Study On Behavior And Stability Of Pile-anchor Support System Of Double-deep Excavation

With the continuous development of city construction,the supporting technology of foundation pits has undergone rapid changes,and the popularity of support forms and design research has not diminished.At present,due to the continuous reduction of ground space caused by the shortage of land,the foundation pit support project is faced with a huge problem of environmental impact.For the pile-anchor support structure,due to its relatively small space requirement for construction,it has been widely used in the foundation pit engineering.With the acceleration of city construction,the height of the superstructure continues to increase and the architectural forms continue to transform and innovate.Regardless of the depth of the foundation pit or the form of the foundation pit,it will be more complex and changeable,which will surely promote the further development of the computational theory of foundation pit support.This article relies on the background of a deep foundation pit project in Changli.The foundation pit is a double-stepped form and uses a pile-anchor support structure system.The elastic foundation beam method was used to analyze the mechanics behaviors of the double-stepped foundation pits,and the internal forces and deformation formulas of the support system were deduced.The foundation pit model was simulated with the numerical analysis software FLAC3 D,and the main work carried out as follows:(1)The research discusses the background and significance and the research status of deep foundation pits at home and abroad.Meanwhile,the research content is established.(2)According to Rankine's theory of earth pressure and beam method of elastic foundation,the distribution of soil pressure of pile-anchor retaining structure in double-pit foundation pit is studied,and the first step of the foundation pit is analyzed by the influence of the step width B on the second step load,and the formula for the second step support pile earth pressure is deduced,and the overall stability of this type of foundation pit is studied.(3)By adjusting the parameters such as the buried depth of the retaining piles and the width of the steps of the foundation pit,the influence of changing parameters on theinternal forces of the retaining piles was analyzed,and the internal forces and deformation rules of the retaining piles were obtained.(4)Finite-difference software FLAC3 D was used to numerically analyze the support structure of double-pit foundation piles.The mechanical properties of the pile-anchor support structure are analyzed and compared with the theoretically deduced calculation results to analyze the stress characteristics of the deep foundation pit and verify the reliability of the double-stepped deep foundation pit.