|
•
<br /> ;'Response of Pressurised Pipelines to Pitrlwscs utalre:l:atecl CO tile pipeline JCUUY.
<br /> Production-Buse Mine Blasting"
<br /> In front of the pipeline, AMAX had instilled
<br /> continued from page 22 both coaxial and fiberoptic phone cables, and also
<br /> had a vertical well off the east end of the 6-in
<br /> PROCEDURES pipeline. The well, of about 120-ft depth, was
<br /> Pipelines instrumented for pressure by Vibronics. It was test-
<br /> Five 2 50-ft-long sections of transmission ed for cement bond log on three occasions: prior to
<br /> pipeline, with properties described in table 1, were blasting, after 4in/s and after 9 in/s. No significant
<br /> installed on the AMAX Coal Company's Minnehaha bond loss was noted. The phone lines were tested
<br /> Mine highwall for testing to destruction. They were by Indiana Bell and will be reported separately.
<br /> all parallel to each other with 10-ft spacings and RESULTS
<br /> also to the highwall at an initial distance of about 500 Between the Bureau and Vibronics,about 34 data
<br /> channels were used for each blast. A comprehen-
<br /> Mble 1. Pipeline Information for Study sive future report will list all measurements; how-
<br /> •CIIt1+d° v{„ fill lettt.t .g° led ever, only highlights are presented in this paper.
<br /> d'Oaater, thickness. '1ter14t 0r,11401, Pst.r►4t Table 3 lists the highest measured ground vibra-
<br /> 1n in 10/11
<br /> tat Itirt _ dons, pipeline vibration responses and strains for
<br /> 1>3ie .tau Cu sco Nor, steel. :42
<br /> Each blast. Figure 4 shows a set of vibration and
<br /> 11.111 .ts° Cu 5243 112.&5 u,.t, ttus I
<br /> 12.1/, .2SO C11 00 N.� stn. 1lz strain records from blast No. 25. Note that the
<br /> 20 t6a lister 5324 sued. steel, OS resemble vibration records, cycling nearly
<br /> • ,.s,1 »:' Shaer 90 ut.d, rife about the zero line. Therefore, ten-
<br /> 120.02,er.ett.d 14106. sion and compression amplitudes were about Null.
<br /> ft as shown in figure 1. The location, in increasing Table 2. Blasts monitored for pipeline response
<br /> distance from the highwall, are as listed in table 1. 01.,.1 2420 rim Child,011,11. Iii 0u1..c.. sal..011t.'c, t 1..r
<br /> teal Pot 4414, " 0204', Cur. ,Iut
<br /> Ohio Valley Pipeline welded and installed the Na
<br /> pipelines, using their standard procedures, after the
<br /> I 2.11 11;10 11:111 Iw 1110 loin 111 0.P140011
<br /> 14160 )di 21:110 ' ISO 1120 10.1 117 00,11 4
<br /> Bureau attached longitudinal and circumferential 1.2 57:54 31.112 1.294 1400 71,2 212 14rtl9
<br /> strain gages and sensors for vibrations in the center 4.1 17110 17.144 1.154 1I0 14.1 20.0 O..r5wrao
<br /> area of the pipelines. Al! pipelines had longitudinal 1.1 "''0 SIMI 10 'N0 11° 242 Parting
<br /> P P P'P g 4.4 11:1e 13.1,1 1.0e ;Cho 33.7 its Parrtin
<br /> strain gages on tops and fronts and the 6- and 20-in
<br /> ° '1 ""' 69.113 =450 41.1 I:1 r,r%I.
<br /> had circumferential as well. Vibration transducers I '.' ='1== U.'{1 1,704 410 22.0 .44 &enterer'
<br /> I td 7118 N.IN s.l&• 450 17 2.,2 0.•131111.'
<br /> 0 {•0 17111 14.711 116 2010 112 100 !mine
<br /> were also placed on the tops and fronts of t1e 6- ' 1•s 14:01 17,709 101 11=0 111 421. *arum.
<br /> 4 1•5 11:10 16.111 1.200 110 11.0 27.1 O,,,p„ro.n
<br /> and 20-in pipes. Other, vibrations sensors were ' 1.1° NI 11.401 2.51• {20 11,7 4l,l O.r►.r4„
<br /> 7 4.1 14:5) 11.242 1.015 1 70 19.7 114 hrtt.l
<br /> place on the surface above the buried 20-in 3 3:3 11:11 11:14 1:111 1010 ;3.3 111 ;;e;
<br /> pipeline. Following installations and the placement '° '' 57111 N,941 1.at 051 7.11 2 e.,.r N..
<br /> T! i•7 11;01:11 01.117 1,411 100 1,11 10.1 0.1,wr,..
<br /> of 3-ft of soil cover, the pipelines Were internally 51 1.11 11:01 20.126 2.111 224 4.07 17,1 &•.rood..
<br /> pressurized. Pressures gradually crept tip in steel 11 lie la' .1:111 5.eie Iii 3:4 1i,, ;urs ee,,
<br /> pipelines to 950-1230 lb/in' as the ground warmed « 5.11 14:=1 °.1r4.,,M
<br /> 47 17 1.21 11:01 Ov,rrwa,
<br /> 1 10.72 ■its•. &grn
<br /> up from early spring to summer. It dropped in the 11 =4.22 11::0 ;; & rte
<br /> 20 11.24 55:57 111 Ov.rovM.'
<br /> PVC to 40 lb/in'in the following months consistent 4D "n. 4 s I..a1111 rr1»Ihn.M 1 b.np .r l{.'tO.plrt,er r.e4e 15.4.4,12c.la.5 W with reports that such o-ring-jointed water pipes
<br /> leak continuously. Note: Figure 1 does not show ,Vibrations
<br /> blasts 26 through 30, done too late to be included. Vibration amplitudes on the buried pipelines
<br /> Mine were less than corresponding R and V components
<br /> The Minnehaha Mine is a surface coal mine, blast- measured on the ground directly above (shallow
<br /> ing overburden by casting and also a thick parting burial). This consistent and significant reduction of
<br /> using hole diameters of 12-1/4 and 10-5/8-in, about 40 pct at a depth of only 3-4 ft was surpris-
<br /> respectively. Charge weights per delay are as high as ing, however, it is entirely in agreement with other
<br /> 2,100 lbs. The highwall, including the pipeline field studies including Bureau of Mints RI 8969 (Ref. 8),
<br /> area, has about 7 ft of clayey soil over-laying about which examined the effects of vibration monitoring
<br /> 40 ft of shale. on basement wails and floors. Figure 5 summarizes
<br /> Monitoring the surface radial vibration component and corre-
<br /> Strains and ground and pipeline vibrations mea- sponding horizontal response of the 20-in pipeline.
<br /> sured by the authors from selected parting blasts and Vertical vibrations behaved similarly
<br /> all nearly overburden blasts are presented in table 2. vibration frequencies of some blasts were low
<br /> In addition, Vibronics Inc. continuously monitored for the relatively small distances. As shown in fig-
<br /> both surface and underground vibrations at several ire 4, the radial component of shot No. 25 is about
<br /> locations as well as pipeline pressures. AMAX and 5.6 Hz. This is possibly a site phenomenon caused
<br /> the IDNR also had blasting monitors In the area for by the clay Iayer over the shale.
<br /> 34
<br />
|