Application Research On Levelling Design Of Variable Stiffness Foundation In Coastal Soft Soil Area

In the trend of economic globalization,countries are strengthening exchanges,economic development is progressing rapidly,cities are prospering,and skyscrapers are rising above the ground.Pile foundations are widely used in engineering construction because they can better meet the bearing capacity of pile foundations.Previously commonly used pile layout methods used natural foundations and evenly distributed piles.When a uniformly distributed load is applied to a composite foundation that is evenly distributed with the natural foundation,the vertical support stiffness is evenly distributed,and the foundation subsidence produces a butterfly-shaped distribution pattern that is large inside and small outside.Produces uneven settlement.If the load on the superstructure is a frame core tube structure or other non-uniform structure,the settlement difference will be more pronounced.Different settlements have a significant impact on the reliability of the superstructure.How to adjust subsidence of different structures to keep them stable is a topic that scholars have been studying in recent years.In soft soil area engineering examples,natural foundations generally fail to meet bearing and deformation requirements,and composite foundation basis form can be used to control uneven subsidence of buildings.Based on previous studies,this paper analyzes the principles of differential settlement controls for variable-rigidity piles in composite foundations,compares the settlement of pile foundations under different foundation morphologies and different pile lengths,and compares the settlement of pile foundations.We propose a design step for variable rigidity leveling.In this article,we will analyze the principles of differential settlement control of variable stiffness piles of composite foundations by combining specific engineering and hydrogeological conditions of the Tianjin skyscraper project.An analytical model was established in combination with FLAC3 D finite element software,and the settlement value of the frame core tube structure after variable stiffness leveling was analyzed in combination with actual measurement results.The conclusions reached are as follows:(1)In combination with actual engineering data,the frame core tube structure skyscraper is designed with variable stiffness such as long pile and short pile setting,pile spacing adjustment,which relatively enhances the pile foundation stiffness in the core area.Weakens the pile foundation rigidity of the outer frame.It can better reduce payment gaps and also reduce construction costs.(2)Analyze the joint analysis of superstructure-foundation-pile-soil,adjust "pilesoil support stiffness distribution as the main line",and rationalize the rigidity of the foundation of the pile by changing the layout method of the pile.This can reduce maximum and uneven settlement.(3)By comparing and analyzing the settlement difference between the natural foundation and the composite pile foundation,the variable rigidity pile arrangement method in the frame core tube structure greatly suppresses the uneven settlement of the foundation and reduces the adverse effect on the building.(4)The values simulated by the model are in close agreement with the results of field observations,and using numerical simulation methods in real projects can more accurately predict the effects of pile subsidence.Similar projects can be used for reference in the future.