the responses eaves concluded t pipeline u ed to blast vibrations, years. many related to mine or rc`p°t>,�s concluded that buried pipelines move with the ground quarry operations. In a research and not differentially The most INTRODUCTION planning document first pre- serious concern was for locations The Bureau of Mines partici. pared in March 1989. the Bureau where the soil-rock characteri). . pouch in a study of blasting identified blasting near pipelines tics abruptly change (ref. 1). The