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Mani project Mani project Document Transcript

  • Worlds longest cross-sea bridgeHangzhou Bay Bridge Submitted by Dathi. Manikanta
  • HANGZHOU BAY BRIDGE:Year of conception : 1994Construction begin : June 8, 2003Construction end : June 14, 2007Opened : May 1, 2008Project type : Sea crossing bridgeTotal length : 35.673km(22min)Project cost : $16 billionProject chief designer : Wang renguinLocation : Across the Hangzhou bay on the East China Sea, crossing the Qiantang river atthe Yangtze river delta. Starting in jiaxing to the north, the bridge ends at Ningbo in the south.Bridge overview : 36km long, 6lane, two-direction highway with 100km/hr speed limit,100 year guaranteed service design, cable stayed design. The bridge will have two main spans,with a 448m northern span, and a 318m southern span.Purpose of bridge :The bridge shortened the highway travel distance between Ningo andShanghai from 400km to 280km and reduced travel time from 4 to 2.5 hoursLocation of bridge : Link (1&2)
  • INTRODUCTION It will not be a hyperbole to say that the rage of being a record holder in a respective fieldis tremendously growing day by day and encouraging people to accept the innovative ideas,techniques, and resources available in the market to fulfill their dreams. The Hangzhou Bay Bridge is the world’s 4th longest bridge 3rd longest over water bridge and theworlds longest Trans-oceanic bridge at 22.17 miles long . Spanning across the Hangzhou Bay on the EastChina Sea and crossing the Qiantang River at the Yangtze River Delta. It surpassed the Donghai Bridge,the longest transoceanic bridge in the World, when it was opened in 2005. The S-shaped Hangzhou Bay Bridge is an important connection in China’s East CoastSuperhighway. Starting in Jiaxing to the north, the bridge ends at Ningbos Cixi county in theSouth. It shortens the ground transportation distance from Ningbo to Shanghai by 120km andTravel time from four hours to two and half hours. It is a six-lane, two-direction highway with a100km/h speed limit, and a 100-year, service guaranteed cable-stayed design. The Hangzhou Bay Bridge was the main component of a 5.2km national highway between theProvinces of Heilongjiang in the north and the Hainan in the south. Wang Yong, chief director of theHangzhou Bay Trans-Oceanic Bridge Construction Command Post, said the bridge would be one of themost important, not only in China but in the world "for it is not only the longest one (over a sea) but alsowill be built in the world’s most complicated sea environment, with one of the three biggest tides onEarth, the effect of typhoons and the difficult content of the sea soil". Link 2
  • Preparatory work started on the bridge as far back as 1994. Construction work began in June 2003and was completed in June 2007 and an opening ceremony was held on 26 June. Several tests andevaluations were conducted for about one year before official opening. The bridge was opened to thepublic in May 2008 and carried about 50,000 vehicles per day in its first year of operation.History The bridge across the Hangzhou Bay was the subject of various feasibility studies forover a decade before the final plans were approved in 2003. An earlier plan placed the bridge further east,closer to the mouth of the bay, which provided an even shorter travel distance between Ningbo andShanghai. Under this plan, the bridge would begin in the north from, Jinshan a suburb of Shanghai. TheGovernment of Shanghai rejected the plan and focused on building the 32.5 km (20 mi)-long DonghaiBridge from Shanghai to its off-shore port at Yangshan in the mouth of the bay. The ShanghaiGovernment sought to feature Yangshan as the chief port on Chinas east coast and refused to allow aCross-bay bridge to be built on its territory, which would improve access to the port of Ningbo at beilun.The Zhejiang Provincial Government was forced to build the bridge further to the west on entirelyZhejiang territory. The Hangzhou Bay Bridge connects Cixi, a local-level city that is part of NingboMunicipality, with Haivan, a county in Jiaxing Municipality. The Hangzhou Bay Bridge has significantlyShortened driving distance between Ningbo and the Yangtze River Delta region and improved theCompetitiveness of the Beilun Port.NATURAL CONDITIONSMeteorological Conditions The Project Area belongs to the typical subtropical zone characterized by a mild, humid, Link 1
  • rainy climate, frequent monsoons and four different seasons. The annual average temperature is 16c withthe highest temperature of 28c in July and lowest temperature of 4℃ in January.Landforms The terrain on the north and south banks at the bridge location is level. The shore consistsof side foreland at river mouth and tidal flats. The south bank is 9 km inwidth while the north bank is 1.5km in width. The terrain at the bay bottom is composed of scouring channels and tidal current ridges,rising mildly from east to west with a reduction in water depth. The average and maximum water depthsare 10 m and 13.6 m respectively with a U-shaped trough deeper in the north and more shallow in thesouth.Hydrologic Features Hangzhou Bay is an informal semidiurnal tidal sea area with flood and ebb tides twiceone day. The flood tide lasts longer than the ebb tide with a typical movement type of reciprocating flow.The observed maximum tidal velocity is close to 5 m/s, the maximum tidal range is almost 8 m and thetidal flow volume is about 1 × 1010 cubic meters. The content of sand and salt in the sea water is1.25kg/m3 and 10.8 g/kg respectively. Hangzhou Bay is in a stable condition at the bridge location,Characterized by scour in winter, silting in summer, scour in the north, and silting in the south.Geological Conditions The stratum at the bridge location is mainly composed of quaternary cover. It is wildlycovered by quaternary stratum in addition to some buttes and monadnocks on north bank. Thick loosedeposits of the quaternary stratum are mainly composed of clayey soil, sandy loam, muddy loam, silty link 3
  • sand, fine sand, gravel and medium-fine sand on south bank, with an average thickness of 130 to 220 m.The stratum belongs to coastal plain. The bedrock is ignimbrite on north bank and mudstone on southbank.The poor geological conditions are mainly composed of soft soil layer and the methane in shallowstratum. The soft soil layer is 8 ~ 45m in depth featured with high moisture, high compressibility,thixotropy-prone, low shear strength, and low capacity. The shallow sandy layer is prone to liquefaction.The methane in shallow stratum is distributed in lensoid-shaped 40-60 m deep sandy layer in the 10 kmtidal-flat area.Hydrogeological Conditions The groundwater is mainly quaternary unconsolidated rock pore water which can beclassified into phreatic water, micro-confined water and confined water at thebridge location. Phreaticwater is mainly distributed in the sandy loam layer at seabottom, of which the first layer phreatic water is50 m in depth with the sandy loam and fine sand with moisture while the second layer is 80 m in depthwith the medium-fine sand with moisture. The groundwater and seawater are weakly erosive.Construction challenges Because of the many difficulties facing such a tremendous build, almost 600 expertsspent nearly a decade designing the bridge. Even after nearly a decade of design, studies, and planning,many different challenges were encountered, the first being the challenge of offshore construction. As asolution, several parts of the bridge had to be completed on land and then transported to the area forwhich they were built. Some components that were constructed using this process were piers, box girders(bridge panels), and even the bridge foundations. Link (3&2)
  • Another construction challenge involved the weather in the region. Wang Yong, chiefdirector of the Hangzhou Bay Trans-Oceanic Bridge Construction Command Post, described the bridge asbeing built in the worlds most complicated sea environment, with one of the three biggest tides on Earth,the effect of typhoons and the difficult content of the sea soil. Erosion of materials and cracking andBubbling of any concrete components became a large problem. To combat bubbling and eventual holes,engineers used a cloth-covered template over the concrete. This would improve the color and density ofthe pieces, making them both more aesthetically pleasing and sturdier. To reduce cracking, engineers usedlow-strength early-stretching technology when constructing box girders. This technology involvescasting (molding) the girder, or bridge panel, letting it harder for no more than three days, and thensqueezing it before it reaches its full density. This gives the girder more room to stretch after the bridge isconstructed, preventing cracks in the concrete over time. "severe marine conditions caused difficulties in anchoring barges and construction vessels."Mostly, construction activity was performed on land and then the prefabricated components weretransported to the site for erection and final installation. For shipping and erecting the girders in sea, giantfloating cranes with accurate anchoring devices and launching gantries were used. Construction onmudflats near the south shore, in an alternating wet and dry tidal area, presented serious technicalproblems. A temporary 10km trestle was erected for pile driving and pier construction. Girders weighing1,430t were erected from the top, starting from the land end and launching towards the sea. Eachpreviously erected span served as the deck for transportation and erection of the next girders as thelaunching gantry moved forward. Also, severe marine conditions caused difficulties in anchoring barges and construction Link 2
  • vessels. Under turbulent tidal flow and typhoon influences, water flow currents were in the range of 2m/sto 3.32m/s at the Hangzhou Bay Bridge sites. The floating cranes could safely transport the 2,000t girderfrom the shore to the site and then anchor stably to erect and install the precast concrete box girder. The third major challenge faced by designers and engineers was an area of toxic methane gas thatwas discovered roughly 50 meters underground below the location of the bridge. No drilling could becompleted before the gas pressure was alleviated. To do this, steel pipes measuring 60 cm in diameterwere inserted into the ground, slowly releasing the methane six months prior to drilling.MAJOR TECHNICAL CHARACTERISTICSLarge Scale The bridge is 36 km in total length, of which 35.7 km is bridges over water. The largescale of the project creates new difficulties for bridge construction, operation, and management.Poor Natural Conditions Effective work time is only 180 days per year due to the complicated hydrological andmeteorological conditions with high tide and torrential flow. The geological conditions is comparativelypoor. There are soft soil layers 50 m in thickness and methane in shallow strata within 10 km in the southshoal, which may have adverse effects on the construction of bridge foundations.Poor Construction Conditions and Constraints Construction conditions may be constrained due to the 9 km long tidal-flat area on southbank. Link (2&3)
  • Tight Construction PeriodThe Project is proposed to be completed in 2008. The 70 m full-span prefabricated box girders of the 18km long approachs have to be erected from water due to the constraints of vessels and equipment whilethe 50 m full-span prefabricated box girders of 10 km long approach in the tidal flat section on south bankmust be transported and erected by trolley onto the bridge below. There is only one work face. Theconstruction plan and organization must focus on making sure the bridge project can be complete in timeeven though the offshore operation distance is long and the work load is heavy.Need for High Structure Durability and Aesthetics The bridge is in a high erosive sea environment which will have substantial effects on thedurability of bridge. Furthermore, the bridge is located in the highly developed economical district in theYangtze delta, so a high standard of aesthetic design is required.Architecture, design and structure The Hangzhou Bay is a gulf in the East China Sea where one of Chinas naturalwonders, the Qiantang River Tide, creates fast water and large waves. The area is also a typhoonprone zone. These factors made construction feasibility a major concern for the project and the plan wasonly finalised after nine years of consultation and over 120 technical studies with the help of more than700 experts from throughout the world. The cable-stayed bridge design was selected for the project as it can withstand the Link (2&3)
  • adverse conditions, multi-directional currents, high waves, and geologic conditions at the site. The bridgestructure has also been designed to seismic criteria and will retain integrity in earthquake conditions up toseven on the Richter scale. The 36km length has highway-class road with six, 3.75m lanes, three in each direction. Theoverall width of the bridge is 33m. The roadway grade at cross-slope is 2% and a maximum 4% atlongitudinal slope.Designed for 100 years of service life, the bridge has speed limits of 100km/h for themain spans and 120km/h for land approaches. The bridge has a height of 62m, enabling fourth and fifthgeneration container ships to pass through in all conditions. The total length of cable used in the project is32.2km.Layout and structure The Hangzhou Bay Sea-crossing Bridge is a component of the national trunk line inthehighway network of China’s “Five and Seven arteries in south-north andeast-west directions”. Itprovides the most convenient way across the Hangzhou Bay on the highway from Shenyang to Haikou.The bridge is also an important component of highway network proposal of “2 transverse and longitudinaltrunk lines separately, 18 link roads, 3 loop highways and 3 road corridors” before 2010 in Zhejiangprovince, and thus will effectively connect the southeast cities of Ningbo and ZhouShan of Zhejiangprovince with Shanghai to reduce driving time to under two hours.The Hangzhou Bay Bridge consists of nine sections. The first is the bank lead road to the north approach. Link (2&3)
  • The north approach rests on low piers with post-tension concrete box-girder spans spanning pre-stressedcontinuous concrete box-girders and drill-shaft pile. The north approach leads to the north navigablebridge; a cable-stayed bridge with twin diamond-shaped towers, double cable and steel box-girders. Themain span of the north approach is 448m. Including side spans, the total length is 908m.The north high piers have continuous, 70m, post-tensioned, concrete box-girder spans with a total lengthof 1,470m.The middle bridge approach is laid on low piers with 70m, post-tension, concrete box-girder spans with atotal length of 9,380m.The south navigable bridge is a cable-stayed bridge with an A-shaped single tower, double-cable and steelbox-girders. The main span is 318m, and the total length including side spans is 578m.The south high piers have continuous 70m, post-tension, concrete box-girder spans with a total length of1,400m.The eighth section measures to a total of 19,373m, and is composed of three sections: 6,020m in-water section with 70m girders and steel piles. 10,100m mud-flat section with 50m girders and drill-shafts. 3,253m land section with 30m to 80m girders and drill shaft foundationsThe ninth section is Bank Lead Road at the south approach.Protecting the Hangzhou Bay Bridge Link 2
  • The Hangzhou Bay Bridge, which spans the East China Sea, is constructed of concreteand steel. Silicone water repellents were selected to protect this important landmark from salt watercorrosion, which could damage the structure and deteriorate its appearance. Silicone water repellentspenetrate the pores of concrete and make the surface more resistant to water penetration.Global positioning system Trimble provided Global Positioning Systems for the monitoring of the construction. Theproject required precise positioning for the bridge span off the coast. By using the Trimble 5700 RTKGPS systems with a reference station for differential corrections, accuracy was improved at longerdistances enhancing the productivity. A total of 50 5700 RTK GPS systems were set up where the bridge crosses the Bay ofHangzhou and additional systems were located on barges in order to provide millimeter accuracy for theReal-time positioning of piles and pre-fabricated sections of the bridge.Auxiliary facilities and structures At the middle of the bridge, a 10,000m² service island is planned for drivers to rest andenjoy a full range of services, including hotels, restaurants, petrol stations and a viewing tower. It is alsoexpected the service island will become a tourist destination for watching the Qiantang River Tide. Theservice island will be built entirely on piers to avoid disrupting the tide. Two public parks are alsoplanned on each side of the bridge. Link (2&4)
  • The bridge required the installation of traffic safety devices, monitoring systems,communications equipment, toll plazas, power supply, lighting and maintenance and office buildings.The service centre was slightly damaged in a fire on the March 23, 2010 but opened to touristson December 19, 2010.Investment partners "Construction of the sea-crossing bridge is an indication of China’s increasingeconomic power, and it is expected to boost economic development in the Yangtze River Delta." Of the total project cost of CNY11.8bn ($1.42bn), approximately CNY149m ($18m) wascontributed by 17 non-governmental enterprises in the province. Around 35% of this amount was raisedfrom private companies in Ningbo; 59% was provided as loans from China’s central and regional banks. Link 2
  • The Songcheng Group is the biggest non-governmental shareholder in the project with its investmentaccounting for 17.3% of the basic capital. Construction of the sea-crossing bridge is an indication ofChina’s increasing economic power, and it is expected to boost economic development in the YangtzeRiver Delta, also called the Golden Industrial Triangle. The officials expect to recover the capital costs ofthe project in 15 years. Lv Zushan, Governor of Zhejiang, China’s fourth-largest provincial economy said: "Thebridge will help form a more convenient and efficient traffic network in the Yangtze River Delta,enabling each part to develop much closer relations with one another… We believe the bridge will openmany more opportunities for the region’s overall development and greatly enhance its economic strengthand competitive power."Contractors China Railway Bridge Bureau Group Co. Ltd. was the main contractor for the project.The contract for consulting and engineering services was awarded to Hardesty & Hanover, LLP. ICEparticipated in the project by the use of three ICE V360 tandem vibratory pile drivers to produce thefoundations for the bridge in the middle of Hangzhou Bay. Ty Lin International was the designer of thebridge. Ben C Gerwick provided ship impact protection systems for the bridge.CONCLUDING REMARKS The economic benefits brought by the Hangzhou Bay Bridge is enormous," said Huang Link (2&5)
  • Renwei, vice president of the Shanghai Academy of Social Sciences. It is estimated that savings intransportation cost and time in southern Zhejiang will amount to Rmb40 billion to Rmb50 billion andRmb10 billion respectively within 10 years of the opening of the bridge The Hangzhou Bay Bridge is a large-scale project with complex construction conditions.The primary material quantities are given in Table 1. The exploration and design work was carried out bya joint venture of CCCC Highway Consultant (HPDI) Co., Ltd (General design, north channel bridge,south channel bridge, approaches in the high pier region, and offshore platform design) and ChinaZhongTie Major Bridge Reconnaissance and Design Institute Co., Ltd (approaches in the low pier regionand link road design).Reference :Link1 : WikipediaLink2 : http://www.roadtraffic-technology.com/projects/hangzhou/Link 3 : paper(pdf) Wang RENGUI Civil Engineer CCCC Highwang Consultants CO. Ltd. 85,Deshengmenwai Street,Xicheng District,(100088) Beijing CHINAwrengui@263.netLink 4: http://www.dowcorning.com/content/discover/success-hangzhou-bridge.aspxLink 5: http://www.hktdc.com/info/mi/a/bacn/en/1X002EZV/1/Business-Alert-%E2%80%93-China/Hangzhou-Bay-Bridge-Spurs-World-s-Sixth-Largest-City-Cluster.htm Link (2&5)