Tunnelling and Underground Structures in Egypt: Past ...

Arabian Tunelling Conference & Exhibition | Dec 10 - 11, 2013 | Dubai, United Arab Emirates __________________________________________________________________________________________________________________________

Tunnelling and Underground Structures in Egypt: Past, Present and Future Fathalla M. El-Nahhas Professor, Faculty of Engineering, Ain Shams University, Cairo, Egypt Email: [email protected]

Abstract From a general glance on Ancient Egyptian tunnels and underground chambers and going through the more recent completed tunnelling and underground projects in different areas of Egypt during the last few decades to the new planned future projects, this paper review records of utilization of underground space in Egypt through more than 4000 years and into the future. A focus look is then presented on some lessons learned from underground projects executed in Egypt during the past 30 years based on the compiled extensive results of geotechnical monitoring programs. It is illustrated that the growing sophistication of TBMs and tunnelling technologies have significantly improved the ground control around large diameter urban tunnels constructed through difficult subsurface conditions. On the other hand, changing environmental conditions could seriously affect the long-term safety of rural underground facilities.

1. Introduction Egypt is located in the center of the Arab countries at the northeast corner of Africa overlooking both the Mediterranean Sea and the Red Sea. The River Nile flows through its southern boundary and forms its delta at its northern edge. Civilization in the Nile valley and its surrounding desert lands over thousands of years resulted in cultural treasures which represent an invaluable heritage not only to Egypt but to all the Arab countries as well as to the whole world. This heritage includes ancient tunnels and underground caverns constructed as early as about 3600 BC. Therefore, exploring the early utilization of underground in Ancient Egypt is considered as an essential step towards preserving this human heritage for future generations as well as learning as much as we can from its long term performance. After long centuries without records of underground activities, the need for constructing tunnels and other underground structures started again in Egypt during the second half of the twentieth century and into the third millennium (El-Nahhas, 1999). These underground projects have been associated with major urban and national development plans. It started in the 1960s with diversion tunnels through granite during the construction of the Aswan High Dam. In the late 1970s, the Ahmed Hamdi roadway tunnel was constructed under Suez Canal. The first line of Cairo Metro under the congested city center and the spine tunnel of Cairo Wastewater Project were executed during the 1980s. The tunnelling activities in Egypt flourished during the 1990s. Construction of the second line of Cairo Metro started in mid 1990s connecting the northern areas of the Greater Cairo with its center together with central and southern Giza. This metro line also included a historical tunnel crossing under the River Nile in the downtown area. During that decade also the implementation of four parallel tunnels under Suez Canal was completed as main a element of El-Salam Siphon to transport Nile water to Sinai. The execution of the needed repair of Ahmed Hamdi tunnel was also completed in 1995. Furthermore, Al-Azhar twin road tunnels in central Cairo and the Spine Wastewater Tunnel of Alexandria were implemented during the 1990s together with several

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underg ground parkin ng garages, grade g separattion underpassses and seve eral pipe-jackking projects for f utility lines. hird millennium m marked the e preparation n for implementing Line 3 of Cairo Metrro (34-km lon ng) The th conneccting eastern Cairo with Northern N Giza. By 2012, co onstruction off its first phase (4.3-km lon ng) was co ompleted and d Phase 2 (7.7 7-km long) will be in servicce in 2014. Tender docum ments of Phases 3 and 4 have been n prepared and their consstruction will start soon. In n-parallel, dessign of the first c Lin nes 1 and 2 with the western Giza districts and the phase of Line 4 is underway connecting b region of the e Sixth of Octtober. suburb Future e plans for underground projects alsso include the implemen ntation of th he long waited Alexan ndria Metro line and the trransportation tunnelling co omplex locate ed south of Port P Said und der Suez Canal to serve the new w industrial development d east of Portt Said. Furth hermore, majjor ground projec cts have bee en proposed to upgrade major conge ested urban corridors c in the underg Strateg gic Urban Development Plan-2050 Visio on. aper presents s a short sum mmary of the utilization u of underground space s in Egyp pt through mo ore This pa than 4000 4 years and into the e future. A general glance on Anccient Egyptian tunnels and underg ground chambers is follow wed by a collection of the more recenttly completed d tunnelling and underg ground projec cts in differen nt areas of Eg gypt during th he last few de ecades and in nto some of the new planned future e projects. Fin nally, several lessons learned from und derground pro ojects executed ears are disccussed base ed on the compiled exten nsive results of in Egyypt during the past 30 ye geotecchnical monito oring program ms.

2. Un nderground d Facilities s in Ancien nt Egypt One of o the oldest uses of unde erground spa ace in Egypt is dated bacck to about 3610 3 BC during Egypt’s Early Dynastic Period. The T Step Pyra amid of King Djoser (Figurre 1-a) is loca ated at Saqqa ara meters southw west of Cairo.. A deep und derground burial chamber and its acce ess region, a few kilom b) are located underneath this unique pyramid p of the e third Dynassty (Baines and tunnelss (Figure 1-b Mάlek,, 1995).

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Figure 1 Ancient Egy yptian Underrground Faciilities (a & b): Step Pyramid at Saqqara, S Egyp ypt (~3610 BC C) – (c): Serap peum (~ 1200 0-340 BC) nd facilities were w discove ered under th he more fam mous Giza Pyyramids, a fe ew Similarr undergroun kilome eters north off Saqqara, which w were dated to the fourth f Dynassty of Egypt’ss Old Kingdo om (2550--2470 BC). Se everal other ancient a underground cham mbers and acccess tunnels were later dug

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through the Thebe es Limestone formation off the Valley of Kings wesst of Luxor in Upper Egyypt om, 1550-107 70 BC. Almo ost all these e subsurface facilities we ere mainlyy during the New Kingdo constructed mainly for burial of pharaohs, qu ueens, high priests, p and other elites. Th hey include the mous King Tu utankhamun (~1330 BC). Several arche eologists high hly magnifficent tomb of the most fam believe e that more underground u caverns are still undiscovvered in the Valley V of King gs including the tomb of o King Ramses VIII (~1130 BC). Anothe er interesting but more recent ancient Egyptian und derground co omplex is called “Serapeum m” (aroun nd 1200-340 BC). It was constructed c f burial of th for he then sacrred Apis bullss less than one kilome eter northwestt of the Step Pyramid. P More details d aboutt ancient Egyyptian tunnelss and underg ground man-made cavities are given by Bainess and Mάlek (1995), Hawa ass (1998), Abdel A Salam (2002), ( Hawa ass (2006) an nd Agaiby et. al (2013)).

3. Co ompleted Tunnels T and Underground Struc ctures in Egypt E Subsurface constru uction activitie es in Egypt started s again during the second s half of o the twentie eth he third mille ennium. Thesse undergrou und projects have been associated a w with centurry and into th major urban and na ational develo opment plans as described and discusse ed in the follo owing sectionss.

3.1 Tunnels of Aswan A Hig gh Dam Aswan n High Dam is i a rockfill structure locatted about 7 kilometers k so outh of Aswan city in Upp per Egypt. It is 3600-m m long and itts height is 111 1 m above e the river be ed. Storage capacity of the u.km (Abu-Z Zeid and El--Shibini, 199 97). The da am upstream lake (Lake Nasser)) is 162 cu mentation inc cluded the co onstruction off six large tu unnels (size of o about 15-m m) through the implem granite e formation of the eastern n bank of the River Nile. These T tunnelss (Figure 2-a) were used as the up pstream inlet elements fo or diversion of o the river water w and bra anching into twelve smaller tunnelss that are co onnected to the electricall generators of the hydro opower station ((Figure 2--b) capaciity of 2.1 million MW). The T upstream m larger tunnels were con nstructed witth cast-in-place reinforrced concrete e lining (1-m m thick). In 1991, the tu unnels were inspected using u Remote ely Operated Vehicles (ROV) and divers in ord der to identifyy any defectss in the lining and propo ose a, 1994). remedial measures (Abdel-Hafizz and El-Molla

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Figurre 2 Diversio on Tunnels fo or the hydrop power station of the Asw wan High Dam m (1960-1970 0)

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3.2 Ahmed A Ham mdi Tunnell After 1869, 1 when Suez S Canal was inaugura ated for interrnational navvigation, no permanent p road connecction was av vailable betwe een Sinai and the rest off Egypt. Therrefore, this ro oad tunnel was w constructed under Suez S Canal about a 17 km north of Suezz (between 1978-1980) affter the libration ai. The four-lane tunnel iss 1.64-km lon ng with an internal diametter of 11.4 m. m Profile of the of Sina tunnel (Figure 3) was selecte ed taking into o consideration the futurre plans for widening and z Canal. The tunnel was excavated using open fa ace TBMs thrrough layers of deepening of Suez ne and claysttone having unconfined u co ompressive strength of ab bout 1.5 MPa and coefficie ent siltston of perm meability of about 10-8 m/ss. First, a sma all size TBM was w used to advance a a pilo ot stretch und der the ca anal before la aunching the e large size TBM. T Each ring r of the tu unnel lining, 600-mm thicck, consissted of 16 ribb bed-type precast segmentss and one keyy-segment.

Fig gure 3 Ahme ed Hamdi Tunnel under Suez S Canal (1 1978-1980) unnel lining ex xperienced so ome structura al deterioratio on due to leakkage of sea water. w Hence, a The tu rehabilitation progra am was execcuted by insttalling a castt-in-place rein nforced concrrete lining, 450 hick. A nonwo oven fleece and a a waterprroofing memb brane were fiixed in betwe een the old and mm th new lin nings. The pro oposed mech hanism of the deterioration of the old lining and details of the design and co onstruction of the new lining are describ bed by Otsuka a and Kamel (1994) ( and Aratani (1994). The most m critical ca ase of loading g in the desig gn of the new w lining was th he influence of o the expected expanssion of Suez Canal above the tunnel. Itt was estimate ed, during the e design stages, that this will w result in a heave of 200-300 mm m at the botto om of the canal. Hence, the t interaction n of the ground he combined system of the old and ne ew linings together with the fleece and the membrane with th was analyzed for these t reboun nd estimates.. Actual perfo ormance of the t tunnel du uring the can nal c th he rehabilitation works, co onfirmed that the assumed expanssion, immediiately after completing reboun nd during the design stage e was overesttimated.

3.3 Tunnels and d Undergro ound Struc ctures in th he Greaterr Cairo Reg gion The Greater Cairo region include es the City off Cairo and so ome of the ad djacent urban n districts of the a Qalioubey ya Governora ates. It is estim mated that th his region acccommodates more than 25 5% Giza and of Egypt populatio on. There have h been mounting do ocumented successful s experiences for f oping the underground spa ace in the Gre eater Cairo re egion during about a three decades d (Figu ure develo 4-a). Such S develop pment has been badly nee eded to keep up with the fast f expansio on of this urban region of more than ten timess in 40 yearrs. Population misdistribu ution was co onsidered mo ore 5% condensattion within 20--km diameterr circle. important where 75 emarkable ste ep of impleme enting the cen ntral undergro ound portion of o the first line e of Cairo Mettro The re (aboutt 4.5-km long)) in the early 1980s (Abde el Salam, 1984 4) proved tha at critical urba an problems, as

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the ma ass transporttation through h downtown Cairo, C could be significanttly alleviated by utilizing the underg ground space e. During g the late 1980 0s, several tyypes of tunnellling boring machines m (up to t 6.1-m diam meter), including BS TB BMs, Open Fa ace TBM with h Compresse ed Air and EP PB TBMs, we ere used for the first time in Cairo to t construct a major part of o the spine tunnel t for the Greater Cairro Wastewate er project (Ab buSaada a, 1991). This tunnel was 9.7-km 9 long (F Figure 4-a) and extended southward fo or about 4.5 kkm severa al years later. The successsful implemen ntation of thesse two projectts contributed d significantly to the tra ansfer of bad dly needed new n construcction technolo ogies such as; a diaphragm m walls, TBM Ms, pipejaccking, groutin ng …etc.

Line 2

Spine Tunnel Wastewater Line 3 Oruba Road Tunnel

Line 1

Al-Azzhar Road Tunnels

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Figure e 4 Major Tun nnels in the Greater G Cairo o Region and d TBM Break k-in unnelling activ vities in Egyp pt and particularly in the Greater G Cairo region flourisshed during the The tu 1990s (El-Nahhas, 2006). Seve eral new tun nnelling and underground projects we ere executed in he Greater Ca airo. For insta ance, the con nstruction of several s underrground phasses different areas of th pleted from 1994 1 to 1999 9. This line iss 21.6-km lon ng, of the second line of Cairo Mettro was comp g a total of 20 0 stations inclluding 12 und derground sta ations. These stations are connected byy a serving double e-track tunnel excavated using u BS TB BMs 9.4-m diameter (Figu ure 4-b). A hu uge network of smalle er branch sew wer tunnels (te ens of kilometters long) wass constructed under many areas of Cairro. a constructted in Cairo. Construction of In late 1990s and into 2005, sevveral road tunnels were also har Road tw win-tunnels (e each 2.7-km long) underr the historiccal old Fatim mid Cairo was w Al-Azh comple eted in 2001 utilizing a BS-TBM B (Abu-Krisha, 200 05). Orouba Road cut-an nd-cover tunn nel under the main rou ute to Cairo In nternational Airport A was constructed ussing diaphrag gm and tange ent alls. During th his period a number n of und derground ca ar parking garrages were also constructed pile wa in diffe erent areas off the Greater Cairo. Two examples e of these t projectss are Omar Makram M Parking Garage under the e southweste ern corner of o El-Tahrir Square in downtown Cairo C and the ground parkin ng of Faisal Islamic Bankk of Egypt in Giza (El-Nahhas and Mo orsy, 2002). All A underg

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these projects werre implementted to deal with w the alarm ming traffic problems p with hin the several C congessted areas off the Greater Cairo. r cons struction of Liine 3 of Cairo o Metro (34-km long) starte ed connecting g eastern Cairo More recently, with no orthern parts of Giza (Figu ure 4-a). Its firrst phase (4.3 3-km long witth five underg ground station ns) was co ompleted in 2012. 2 Constrruction of Pha ase 2 (7.7-km m long with fiive undergrou und stations) is almostt finished and d will be in serrvice in 2014.. Large diame eter Earth Pre essure Balancced (EPB) TB BM (9.4-m m diameter) was w used to construct c a major m section n of the doub ble-track tunn nels connecting some stations s of thiis line.

yphon Projject 3.4 El-Salam Sy This project p consis sts of four pa arallel tunnels, 775-m lon ng each, constructed under Suez Can nal (Figure e 5) south of Port Said to provide p irrigattion water for 400,000 fedd dans of a reclamation proje ect in norrthern Sinai (Mazen and Craig, 1994 4). One BS TBM, 6.56-m diameter, was used for f advanccing the four tunnels. Th he tunnels were w provided d with two liinings with a waterproofing membrane in betwe een. The prim mary lining con nsisted of sollid precast reiinforced conccrete segments, h ring was forrmed of 7 seg gments and a key-segmen nt. The secon ndary lining was w 300 mm thick. Each st-in-place pla ain concrete. The main fun nction of the primary lining g was to enab ble a 320 mm thick cas econdary linin ng to be consttructed in a safe s and dry environment. e The seconda ary the unreinforced se ed to carry the t full overb burden and hydrostatic h p pressures. Exxecution of the lining was designe dary lining off each tunnel was carried out only afterr complete exxcavation of the t neighboring second tunnelss in order to prevent p any damage d to the e secondary lining. Constrruction of the tunnels started in 1995 5 and was co ompleted in 19 997.

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Figure 5 Tunnels T of El-Salam E Syphon Project under Suez Canal (1995--1997)

3.5 Alexandria A Wastewate W er Project Severa al kilometers of soft ground d tunnels and d pipe-jacking g were constrructed during the 1990s ass a part off Alexandria Wastewater W P Project. The central c main collector of th he network was w constructed under central Alexa andria starting g from the Me editerranean coast c and advvancing south hward for abo out m. This tunnel was excava ated, through layers of san nd, silty sand, clay and sa andstone, using 3.5 km earth pressure p bala ance (EPB) TBMs of abo out 2.85 m diameter d in co onjunction wiith pipe jacking system ms. The collec ctor was form med of precastt reinforced concrete c pipess having interrnal diameter of 2.25 m. m Results of an in-situ mo onitoring prog gram and num merical mode eling of a testt section of th his tunnel are given by Abdrabbo et al. (1998).

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4. Some Future Underground Projects in Egypt 4.1 Cairo Metro Lines Previous transportation studies indicated that the Cairo Metro Network should include at least six lines in order to provide reasonable coverage of mass transportation over most areas of the Greater Cairo. Lines 1 and 2 are currently in full operation for a number of years. As indicated in Section 3.3, Line 3 of Cairo Metro (34-km long) will connect eastern Cairo with northern Giza (Figure 4-a). Its first phase (4.3-km long) was completed between Attaba and Abbasia under central Cairo in 2012. Phase 2 (7.7-km long with five underground stations) connecting Abbasia to Heliopolis will be in service in 2014. Tender documents of Phases 3 and 4 of this line have been prepared and start of their construction is expected in the near future. Phase 3 (17.7-km long) includes 15 underground stations between Attaba and Giza and will cross the two Nile channels bordering the Zamalek district. As shown on Figure 4-a, this line will be divided into two branches in Giza; one goes to the north and the other goes southward. The fourth and final phase of Line 3 (about 14-km long including 9 stations) will extend the alignment northeast from Heliopolis to Cairo International Airport. Final design of the first phase of Line 4 is currently being prepared. This phase is about 18-km long with 17 stations and will be connecting the existing Lines 1 and 2 with the western districts of Giza and the suburb region of the Sixth of October. Unlike the previous 3 lines, the rolling stock of Line 4 will run through twin smaller tunnels to accommodate the limited available subsurface space along some stretches of the proposed alignment. All tunnels of Line 4 will be constructed using EPBTBMs.

4.2 Alexandria Metro As the second largest city in Egypt, plans for Alexandria Metro were prepared more than 25 years ago and have been updated several times. The proposed regional line extends over about 46 km from Abou Kir at the east end to the North-Coast Highway at the west side. The middle stretch of the alignment (about 8.5-km long) will be constructed underground passing under the congested central area of Alexandria. The eastern stretch will utilize the existing on-grade lines between Abou Kir and Misr Stations.

4.3 Port Said Tunnels This project is currently being studied to connect Port Said city on the east side of Suez Canal to the newly developed industrial area and new agricultural reclamation lands at the northeast corner of Sinai. It is also considered as a strategic alternative to cross the Suez Canal in the northern region. It is expected that the project will consist of three parallel 12-m excavated diameter tunnels passing under the Suez Canal at a selected location a few kilometers south of Port Said City. Two of the tunnels are being considered as double-lane route for cars and trucks in each direction while the third tunnel is assigned as a double-track for railway usage. The preliminary alignment of each tunnel includes a central stretch under the canal about three kilometers of TBM construction with a cut-and-cover portal on each side.

4.5 Cairo Vision 2050 A recent extensive study on formulating the future of the Greater Cairo up to 2050 was conducted in 2009. The outcome of this vision was presented in a document entitled: “The Strategic Urban Development Plan of Greater Cairo Region”. The utilization of underground space in urban areas represented a key element in this plan. For instance, Figure 6 illustrates how the underground

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space under Game et-Eldoual-Ela arabia Street in i Giza can be b utilized for car parking and a commerccial ndition at the ground surface. use in order to imprrove the envirronmental con

Figure 6 Proposed P Util ilization of Un nderground Space Un nder Gamet-E Eldoual-Elara abia Street, Giza G (Cairo Vision V 2050)

5. So ome Learne ed Lessons s There are plenty of o lessons to be learned from the casse-history of tunnelling an nd utilization of ground in Egy ypt. Some of these t lessonss are offered here: underg 1. T The outstand ding stability and survivall of many An ncient Egyptiian man-mad de cavities and t tunnels for thousands of years y deserve e not only app preciation but also great efffort to preserrve t this human he eritage. 2. T The premature deterioration of reinforcced concrete segments off Ahmed Ham mdi Tunnel and t implemen the nted rehabilita ation works as a described by b Otsuka an nd Kamel (199 94) and Arata ani (1994) offer several s lesso ons on the efffect of enviro onmental chan nges on safe ety of rural road t tunnels and how h to fix succh damage. 3. T Tunnelling in the Greater Cairo provide ed an excellent opportunityy to compile field f monitoring d data on ground settlement due to urba an tunnelling. Several gene erations of TB BMs have been e past 30 ye ears. Figure 7 compares the settleme ent used in the Greater Cairro during the piled during advancing a so ome of the BS-TBMs. The e TBM shown n in Figure 7-a 7 records comp utilized rubbe er tail-seal wh hile that show wn on Figure e 7-b was equipped with steel-brush s ta ails seal. Both TB BMs were 6.1-m diamete er bentonite slurry s used fo or the spine tunnel of Cairo W Wastewater Project. P Thesse two TBMs were of the late l 1980s models m and the e annular gro out f the two ca for ases was pum mped through the segmentts. O the otherr hand, Figurre 7-c shows similar records of the larger (9.4-m diameter) On d mo ore s sophisticated BS TBM of the mid 1990s. This TBM M was used to t construct Line L 2 of Cairo w steel-brussh tail-seal an nd annular gro out Metro and Al--Azhar road tunnels. It wass equipped with w injected through the TBM was T tail. he settlementt records during the consstruction of Line L 3 of Cairo More recently, most of th ameter (BS and a EPB) TBM Ms were arou und or even below b the low wer Metro above the 9.4-m dia limit shown on Figure 7-c. t the grow wing sophistication of TBM Ms and tunnellling technolo ogies during the It is evident that past 30 years s have signifficantly improvved the contrrol of ground loss around large diametter urban tunnels s constructed through difficcult subsurfacce conditions..

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(a)

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Fiigure 7: Meas sured Surfac ce Settlemen nt above Thre ee Different B Bentonite Sllurry TBMs a & b) Cairo Wastewater W Project P (6.1-m m diam.) and c) Cairo Mettro Line 2 (9.4-m diam.)

6. Co onclusions This pa aper presents s a short sum ore mmary of the utilization u of underground sspace in Egyp pt through mo than 4000 4 years and into the e future. A general glance on Anccient Egyptian tunnels and underg ground chambers is follow wed by a collection of the more recenttly completed d tunnelling and underg ground projec cts in differen nt areas of Eg gypt during th he last few de ecades and in nto some of the planne ed future projjects. Finally,, several less sons learned from underg ground projec cts executed in Egypt are discussed d based on th resu ms. he compiled extensive e ults of geotecchnical monito oring program It is illu ustrated that the growing ssophistication n of TBMs an ast nd tunnelling technologies t during the pa 30 yea ars have sig gnificantly imp contro els proved the ground g ol around larrge diameter urban tunne constructed through h difficult subssurface condiitions.

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