A New Method of Estimating Wave Energy from Ground Vibrations

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1 Gomatials, 215, 5, Publishd Oli Apil 215 i SciRs. A Nw Mthod of stimati Wav fom Goud Vibatios K. Ram Chada *, V. R. Sast Dpatmt of Mii ii, Natioal Istitut of Tcholo Kaataka, Suathkal, Maalo, Idia mail: * kc_kaa@ahoo.com Rcivd 28 Jaua 215; accptd 25 Fbua 215; publishd 2 Mach 215 Copiht 215 b authos ad Scitific Rsach Publishi Ic. This wok is licsd ud th Cativ Commos Attibutio Itatioal Lics (CC BY). Abstact Pfomac of xplosiv is atd i a umb of was, obtaid ith fom thotical calculatios o fom xpimtal tsts. Howv, it is difficult to dtmi th amout of th xplosiv tasfd to th ock ad covtd ito fficit wok i th applicatio of ock blasti. Althouh masumt of som of th ffcts of xplosiv i ock mass is oud vibatio, ois, tc., which a usuall coductd fo blast cotol/aalsis pupos, th sults a al usd o cott. tasfd to th ock i th fom of sismic wavs is calld sismic. I covtioal aalsis of blast sults, all, th oud vibatios atd du to blasti opatios a moitod at a kow distac fom blast sit with a opho/oud vibatio moito, i th mutuall othooal dictios. Usi such wav foms, a compot is stimatd fom all th wav foms i th dictios, usi a sophisticatd sial pocssi softwa, which is tmd as wav. Th wav is compad with th stimatd sismic. A ivstiati poam was tak up ivolvi 31 blasts coductd at a had ock xcavatio sit to assss th ifluc of dpth of xcavatio ad scald distac o th sismic wastd i th fom of oud vibatios. Kwods Distibutio, Wav Fom, Goud Vibatios, 1. Itoductio Assssmt of blast pfomac is sstial i od to su that th xtt of objctivs of blasts is achivd. Th a vaious mthods of blast pfomac aalsis mthods usi famtatio aalsis ad oud vibatios data atd dui blasti opatios. [1]-[3] hav usd difft mthods of famtatio aalsis * Cospodi autho. How to cit this pap: Ram Chada, K. ad Sast, V.R. (215) A Nw Mthod of stimati Wav fom Goud Vibatios. Gomatials, 5,

2 mthods usi difft iitiatio sstms to assss blast pfomac; th [4] [5] hav usd oud vibatio data to assss blast pfomac. Thi stud focusd o stimatio of wastd i th fom of oud vibatios b aalzi oud vibatio wav foms. Thoticall th hihst amout of is quivalt to dtoatio. ffctiv compaiso of of difft xplosivs is do basd o wiht stth. Ol a factio of dos usful wok i ock blasti ad th maii is wastd i poduci dtimtal ffcts lik oud vibatios, fl ock, back bak, tc. Gall blast pfomac is aalzd i tms of famtatio ad oud vibatio, but ths sults caot b xpssd dictl i tms of thi cott. Th aso fo this ma b that, it is ot th cosumptio i difft phoma that matt, but ath th d ffcts of blasti lik d of famtatio, thow ad vibatio lvls. Data ad stimatios o compots i ock blasti a thus limitd to a fw sachs. [6]-[8] stimatd th amout of tasfomd i kitic of th ock, factu atio ad sismic wavs. Attmpts w mad b som sachs to masu th xplosiv i laboato scal usi clid xpasio tst. I this tst, copp tubs filld with xplosivs w shot, ad th xplosiv vlocit of dtoatio (VOD) ad th xpasio vlocit of th tub wall w masud. Sum of th kitic of th copp tub ad th adial kitic of th ass is calld Gu (c). c is th masu of th wok capacit of th xplosiv [8]. lasd b a xplosiv ca b oupd ito asous ad shock, woki o th suoudi stata sulti i famti th mdium thouh vaious baka mchaisms. Som of ths mchaisms a sposibl fo (a) factui that ultimatl is sposibl fo cati w sufacs i th ock famts; (b) tasfd as shock wavs ito th ock mass popaati as sismic wavs o oud vibatios bod th famtatio zo; ad (c) to displac th famtd matial ad fom th muck pil that appas as kitic. This patitioi is latd to th chaactistics of xplosivs ad th stata, ad to som xtt to th blast omt. Th balac of th blast ca thus b xpssd as [7]. = F + S + K + NM (1) wh, = xplosiv, F = famtatio, S = sismic, K = kitic, NM = foms ot masud. Th tasfd to th ock i th fom of sismic wavs is calculatd as th ital of th flow past a cotol sufac at a iv distac fom th blast. Th flux (th pow o at of wok, p uit aa) is th scala poduct of th stss at th sufac ad th paticl vlocit [9]. Calculatios of sismic ad its compaiso with xplosiv hav b potd b [1]-[14] ad mo ctl b [15]. [6] attmptd to us som of th cocpts i picipls of blast dsi. passi thouh ock mass i th fom of sismic wavs is sismic. [16] sustd th followi fomula to stimat th sismic. 2 2 S = 4π ρc f ν dt (2) L ( ) ν = ν + ν + ν wh, S = sismic (MJ), = distac (m), ρ = ock dsit (m/cc), C L = loitudial wav vlocit (m/s), ν = maitud of th vcto sum of th vlocitis (m/s), ν 1 = masud vlocit i loitudial dictio, ν 2 = masud vlocit i tasvs dictio, ν 3 = masud vlocit vtical dictio. 46

3 Th authos hav poposd aoth cocpt i stimati b aalzi th complt wav foms obtaid fom oud vibatio moitoi. Oc th xplosiv is iitiatd i th blast hol, dissipats ito th ock mass, ati stai wavs. Th itsit of th wavs is captud at a poit fom a kow distac fom blast sit with oud vibatio moito. Th opho captus th wav foms i th mutuall othooal dictios aml, loitudial, tasvs ad vtical dictios fo a fixd duatio. Th sms to b a latioship btw th xplosiv dissipatio ad th atu of th wav foms. I al th aa withi th cuv of foc-displacmt diaam is a wok do; th sam picipl is applid fo wav foms atd fom blast vibatios (Fiu 1). As th wav fom cosists of vlocit vs tim, o uit is iv i tms of. Ol th quatitativ valus a usd fo aalsis. Som mo sach wok is oi o i this aspct. I cas of a ula cuv of qual wav lth, th squa of th amplitud ca b itatd to t th aa of th cuv. Howv, wav foms poducd fom blasti opatios a complx ad th is a wid vaiatio i wav lth. Wav foms, thfo, a aalzd with th hlp of a sial pocssi softwa DaDiSP. Summatio of i all th dictios is tak fo stimati th total wav fom ach vt. 2. Cas Stud A cas stud was tak up i a civil ii pojct sit wh had ock is bi xcavatd fo costuctio of a statio fo a udoud mto ail. Th had aitic fomatio is xposd almost to th sufac. Total dpth of xcavatio quid is aoud 2 to 24 m. So, it was plad to mov th ock b bchi mthod usi dilli ad blasti tchiqu. Th aa of xcavatio is suoudd b impotat buildis. Fiu 2 show th dilli pocss at th sit. Aft dilli, ach blast hol is chad with cat idd xplosivs ad shock tub iitiatio sstm is usd to iitiat ach blast hol (Fiu 3). As umbs of impotat buildis a th i th suoudis ad thfo, fl ock is a majo coc. Muffli was do usi ubb blast mats (Fiu 4). ach blast was moitod usi Miimat, Istatl, Caada, fo oud vibatios atio at spcific distacs (Fiu 5). I total 31 blasts w cosidd fo aalsis pupos. Dtails of blasts lik maximum cha p dla, moitoi distac, pak paticl vlocit, dpth of xcavatio fom sufac tc., a iv i Tabl 1. Rssio aalsis was pfomd btw pak paticl vlocit ad scald distac ad th ssio cofficit was foud to b.81, which idicats that th data has a v ood colatio (Fiu 6). Sismic was stimatd as p quatio (2) usi th pak paticl vlocitis i loitudial, vtical ad tasvs dictios, th dtails of which a iv i Tabl 2. Fiu 7 shows th colatio btw sismic ad scald distac, with a colatio cofficit of.79 idicati a v ood colatio. Th oud vibatio vt sials w aalzd usi DaDiSP softwa. Aa of ach sial i ach dictio was dtmid ad th total wav was stimatd b summi up th i loitudial, vtical ad tasvs dictios (Tabl 2). Fiu 8 show th plot btw total wav ad th scald distac. Th wav fom ach blast was compad with th stimatd sismic. Thouh it has a poo s- Fiu 1. Aalsis of oud vibatio wav foms usi sial pocssi softwa. 47

4 Fiu 2. A viw of dilli opatio at xcavatio sit. Fiu 3. A viw of blast sit. Fiu 4. Muffli aamt o blast aa. 48

5 Fiu 5. Goud vibatio moitoi. 1. Pak paticl vlocit (mm/s) = x R 2 = Scald disatc (m/k**.5) Fiu 6. Pak paticl vlocit vs scald distac. = x R 2 =.7947 (MJ) Scald Distac (m/k**.5) Fiu 7. Sismic vs scald distac. 49

6 Tabl 1. Dtails of blasts coductd. Blast No. PPV (mms) MCD (k) Distac (m) Dpth (m) SD (m/k.5) PPV: Pak paticl vlocit, MCD: Maximum cha p dla, SD: Scald distac. sio co-fft, it has simila td to th pvious cuvs, which ca b also a idicato of blast pfomac. Fiu 9 show th compaiso of sismic ad wav at difft scald distacs ad at a costat dpth of xcavatio of 15 m fom sufac. At all th scald distacs, th sismic ad th wav shows simila tds. At a low scald distac (26.63), th sismic ad wav w hih 5

7 Tabl 2. Wok do ad sismic of difft blasts. Blast No. PPV (mms) MCD (k) Distac (m) Dpth (m) SD (m/k.5) Total Wav S (MJ) Tas Vt Lo Tas Vt Lo 1.69` SD: Scald distac, S: Sismic. compad to hih scald distac. Simila to th abov, two mo sts of data w tak up at 17 m ad 19 m dpth of xcavatio fom sufac (Fiu 1 & Fiu 11). Simila td was foud as pvious cas. This shows that at a costat dpth of xcavatio as th scald distac icass th sismic ad th wav dcass. This is du to th fact that a hih scald distac idicats ith lss maximum cha p dla o icasd distac fom 51

8 = x.4543 R 2 =.161 Wok Do Scald Distac (m/k**.5) Fiu 8. Wav vs scald distac Wav Scald Disatc (m/k**.5) Fiu 9. Sismic ad wok do at difft scald distac ad at a costat dpth of 15 m Wav Sacld Distaac (m/k**..5) Fiu 1. Sismic ad wok do at difft scald distac ad at a costat dpth of 17 m. o moitoi poit. Fiu 12 shows th compaiso btw sismic ad total wav at difft dpths of xcavatio ad at a costat scald distac of 58. As th dpth icass, sismic ad wav also i 52

9 12 Wav Scald Disatc (m/k**.5) Fiu 11. Sismic ad wok do at difft scald distac ad at a costat dpth of 19 m. Fiu 12. Sismic ad wok do at difft scald distac ad at a costat dpth of 58 m. casd. Simila aalsis was caid out at a scald distacs of 5 ad 69, ad simila td was obsvd i th sults (Fiu 13 & Fiu 14). This is du to that as th dpth icass th ock fomatio was foud to b had i th fild. Thouh had ock fomatio th wav popaatio is mo activ so it sultd i hih sismic ad hih wav as th dpth icass. Aoth aso is that th hoizotal moitoi distac is btw 22 ad 45 m ad dpth of xcavatio is btw 12 to 25 m. So, at shallow dpths of xcavatio, th sismic wav achs th sufac much bfo th moitoi poit which has ld to a low PPV codi b opho, wh as i cas of dp xcavatio poit, as th sismic wav achs th sufac v a to th opho ad a hih PPV was codd. So, dp xcavatio sultd i hih sismic ad wav thouh th scald distac ad oth paamts w sam. 3. Coclusios Wav Dpth (m) Th aalsis caid out i th chos costuctio sit has idicatd th followi usful ifcs. 1) Th sismic dissipatd ito th ock mass is havi ood colatio with scald distac ad sismic. 2) Th wok do dtmid basd o th mutuall othooal dictios of oud vibatio vts is havi ood colatio with th sismic, which is stimatd, basd o PPV ad ock poptis. 3) Th sismic dissipatd ito th ock mass ad th wok do b th xplosiv a foud to dcas with icas i scald distac at a iv dpth of xcavatio. 4) At a costat scald distac, as th dpth of xcavatio icass th sismic, th wok do also icass. 5) Aalsis of wav foms usi sial pocssi softwa is foud to b quit usful i aalzi th blast sults. 53

10 Wav Dpth (m) Fiu 13. Sismic ad wok do at difft scald distac ad at a costat dpth of 5 m Wav Dpth (m) 24. Fiu 14. Sismic ad wok do at difft scald distac ad at a costat dpth of 69 m. 6) Th wok do ad sismic stimatio aalo ca b xtdd futh to colat with famtatio. Rfcs [1] Sast, V.R., Ti, V. ad Ram Chada, K. (23) Shocktub Iitiatio fo co-fidl Blasti: A Fw Cas-Studis. Istitut of is (Idia), Kolkata, [2] Sast, V.R. ad Ram Chada, K. (24) Shocktub Iitiatio fo Btt Famtatio: A Cas Stud. Th Itatioal Joual fo Blasti ad Famtatio, 8, [3] Sast, V.R. ad Ram Chada, K. (25) Ifluc of Iitiatio Sstm o Nois Lvls Poducd b Blasti Opatios i Limsto Mis. Istitutio of is (Idia), Kolkata, [4] Sast, V.R. ad Ram Chada, K. (28) Famtatio ad Thow Du to Blasti Rol of Iitiatio Sstms. Itatioal Cofc of IS, Jaua 28. [5] Sast, V.R. ad Ram Chada, K. (28) Assssmt of Blast Pfomac Basd o Distibutio: Pocdis of 42 d Amica Rock Mchaics Associatio Cofc, Sa Facisco, 29 Ju-2 Jul 28. [6] Bta, G. (199) xplosivs: A ii Tool. Italsplosivi, Milao. [7] Spathis, A.T. (1999) O th fficic of Blasti. Th 4th Itatioal Smposium o Rock Famtatio b Blasti, Johasbu, 5-8 Jul 1999, [8] Ouchtlo, F., Nb, U. ad Olsso, M. (23) Th Balac of Poductio Blasts at Nokalk s Klitha Qua. Pocdis of th Scod Wold Cofc o xplosivs ad Blasti, Pau, 1-12 Sptmb 23, [9] Achbach, J.D. (1975) Wav Popaatio i lastic Solids. lsvi, Amstdam, 166. [1] Howll, B.F. ad Budsti, D. (1955) Distibutio i xplosio Gatd Sismic Pulss. Gophsics, 2,

11 [11] Folso, D.., Atchiso, T.C. ad Duvall, W.I. (1959) Popaatio of Pak Stai ad Stai fo xplosio-gatd Stai Pulss i Rock. Pocdis of th 3d US Smposium o Rock Mchaics, Gold, 2-22 Apil 1959, [12] B J., J.W. ad Cook, K.L. (1961) is, Maituds ad Amplituds of Sismic Wavs fom Qua Blasts at Pomoto ad Laksid, Utah. Bullti of th Sismoloical Socit of Amica, 51, [13] Nicholls, H.R. (1962) Coupli xplosiv to Rock. Gophsics, 27, [14] Atchiso, T.C. (1968) Famtatio Picipls. I: Pflid,.P., d., Suf Mii, Th Amica Istitut of Mii, Mtalluical ad Ptolum is, Nw Yok, [15] Hiz, K.-G. (1998) Compaiso of Sismic ad xplosiv i Fiv Smooth Blasti Tst Rouds. Itatioal Joual of Rock Mchaics ad Mii Scics, 35, [16] Sachidia, J.A., Saa, P. ad Lopz, L.M. (26) Compots i Rock Blasti. Itatioal Joual of Rock Mchaics ad Mii Scics, 44,