ML19322B882
| ML19322B882 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 11/29/1979 |
| From: | DAMES & MOORE |
| To: | |
| Shared Package | |
| ML19322B881 | List: |
| References | |
| TASK-02-04, TASK-2-4, TASK-RR NUDOCS 7912110246 | |
| Download: ML19322B882 (11) | |
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ORAFT PRELIMINARY REPORT PP.0P05ED MEASURE TO MITIGATE TLiE POTENTIAL FOR LIQUEFACTIO!L AT LActMR PLAftf SITE NEAR GENDA MISC 04 SLY DAIRYLAfiD POWER COOPEPATIVE U
INTRUlyJCTION At ttre cczc1crvicu of the Nove:ter 2 cocting, tn Gutlear kge";3-tory Comissica (TJI} directed DairyTand Pour Coperat% (DPC) te prerwa nessures to nitipte the postulated poteRtfat for TicpzeQct-ica fu the event that the LACBET plant site experiences sofi 1%safarth irt ttre tg 40 feat due to a Safe Stratha Earthqu21e (SSEJ resvit.ing in a gremd surface accel-ention of 0.12 9 Dames & Moore reviewed befefly the ca. Ioas alternatits anilable to accocsifsh this guaT. The following dh.conten prewrrts sur I
pecifminary conclusions regarding the feasibility of the varicas teethods ar-ailable for densifying and/or tgroving the fn=adatics caraditica; to miti-gate liquefactica ptential.
NETf!01)5 0F DESSITTILG. rid /OR IFPidIJIllG sat!Irf SDIL_5 The fattowfag methods are generally used for densifying and/or improving cohesionless solls:
- Blasting
- VReatory Prube
- Vibratocy Rollers,
- Com;raction Piles
- Reavy Tamping (Dynamic Consolidath)
- Vibrof1 station
- Gm uting
- Displacement Grauttag
- Mbre-Replace: rent Stase Celsmac.(Gravel Drafos) i
- Freering
-- Dcuatering L
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Each of the above methods. was cassidered the its applicMrnity to LT< CUM plat site where an apeyatity nuclear POW 2P PIMt exists. A erser 35 tw were eNfsated imediately because of sone serious ifnitaticus or otter restrfetiws wit!t resoect to the LACBEL site.
BUtsTIsi. Suteessive detonath of scalT enicsive chartps en be a rvfd aM eceritatcaT runs oc denvificatias cf cabesiastes.s. scMs. F M Nee,tian shock waves-and vibrat. fens resultig from blas.tig nay ceau I?cif Ti w-9 factias, minstrifem disphenment aed rcsreidig of sotT.
hcase af poter,tfa7 Meerse effects ca eristtre structwes and rrfTe femfatton at the tWM plamt' site and the dmprs associated with osing erplosfwr tr, a sece.rity sem sltise area, the blesting technique was. eltnfrratW from f:rtber cuidwCic=.
't1 MOW PMDBE (TEIE0i%rEl-TMs mett:cd essumtirny rt=dsts of Janifyi@
- a. certatu ::=e of the soil by tasertig a v'tirating prr3.t ta the df.55YEd depth this mened ts best suited fre m c;res edewbr;ad arts Settl# W s wi71 he in.futed hecame of ufbrattaas. Pctevtial damep tu ruhgrmr4 piire-Its:es crmW resu1L /dse,. it wH1 nat be passtMe in hify the sails endIr existing strurtr.res ssig narmT workfrq cvai; rent am:i 1cckeiquen Tfrarefore,
-_the Tfrrerotie_te:Wique was censidered nasuttable for_ further ecarideratten far thn LAtEM1 plant site.
VfBRA10H EcttEB5; Cmpaction of the soil is actriev.ed by a self-fwnyeIIed a d t m d viL atory rotter. As this method is tr2. effective at deptfn; cf rasghly 5 feet beTex tire grcoat surftrte, and the need to kn;were tha seiIs
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further considwatics.
COMPACT!Q4 f_IEES: Dy drivim3 displacemet pues at close spacing, densifi-catien of the soll cas be accmpItshed. In additics to increasire tite tex-sity (tha increase la density may unt he very s.tgaificat eeTess tAe sysetsg is very c?aan), the coefficient of Iateral earth pressare increases ad results in, a considerable increase fm cycifc shear stregth. his is si -
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stitcast from the psist af view of nitigatfos af the lignefacttra proMts at LACBWR site. Therefera, this methsd ney be ces;sidervi as, an applicatrie option regetring further considerath ameser, this methad also suffers from the disadvantage that it is unsultaMe where there are cwistig stru>
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PIAW TXRPTEG-(DVfdNtfGWittIEIMifMN In tMs method, repeatid ~trapectF~af a very heavy weight droppet[ fToct a hefskt are used at predetged sp
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.e rnethnd is obyfensTy nec suftable at sites with existfar stracteres.
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of a Mbrarf;tet" (a cylim!rical genetratae atsrat 4DD rxer in dianter ed 2 rr>srs Ica9 str. pended by a crane,leigfumf absat 2 tens ad detopig a tmrisch+I cen.trffwp1 force at IL*TA rpml Gramf ar bactffTI wtU he used to fill ca the bnles u4ich wi also be cwpcted by virratica. Again, this rectM cua-nut be md for demifying softs and2r struratwe3, f.aDTtim hk matked of stabf1fzat-ion cassists of ef tt& 1-fitics fu the rutds ta th scil mass with cement er clay (partiedate gathrg), er infectitg diffwert. ctricals whfch fateract ta solidtfy art nwedtra tfe sot? russ tvr the femstica of e get ire their pms (chsical 9mstingh or stsilizia9 the soH mss by injectisg kic.kly dcteas grerat in dfsplen h scH cr by presssf2d compactica (dtsplacearst gnating aw cwgac.tip get:rrig). h dispiannen graatiss} aad cwyactica grovting oxy vmdt in grekats of satrated sad. The sud particle size at LACbM site is rd. q set 1 salted for pzrtice} ate gemrt-hrg Chemical gravtfag is feasfMe but at very ki$ inititi cest. An additial disadvar.tase is. the extreme ettfff-cutty ta rew: hts beIcw tfm s'ducares suppsrted ca. mrmercus Pfles. Y E90-REPLACUiffri 5It'E ccWP.E:. T&h rethmt is sftsflar tu vibroflotatia,. _.1 1. _excert._tbat_thLgransTar_bxtftItwwdMU he_tearse_gchth_Atpdat[P t i = here is, in addif.fon to dustfica.tica, the werall effective pemeability of the systs will be fat:reased 50 as to enable the dissipatica ni excess. pore pressure as fast as it is generated darfsp ttte earthrped:e Lite scy other nettrd;. ducrikad earlier, skis mettad can anty Em applicable to areas when there are no edsting structures. TktTTIBM Freeria; the ground and keeping it frquern for the lifette of the strtreture caa% elimisate the potent.fal for liqpefacties Esr,tever, this seTutics is practical caly for tempsrary rather then perraast caliticas, h & methed alsa is relatively very expensive and my have the eWestrable l effect et freedg aH the aarfeirycend pipe 7ives. i 3 E
~ DEWATERD& Ibe presence of water is. wtat. sakes the $ards susceptible t* Tiquefaction. If the pere water is entirely remved by punpinghe ywsd weter and, matatainiep the water table at a lamerJewel the petentiaY for liquefactfaa fs entirely eliminated above the water table. The.potestf61 for liquefacttes is reduced under the w6ter takle btneae. whru the water table is Towered, the effective stresses are increased. ad fouwwwtty tire cyclic shnar stresytb fs iNcd. After a preliminary favestigatier of tras hydrepelegic cosMt. en at tk LACBWY site, tia dewitterin1} optfan was coas-fdered a feasible optror anti therefore,. a pelinivary design of the deutering Erstm ws preparei for pres.mtstica to the llPI. Mter revieus ast approvci t>y SE., fitstter detatis of the dewateria5 system wul be cc:zsidered ff mr.essary. PEEt!MIERY DESIGR Of Tif DEWATEPJHG SYSTEM GLW RTL An ares of appraxtnately MC by la feet is dinienstes cr"prising of ttu reactor car,taftsnent, tie twhine betIdina, the waste. dis;nnal Emildag aTd tfie stad. was ecostdered fw dewstering. The depth of tb sandy safTs suspected tn be potentially ifquef%Ie at the LAC 51E s.ite is 40 feet.. The granad ster level fluctuates between 8 to M feet helav the entsting plat grade. Figure T shaws the eWect cf the depths to water table below the piant grade on the facters of safety against Ifquefattice peasttal at varfm depths. Figwe 1 alsu $bews tirat lowertup the water table to atmmt 20 feet beTow grade wenld increase the factor crf safety from I.39 to 12 at a depth ef 3a feet and froar T.55 to 1.93. at a derth of 43 feet. The sime infceratien is prescated ta Table T in ta6atar fornt. Therefore, the dewatering systm wtIl be considered adMaste if the wter tabte can be 1ctered by ir mximm af Tir feet front its existfng level. Itawever, the preliminary desis= is per-- formed for a maximtsn draw dowrr of 16 feet below the existing water table etevation that id, 25 feet belaw the phurt Brade. The flaft) drawdow death will be detemised after appropriate field and laberatory remeabilitt tests are dane. e.
GUAGGEGLTitTCCOSMTIDE AT LACEWE itTE F%are 2,se:;;;ts. a schematic cross section of_the sahasti coa-ditfans at the LACRR site. nsefag the fiosds. of April 1955 evidene af j direct by* antic connection between , agaffer at the sf te awd the e.d) scent river uss shservei h ranknTe essers at the plant grah (approxicate eTe-i ution c:rf +D9+) were forced open by the flonf uater where the water lewt at the river was also appecaimate!y +E3&t. h comat water 1ewT eTentier. of the riwr is +6201 He grasmf watec level at the site fhictestes betxcen +01 to +627. If the water table is lowered to +61M_ (25 feet below the plant rade), and tr,aintained at that level, then there will he a perrsnst retirarge from tke vtwr f9to the ac;stfer because of the dirert t:-p.re.alic maaertien trattened entier N average gemeabi)ity of the sac 4s in tire arpifer was estfratad ~ to be 80 ft/ day esing the tr,farmation from grata sim:e mislyses. So:ne of the informatica providst by the DPC persarmel regardire the quantities. c' tater pumped out and the avers of excantiert during the plant ensstraetta cf tte containme:rt ar# the turtrire hattding, the. gercwhitity valttes. were WJc - calculatei The average resulting wlae of the pemeability was apprat:tztely 150 ft/ dry. This higher value. was nsed foe the design. of tke dewatering sr,- However, ys.f m, tests will be perfemed te verify or assumtions. i tem. IRE PRUP05ES SYSTER GF DNATRITG Few dffferest. systens of dewatering were cars.fdered: 1. A perimeter wen potat system with a. cestral paging station; 2. A permeter system of suctign wc11s with a_ central purrptsy station; 3. A system of individwal wells with indMdual pamps and 4. Ranney wens with harizonta7 screens. The perimeter well point system was. consideret' ustritaMe berzuse af ttm. close speciap (appsatmately 1-1/2 feet apart) mudated by the design calculations. The i:xrimeter system of swtise wells was also constdered ~ unsvitaMe becatse er practical Timitatieris an ptiming head. Ramirey weils with horizontal screuss require special ennstracth tectaignes and therefere t -s-l i
'--were marcansideredTsrther.7 proposiid systemTis~ chief of fdifftdsaI-Ils ~~ with indtvidual pegs enanected to a comen discharge pipeline,. as skaum fa Ffgare 3 PREUMIBRef UESIGE SERIES FOR Ti1E PROF 0 SED SYSTEM We have tentatively estfriated that a total flow of 5003 g.c will kave to be punged centiaanasty in order to addeve a draw dous crf.pr w.iimately i 15 feet at the center of the dewateria, systers We have estinated that 5 ~~~ fndividtral wells, U-T thresgh W-5, coch naawted with a 1033 ggn pamp, as shws to Figrre 3,, will perfam tire regrfred dexaterias function. A sixth well, V-6,. is provided as a Man for the devaterfr4 system The following are the desfga detaffs of ttze wells. and tte pwrcs. FELTS Fepth 100 feet itisimum diameter cf the knie 20 inches F1Enim:m diameter of casing 12 fuches Mimicam dio.4w of screer 12 inckes Misimsa length of screen 65 feet ifnimun Icagth af klank castsy 40 fest Typa of screen Johaton Stainless Steel (or es;:iivalect) Widtft of~ sist 20-slot (Q.020 faches) Grawl pack. Proper stae and quantities to fill fn the asustar space of the welis. FUMPS fferetrench American Carlaration's punp Bs 10015 er equivaTest is prewre ? This pump fits into a 12 fach casful and will pump 1800 gyn at 70 feet of head, and has a 20 horsepower submersfhle motor. ~j i DISOIRGE PIPELIBES It is pvupased tiet the dtwaterin5 5Fstem commected by two sections l of a inch pipeitans totalitag 45E feet ts length discharge fato am 18 tsch pfpettaa abast 128 feet tw length ukich picts up the contifned flow and dis-charges fats the riwr, as shows is Figare 3. p
4 wee 5fJak.@,p6.p....Aq3gg73ygg.g,;(Jp,g.g.g.,jppgeggi.6.:eqq.g9dglLgy.t.;,qpcA..p y(.bjp,Q t DTHER CtNSIDE!mT&JS Osr preliminary evaluath is that the prapased de:aterieg systm oculd critigate lipactica poteatial at time UkCBWR sibe dt: ring Safe Shutdswa ) Earthgate condiths. 1 There are other rzmifications of dewatericg, two 4ere cawsidered i in t1ris study. The first is the settlement resulting frca increased effcc-tive stresses; the scrwrd is the down drag en the piles resulting fram tize j settiment. Gar preliminary calculations show that the settlement ressalting froa 1!ewatering of a lknitzd area is about a qearter of as incG. The de-watercd area is expected to emperience this settlement uniformly and ia car 1grfeien will met adversely affect the facilities at the site. ike dews drag effects en the piles as a result of the settlement is espected to increase the had carried by the piles. Dar preliminary calculatians ledicate that 19te Du:rease of vertical lead en piles is small. Ikis increase, la ser spia% is not large enough -to canno any concera en the safety of the fasadations at the LACER site. Feather detailed calcula-tiens will be made ta serify sur pretterisery fi1 stings. l
Table - 1 Effects of Depths to Water Table Below Plant Grade On Factors of Safety Agaiut Liquefaction (a, v 0,12 g) va0 v=10 va20 W W Depth Below T T F.3. T F.3, T F.3, 1 F,$, 1 F.3, ayg Grede (ft) (FSF) (P8F) (PSF) (P5F) (P2P) (PSF) 10 86 15 0,87 NL NL NL NL , 20 163 150 0,98 240 1,47 NL NL NL a 30
- 33 230 0.99 385 1,59 440 1,89 I
NL NL 40 290 340 1,17 450 1,55 560 1,93 080 2,34 NL average cyclic shear stress T a ays cyclic shear strength T = depth to water table (ft) 9
- NL a no liquefactign l
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