Calculation And Analysis Of The Structural Effect Of Shield Tunneling Driving Crossing Platform

Present,along with the rapid development of economy,significantly speed up the process of urbanization,the city population density increase rapidly,followed by traffic congestion problems also gradually highlights,is becoming more and more attention by the people,for the big cities are constructing subway,alleviate the urban traffic pressure.So far,most of the subway when the building is still adopt the way of the station structure and interval structure construction respectively.Common construction methods are applied to the station: cut and cover,covered excavation,PBA method,Common interval construction method including: cut and cover,mine tunnelling method,Shield Method.In many construction method,using the PBA method to build the station and the shield method is used to build interval applied most widely.But in this two kinds of method,is employed in the process of building of the subway,often because of unreasonable construction coordination,causing delays and other issues.To solve these problems,this article selects the Beijing subway line 16 wan quan river bridge station project as an example,for its use of shield interval with PBA station building construction method optimization research,comparison of structural displacement caused by different construction schemes,on this basis,the research analysis in the process of the construction structure internal force and bearing capacity,and determine whether the structure safety.Through this study,solve the problem of engineering with construction of station and the interval,and provide reference for such projects in the future design and construction.During the study adopts the method of combining theoretical analysis and numerical simulation,through the establishment of multiple computing model simulating the construction process,from the aspects such as structure displacement and structure stress analysis of construction schemes comparison,finally get the optimum construction scheme and parameters of shield construction.Research methods and research the conclusion summed up as follows:?1?Shield tunnel structure system research mainly include: engineering geology,the supporting system of tunnel construction,time effect and space effect and so on four aspects.By analyzing on the mechanical behavior of a single tunnel construction,shield construction for the front shield is the process of extrusion-shear-unloading of soil.?2?Establish "formation-structure" model to simulate the proposed construction plan,by comparing the different construction scheme of structure of pile,pile,vault key positions such as node displacement of construction scheme optimization.Finally confirmed by this study proposed scheme 2 to cooperate in the process of construction,shield construction of the station structure affect the minimum.?3?Combining the calculation formula of shield thrust,optimize the jacking force of shield construction,finally confirmed when shield thrust for 0.8k₀?h,minimal impact of shield construction of the station structure.?4?"Load-structure" model is established,and the structure construction process are uniformly distributed load and model structure formation-the calculated displacement as the load on the model,key location structure internal force is calculated.After analysis and comparison to the following conclusion:?Initial internal force of retaining structure in the shield construction process compared to shield construction before the change is not big,but according to the early underground engineering supporting structure design experience and reference for similar project design,the structure in the process of construction safety.?In accordance with the relevant specification for the station structure steel pipe concrete pile and concrete pile used for calculation,the structure of pile internal force does not exceed their bearing capacity,the existing structure meets the requirement of security and stability of pile foundation.