Force Analysis And Construction Technology Research Of Temporary Facilities Of Qimen Port Cable-stayed Bridge

In recent years,in our country’s rivers,one after another "the world’s most" bridges are in full swing.With the continuous increase of bridge span and the continuous encryption of railway,highway and other transportation networks,bridge experts and bridge engineers have to innovate and explore the construction technology of bridges.It is also a bold attempt again and again that makes the construction technology of bridges increasingly rich and mature.Cable-stayed bridge,as a cable-stayed system,is the main type of long-span bridges and the most popular type of long-span bridges in China.At the same time,the cable-stayed bridge has strong spanning capacity and is less restricted by the clearance under the bridge and the elevation of the bridge deck,so it is easy to navigate.The newly-built Qimen Port cable-stayed bridge spans Qimen Port,and its engineering geological and hydrological conditions are complex.The design and calculation of steel trestle,drilling platform and cofferdam are needed in the construction of super-large bridge.In the current construction,the selection of trestle,drilling platform and cofferdam scheme will often affect the construction difficulty of the project,thus affecting the size and duration of the project.Therefore,the design of temporary facilities is of great significance for bridge construction.Taking Qimen Port Cable-Stayed Bridge as an example,this paper focuses on the following aspects:The layout of hole spans and structure selection of steel trestle and drilling platform are designed.The unfavorable loads are analyzed and combined.The structure is checked by Midas Civil finite element software.It is concluded that the force of Bailey sheet,the force of distribution beam and the length of steel pipe pile meet the requirements of the code to ensure the safety and reliability under construction load.Combining with the design scheme of Qimen Port cable-stayed bridge,considering the topographic and geological conditions of pier,local meteorological and hydrological data,and combining with the development of cofferdam construction technology in recent years,the advantages and disadvantages of various cofferdam construction and other requirements,the type of cofferdam is finally selected as Larsen IV steel sheet pile cofferdam,and the construction steps of cofferdam are analyzed.In order to select the reasonable type of steel sheet pile and the characteristics of internal supporting material,the strength calculation of Larsen IV steel sheet pile and the stress calculation of purlin are carried out,and the characteristics of materials required for internal supporting structure are established.In order to ensure the safety of construction,the checking calculation of uplift resistance of foundation pit bottom soil and piping at foundation pit bottom of cofferdam are carried out,which ensures the feasibility and safety of cofferdam design scheme.On the basis of ensuring construction safety,referring to the checking resultsand the construction requirements of Larsen IV steel sheet pile,the steel sheet pile cofferdam of 22 # and 23 # piers of Qimen Port cable-stayed bridge is designed,and the feasibility and reliability of construction are demonstrated.Based on the results of design checking and combined with engineering geology,hydrogeology and climatic conditions,the construction technology and process of steel trestle,drilling platform and steel sheet pile cofferdam are comprehensively expounded.Finally,the construction methods and techniques of the main tower construction scheme,tower crane layout scheme,main tower column construction,main tower cross beam construction,main beam construction scheme,0# block cast-in-place construction,hanging basket cantilever construction,main beam closure section construction,cable-stayed hanging and cable-stayed tensioning of Qimengang cable-stayed bridge are elaborated.Midas Civil structural analysis software is used to simulate and analyze the construction stages of cable-stayed bridge.The cumulative displacement of the girder after creep is completed and the maximum vertical displacement of the girder under live load is calculated,which provides a basis for setting the pre-camber of the girder.