Pitfalls in interpretation of cone penetration test data recovered from unsaturated geomaterials

Transcription

1 Pat 2018 RJ Jwll and AB Fouri (d) 2018 Autralian Cntr for Gomchanic, Prth, ISBN Pitfall in intrprtation of con pntration tt data rcovrd from unaturatd gomatrial AR Rull UNSW Sydny, Autralia D Rid Th Univrity of Wtrn Autralia, Autralia Abtract Laboratory-controlld and fild con pntration tt (CPT) rult for unaturatd gomatrial (and, ilty and, tailing) how that uction ha a pronouncd influnc. Th pntration ritanc incra ignificantly du to th prnc of uction whn compard to tho for aturatd or dry tat, for a givn rlativ dnity and nt confining tr. For unaturatd and, whn uction i includd in th ffctiv tr, th am mi-mpirical xprion ud for aturatd condition ar found to link pntration ritanc to th rlativ dnity and ffctiv confining tr. Howvr, th am i not tru for unaturatd ilty and, a aturatd and unaturatd ilty and bhav vry diffrntly around a pntrating con. Suction alo ha implication whn uing claification chart. Con pntration tt rult from a rang of oil and tailing for both aturatd and unaturatd condition ar plottd in on typ of chart. Suction-inducd incra in pntration ritanc, and chang of oil bhaviour from partially draind/undraind to draind cau incorrct claification and amnt that gomatrial ar dilativ. Failur to account for uction influnc, and th altrd matrial rpon, may alo lad to ovrtimation of cyclic ritanc ratio. Kyword: con pntration tt (CPT), uction, unaturatd, trngth, claification, cyclic ritanc ratio 1 Introduction Unaturatd gomatrial (oil and tailing) ar widly ncountrd and nd to b dalt with in many nginring problm. Thir bhaviour i complx and influncd by many factor including xtrnally applid tr, gomatrial typ, tructur, dnity and uction. Suction, in particular, incra th har trngth and may contribut to th tiffning of th gomatrial. Th charactriation of unaturatd gomatrial may involv xpniv and tim-conuming invtigation including oil boring and unditurbd ampling for laboratory tting. Prforming th con pntration tt (CPT), a widly ud in itu tt, in an unaturatd gomatrial may nabl l cotly and mor rapid charactriation of th unaturatd gomatrial proprti. Th valuation of proprti from CPT rult ha bn an ara of intn practical intrt. For both coar and fin-graind aturatd gomatrial, many corrlation hav bn dvlopd that link con pntration ritanc (q c) to in itu tat and har trngth (.g. Baldi t al. 1982; Robrton & Campanlla 1983a, 1983b; Jamiolkowki t al. 2003). Howvr, it i only in th pat fw yar that corrlation hav mrgd for th CPT that tak into account th ffct of unaturation (Pournaghiazar t al. 2013; Yang & Rull 2016). So far th hav bn limitd to a clan quartz and and a ilty and (dcompod granit). Th and othr tudi (Lhan t al. 2004; Collin & Millr 2014) how that uction ignificantly incra q c. Mot notably, Pournaghiazar t al. (2013) howd that for an unaturatd and, providd uction i corrctly incorporatd in th ffctiv tr, corrlation dvlopd for th and whn aturatd/dry to tablih th pak friction angl and rlativ dnity from th maurd q c ar qually applicabl to th and whn it i unaturatd. Thi i bcau th and whn unaturatd did not xhibit uction hardning, whr uction hardning only xit if th yild urfac iz and iotropic normal conolidation lin location Pat 2018, Prth, Autralia 483

2 Pitfall in intrprtation of con pntration tt data rcovrd from unaturatd gomatrial AR Rull and D Rid dpnd on uction (Rull & Khalili 2006a), and th and bhavd lik a draind matrial during con pntration irrpctiv of whthr it wa dry, aturatd or unaturatd. Th am wa not tru for an unaturatd ilty and. Yang & Rull (2015, 2016) howd that th unaturatd ilty and bhavd lik a draind matrial. Thi i bcau th air in th por pac prmittd volumtric comprion to tak plac around a pntrating con. Furthrmor, inc th ilty and xhibitd uction hardning, th rlationhip which link pntration ritanc to ffctiv tr and rlativ dnity for draind aturatd condition would not apply to draind unaturatd condition. Th ar highly ignificant fatur to not and ar th main raon why CPT chart and rlationhip dvlopd for aturatd ilty and (or any oil or tailing with ay mor than 5% fin, i.. ub 75 micron in iz) hav no applicability to unaturatd ilty and. Any corrlation for CPT in aturatd ilty and, whr undraind or partially draind condition prvail around th pntromtr, ar inapplicabl to th intrprtation of th CPT in th am oil whn unaturatd. Thi papr ummari th laboratory-controlld CPT rult for th two unaturatd oil obtaind. Th ffct of uction ar highlightd. Th papr go on to dmontrat how nglcting to account for uction can lad to incorrct claification, incorrct timat of a oil or tailing tndncy to dilat or contract and incorrct timation of th cyclic ritanc ratio (CRR). Thi may lad to unaf conqunc, for xampl whn uing th CPT to a th potntial for liqufaction, and whn digning to rit arthquak loading. 2 Effctiv tr Following th work of Bihop (1959) th ffctiv tr i dfind a: whr a prim ymbol dnot th tr invariant to b ffctiv, i th total tr in xc of por air prur (u a) alo rfrrd to a th nt tr, i th uction, bing th diffrnc btwn por air and por watr prur (u a u w), and i th ffctiv tr paramtr, having a valu of 1 for aturatd gomatrial and 0 for dry gomatrial. 3 Con pntration tt rult in unaturatd Sydny and and Lyll ilty and Th calibration chambr ud wa dtaild by Pournaghiazar t al. (2011). Th tting wa conductd uing a contant tr boundary condition. Th chambr accommodatd cylindrical pcimn with a hight of 840 mm and a diamtr of 460 mm. Th chambr ha high air ntry cramic mbddd in th ba plat for impoing uction in a pcimn uing th axi tranlation tchniqu (i.. impoing uction by lvating th por air prur abov a poitiv por watr prur). Th axi tranlation tchniqu wa ud for om pcimn, whil othr wr ttd with uction bing maurd uing vibrating wir pizomtr. Th por watr and oil ud in th tt wr abnt of alt, maning th uction ar matric uction. If alt wa prnt thn omotic uction would alo xit. Omotic uction may altr a oil mchanical bhaviour and CPT rult if it compri crtain clay minral. Thi iu i dicud latr in th papr in th contxt of CPT in two othr gomatrial in which alt i prnt. CPT wr conductd uing a miniatur lctrical con with a diamtr of 16 mm and a con tip ara of 2 cm 2. Th con wa puhd into th oil at a contant rat of 2 cm/c. Th miniatur con wa ud to incra th chambr to con diamtr ratio (R D), which ha a valu of 29 in thi tudy. Sydny and i a prdominantly quartz and ourcd from th dun around Kurnll, Sydny, Autralia. An xtniv xprimntal program wa conductd by Rull & Khalili (2006a) to charactri aturatd and unaturatd Sydny and including th oil-watr charactritic curv and mchanical bhaviour. (1) 484 Pat 2018, Prth, Autralia

3 Nw dvlopmnt Indx proprti of th oil includ a particl dnity of = 2.65 g/cm 3, a minimum dry dnity of min = 1.38 g/cm 3 corrponding to th maximum void ratio max = 0.92, and a maximum dry dnity max = 1.66 g/cm 3 corrponding to th minimum void ratio min = Pak friction angl obrvd in draind triaxial comprion, for both contant cll prur and contant p' load path, may b timatd uing: 3 p i c D 3.7 ln 0. 9 r p a in which D r i th rlativ dnity, c = 36.3 i th critical tat friction angl, and p' i i th man ffctiv tr at th bginning of har. Rull & Khalili (2006a) found for Sydny and that: for for for whr i th uction valu parating aturatd from unaturatd tat. Lyll ilty and i a dcompod granit from th catchmnt ara of Lyll dam, Nw South Wal, Autralia. It contain 27% fin, including 4% clay (ub 2 micron). Indx proprti of th oil includ = 2.55 g/cm 3, min = 1.51 g/cm 3 corrponding to max = 0.69, and max = 2.02 g/cm 3 corrponding to min = obrvd in th triaxial comprion tt on unaturatd ampl with contant uction may b timatd uing: (2) (3) whr c = may b xprd a: 3 p i c D 4.9 ln 1. 0 r p a (4) Numrou CPT wr conductd on aturatd and unaturatd Sydny and within th calibration chambr (Pournaghiazar t al. 2013). Dry and pcimn wr prpard by th pluvial dpoition tchniqu. Unaturatd pcimn wr formd by firt aturating th pcimn and thn ltting th moitur contnt rduc and thn applying th axi tranlation tchniqu to achiv a targt uction. Two initial rlativ dniti (D r = 0.61 and 0.33) and fiv nt confining tr (25, 30, 50, 100 and 150 kpa, ach applid iotropically) wr ud to tt pcimn. For a givn rlativ dnity and confining tr combination, a tt on a aturatd pcimn wa prformd, along with a numbr of tt on unaturatd pcimn with initial uction maurmnt ranging from lightly largr than to 200 kpa. It i notd that unaturatd Sydny and pcimn prpard in thi way do not xhibit uction hardning (Rull & Khalili 2006a). for for 1 1 (5) Pat 2018, Prth, Autralia 485

4 Man ffctiv tr (kpa) Pitfall in intrprtation of con pntration tt data rcovrd from unaturatd gomatrial AR Rull and D Rid Sampl of Lyll ilty and wr prpard uing tatic compaction of oil curd at crtain moitur contnt. Aftr compaction of om ampl, a CPT wa conductd immdiatly o that th ampl uction wa qual to th a-compactd valu. For othr ampl, th axi tranlation tchniqu wa ud to rduc moitur contnt and incra uction. Th axi tranlation tchniqu nabl mor dirct control of th uction applid. Howvr, th tt oil had a low hydraulic conductivity (around m/c for aturatd condition, and much lowr for unaturatd condition), which prvntd uniform moitur and uction profil from bing achivd in raonabl timfram (Yang t al. 2014). Thrfor, th moitur contnt of th ampl maurd aftr a CPT wa conductd wr ud to infr uction. In ampl in which CPT wr conductd without u of axi tranlation, th uction valu wr maurd by thr vibrating wir pizomtr. Bfor inrting th pizomtr, thir tip compriing high air ntry valu dik wr carfully aturatd. For Sydny and, Pournaghiazar t al. (2013) prnt th plot of q c vru dpth for aturatd and unaturatd pcimn. Suction ha a ignificant influnc on q c. In all ca, uction cau th q c to incra abov th valu maurd in a aturatd pcimn for a givn combination of rlativ dnity and nt confining tr. For loo pcimn, uction of 25 and 200 kpa incrad q c by 24 and 50% whn th nt confining tr wa 50 kpa, and by 14 and 31% whn th nt confining tr wa 100 kpa. For mdium-dn pcimn, th uction-inducd incra of q c wa l than for loo pcimn for th confining tr conidrd. To intrprt th Sydny and rult furthr, it may b aumd that con pntration in Sydny and occur undr draind condition; that i, whn uction i contant, vn though a contant moitur contnt condition actually xit. Th diffrnc in th Sydny and tr train bhaviour for contant uction and contant moitur contnt condition ar ngligibl, a long a th dgr of aturation i l than about 10% (which i almot alway th ca in unaturatd and) (Rull & Khalili 2006b). Th contant uction aumption in Sydny and man that th uction around th con tip can b aumd qual to th initial or far fild valu. Alo, a in th rlationhip do not vary ignificantly with and dformation, it can alo b aumd that around th con tip i alo qual to th initial or far fild valu. Thi gratly implifi intrprtation of th rult. A plot of q c vru impod man ffctiv tr p i prntd in Figur 1, whr p = p u w for aturatd and (u w i th por watr prur), p = p + for unaturatd and, and p i th man nt tr. An air ntry valu of = 7 kpa wa ud in th calculation of. Th data can b raonably wll fittd by th powr law xprion in th figur caption. Con ritanc, q c (kpa) ,000 20,000 30,000 40,000 Saturatd = 0.33 D r 50 Unaturatd = 0.33 Unaturatd = 0.61 Saturatd = 0.61 D r D r D r D r = 0.33 D r = Figur 1 Comparion of CPT rult for Sydny and and timation uing th powr law rlationhip q c = 45(p ) 0.85 xp(2.78d r) 486 Pat 2018, Prth, Autralia

5 Nw dvlopmnt Lyll ilty ampl wr ubjctd to a rang of iotropic nt confining tr. Yang & Rull (2016) prnt plot of q c vru dpth for CPT prformd in unaturatd ampl. Strongr uction caud largr con pntration ritanc. A uction of 37 kpa i aociatd with a q c that i 50 % largr than th valu for a uction of 24 kpa. A uction of 72 kpa i aociatd with a q c that i 55% largr than th valu for a uction of 24 kpa. Saturatd CPT in ampl at void ratio comparabl to tho ud in unaturatd CPT wr not conductd. Howvr, inight into th diffrnc that would xit in CPT rult from aturatd and unaturatd Lyll ilty and can b obtaind from cavity xpanion analyi an analogu to th CPT. Th prur at th wall of an xpanding phrical cavity (σ L) i rlatd to q c. Th mot rlvant finding of Yang & Rull (2015), who tudid cavity xpanion in unaturatd Lyll ilty and, ar ummarid hr. Th ffct of thr diffrnt drainag condition (contant uction, contant moitur contnt and contant χ) on σ L wr tudid. For ach drainag condition, thy obrvd that a ignificant chang of void ratio occur around an xpanding cavity in th unaturatd oil, and analogouly occur around th tip of a pntrating con. Thy found that, for a contant moitur contnt condition and full hydro-mchanical coupling, th chang to χ and motly countract ach othr and contant χ may b aumd to giv a raonabl approximation. Th aumption of χ bing a contant may b ud to implify intrprtation of th CPT rult. Yang and Rull (2015) xplaind that th unaturatd ilty and around a cavity bhav mor lik a aturatd draind oil than a aturatd undraind oil a th air in th por pac prmit volumtric comprion. Howvr, a Lyll ilty and xhibit uction hardning, thr i not a 1:1 corrlation btwn aturatd draind bhaviour and unaturatd draind bhaviour. Thi i in contrat to unaturatd Sydny and, which did not xhibit uction hardning, maning unaturatd draind and aturatd draind bhaviour wr virtually idntical. Thi i a ignificant fatur to not, and th main raon why CPT chart and rlationhip dvlopd for aturatd ilty and (or any oil or tailing with, ay, mor than 5% fin) hav no applicability to unaturatd ilty and. Th aturatd oil i partially draind or undraind, whra th unaturatd oil bhav lik it i draind cauing diffrnt tr train bhaviour. Th CPT rult ar prntd in Figur 2 in th q c vru p' plan uing olid ymbol. Th valu of D r rangd from 0.08 to Th initial χ wa ud in th computation of p'. Th data can b raonably wll fittd by th powr law xprion in th caption of Figur 2 in which q c and p' hav unit of kpa. Th prdictd q c valu from thi xprion ar hown uing hollow ymbol. Th rror aociatd with th xprion to obtain q c i l than 30%. Figur 2 Comparion of CPT rult for Lyll ilty and and timation uing th powr law rlationhip q c = 162(p ) 0.65 xp(2.6d r) Pat 2018, Prth, Autralia 487

6 Pitfall in intrprtation of con pntration tt data rcovrd from unaturatd gomatrial AR Rull and D Rid 4 Suction influnc on oil claification A chart for claifying oil or tailing typ, and aing whthr th oil or tailing bing ttd i contractiv or dilativ, ha bn propod by Robrton (2010). Only that chart will b focud on hr, although many othr xit in th litratur (.g. Schmrtmann 1978; Oln & Farr 1986). Th finding mad hr would alo b vidnt in othr intrprtation framwork, if thy wr put undr th am crutiny. In uing th chart, th normalid con ritanc, whr ach i dfind a: Q tn Q tn, i plottd againt th normalid friction ratio, F r, qc v pa p a v Fr (%) q c n f 100 Th xponnt n i th xponnt that rlat q c to σ' v or p' in powr law rlationhip. Thu, n = 0.85 for Sydny and whil aturatd and unaturatd, and n = 0.65 for Lyll ilty and whil unaturatd. f dnot th lv friction. Th chart i plottd a Figur 3, and it can b n that th location of th Q tn, F r coordinat nabl claification of oil or tailing typ and whthr it i contractiv or dilativ. v (6) (7) Figur 3 Con pntration tt data for Sydny and with th ffct of uction corrctly incorporatd in th circular ymbol (olid ymbol rprnting aturatd or dry tt and hollow ymbol rprnting th unaturatd tt). Alo hown i data whn th ffct of uction ar ignord in th unaturatd tt uing th cro ymbol Figur 3 alo how th Sydny and data with th ffct of uction corrctly incorporatd in to σ' v, with olid circular ymbol rprnting aturatd or dry tt and hollow circular ymbol th unaturatd tt. Alo hown i th Sydny and data whn th ffct of uction ar ignord, that i whn σ' v i takn to b qual to σ v for th unaturatd tt, with cro ymbol rprnting th unaturatd tt. It can b n that th circular ymbol, hollow and olid, ar locatd in rgion 6 blonging to clan and. Corrct intrprtation of th CPT rult, uing th ffctiv tr concpt, rult in th corrct oil claification. Th cro, rprnting data whn uction i ignord, plot a littl highr than th hollow circular ymbol, indicating th oil i mor dilativ than it actually i, although not to th xtnt that an incorrct oil claification would rult. Car hould b takn and account givn to χ in th ffctiv tr bfor chart lik thi ar ud, vn for clan and. 488 Pat 2018, Prth, Autralia

7 Nw dvlopmnt Figur 4 how data for a quartz marin and, including up to 8% fin, takn from a rclaimd land it in Hong Kong (L t al. 1999). It wa not poibl to incorporat th ffct of uction corrctly into σ' v. Calibration chambr tt on that oil (whil aturatd) nabld th xponnt n = 0.8 to b dtrmind. Solid circular ymbol rprnt aturatd tt data and cro ymbol rprnt th unaturatd tt data (whr σ' v i takn to b qual to σ v). It can b n that th olid circular ymbol ar locatd acro rgion 4 and 5, blonging to ilt and and mixtur, and all but on data point indicat that th oil i lightly dilativ. Th cro ymbol ar locatd in rgion 6, incorrctly implying that th oil i a clan and and vry dilativ. Th dratic hift of th unaturatd data for thi oil mot probably com from th pronouncd affct uction ha on th ffctiv tr, ariing from th ignificant fin contnt, and alo from th and bhaving mor lik a partially draind/undraind matrial whn aturatd a pntration occur, compard to it bhaving mor lik a draind matrial whn unaturatd a pntration occur. Figur 4 Con pntration tt data for marin and with up to 8% fin. Solid circular ymbol rprnt aturatd tt data and th cro ymbol rprnt th unaturatd tt data. Th ffct of uction wr not incorporatd Alo, alt bing prnt in th por watr may or may not hav an influnc on th CPT rult. Th alt induc an omotic uction which, if th fin of th marin and contain crtain clay minral, may altr th mchanical bhaviour of th oil around th pntrating con compard to whn alt i abnt. It i poibl that, if crtain clay minral ar prnt, th oil, whn aturatd with alty watr, may xhibit a largr trngth and tiffn, and thu produc a largr q c, compard to what thy would b if th oil wa aturatd with frh watr. A th clay contnt i unknown, thi add furthr uncrtainty to th accuracy of th claification implid by th chart. It i mor difficult to pculat what might happn whn th oil bcom unaturatd with alty watr in th por pac. Both omotic and matric uction would xit, yt thr i no mchanically bad undrtanding of how th two uction typ combin to ffct oil trngth and tiffn (Blight 2013), lt alon CPT rult. Figur 5 how data for a gold tailing. For thi matrial, CPT probing wa undrtakn in th am location in a tailing facility at rgular intrval, acro which th phratic urfac (infrrd through diipation tt) wa n to vary. Again, it wa not poibl to incorporat th ffct of uction corrctly into σ' v. Solid circular ymbol rprnt aturatd tt data, and cro ymbol th unaturatd tt data (whr σ' v i takn to b qual to σ v). It can b n that th olid circular ymbol ar locatd acro rgion 3 and 4, blonging to clay and ilt mixtur, and all data point indicat that th tailing i highly contractiv and ucptibl to liqufaction. Th cro ymbol locat in rgion 4, incorrctly implying that th tailing i a Pat 2018, Prth, Autralia 489

8 Pitfall in intrprtation of con pntration tt data rcovrd from unaturatd gomatrial AR Rull and D Rid ilt mixtur that i lightly contractiv or lightly dilativ. Again, uction cau a dratic hift of th unaturatd data for thi tailing, and can giv an unaf and fal indication of th tailing ucptibility to contractiv bhaviour and liqufaction if not accountd for. Figur 5 Con pntration tt data for a gold tailing. Solid circular ymbol rprnt aturatd tt data and th cro ymbol rprnt th unaturatd tt data. Th ffct of uction wr not incorporatd Th commnt givn abov for th marin and rgarding th prnc of alt in th por watr apply to th tailing a thy ar hypralin. It i ritratd that CPT rult may dpnd on th prnc of crtain clay minral and alt concntration, yt th influnc of alt on CPT rult hav nvr bn th ubjct of targtd rarch a far a th author ar awar. 5 Suction influnc on timation of cyclic ritanc ratio Th CPT data for th marin and and th gold tailing i now intrprtd furthr to timat th CRR, uing th procdur of Robrton and Wrid (1998), to highlight th problm which may b ncountrd if uction i ignord. For th marin and, whn aturatd, th bhaviour typ indic (I c) rangd from 2.38 to Aftr making variou corrction to dtrmin quivalnt Q tn valu for clan and, th timatd valu of CRR (for M = 7.5 arthquak) rangd from 0.08 to 0.28, although motly rangd from 0.10 to For th unaturatd condition, and whn σ' v i incorrctly takn to b qual to σ v, th I c rangd from 1.57 to 1.85, and th timatd CRR wr all vry much largr than th thrhold whr liqufaction i no longr of concrn. For th gold tailing, whn aturatd, th I c rangd from 2.79 to Aftr making variou corrction to dtrmin quivalnt Q tn valu for clan and, th timatd valu of CRR rangd from to Whn in th unaturatd condition, and whn σ' v i incorrctly takn to b qual to σ v, th I c rangd from 2.53 to 2.86 and th timatd CRR rangd from 0.10 to Th two xampl how that ignoring uction in th intrprtation, that i whn σ' v i incorrctly takn to b qual to σ v, th timatd CRR bcom highr than what thy would b if th gomatrial bcam aturatd at a latr dat, for xampl by a ri in th phratic urfac. Rlying on incorrctly dtrmind and lvatd CRR valu, uing CPT rult conductd in an unaturatd gomatrial, could lad to unaf dign. 490 Pat 2018, Prth, Autralia

9 Nw dvlopmnt 6 Concluion Con pntration tt conductd in aturatd and unaturatd Sydny and and unaturatd Lyll ilty and highlight th ffct of uction on con pntration ritanc. In gnral, th ffct of uction wr mot pronouncd for th lowt rlativ dniti conidrd. Alo, th ffct of uction bcam mor ignificant a th applid nt confining tr dcrad, and thu th ffct of uction in fild tting ar mot important for hallow pntration (up to 5 m) whr a oil i mot likly to b unaturatd. Th unaturatd Sydny and around a pntrating con bhav jut lik th aturatd Sydny and. Th am mpirical powr law rlationhip linking D r, q c, and p' hold for aturatd and unaturatd condition, bcau unaturatd Sydny and do not xhibit uction hardning. Convrly, th unaturatd ilty and around a pntrating con bhav mor lik a aturatd draind oil than a aturatd undraind oil a th air in th por pac prmit volumtric comprion. Howvr, a Lyll ilty and xhibit uction hardning, thr i not a 1:1 corrlation btwn aturatd draind bhaviour and unaturatd draind bhaviour. Thi i a highly ignificant fatur to not and i th main raon why CPT chart and rlationhip dvlopd for aturatd ilty and (or any oil with ay mor than 5% fin) hav no applicability to unaturatd ilty and. Thi i alo vidnt whn CPT data from a rang of gomatrial (a marin and and a tailing) for both aturatd and unaturatd condition ar plottd in claification chart. For unaturatd gomatrial that hav a ignificant amount of fin (ay mor than 5%), th uction-inducd incra in con ritanc, and th chang of th oil bhaviour from partially draind/undraind to mor lik draind, cau incorrct claification and an incorrct amnt that th gomatrial i dilativ. Alo, ignoring uction lad to lvatd timation of CRR bing highr than what thy would b if th gomatrial bcam aturatd at a latr dat, for xampl by a ri in th phratic urfac. Failing to account for uction, and incorrctly auming σ' v i qual to σ v whn unaturatd, could lad to unaf dign in om ituation. Acknowldgmnt Thank go to UNSW Sydny for funding through th Indutry Rarch Fllowhip chm for David Rid to viit Adrian Rull, and to th Autralian Rarch Council for funding through th Dicovry Projct chm (DP ). Thank alo go to th Autralian Gomchanic Socity for granting prmiion to ru prviouly publihd matrial (Rull & Rid 2016). Rfrnc Baldi, G, Bllotti, R, Ghionna, V, Jamiolkowki, M & Paqualini, E 1982, Dign paramtr for and from CPT, Procding of th Scond Euro Sympoium on Pntration Tt, vol. 2, A.A. Balkma, Rottrdam, pp Bihop, AW 1959, Th principl of ffctiv tr, Tknik Ukblad, vol. 106, pp Blight, GE 2013, Unaturatd Soil Mchanic in Gotchnical Practic, CRC Pr, Boca Raton. Collin, R & Millr, GA 2014, Con pntration tting in unaturatd oil at two Intrumntd tt it, Procding of th 6th Intrnational Confrnc on Unaturatd Soil, vol. 2, A.A. Balkma, Li, pp Jamiolkowki, M, Lo Prti, DCF & Manaro, M 2003, Evaluation of rlativ dnity and har trngth of and from CPT and DMT, Soil Bhavior and Soft Ground Contruction, ASCE Gotchnical Spcial Publication 119, pp L, KM, Shn, CK, Lung, DHK & Mitchll, JK 1999, Effct of placmnt mthod on gotchnical bhaviour of hydraulic fill and, Journal of Gotchnical and Gonvironmntal Enginring, vol. 125, no. 10, pp Lhan, B, Imail, MA & Fahy, M 2004, Saonal dpndnc of in itu tt paramtr in and abov th watr tabl, Géotchniqu, vol. 54, no. 3, pp Oln, RS & Farr, V 1986, Sit charactrization uing th con pntration tt, in SP Clmnc (d.), Procding of In-Situ 86, Amrican Socity of Civil Enginr, Rton, pp Pournaghiazar, M, Rull, AR & Khalili, N 2011, Dvlopmnt of a nw calibration chambr for conducting con pntration tt in unaturatd oil, Canadian Gotchnical Journal, vol. 48, no. 2, pp Pat 2018, Prth, Autralia 491

10 Pitfall in intrprtation of con pntration tt data rcovrd from unaturatd gomatrial AR Rull and D Rid Pournaghiazar, M, Rull, AR & Khalili, N 2013, Th con pntration tt in unaturatd and, Géotchniqu, vol. 63, no. 14, pp Robrton, PK 2010, Evaluation of flow liqufaction and liqufid trngth uing th con pntration tt, Journal of Gotchnical and Gonvironmntal Enginring, vol. 136, no. 6, pp Robrton, PK & Campanlla, RG 1983a, Intrprtation of con pntration tt. Part I: and, Canadian Gotchnical Journal, vol. 20, no. 4, pp Robrton, PK & Campanlla, RG 1983b, Intrprtation of con pntration tt. Part II: clay, Canadian Gotchnical Journal, vol. 20, no. 4, pp Robrton, PK & Wrid, CE 1998, Evaluating cyclic liqufaction potntial uing th con pntration tt, Canadian Gotchnical Journal, vol. 35, pp Rull, AR & Khalili, N 2006a, A unifid bounding urfac platicity modl for unaturatd oil, Intrnational Journal for Numrical and Analytical Mthod in Gomchanic, vol. 30, no. 3, pp Rull, AR & Khalili, N 2006b, On th problm of cavity xpanion in unaturatd oil, Computational Mchanic, vol. 37, no. 4, pp Rull, AR & Rid, D 2016, Effct of uction on CPT rult and oil claification, Procding of th 5th Intrnational Confrnc on Gotchnical and Gophyical Sit Charactriation, vol. 2, Autralian Gomchanic Socity, Prth, pp Schmrtmann, JH 1978, Guidlin for Con Pntration Tt: Prformanc and Dign, Fdral Highway Adminitration rport FHWA-TS-78209, Unitd Stat Fdral Highway Adminitration, Wahington, DC, 148 p. Yang, H, Khohghalb, A & Rull, AR 2014, Fractal-bad timation of hydraulic conductivity from oil-watr charactritic curv conidring hytri, Géotchniqu Lttr, vol. 4, pp Yang, H & Rull, AR 2015, Cavity xpanion in unaturatd oil xhibiting hydraulic hytri conidring thr drainag condition, Intrnational Journal for Numrical and Analytical Mthod in Gomchanic, vol. 39, pp Yang, H & Rull, AR 2016, Th con pntration tt in an unaturatd ilty and, Canadian Gotchnical Journal, vol. 53, no. 3, pp Pat 2018, Prth, Autralia