沉管隧道介绍英文学习教案.pptx

会计学1沉管隧道沉管隧道(sudo)介绍英文介绍英文第一页，共45页。第1页/共44页第二页，共45页。Immersed tunnels are,n nmore advantegous as a subaquous solution in soft soilsn nincreasingly used alternative to traditionally used shield tunnelling,without having the risks associated with pressure chambers and inrush of water.n nalso suitable in water deeper than also suitable in water deeper than it it is possible with the shield method,which essentially is restricted to less than 30 m of water(concerning the maximum air pressure at which workers can safely work).n nAdvantegous as there is less loss in height than with tunnelling deeply under the riverbed,and the tunnel may therefore be shorter overall.第2页/共44页第三页，共45页。n nThe worlds longest and deepest application to date is the twin-tube subway crossing of San Francisco Bay,constructed between 1966 and 1971 with a length of 3.6 miles(5,8 km)in a maximum water depth of 41 m.The 100 m long,15 m wide sections were constructed of steel plate and launched by shipbuilding procedures.n nThe first tunnel of the concrete type was constructed in 1940 in Rotterdam under the Maas estuary.第3页/共44页第四页，共45页。n nThe most profound effect of an immersed tuThe most profound effect of an immersed tun nnel on the environment nel on the environment concerns the element it is meant to bypasswater.concerns the element it is meant to bypasswater.n nThe influence of the tunnel on the groundwater and the surface water The influence of the tunnel on the groundwater and the surface water in the area plays a predominant role in the tunnel design and in the area plays a predominant role in the tunnel design and construction methods.construction methods.n nAn aspect of more recent concern affecting construction is the An aspect of more recent concern affecting construction is the possible presence of contaminated soils that must be removed for possible presence of contaminated soils that must be removed for the tunnel trench.Ways of removing these soils and transporting the tunnel trench.Ways of removing these soils and transporting them to depositories that are especially equipped to receive them them to depositories that are especially equipped to receive them are environmental problems requiring novel techniques and quality are environmental problems requiring novel techniques and quality control procedures.control procedures.n nThe more traditional environmental aspects are those encountered on any The more traditional environmental aspects are those encountered on any construction job:noise,dirt,and traffic hindrance.construction job:noise,dirt,and traffic hindrance.第4页/共44页第五页，共45页。n nThe top of the tunnel should be protected by adequate protective backfill,The top of the tunnel should be protected by adequate protective backfill,extending about 30 m on each side of the structure and confined within dykes or extending about 30 m on each side of the structure and confined within dykes or bunds.The fill must be protected against erosion by currents with a rock blanket,bunds.The fill must be protected against erosion by currents with a rock blanket,protective rock dykes or other means.protective rock dykes or other means.n nTides and current effects of the waterway must be evaluated to determine conditions Tides and current effects of the waterway must be evaluated to determine conditions during dredging and tube sinking operations.during dredging and tube sinking operations.n nImportantly,dredging and backfilling operations should be executed in such a Importantly,dredging and backfilling operations should be executed in such a manner as to limit disturbance in the manner as to limit disturbance in the natural ecological balancenatural ecological balance at the at the construction site.construction site.n nGovernmental agencies having jurisdiction over environmental protection,natural Governmental agencies having jurisdiction over environmental protection,natural resources or local conditions must be consulted and approval of authorities should be resources or local conditions must be consulted and approval of authorities should be obtained in the preliminary design stage.obtained in the preliminary design stage.第5页/共44页第六页，共45页。FoundationFoundationn nThe foundation method to be used must be chosen with due consideration,The foundation method to be used must be chosen with due consideration,first of all,for the subsoil conditions and the degree to which the tunnel will first of all,for the subsoil conditions and the degree to which the tunnel will be subject to be subject to dynamic loadingsdynamic loadings,and,and earthquake loadingsearthquake loadings in particular.Pile in particular.Pile foundations are an option but this solution has been used for a few tunnels only.foundations are an option but this solution has been used for a few tunnels only.For both steel and concrete types of tunnels,the main tasks are:For both steel and concrete types of tunnels,the main tasks are:n nExcavation of a tunnel trench to specifications and to keep it free of siltation Excavation of a tunnel trench to specifications and to keep it free of siltation that may be detrimental to the permanent foundation until this foundation has that may be detrimental to the permanent foundation until this foundation has been constructed and the tunnel has been brought to rest on it.been constructed and the tunnel has been brought to rest on it.n nConstruction of watertight and durable tunnel elements.Construction of watertight and durable tunnel elements.n nInstallation of the tunnel elements in the tunnel trench.Installation of the tunnel elements in the tunnel trench.n nConstruction of watertight and durable joints between the tunnel elements.Construction of watertight and durable joints between the tunnel elements.n nConstruction of a durable foundation for the tunnel.Construction of a durable foundation for the tunnel.第6页/共44页第七页，共45页。n nOnce completed,an immersed tunnel is no different operationally from any other tunnel.Once completed,an immersed tunnel is no different operationally from any other tunnel.However,it is built in a completely different way.However,it is built in a completely different way.The Construction technique:The Construction technique:n nA trench is dredged in the bed of the water channel.A trench is dredged in the bed of the water channel.第7页/共44页第八页，共45页。Tunnel Trench DredgingTunnel Trench DredgingThe dredging works required for the construction of an immersed The dredging works required for the construction of an immersed tunnel will normally comprise some,or all,of the following items:tunnel will normally comprise some,or all,of the following items:n nDredging of a casting or launching basin.Dredging of a casting or launching basin.n nDredging of test pits in the waterway for evaluation of siltation of tunnel Dredging of test pits in the waterway for evaluation of siltation of tunnel trench.trench.n nWidening of the existing navigation channel in order to provide temporary navigation Widening of the existing navigation channel in order to provide temporary navigation channels outside the marine working area.channels outside the marine working area.n nCompensation grouting to make up for the reduction of the waterway cross Compensation grouting to make up for the reduction of the waterway cross section caused by the permanent tunnel works,and thereby avoiding section caused by the permanent tunnel works,and thereby avoiding changes in hydrographical and biological conditions in the waterway.changes in hydrographical and biological conditions in the waterway.n nDredging of the tunnel trench for the immersed tunnel section.Dredging of the tunnel trench for the immersed tunnel section.n nDredging of an access channel between the casting/launching basin and the tunnel Dredging of an access channel between the casting/launching basin and the tunnel trench.trench.n nMaintenance dredging.Maintenance dredging.第8页/共44页第九页，共45页。The dredging volume is generally in the order of l million m3 per The dredging volume is generally in the order of l million m3 per km for a typical four-lane motorway tunnel.km for a typical four-lane motorway tunnel.The excavation must provide space for the prefabricated tunnel The excavation must provide space for the prefabricated tunnel body;the sand or gravel foundation under the body as wells as the body;the sand or gravel foundation under the body as wells as the protective backfill on the sides and on the top of the tunnel.protective backfill on the sides and on the top of the tunnel.Because the top of the backfill has to be kept below the existing Because the top of the backfill has to be kept below the existing or future navigation channel profile,a trench bottom level at or future navigation channel profile,a trench bottom level at between 25 and 30 m below Low Water level is quite common.between 25 and 30 m below Low Water level is quite common.Immersed tunnels in deep or open sea may require specially built Immersed tunnels in deep or open sea may require specially built dredgers.dredgers.第9页/共44页第十页，共45页。Except for cases where very soft subsoil,deemed unsuitable for support of the Except for cases where very soft subsoil,deemed unsuitable for support of the tunnel,has to be removed and replaced by suitable materials,the general tunnel,has to be removed and replaced by suitable materials,the general requirements for the dredging of the trench bottom are:requirements for the dredging of the trench bottom are:n nA clean,even surface,as close as possible to the upper acceptable limit in order to avoid A clean,even surface,as close as possible to the upper acceptable limit in order to avoid the economic consequences of having to fill overdredged areas;the economic consequences of having to fill overdredged areas;n nA minimum disturbance of the remaining exposed upper soil layers in the trench A minimum disturbance of the remaining exposed upper soil layers in the trench bottom,in order to limit the changes in the geotechnical characteristics of the subsoil.bottom,in order to limit the changes in the geotechnical characteristics of the subsoil.The possible physical disturbance and softening of the exposed soil layers in the The possible physical disturbance and softening of the exposed soil layers in the trench bottom,particularly in cohesive subsoils,can have a considerable influence trench bottom,particularly in cohesive subsoils,can have a considerable influence on the geotechnical behaviour of these soil layers later-and,hence,on the quality of on the geotechnical behaviour of these soil layers later-and,hence,on the quality of the tunnel support as a whole.This in turn influences the design of the structural the tunnel support as a whole.This in turn influences the design of the structural tunnel body and,thus,eventually the overall economy.These technical tunnel body and,thus,eventually the overall economy.These technical requirements are met by:requirements are met by:n nUsing the proper type of dredger(s).Using the proper type of dredger(s).n nCareful controlling the position of the cutting tool,bearing in mind that the dredging Careful controlling the position of the cutting tool,bearing in mind that the dredging normally has to be done in tidal waters and sometimes in waters subject to swell and normally has to be done in tidal waters and sometimes in waters subject to swell and waves.waves.n nCareful planning the dredging operation in order to avoid undesirable failures of the slopes.Careful planning the dredging operation in order to avoid undesirable failures of the slopes.n nTiming of the dredging operation,in order to limit the time that the trench bottom is exposed Timing of the dredging operation,in order to limit the time that the trench bottom is exposed and,at the same time,to limit the sedimentation caused by subsequent dredging nearby.and,at the same time,to limit the sedimentation caused by subsequent dredging nearby.第10页/共44页第十一页，共45页。第11页/共44页第十二页，共45页。Construction of Tunnel Elements Construction of Tunnel Elements n nThe tunnel elements are made fully or partially buoyant by means of temporary bulkheads The tunnel elements are made fully or partially buoyant by means of temporary bulkheads installed at the element ends.installed at the element ends.n nIn addition to providing proper structural strength and controlling the weight of the element,the In addition to providing proper structural strength and controlling the weight of the element,the main design and construction task of the reinforced concrete tunnel is to provide a watertight main design and construction task of the reinforced concrete tunnel is to provide a watertight structure.structure.For many years,the answer was to wrap the tunnel element in a watertight For many years,the answer was to wrap the tunnel element in a watertight membrane composed of steel on the bottom,outer walls and even on the roof.membrane composed of steel on the bottom,outer walls and even on the roof.Alternatively,bituminous membrane has been used on the outer walls and roof.Alternatively,bituminous membrane has been used on the outer walls and roof.n nIn recent years,reinforced concrete tunnels without a membrane at all are being used.Above In recent years,reinforced concrete tunnels without a membrane at all are being used.Above all,this will require sophisticated control of concrete temperature during hardening to avoid all,this will require sophisticated control of concrete temperature during hardening to avoid cracking.In order to reduce the development of cracks during hardening,primarily in the cracking.In order to reduce the development of cracks during hardening,primarily in the walls when they are cast after the bottom slab,cooling of the lower part of the walls has been walls when they are cast after the bottom slab,cooling of the lower part of the walls has been the practice for many years.Insulation of the formwork and careful sequencing of stripping of the practice for many years.Insulation of the formwork and careful sequencing of stripping of the forms are also used to control the concrete temperature.the forms are also used to control the concrete temperature.n nImproved field concrete technology aimed at minimising the development of cracks during Improved field concrete technology aimed at minimising the development of cracks during hardening,combined with moderate prestressing,seems to be the course to follow.hardening,combined with moderate prestressing,seems to be the course to follow.第12页/共44页第十三页，共45页。n nTunnel elements are constructed in the dry,for example in a casting basin,a Tunnel elements are constructed in the dry,for example in a casting basin,a fabrication yard,on a ship-lift platform or in a factory unit.fabrication yard,on a ship-lift platform or in a factory unit.第13页/共44页第十四页，共45页。Casting BasinsCasting Basins n nThe tunnel elements can be prefabricated in a casting basin or in a dry dock.For shorter roadway and