Full-scale testing of Ground Anchors in Neogene Clay

P ocedia Enginee ing 172 ( 2017 ) 1129 – 1136 A ailable online a www.sciencedi ec .com 1877-7058 © 2017 The Au ho s. Published by Else ie L d. This is an open access a icle unde he CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/). Pee - e iew unde esponsibili y o he o ganizing commi ee o MBMST 2016 doi: 10.1016/j.p oeng.2017.02.170 ScienceDi ec Mode n Building Ma e ials, S uc u es and Techniques, MBMST 2016 Full-scale Tes ing o G ound Ancho s in Neogene Clay -DQâWHIDĖiNa*/XP U0LþDb-XUDM&KDOPRYVNêc, Augus in Lei e d3DYHO7LFKêe a,b,c,dDepa men o Geo echnics, Facul y o Ci il Enginee ing, B no Uni e si y o Technology, Ve e i 95, 602 00 B no, Czech Republic eSTRIX Chomu o a.s., 28 ijna 1081/19, 430 01 Chomu o , Czech Republic Abs ac The esea ch campaign aimed on he be e unde s anding o beha io o p es essed soil ancho s in neogene clay, including conduc ion o a ie y o in-si u (CPT, PMT) and labo a o y (T iaxial es , Simple shea es an Oedome ic es ) g ound in es iga ion me hods, has been done du ing 2012 ± 2015 in Czech Republic. The s ess ± s ain diag ams and dis ibu ion o axial o ce along he ancho ee leng h and ancho bond leng h was de e mined, based on he da a ob ained om a ie y ypes o senso s placed on o he endon and in o he g a i y and pos -g ou ed pa o he g ou body. On he basis o his in o ma ion he so wa e applica ion o p edic ion o he ancho pull-ou o ce and s ess-s ain diag am was de eloped, calib a ed and e i ied. The applica ion o pu poses o conduc ion o p es essing es s and es epo s elabo a ion was p og ammed also. Resea ch ac i i ies leading o de elopmen o he pai o o enamed so wa e a e desc ibed in pape .  2016 The Au ho s. Published by Else ie L d. Pee - e iew unde esponsibili y o he o ganizing commi ee o MBMST 2016. Keywo ds:Rock ancho s; Geo echnical measu emen ; Full - scale load es ing; Moni o ing; So wa e de elopmen . 1. In oduc ion G ou ed g ound ancho is a s uc u al componen used o ansmi ension o ce om he s uc u e o he subg ade. G ound ancho s a e ypically used as a suppo s o e aining s uc u es o exca a ions o o slopes s abilisa ion. They a e also used agains he upli o o e u ning o s uc u es. The esea ch p ojec ocused on be e unde s anding and imp o emen o design p ocess o hose membe s was conduc ed by esea ch g oup ga he ing he membe s in ol ed in he ield o ealiza ion (STRIX Chomu o ,a.s.) design (SG-GEOPROJEKT, spol. * Co esponding au ho . Tel.: +420 54114 7232 E-mail add ess:s e anak.j@ ce. u b .cz © 2017 The Au ho s. Published by Else ie L d. This is an open access a icle unde he CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/). Pee - e iew unde esponsibili y o he o ganizing commi ee o MBMST 2016 1130 Jan Š e aňák e al. / P ocedia Enginee ing 172 ( 2017 ) 1129 – 1136 s. .o.) and esea ch (B no Uni e si y o Technology, Facul y o Ci il Enginee ing) in yea s 2012 - 2015. Financial suppo o he esea ch ac i i ies has been ob ained om he Minis y o Indus y and T ade o he Czech Republic. The c ucial pa o he esea ch was conduc ion o he ull-scale load es ing p og am pe o med a he expe imen al si e loca ed in B no, Czech Republic (130 km no h o Vienna). The a ious aspec s o his ex ended load es campaign we e e iewed, e.g. soil in es iga ion, ancho and measu emen sys em ins alla ion me hods [1], [2] [3] [4], eco ding an in e p e a ion o load es s [5] [6], moni o ing [7] a ie y o design me hods [8] [9] and design assump ions [10] [11] e c. Mo eo e a en ion was paid o he expe ience wi h g ound ancho s o se e al Czech special ounda ion con ac o s in sense o building up a da abase o es eco ds conduc ed on si es in las en yea s. The s a is ical analysis based on da a om hose es s has been pe o med [12] [13] [14]. In addi ion, ancho ing echniques like a SBMA [15], which use is ecen ly no common in Czech Republic now, ha e been es ed and he esul s ha e been analyzed. On he basis o a se o load es s, de ailed analysis o geological and geo echnical condi ions and echnological aspec s, an applica ion sys em has been de eloped. The sys em can be applied in he design and assessmen o geo echnical s uc u es and in a comple e se o p ojec p epa a ion, implemen a ion wo k and moni o ing o special geo echnical s uc u es. The applica ion sys em o he design o g ound ancho s is mean o enable ele an , sa e and economical design and geo echnical assessmen o he s uc u al elemen s o buildings, which o en makes up 50% o he p ice o wo k and deli e ies o special geo echnical s uc u es. 2. G ound In es iga ion The esea ch ac i i ies associa ed o ull-scale es ing we e di ided in o he wo phases. The de ailed geo echnical si e in es iga ion was pe o med be o e ins alla ion o he ³Phase I´ Ancho s. The CPT es s ha e been pe o med and e alua ed [16]. The samples o he physical and index p ope ies o he soil labo a o y de e mina ion has been aken om bo eholes. The PMT p essu eme e es s ha e been pe o med in hose bo eholes also. The oedome ic es s, iaxial es s, and simple shea es s ha e been pe o med on he samples o he soil o he pu pose o de e mina ion o he mechanical and de o ma ion p ope ies o he soil. The soil has been classi ied as a Cl ± Clay acco ding o he EN ISO 14 688 [17]. The consis ency o he uppe laye (0.0 m ± 2.0 m) was s i . In he lowe laye s he consis ency has changed in o i m. The hin- ace calcium ca bona e s a a ha e been p esen in he samples. The aim o all hose es s pe o mance was o ob ain inpu alues o i s es ima e o he ul ima e ancho capaci y in he Neogene clay, which soil is he ypical subsoil in B no a ea. 3. Full-scale es ing A e ini ial su ey, i was p oposed by he p ojec eam o se up wo k a ull-scale es ing in he A bo e um belonging o he Mendel Uni e si y in B no, Czech Republic. Se en p essu e g ou ed [18] (6 o hem using Selec i e and Repea able Injec ion IRS me hod, and 1 o hem using Global and Unique Injec ion IGU), s ands ancho s we e ins alled and es ed on he a bo e um si e du ing wo seasons 2013 and 2014. All bo eholes o ancho s ha e been d illed e ically. The o a y d illing wi hou casing has been used o d ill he bo eholes. Diame e o he bo ehole was d = 180 mm. Rela i ely high alue o he bo ehole diame e was chosen due o a oiding he damage o ins alled senso s. The c ane has been used o inse he ancho s in o he d ills due o he same eason. Tes ed ancho s cha ac e is ics a e summa ized in Table 1. Table 1.Tes ed ancho s desc ip ion. ID No. o s ands ij 15,7 / 1860 Type o ancho Ex ension leng h Le [m] Tendon F ee leng h L [m] Tendon bond leng h L b[m] To al leng h [m] Phase I (2013) I-A1 6 S anda d 2,0 5,0 6,0 13,0 I-A2 6 S anda d 2,0 5,0 6,0 13,0 I-B 5 S anda d 2,0 5,0 8,0 15,0 1131 Jan Š e aňák e al. / P ocedia Enginee ing 172 ( 2017 ) 1129 – 1136 Phase II (2014) II-B 5 S anda d 2,0 5,0 8,0 15,0 II-C1 7 S anda d 2,0 5,0 10,0 17,0 II-C2 7 S anda d 2,0 5,0 10,0 17,0 III SBMA 2,0 2 x 3,0 The esea ch ac i i ies associa ed o ull-scale es ing we e di ided in o he wo phases, as s a ed abo e. The i s eason o phasing wo k was o e alua e he design assump ions and es ima es and ake he conclusions in o accoun in he nex phase. The second eason was he e alua ion o unc ionali y o selec ed ypes o senso s. The sho desc ip ion o senso s used is in nex pa ag aph. 3.1. Measu emen sys em One o he adjacen goals o he esea ch was o es he easibili y o ins alla ion o a ie y o senso ypes o pu pose o measu emen o desi ed magni udes. Simple desc ip ion o selec ed senso s ha we e used is in Table 2. Table 2.Tes ed senso s desc ip ion. Measu ed magni ude Used ype o senso P inciple o measu emen Posi ion o he senso Displacemen LVDT Linea a iable di e en ial ans o me Ancho head Po en iome ic o a y senso Po en iome e Ancho head S ain Foil esis ance s ain gauge Change in elec ical esis ance Tendon, g ou Vib a ing wi e s ain ansduce Change in he equency o oscilla ion o he s ing Tendon, g ou Fo ce Load cell Resis ance s ain gauge Ancho head S ess Magne o-elas ic o que senso Change in he magne ic ield a ound he endon Tendon Basic moni o ing consis ed o measu emen o displacemen o he endon and o p es essing o ce. The load cell SISGEO 0L219V18000 has been used o he o ce measu ing, and pai o LVDT ansduce o he displacemen measu ing. Ad anced moni o ing echniques ha e been used o pu pose o he quasi-con inual measu ing o he o ce in he whole leng h o he endon. The Foil esis ance s ain gauges HOTTINGER 1-LY-3 /350 ha e been as en o he s ands in he ancho bond leng h L b. The Magne o-elas ic o que senso s INSET ha e been ins alled in he ancho ee leng h L and also in he ancho bond leng h L b [19]. The ib a ing wi e S ain gauges SISGEO 0VK4200VC00, GEOKON 4200 / 42002 and oil esis ance s ain gauges HOTTINGER 1-LY-3 /350 ha e been placed in he p essu e and g a i y g ou ed pa s o he g ou body o he pu pose o measu emen o he s ain in he g ou . Figu e 1 shows he ins alled oil esis ance s ain gauge wi h wa e p o ec ion and he ib a ing ansduce ixed o he endon. a b 1132 Jan Š e aňák e al. / P ocedia Enginee ing 172 ( 2017 ) 1129 – 1136 Fig. 1. (a) he oil s ain esis ance gauge s uck on he endon; (b) he Vib a ing wi e s ain ansduce ixed o he endon. 3.2. In es iga ion es s All ancho s ha e been es ed acco ding o he p EN ISO 22477-5 [20]. The in es iga ion es using cyclic load es p ocedu e TM1 has been conduc ed (a e eaching he maxim le el o he p es essing o ce in e e y cycle, he o ce was kep cons an , and he displacemen o he endon was measu ed and egis e ed in speci ied imes). The load bea ing s eel ame was designed and ab ica ed o dis ibu ing he eac ion om s essing o ce in o he pai o s eel pads. The s i ene s we e added o he ame p o iles o inc ease la e al buckling esis ance [21]. The b idge has been placed o e he es ed ancho , on wha he LVDT ansduce s has been as ened. So he displacemen measu emen has no been a ec ed by he de o ma ion o he bea ing ame. Figu e 2 shows se ing up he hyd aulic jack and measu emen de ices p io he s a o in es iga ion es . a b Fig. 2. (a) he in es iga ion es se ing up; (b) b idge o he independen measu emen o he endon displacemen . 1133 Jan Š e aňák e al. / P ocedia Enginee ing 172 ( 2017 ) 1129 – 1136 3.3. Da a om moni o ing The simila p ocess o beha io unde loading and ailu e mode o es ed ancho s was obse ed on all es ed membe s. A e eaching he ul ima e esis ance (maximum alue o p es essing o ce), he sudden dec ease o p es essing o ce occu ed. I was accompanied by he eye isible displacemen o g ou body ou o he g ound. A e he ancho was ully unloaded, he p es essing o ce was inc eased again. The le el o 50 % - 55 % o p e ious maximum alue o p es essing o ce was achie ed by his ope a ion. The p o usion o g ou body ou o he g ound was obse ed again, when his le el o o ce was ied o be kep by he hyd aulic jack pis on li . The eco d o measu ed p es essing o ce and endon displacemen om es conduc ed on ancho II-B, whe e he abo e desc ibed phenomena a e eco ded, is shown in ig. 3. Fig. 3. The loading p ocedu e es eco d o ancho II-B. 4. Resul s All expe iences, ha he au ho s acqui ed om wo k and i s esul s desc ibed in p e ious chap e s has been capi alized in las phase o he p ojec , which consis ed o c ea ion o he e icien and p ac ically usable applica ion sys em, as s a ed in In oduc ion. I was achie ed by w i ing he wo so wa e applica ions, which simple desc ip ion is in nex pa ag aphs. 4.1. So wa e applica ion o g ound ancho s design based on load- ans e unc ions De e mina ion o he g ound ancho s ul ima e ca ying capaci y is mos ly conduc ed using a ious empi ical and semi-empi ical me hods [22] [10] [11] e c. These p ocedu es a e usually success ul bu highly simpli ied. Wide ange o empi ical ac o s is equi ed, which knowledge is limi ed only o ce ain ypes o soil. One o he majo simpli ica ion o hese me hods is an assump ion ha he bond s ess on he soil ± g ou in e ace is mobilized uni o mly along he whole ixed leng h. The esul o hese me hods is mos ly only ul ima e ca ying capaci y wi h no addi ional in o ma ion abou he displacemen equi ed o mobilize his ul ima e o ce. An inno a i e app oach 1134 Jan Š e aňák e al. / P ocedia Enginee ing 172 ( 2017 ) 1129 – 1136 inco po a ing load ans e unc ions [23] is he e o e p oposed. A load ans e unc ion ( -z cu e) is he dependence o shea s ess mobilized on he su ace o a membe on he e ical displacemen o a co esponding membe . The load ans e unc ion is equen ly adop ed o de e mina ion o he load ± se lemen cu e o e ically loaded piles [24]. Howe e i s use o g ound ancho s is a e. The impo an ea u e o he p oposed app oach is he possibili y o de e mine -z cu es as a combina ion o s anda d labo a o y es s esul s (e. g. di ec shea es ) and ce ain assump ion o shea s ess mobiliza ion in adial di ec ion [25]. The p og am applica ion inco po a ing his assump ion was c ea ed. The newly de eloped algo i hm also includes se e al o he ea u es: e. g. axial s i ness change due o he occu ence o ensile c acks in he g ou ma e ial, adial s ess inc ease due o he pos -g ou ing (cylind ical ca i y expansion heo y [26] is he e o e adop ed) ollowed by i s dec ease caused by he g ou consolida ion [27] [28] [29] e c. Back analysis o h ee g ound ancho s using his applica ion was desc ibed in [30]. Use o he newly de eloped applica ion is demons a ed on ig. 4 whe e he measu ed and p edic ed load- displacemen cu es o he II-B ancho a e compa ed. Fig. 4. Measu ed and p edic ed dependence be ween he p es essing o ce and ancho head displacemen o ancho II-B. 4.2. So wa e applica ion o g ound ancho s es ing Each g ound ancho has o be es ed in a way o p es essing. The aim o he es is o p o e accomplishmen o accep ance c i e ia, which has been de ined o demons a e he capaci y and se iceabili y o es ed ancho . The ecommenda ions o es ing o ancho s in Eu ope a e changing ecen ly. The new ecommenda ions [20] demand new s yle o es eco ds. The inding was done, based on he e alua ion o eco ds om pas yea s elabo a ed by local con ac o s, ha none o hem sa is ies hose new code demands. This si ua ion, which he con ac o s ela i ely easily could deal wi h, was judged, wi h some eason, di icul and incon enien o hem by he esea ch eam. The so wa e u ili y has been de eloped o pu pose o keeping he es eco ds sui able o hose demands. The u ili y acili a es and au oma es also he p ocess o de i ing he accep ance c i e ia alues [31]. The bonus o eco ds wo ked up using p oposed applica ion o u u e esea ch is he ac , ha eco ds a e s o ed in digi al iles. Those iles can be ela i ely easily p ocessed in sense o ex end he da abase o es eco ds o u u e analyses. The in e ac i e empla e o eco d consis s o hose componen s: x The ex ields o eco ding he key in o ma ion iden i ying he conc e e es (e. g. he si e e e ence, loca ion e e ence, da e o he es execu ion e c.). Fo he pu pose o ma k he ancho in e ms o wo king ime (sho - e m, long- e m) he d op down menu is a ailable. The alues yped in cells, whe e use speci ies geome ical 1135 Jan Š e aňák e al. / P ocedia Enginee ing 172 ( 2017 ) 1129 – 1136 and mechanical p ope ies o he ancho endon and ancho bond, se es as inpu alues o de e mina ion o he appa en ee leng h o he ancho Lapp, as same as he alues o p es essing o ce le els PP and Pa . x The nex pa o he eco d has he o m o a able, in o which he measu ed de o ma ion o he ancho endon is w i en. Those alues a e used as inpu s o he g aphs plo ing. In he las ow o his able he c eep coe icien Į1 is calcula ed based on he las ou eco ded alues o de o ma ion. The leas squa e me hod is used o de e mina ion o his coe icien , whe e R2 indica es, how well he measu ed da a i he s a is ical model wi h linea end. x The g aphs, ha a e au oma ically d awn, se e o pu pose o documen a ion he load es p ocess and o de i ing he desi ed accep ance c i e ia and esul s o es : 1) Reco d o loading p ocedu e in ime; 2) Ancho head disSODFHPHQW YV ORJDULWKP RI WLPH  $QFKRU KHDG GLVSODFHPHQW YV ORDG  9DULDWLRQ RI Į wi h he applied main ained load ( he g aph se es o de e mina ion o pull-ou esis ance in case o in es iga ion es ). x A he end o he empla e use can see alues de e mined om inpu da a and d op down menu o es esul inpu (OK/no OK). 5. Conclusions A e de ailed g ound in es iga ion, se en ull-scale in es iga ion es s on p es essed g ound ancho s in neogene clay we e conduc ed. The applicabili y o a ie y o senso s o measu emen o desi ed magni udes (Displacemen , Fo ce, S ess and S ain) on di e en c oss sec ions o ancho was es ed. All ins alled senso s we e e alua ed o be sa is ac o y o pu pose o moni o ing he beha io o ancho du ing p es essing. The esul s o basic and ad anced moni o ing ga e he de ailed desc ip ion o s ess-s ain beha io o es ed elemen s. I p o ed he s ong dec easing o he p es essing o ce, a e eaching he c i ical mobilized skin ic ion. The s abile esidual alue o p es essing o ce was in ange o 50 % - 55 % o i s peak alue. The conside able di e ence be ween he ul ima e and esidual o ce p o ed he p og essi e debonding (dec easing o he shea s ess along he bond o he ancho ). Dis ibu ion o axial o ce in he endon and in he g ou along he ancho leng h was also ecei ed om measu emen . The new p og am applica ion was c ea ed, which was calib a ed and e alua ed on basis o da a om measu emen desc ibed abo e. The main ad an age o his applica ion is i s abili y o p edic he s ess-s ain diag am o he ancho and dis ibu ion o axial o ce and o shea s ess along he ancho ixed leng h, ins ead o jus gi e he es ima e o he pull-ou esis ance. The inding was done, ha none o exis ing es eco ds empla es used by local con ac o s sa is ies new code equi emen s on hose eco ds. Thus he second applica ion was p og ammed, which acili a es and au oma es he conduc ion o ancho es ing and elabo a ion o he es eco ds. Acknowledgemen s This esea ch was inancially suppo ed by he esea ch p ojec o Minis y o Indus y and T ade o he Czech Republic No. FR-TI4/329. Re e ences [1] A. Ene e al., Tes ing o g ound ancho ages o a deep exca a ion e aining sys em in Bucha es , in: XV Danube - Eu opean Con e ence on Geo echnical Enginee ing (DECGE 2014): Pape No. 176. Vienna, Aus ia, 2014. [2] M. Bus aman e e al., Beha iou o p es essed ancho s in plas ic clay, 5HYXHIUDQFDLVHGHJpRWHFKQLTXH. b. ., 3 (1978) 79±87. [3] D.A. Jones, I.M. Spence , Clay ancho s ± A Ca ibbean case his o y, G ound Enginee ing 17(1) 1978. [4] J. &KDOPRYVNê, L. 0LþD, In luence o P essu e G ou ing on he Ancho s Ca ying Capaci y in Fine G ained Soil, in: 11 h In e na ional Con e ence on Mode n Building Ma e ials, S uc u es and Techniques, MBMST 2013. Vilnius, Li huania: P ocedia Enginee ing, 2013, pp. 222±231. [5] P. Xan hakos Pe os, G ound ancho s and ancho ed s uc u es, New Yo k: Wiley, 1991. 1136 Jan Š e aňák e al. / P ocedia Enginee ing 172 ( 2017 ) 1129 – 1136 [6] Pos Tensioning Ins i ue (PTI). Recommenda ions o p es essed ock and soil ancho s, 4 h ed. Phoenix, AZ: PTI, 2004. [7] C. Jacqua d Fondasol, )RXQGDWLRQVE SUHVWUHVVLQJDQFKRUVRIWKH9LOOD0pGLWHUUDQpHLQ0DUVHLOOHIURPGHVLJQWRPRQLWRULQJ, in: Soil- S uc u e In e ac ion, Unde g ound S uc u es and Re aining Walls: P oceedings o he ISSMGE Technical Commi ee 207 In e na ional Con e ence on Geo echnical Enginee ing, S Pe e sbu g, Russia, 2014, pp. 127±131. [8] N.K. 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