Concrete arches and reinforced soil: a sustainable alternative structure for road bridges

Conc e e a ches and ein o ced soil: a sus ainable al e na i e s uc u e o oad b idges A ches en bé on e sol en o cé: une s uc u e al e na i e du able aux pon s ou ie s K. Malekmohammadi*, A. Moncada Depa men o Ci il and En i onmen al Enginee ing, Uni e si a Poli ècnica de Ca alunya·Ba celonaTech (UPC) / In e na ional Cen e o Nume ical Me hods in Enginee ing (CIMNE), Ba celona, Spain I.P. Damians In e na ional Cen e o Nume ical Me hods in Enginee ing (CIMNE), Uni e si a Poli ècnica de Ca alunya·Ba celonaTech (UPC) / VSL In e na ional, Ba celona, Spain *khashaya [email protected] ABSTRACT: Road b idges a e necessa y in as uc u es o anspo a ion. As such, hey a e subjec o ho ough sc u iny o hei en i onmen al, social, and economic impac s. An adequa e subs an iali y assessmen applied o b idge design mus minimize he nega i e impac s o he s uc u e on he su ounding en i onmen . A conc e e deck and piles, oge he wi h can ile e abu men s, is a well-es ablished and con en ional b idge design op ion. An al e na i e solu ion is p ecas conc e e a ches, widely used in b idge and unnel cons uc ions, p o iding s able, long-las ing suppo e en unde hea y load condi ions. Conc e e a ches can be cons uc ed oge he wi h ein o ced soil walls (RSW) solu ions, o bo h embankmen and abu men zones, which a e conside ed cos -e ec i e solu ions wi h sho cons uc ion pe iods, making hem an a ac i e op ion o such s uc u al and geo echnical enginee ing p ojec s. The compound conc e e a ch and RSW s uc u e esul s in a esilien , e icien , and cos -e ec i e design. This s udy p esen s a simple app oach o an en i onmen al and economic assessmen o wo b idge designs: a classical solu ion wi h can ile e abu men s and a conc e e deck slab, and conc e e a ches wi h RSW on op. Based on he en i onmen al impac , and associa ed cos s, he p ecas a ch b idges wi h RSW solu ion a e judged o be he be e al e na i e. RÉSUMÉ: Les pon s ou ie s son une in as uc u e nécessai e au anspo . À ce i e, ils on l’obje d’un examen minu ieux quan à leu s impac s en i onnemen aux, sociaux e économiques. Une é alua ion adéqua e du ca ac è e subs an iel appliquée à la concep ion du pon doi minimise les impac s néga i s de la s uc u e su l’en i onnemen en i onnan . Un ablie e des pieux en bé on, ainsi que des culées en po e-à- aux, cons i uen une concep ion de pon bien é ablie. Une solu ion al e na i e consis e en des a ches en bé on p é ab iqué, la gemen u ilisées dans la cons uc ion de pon s e de unnels, o an un suppo s able e du able, même dans des condi ions de cha ge lou de. Les a ches en bé on peu en ê e cons ui es a ec des solu ions de mu s en sol en o cé (RSW), an pou les zones de emblai que de culées, qui son considé ées comme des solu ions en ables a ec des pé iodes de cons uc ion cou es, ce qui en ai une op ion a ayan e pou de els p oje s d'ingénie ie s uc u elle e géo echnique. L'a che en bé on composée e la s uc u e RSW donnen lieu à une concep ion ésilien e, e icace e en able. Ce e é ude p ésen e une app oche simple pou une é alua ion en i onnemen ale e économique de deux modèles de pon : une solu ion classique a ec des culées en po e-à- aux e une dalle de ablie en bé on, e des a ches en bé on a ec un RSW. Su la base de l'impac en i onnemen al e des coû s associés, les pon s en a c p é ab iqués a ec la solu ion RSW son considé és comme la meilleu e al e na i e. Keywo ds: Geosyn he ic ein o cemen ; p ecas a ch b idges; ein o ced soil walls; sus ainabili y assessmen . 1 INTRODUCTION Ci il enginee ing wo ks encompass a wide ange o s uc u es, including, bu no limi ed o, buildings, pa emen s, b idges, ounda ions, and ein o ced soil s uc u es. The inclusion o sus ainabili y c i e ia in he decision-making p ocess o ci il enginee ing design, including geo echnical enginee ing p ojec s, is becoming p e alen (Aguado e al., 2012; MacAskill and Gu h ie, 2013, Basu e al., 2014). Sus ainabili y encompasses he ul illmen o h ee dis inc se s o c i e ia ega ding en i onmen al, economic, and socie al/ unc ional aspec s (A no G oup, 2012; ISO, 2006). B idges made o conc e e a ches wi h ein o ced soil walls (RSW) a e used o pedes ians, oad, and ail a ics. The complexi y o conc e e a ch P oceedings o he XVIII ECSMGE 2024 GEOTECHNICAL ENGINEERING CHALLENGES TO MEET CURRENT AND EMERGING NEEDS OF SOCIETY © 2024 he Au ho s ISBN 978-1-032-54816-6 DOI 10.1201/9781003431749- Open Access: www. aylo ancis.com, CC BY-NC-ND 4.0 license 102 647 P oceedings o he XVIII ECSMGE 2024 A – New de elopmen s on s uc u al design and ein o ced soil b idge sys ems esides in he p ope assessmen o soil-s uc u e in e ac ion, he impac o la e al soil p essu e, and he bounda y condi ion a he base o he b idge suppo s. This s udy p esen s a simpli ied and educed app oach and esul s o e alua e and compa e he en i onmen al and economic aspec s o a sus ainabili y assessmen o wo b idge designs composed o (i) can ile e abu men s and conc e e deck slab, and (ii) p ecas conc e e a ches and back- o-back ein o ced soil wall embankmen /abu men . The assessmen o en i onmen al ac o s is conduc ed u ilizing a educed Li e Cycle Assessmen (LCA) me hodology (e.g., Damians e al., 2016). Ideally, a LCA should comp ehensi ely e alua e all po en ial en i onmen al implica ions associa ed wi h he cons uc ion p ocess and ma e ials employed in p ojec ac i i ies. 2 CASE STUDY AND METHODOLOGY Figu e 1 shows a schema ic ep esen a ion o he wo ypes o oad b idges included in his s udy. Dimensions we e de e mined h ough con en ional design me hods. To p ope ly e alua e he en i onmen al impac ac oss bo h al e na i e solu ions, a Func ional Uni (FU) mus be de ined. In his pa icula scena io, he compa a i e FU is de ined as a b idge wi h a wid h o 12 me e s and a span o 10 me e s, designed o accommoda e a wo-lane ci ilian oadway wi h a dis ibu ed a ic su cha ge load o 10 kPa, o e a design li e o 100 yea s. In his s udy, i is assumed ha bo h al e na i es a e ins alled on a compe en /s i ounda ion and does no ake in o accoun he en i onmen al and economic implica ions o si e p epa a ion and inal g ading (i.e., ounda ion p epa a ion), as hese impac s a e expec ed o be compa able be ween he wo ypes o s uc u es. In he same way, he scope o his s udy is es ic ed o he b idge span S (see Figu e 1). The analysis o he Can ile e +deck b idge does no ake in o accoun he ma e ial/ illing loca ed behind he can ile e abu men s. Likewise, he A ch+RSW solu ion does no conside he RSW beyond he leng h S (see he limi o he s udy de ailed zone in Figu e 1). Fo he A ch+RSW b idge design, he back- o-back ein o ced soil s uc u e uses polyme ic s ap ein o cemen and p ecas ein o ced conc e e panels. The li e-cycle s ages encompass he en i e p ocess om he ex ac ion o aw ma e ials om he na u al en i onmen . In e media e s ages include ma e ial p ocessing o c ea e he necessa y componen s, anspo a ion o ma e ials/componen s, ins alla ion wo k, e c. B idge deck slab S = 10 m H = 10 m 6 m 9.2 m 1.2 m Limi o he s udy 0.8 m Can ile e 1 m (a) Geome y o Can ile e +deck. (b) Geome y o A ch+RSW. Figu e 1. Schema ic geome y o (a) Can ile e +deck and (b) A ch+RSW. H = 10 m 6.6 m 0.25 m Rein o ced soil S = 10 m Panels (RSW acing) Limi o he s udy 0.6 m 0.6 m Table 1 shows he en i onmen al in en o y pe aining o he ma e ials and cons uc ion- ela ed ac i i ies included in he p esen in es iga ion. The deck b idge and can ile e abu men al e na i e equi es conside ably mo e conc e e and ein o cing s eel (i.e., eba ) compa ed o he a ch b idge segmen s and back- o-back RSW solu ion. The main s uc u al componen o he con en ional b idge is he ein o ced conc e e, while ha o he a ch b idge is he ein o ced soil (i.e., back ill and polyme ic s ap ein o cemen s). Back ill ma e ial is assumed o be b ough om a dis ance o 10 km. The can ile e +deck b idge includes on-si e conc e e pou ing. The expec ed dis ance o he anspo a ion o p ecas conc e e panels and p ecas conc e e a ches om he manu ac u ing si e was 10 km. In addi ion, he anspo a ion dis ances o conc e e mix ucks, s eel eba , and polyme ic ein o cemen s aps we e assumed o be 10 km because o conside a ion o he same dis ance/condi ion o anspo a ion o all solu ions. Li e cycle assessmen s (LCA) we e ca ied ou using SimaP o 9.4.0.2 so wa e (PRé Consul an s B.V., 2010). Inpu alues o ma e ial and ene gy usage we e ob ained using he Ecoin en 3.8 da abase (Ecoin en Cen e, 2014) and ReCiPe 2016 me hod 1.1 (Huijb eg s e al., 2017), all a ailable wi hin SimaP o. The economic analysis was conduc ed o 648 P oceedings o he XVIII ECSMGE 2024 Conc e e a ches and ein o ced soil: a sus ainable al e na i e s uc u e o oad b idges bo h solu ions using he ITeC BEDEC cos da abase. The en i onmen al impac is assessed using only wo midpoin indica o s: he Global Wa ming Po en ial (GWP), which measu es he impac o ca bon dioxide equi alen (amoun o CO2 eq.) emissions on he a mosphe e, and he Cumula i e Ene gy Demand (CED), employed o he assessmen o ene gy consump ion (in Joules). Bo h en i onmen al indica o s a e analyzed ac oss he whole li e cycle o he main in ol ed ma e ials, p oduc s, p ocesses, and/o cons uc ion- ela ed ac i i ies in bo h p oposed b idge cons uc ion al e na i es. 3 ENVIRONMENTAL AND ECONOMIC ASSESSMENT Figu e 2 shows he o al GWP (2a) emissions and CED (2b) o bo h al e na i es. As an icipa ed, he adi ional solu ion (Can ile e +deck) esul s in he highes emissions o CO2 eq. and ene gy consump ion. GWP and CED alues o he A ch+RSW s uc u e we e ound o be abou 85% and 82% lowe han hose o he Can ile e +deck design, espec i ely. This is explained by he high ene gy equi emen s in he p oduc ion o s eel and conc e e, which se e as he main s uc u al componen s o he con en ional b idge case. Combined con ibu ions o conc e e and s eel componen s a e he mos signi ican ac o s in he o e all en i onmen al impac o bo h cases, accoun ing o 58% and 37% o o al CO2 eq. and 46.2% and 45% o CED alues, o he con en ional and a ch solu ions, espec i ely. Compa ed o conc e e and s eel, cons uc ion ac i i ies and ma e ial anspo a ion con ibu e a small po ion o o al CO2 eq. and GJ alues. Fu he mo e, acco ding o he ou comes o he economic analysis, A ch+RSW solu ion led o abou 47% educ ion in cons uc ion cos s wi h espec o he con en ional b idge s uc u e (Figu e 3). In his solu ion, he RSW s uc u e con ibu es mos o he cons uc ion cos s, a 56.7%, because mo e componen s need o be used o cons uc ion. Table 1. En i onmen al in en o y including ma e ials, cons uc ion ac i i ies and anspo a ion de ails. Case Ca ego y I ems Uni Value Can ile e +deck S uc u al ma e ial Conc e e m3 501.6 Rein o cing s eel ( eba ) 39.3 Cons uc ion Pou ing conc e e h 16.72 Rein o cing ( eba ) ixing h 263.3 Fo mwo k ins alla ion h 796 T anspo a ion Conc e e, ein o cing s eel, e c. km 10 A ch+RSW S uc u al ma e ial Conc e e ( oo ing) m3 8.4 P ecas a ches m3 55.32 P ecas panels m2 100.2 Polyme ic s ap kg 288 Cons uc ion Rein o ced back ill m3 601.2 Panel ins alla ion h 44.5 Ea h wo k (back illing and compac ing) h 22.5 T anspo a ion Conc e e, p ecas a ches/panels, ein s., e c. km 10 Back ill ma e ial km 10 (a) To al GWP o bo h b idges. (b) To al CED o bo h b idges. Figu e 2. To al (a) GWP, (b) CED o cons uc ion o bo h b idge solu ions. Can ile e +deck A ch+RSW 0 50 100 150 200 250 Type o S uc u e Global wa ming po en ial: CO2 eq S (14.4%) Co (51.4%) Co (60%) Ps (4.1%) So (14.4%) C (15.7%) S C (1%) S (39%) S – S eel eba Co – Conc e e C – Cons uc ion ac i i ies & T anspo a ion So – Soil Ps – Polyme ic s ap Can ile e +deck A ch+RSW 0 400 800 1200 1600 2000 Type o S uc u e Cumula i e ene gy demand: GJ C (22%) C (1%) Co (48%) Co (35%) S (51%) C – Cons uc ion ac i i ies & T anspo a ion Co – Conc e e S – S eel eba So – Soil Ps – Polyme ic s ap S (15%) Ps (9%) So (19%) 649 P oceedings o he XVIII ECSMGE 2024 A – New de elopmen s on s uc u al design Can ile e +deck A ch+RSW 0 40000 80000 120000 160000 200000 Type o S uc u e Cons uc ion cos ing: € Ca (75.6%) A (27.5%) Rs (56.7%) T (15.8%) De (20.3%) T (4.1%) Ca – Can ile e De – Deck A – A ch Rs – RSW T – T anspo a ion Figu e 3. Cons uc ion cos s o bo h b idge solu ions. 4 CONCLUSIONS A simpli ied li e-cycle and economic assessmen o Can ile e +deck and A ch+RSW b idge solu ions ha sa is y he same unc ion we e pe o med, and some esul s we e p esen ed. The p ima y indings o he compa ison a e as ollows: • A ch+RSW wi h ein o ced soil s uc u es showed educed CO2 eq. emissions and ene gy equi emen s compa ed o a con en ional Can ile e +deck b idge design. A ch+RSW solu ions esul ed in educ ions o abou 85% and 82% o CO2 eq. emissions and CED, espec i ely, wi h ega ds o he Can ile e +deck design app oach. • Reduced en i onmen al indica o s o he a ch b idge al e na i e a e a ibu ed o he use o compac ed soil and polyme ic ein o cemen s as he p ima y s uc u al elemen s, as opposed o conc e e and s eel in he con en ional solu ion. • A ch+RSW b idges can esul in cons uc ion cos educ ions o abou 50%. This s udy was limi ed o he en i onmen al and economic impac s o wo di e en b idge ypes: can ile e abu men wi h b idge deck slab and ein o ced soil walls o e p ecas a ches. Fo hcoming esea ch equi es a comp ehensi e s udy o ull sus ainabili y assessmen including en i onmen al, economic, and socie al/ unc ional/ echnical aspec s h ough mul i-c i e ia analysis and di e en s akeholde scena ios. Fu he mo e, i is ecommended o expand he scope o his s udy o encompass a ious ypes o b idges, including di e en dimensions and echnologies. ACKNOWLEDGEMENTS The au ho s wish o acknowledge he suppo ecei ed om VSL Cons uc ion Sys ems (Spain) and Eng. Vi omi Nikolic o his aluable da a on cons uc ion me hods, GECO Indus ial (Ko ea, Rep. o ), he Depa men o Ci il and En i onmen al Enginee ing (DECA) o Uni e si a Poli ècnica de Ca alunya·Ba celonaTech (UPC), and he In e na ional Cen e o Nume ical Me hods in Enginee ing (CIMNE). REFERENCES A no G oup (2012) CEN/TC 350: Sus ainabili y o Cons uc ion Wo ks. 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