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• <br />• <br />• <br />560 <br />SUSFACE MINING <br />levels from blase and m aasrclan rheae with damagq thereby <br />petmlttiag the avoidaaea of ooaditiana that may lean to <br />dames;e or aanoyanm ILe sseond appsoseh hu bem an <br />investigation of methods wheeeby blast vibratiaa LrwL may <br />be reduced. <br />This in fora Lu led is moray iastanaea to legislation <br />aorteaaing bLttting is ptammiry to naamiae err quarry owned <br />property such u dwellungt or planes <br />In reemt yeas the gtwtim of who ootudmtas a valid <br />aherioa for damage Las been dlumud by a number of <br />autLars. Fswtsiw mtistinl ttvie:n Law beta made of pnb- <br />IisLed vibration dau to determine which edthe bLut-iaduted <br />parameters each a pardele displaammr, vdtaary, or amel- <br />aation bast mnaure the damaging effeen of a vtbtatioael <br />ware on a strttaure. <br />the current eonahuion is that damage teas bees be oor- <br />I[Lted WILL peal( puaok velocity of eLa ww Kgaedleu of <br />the dirsctlon of sbe motion; R' t~•t vortical, or trant- <br />veru (Edwards and Northvrood, 1960; Lasgfon, d a1,193g; <br />N~choL, et al, 1911). Because d this, some inwttigatiom <br />use tLe ptah taultant panWe velocity. It bet also bees <br />mnctuded that due t0 the e®ples assure of the woes gm- <br />erated daring blaatiug, :arh as P. 5, liayldg}t, Low wren <br />eta, rhat it is impassible to eo:relate damage theoterirally <br />with a tpes:ifie wave farm. Betsme of eLia, It 6 used to lump <br />all of the woes together by mnsudng the o®poaite ware <br />farm and W correhte the rauln empaitxlly. <br />Some iavestigatiaas Law given eoaaidaation to Lhe fm- <br />gamry rnponu spectra of st[octaret whie•L is somet®es <br />being used For geaaal applitatlon thla b not aeassary. <br />Blast Vlbretlon Meawrement <br />Ia the taeatusaneat of vibration, the obJective is m detect <br />and record the nbntory motion of the gromd. The gttsntitie <br />tsteasured mmt resort ie a IbU desaiptiw for the w'btuory <br />event This requires tLrne orthogonal eompommta of euthsr <br />particle dispLesmeat [x1, vehrdry (r), err aoeelention (a), <br />to 6e recorded as a functloa of time (r). Tits three eampooeats <br />~u termed: <br />1. Longitudinal, [m:mal m the dhaados d the blot in <br />the hotizonnl plane. <br />2 Transverse, petpeadieuLr to the direetiaat of the blast <br />is tLe horizontal pLaa <br />3. Vertical, peapeadleuLr m the dhttaitm of the bLtt is <br />the veRiaal pLme. <br />TLe beau problem associated with the meantremmt of <br />blasdng vibrations b the atabUshmeat of a 9sed poiat'in <br />space from which to mworc. Dmiag she pawp of tdmtie <br />energy, the entire aovL~onmmt v is masioo which iadudes <br />the measutrs sad the mrssmiag h.rr.•....w. The sdsmo• <br />meta (or vibmgnph) oveteamea tb4 problem by esnblisL- <br />iag a trfereace point within itself the tends m reaaaia god <br />during tLe mov®ent of its h0usiag, <br />For typical blot vibntiaos it h amersuy that the sew <br />maaeta should be able m :eeord the following rattgea: <br />Frequenry, 1 to IOD Hs. <br />Ditplaeemeat, 0.00234 to 12.7 ttao. <br />Velocity, 0.254 to 234 mm/s. <br />Aeeekration, 0.005 to 2 g. <br />For overburden bLwts sad other Large 61un mesantsd <br />u tl4nncq greara thsa 305 m (1000 ft). the blast frequmey <br />is amarallY in the 1 m 20 l!z ranee (Attesxll sad Farmer. <br />1966} HigLa fregeaades aro eape.ienaed elasa to the shot <br />peat cad frequmry resPoate+ of 300 Ha sad atop era re• <br />quited for inserumaou meaNaiug dote m bhun m LigL <br />stttxgth raks each at ~nnites. <br />For aoeuate seoasdingr it is eamtlal that the seisetta. <br />atsta to>oarsia 5~ted o®ud with the grottrtd or other tmfaea <br />tbtonghotu the daratios fhr the nbntloa paauge. If the <br />mawitormt head slips ~ a hoti+mntal direetiaa and/or ]ores <br />eaaaurs is a vetial direotioa, a useless awmogram will <br />result <br />There are three nudn types of sdsmomda• Use type urea <br />• ter,-.a~.t optical sysbm. iheu amts measure amPUavae <br />sad frequency. tsoally fs sae campoaeas dh'eedon only, by <br />dlseet writhsg oa papa or by light beam on pbotographic <br />Papa <br />tyseema utilise d$eretttial disylaceatmt <br />bdween a moving ooil sad a soft tree mass (or vice vase) <br />ptodaeing as eleorrieal dgttal autpst Dmportioasl to she <br />seistmo event. This otdt is refenad m at a ttansdurrt. The <br />ripe] so produced fs thm ampUfled by • topped gain netting <br />and lbd into a reeordrt to give vdod4. 1'augtrtntg and <br />d1HlSeatiatlag dream may 6e ittdoded m red displacement <br />or aeceleradon. Oaspnt is mually via a timed. variable speed. <br />aired print Paper. the three mutually perpeaa;^..t., oam- <br />pmaaa being raeasused eimtthaaeoasly. <br />Hach of She pmiom systems asCa m agate extent from <br />sympatLetie rmaaaoe of the iastrumeat u eeetin finquea- <br />des. Thh! L overeoms using tadibratioa charts. In an attempt <br />m ooereet minoriase:psebtianal dlldaulela due to rnoaance. <br />a third typo a[ sdtmometar has ban developed baud on <br />tolid•tnn aaedoramerrae fcadisg ism inugratiag deeaita <br />6ergsSe:ale Open Pi! Bhuts <br />Fig. 39 pretests peak Partials vdadry Plotted vs. soled <br />disranoe for open put sstd reds strip mina multiperiod bLsn <br />which eootaina mote thm 10.000 data poian recorded world- <br />wide (repsaearative den only being alawa oa the graph <br />ifsaU). As aaoL, pig. 39 «ptetean a very caasetvative chip <br />aiteaa whoa the upper limit Use is used for chip parpasn. <br />tanw t..•w.d <br />s\ <br />,'t: <br />io ... . i' <br />3 ` <br />'ire+ <br />i .. /urorlJdr <br />~h <br />s.nw ob~w•,mnNtl.ivll~/rw~wrk <br />Flg. g9. Typial ribreUon den from muOlpariod delay blssn i^ <br />open Alts and aVlp mMas. <br />'~: <br />i;v::. <br />