Optimization And Design Optimization Of Deep Foundation Pit Support Scheme For Foshan Subway Railway Station

The metro has become an increasingly popular solution to urban traffic congestion with the rapid development of my country’s urbanisation level,however,the process of building subway station involves the arduous task of excavating deep foundation pits,the complexity and variability of engineering has promoted the research and development of new support technology for deep foundation pits,so establishing a fuzzy optimum selecting model in complex and diverse support schemes has certain theoretical and practical application value.Consequently,in an effort to meet the safety feasibility,construction convenience and environmental economy of deep foundation pit support.This paper relies on the project of the subway station of Foshan Line 3 Railway Station.The major issues are the following:(1)Appropriate to the background,engineering geology and hydrological conditions of the project,an integrated assessment on the benefits and limitations of common deep foundation pit support types have been taken.Four primary options for the vertical enclosure structure of foundation pits have been determined: drilling grouting piles +water seal,underground diaphragm wall,pile formed by TRD method + section steel,and composite soil nail wall + prestressed anchorage cables.(2)After the systematic establishment of the evaluation index system of the deep excavation supporting structure of the metro station,the subjective and objective weights of the evaluation indexes are respectively determined,which based on the theoretical framework of the Analytic Hierarchy Process and the Entropy Weight Method.After that,the two are combined by game theory to obtain the comprehensive weight.Subsequently,make a comprehensive fuzzy judgement by identifying the associated membership degree matrix.The optimal alterative of the model is shown as underground diaphragm wall support.This scheme’s overall value based on the first grade indexes is 0.5674,and the total value using the second indexes is 0.552.(3)The variation characteristics of the enclosure structure are summarized by the sorting and analysis of the measurement projects and data.First of all,the horizontal displacement curve of the wall is distributed in a "parabolic" shape,which showing a large absolute value in the middle area.Secondly,the surface subsidence of the periphery is distributed to form a groove.The deformation is constantly increasing with the demolition of the support.In addition,with the progress of the construction and the environmental impacts,the axial force value of the inner support fluctuates.(4)Using FLAC3 D finite difference technology to simulate the complete process of excavating and supporting the station’s deep foundation pit.Moreover,the variation characteristics of the enclosure structure were identified,which combined with different excavation phases’ information and the comparison with actual monitoring data.The reliability of FLAC3 D software is preliminarily verified.Finally,the support scheme is optimally designed in accordance with two influencing parameters,horizontal intervals and vertical intervals of the support.Figure [50] Table [23] Reference [83]...