Birth of a Mod­ern Marvel

Af­ter six years of prepa­ra­tion and eight years of con­struc­tion, the HZMB, which has been re­ferred to as a “Bridge Marvel,” is ready for op­er­a­tion.

China Pictorial (English) - - CONTENTS - Text by Yang Yun­qian

The Hong Kong-zhuhai-macao Bridge (HZMB) holds many world records: it is the long­est crosssea bridge in the world, and has the long­est steel bridge as well as the long­est un­der­wa­ter im­mersed road tun­nel. As the most tech­ni­cally chal­leng­ing high­way bridge project with the largest con­struc­tion scale to date in the his­tory of high­ways, the dif­fi­culty of its con­struc­tion can be ranked among the high­est in the world.

To­tal­ing 55 kilo­me­ters, the bridge con­nects Hong Kong’s Lan­tau Is­land, the Macao Penin­sula and Zhuhai City of Guang­dong Province from east to west. Af­ter six years of prepa­ra­tion and eight years of con­struc­tion, the prin­ci­pal sec­tion of the bridge is ready for op­er­a­tion af­ter the project’s man­age­ment au­thor­ity com­pleted an ac­cep­tance check in Fe­bru­ary 2018.

The bridge will cut travel time across the Pearl River Delta—pre­vi­ously four hours by car and one hour by boat—to about half an hour.

Three Sets of Dis­tinc­tive Bridge Tow­ers

The mega-project con­sists of three parts over­all: the Main Bridge; BoundaryCross­ing Fa­cil­i­ties for Hong Kong, Zhuhai and Macao; and Link Roads into the three re­gions. Ap­proach­ing the Zhuhai end of the bridge fea­tures a six-lane high­way just past a toll sta­tion, over­look­ing the sea dot­ted with is­lands and ves­sels. Oc­ca­sion­ally, Chi­nese white dol­phins leap out of the wa­ter.

To name the 29.6-kilo­me­ter sec­tion cobuilt by the three re­gional gov­ern­ments “Main Bridge” can be a bit con­fus­ing, given the fact that it is a com­bi­na­tion of bridges, ar­ti­fi­cial is­lands and a tun­nel. The scale of the project is of­ten deemed daunt­ing. A case in point would be the 425,000 tons of steel used for deck gird­ers and bridge tow­ers, equiv­a­lent to 60 Eif­fel Tow­ers. The 22.9-kilo­me­ter bridge sec­tion in­cludes the Ji­uzhou Chan­nel Bridge, Jiang­hai Chan­nel Bridge, Qingzhou Chan­nel Bridge and a 20-kilo­me­ter non-nav­i­ga­ble bridge. Over the three chan­nel bridges sit seven tow­ers, shaped like sails, dol­phins and Chi­nese knots, re­spec­tively, all adorned with sim­ple pat­terns that are deeply mean­ing­ful.

The Ji­uzhou Chan­nel Bridge is the clos­est to the city proper of Zhuhai. Tow­er­ing over the Lingdingyang wa­ter­way, the “sail” de­sign can be seen from Lover’s Road, a land­mark thor­ough­fare along the city coast. Be­cause of its prox­im­ity to the Macao air­port, build­ings were lim­ited to a height of 122 me­ters, so the two “sails” stand at 120 me­ters. Jiang­hai’s three dol­phin-de­sign steel tow­ers were trans­ported and erected on the bridge af­ter con­struc­tion in a fac­tory, the first time such a strat­egy was em­ployed in China. “Each steel tower is con­nected by shafts at its seat,” says Zhang Jin­wen, di­rec­tor of engi­neer­ing of the HZMB Au­thor­ity. “Lifted by huge steel ca­bles and two float­ing cranes, the 3,000-ton tower was turned ver­ti­cally from hor­i­zon­tally to be erected on the bridge in one go, a ma­neu­ver that no one had ever at­tempted be­fore.”

Shaped like two Chi­nese knots, the Qingzhou Chan­nel Bridge tow­ers are a to­ken

of bond­ing and con­nec­tion among Hong Kong, Zhuhai and Macao. “It took 100 days to in­stall the Chi­nese knots be­cause every de­tail was so im­por­tant. Only with high­pre­ci­sion in­stal­la­tion of each piece came the ul­ti­mate suc­cess­ful con­nec­tion.” Zhang con­tin­ues. Ac­cord­ing to him, the Pearl River es­tu­ary is a na­ture re­serve for a na­tional pro­tected an­i­mal: the Chi­nese white dol­phin. So the tow­ers of the Jiang­hai Chan­nel Bridge were de­signed in the shape of dol­phins.

Fur­ther­more, the deck sur­face hav­ing been paved in the Main Bridge sec­tion to­tals 700,000 square me­ters, also the largest project of its kind in the world. When they so­licited bids to pro­vide ma­te­ri­als for the work, the HZMB pro­cure­ment team found no qual­i­fied com­pany. Good ma­te­ri­als are cru­cial el­e­ments of a qual­ity project. So the HZMB Au­thor­ity pro­posed the idea of set­ting up a fac­tory ded­i­cated to pro­duc­ing its ag­gre­gates, which re­sulted in the birth of the most ad­vanced Zhong­shan Ag­gre­gate Fac­tory.

“Con­trac­tors de­ter­mine the qual­ity of a project,” re­marks Gao Xinglin, as­sis­tant di­rec­tor of the HZMB Au­thor­ity and head of its Plan­ning and Con­tract Depart­ment. “The con­trac­tors did a bet­ter job than we ex­pected. We used uni­form-sized ag­gre­gates with a low pro­por­tion of mud so that our stan­dards stayed on par with in­ter­na­tional norms.” He be­lieves the HZMB rep­re­sents an in­no­va­tion in the field of the coun­try’s bridge sur­fac­ing.

Two Shell Is­lands

About 20 kilo­me­ters from the Zhuhai port, past the Qingzhou Chan­nel Bridge sits a west­ern ar­ti­fi­cial is­land, which con­nects to an east­ern ar­ti­fi­cial is­land to­wards Hong Kong through an un­der­sea tun­nel. Viewed from above, the HZMB re­sem­bles two drag­ons ris­ing from the sea, one wind­ing to the east, the other to the west. The two ar­ti­fi­cial is­lands also re­sem­ble two round shells or two huge ves­sels meet­ing each other half­way.

The two is­lands have sim­i­lar build­ings but dif­fer­ent func­tions. The east­ern is­land serves as a com­pre­hen­sive op­er­a­tion cen­ter cov­er­ing trans­porta­tion, man­age­ment, ser­vices, res­cue and tourism. It of­fers sight­see­ing plat­forms and cor­ri­dors. The west­ern one fo­cuses on mon­i­tor­ing, main­te­nance and of­fice work.

Com­plet­ing the tun­nel and the two beau­ti­ful ar­ti­fi­cial is­lands pro­vid­ing tran­si­tions from the bridge to tun­nel was the most chal­leng­ing task for the con­struc­tion team.

The Lingdingyang wa­ter­way, un­der which the tun­nel runs, is an im­por­tant global trade pas­sage that han­dles 4,000 cargo ves­sels, fish­ing boats and pas­sen­ger ships each day. To guar­an­tee the safety of ships, the height of a bridge must stay above 80 me­ters and bridge tow­ers 200 me­ters, but the neigh­bor­ing Hong Kong In­ter­na­tional Air­port re­quires nearby build­ings to stay lower than 88 me­ters, dic­tat­ing the con­struc­tion of an un­der­sea tun­nel. The project re­quired a wa­ter ob­struc­tion rate of less than 10 per­cent to pre­vent mud and sand from ac­cu­mu­lat­ing and block­ing the wa­ter­way, which would re­sult in Lingdingyang be­com­ing a flood plain.

“A 300,000-ton ves­sel needs to be able to nav­i­gate through the bridge align­ment, yet air­line routes re­quire low build­ings and the im­pact on the en­vi­ron­ment also needs to be taken into con­sid­er­a­tion,” ex­plains Zhang Jin­wen. “So, this sec­tion had to go un­der the wa­ter.”

Un­der­sea Tun­nel The de­sign of the west­ern ar­ti­fi­cial is­land eases the drop into the 6.7-kilo­me­ter un­der­sea tun­nel. Along the un­der­sea land­form, the

tun­nel fea­tures two sloped stretches that can hardly be felt while driv­ing. “In­side the tun­nel main­tains a fixed tem­per­a­ture, and its ven­ti­la­tion sys­tem is de­signed to pro­duce the same con­di­tions as a road tun­nel,” ex­plains Zhang Jin­wen. “The tun­nel is il­lu­mi­nated by LED light, which is suit­able for driv­ing.”

This long­est road im­mersed tun­nel in the world is com­posed of 33 pre­fab­ri­cated im­mersed el­e­ments and a 12-me­ter clo­sure joint that weighs 6,300 tons. The tun­nel is 6,700 me­ters long in to­tal, with the sec­tion un­der the sea ex­tend­ing 5,664 me­ters. The deep­est reaches 46 me­ters un­der wa­ter.

China is al­ready home to sev­eral crosssea bridges, but the HZMB has the coun­try’s largest and deep­est im­mersed tun­nel—and in fact, one that im­mersed the deep­est un­der the seabed in the world.

Work­ers first dug a groove on the seabed, treated the foun­da­tion trench, and then placed the pre­fab­ri­cated im­mersed el­e­ments into the groove be­fore con­nect­ing them one by one un­der the sea. Some projects in other parts of the world have also used such a method, but the tun­nel el­e­ments for this project were placed far deeper un­der the seabed. The HZMB project marked the world’s first deep-im­mersed un­der­wa­ter tun­nel be­cause of strict en­vi­ron­men­tal re­quire­ments and con­sid­er­a­tion for sur­round­ing trans­porta­tion.

It was pre­vi­ously con­sid­ered a tech­no­log­i­cal taboo to bury tun­nels deep in the soil un­der wa­ter as deep as 40 me­ters. So this sec­tion pre­sented the great­est chal­lenge of the HZMB project. To make sure the tun­nel can with­stand the pres­sure of the 30-me­ter-deep mud, its builders man­aged to pre­cast con­crete struc­tures of a mil­lion cu­bic me­ters free of cracks, and cre­ated a “half-rigid” tun­nel struc­ture—nei­ther ut­terly rigid nor flex­i­ble by cre­at­ing dif­fer­ent shear forces at dif­fer­ent points with metic­u­lous cal­cu­la­tion—which en­abled them to make the fin­ished tun­nel com­pletely wa­ter­proof.

But ac­tu­ally plac­ing and con­nect­ing these el­e­ments 40 me­ters un­der the sea with high pre­ci­sion was ex­cru­ci­at­ingly dif­fi­cult and re­quired ac­cu­rate re­mote con­trol, cal­cu­la­tion and com­put­ing com­pa­ra­ble to space­craft dock­ing. The con­struc­tion team set up a Global Nav­i­ga­tion Satel­lite Sys­tem (GNSS) base sta­tion, col­lect­ing data from 20,000 me­ters above sky to guide the project and con­trol the er­ror range to within seven cen­time­ters when con­nect­ing the el­e­ments. Af­ter the el­e­ments were con­nected, wa­ter stops at the el­e­ments’ ends were sealed un­der wa­ter pres­sure.

From im­mers­ing the first tun­nel el­e­ment in May 2013 to in­stalling the clo­sure joint in May 2017, im­mer­sion of the tun­nel struc­ture took as long as four years. On June 7, 2017, the un­der­sea tun­nel was pass­able for con­struc­tion ve­hi­cles. “This project fea­tures 64 in­no­va­tions that bridged many tech­no­log­i­cal gaps,” notes Lin Ming, chief en­gi­neer of the HZMB’S is­land and tun­nel project with China Com­mu­ni­ca­tions Con­struc­tion Co., Ltd. The tun­nel has drawn great at­ten­tion from engi­neer­ing in­sti­tu­tions around the planet and has been re­ferred to as a “Bridge Marvel.”

An In­dus­trial Revo­lu­tion

Out of the east­ern ar­ti­fi­cial is­land and at the tran­si­tion part to the un­der­sea tun­nel, Hong Kong’s Lan­tau Is­land can be seen clearly.

Built jointly by Hong Kong, Zhuhai and Macao, the HZMB had to meet the tech­no­log­i­cal and qual­ity stan­dards of all three re­gions. Ac­cord­ingly, the HZMB

Au­thor­ity de­vel­oped its own de­sign, man­age­ment and con­struc­tion meth­ods. The project is de­signed to last for 120 years and with­stand an 8-mag­ni­tude earth­quake as well as su­per ty­phoon. Ad­di­tion­ally, both 300,000ton oil tankers and 150,000-ton cargo ves­sels can pass over the tun­nel and un­der the bridge at any time.

With re­gard to bridge con­struc­tion, many have noted that Europe and the United States dom­i­nated the 1960s and 70s be­fore Ja­pan took the torch in the 1980s and 90s. Now it’s China’s turn.

“Many com­pa­nies con­sid­ered the HZMB project a his­toric op­por­tu­nity, so the project at­tracted elite global re­sources and pro­moted in­dus­trial devel­op­ment,” says Gao Xinglin.

To pro­tect Chi­nese white dol­phins, en­vi­ron­men­tal pro­tec­tion groups made 300 ex­pe­di­tions and took 300,000 pho­tos which served as ref­er­ence points for pro­tec­tive mea­sures added to the project.

To pre­vent work­ers from fall­ing vic­tim to oc­cu­pa­tional mal­adies, the se­cu­rity and en­vi­ron­men­tal pro­tec­tion depart­ment pro­vided phys­i­cal ex­am­i­na­tions be­fore and af­ter work­ers’ terms of em­ploy­ment.

Ac­cord­ing to in­com­plete statis­tics, the engi­neer­ing marvel has in­volved 1,000 re­search in­sti­tu­tions and over 1,000 sci­en­tific and tech­ni­cal work­ers since 2003. Early par­tic­i­pants car­ried out 300 re­search mis­sions, in­vested 500 mil­lion yuan, cre­ated over 40 new con­struc­tion meth­ods, won over 100 patents, com­piled 63 man­u­als for tech­ni­cal stan­dards and reg­u­la­tions and pub­lished more than 500 es­says as well as a dozen tech­ni­cal mono­graphs.

The project marks the hey­days of Chi­nese in­fra­struc­ture con­struc­tion. Al­most all con­trac­tors in­volved in the HZMB felt lucky to have seized the chance to par­tic­i­pate in the his­toric project.

From a bird’s-eye view over the blue Lingdingyang, the rolling bridge ap­pears like a pearl neck­lace and the two ar­ti­fi­cial is­lands like two pieces of jade, giv­ing the bridge the aura of “pearls and jade—a per­fect pair.” The coun­try just pro­posed the con­cept of a Greater Bay Area around Guang­dong Province, Hong Kong and Macao, and the HZMB is ex­pected to play an im­por­tant role in the fu­ture devel­op­ment of the re­gion. “Rid­ing China’s im­pres­sive na­tional devel­op­ment as of late, the econ­omy of the Pearl River Delta con­tin­ues to grow fast, and both Hong Kong and Macao as­pire to reap the re­wards of the coun­try’s fur­ther devel­op­ment,” notes Yu Lie, deputy di­rec­tor of the HZMB Au­thor­ity. “In­fra­struc­ture con­nec­tiv­ity around the bay area will def­i­nitely ac­cel­er­ate the process.”

The Hong Kong-zhuhaiMa­cao Bridge passes through the na­ture re­serve for the na­tional pro­tected Chi­nese white dol­phin at the Pearl River es­tu­ary, so the tow­ers of Jiang­hai Chan­nel Bridge are shaped like dol­phins. by Duan Wei

2015: The sail-de­sign tower at Ji­uzhou Chan­nel Bridge an­gled straight above the sea. Be­cause of its prox­im­ity to Zhuhai city proper and the Macao air­port, build­ings were lim­ited to a height of 122 me­ters, so the “sail” stands at 120 me­ters. cour­tesy of HZMB Au­thor­ity

The east­ern ar­ti­fi­cial is­land. Xin­hua

The un­der­sea tun­nel un­der con­struc­tion.

April 13, 2013: The west­ern ar­ti­fi­cial is­land un­der con­struc­tion. The is­land is en­cir­cled by steel cylin­ders, which are in­jected with sand and re­quire a series of treat­ments such as drainage con­sol­i­da­tion. by Sun Li

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