Study On Deformation Law And Influencing Factors Of Deep Foundation Pit Support Structure In Silty Clay Layer

With the rapid development of the city and the rapid growth of the urban population,a series of problems that have emerged urgently need to be solved.Among them,the increasing pressure of urban transportation and the imbalance of national transportation lines seriously limit the urbanization process.Subway transportation The emergence of has solved the problem well.Therefore,various problems of deep foundation pit engineering have gradually emerged.It is particularly important to ensure the safety and stability of deep foundation pits and avoid safety accidents.It is of great significance to study the deformation and deformation laws of deep foundation pits.This paper relies on the deep foundation pit engineering of the working well on the south bank of the Yellow River Tunnel in Jinan,using theoretical analysis,on-site monitoring,numerical simulation and other methods to study the mechanism of deformation and failure of open excavation of deep foundation pits in silty clay layer;through on-site monitoring technology and on-site data analysis,research The deep horizontal displacement of the underground continuous wall,the horizontal displacement of the top of the wall,the vertical displacement of the top of the wall,the axial displacement of the support,the uplift displacement of the bottom of the pit,and the surrounding surface subsidence amount change law are studied in the deep foundation pit of the silty clay layer,and the numerical simulation is used The software fits the deformation of the foundation pit;the influence of the thickness,embedding depth and elastic modulus of the soil structure on the deformation of the foundation pit is studied,and the factors aflFecting the deformation of the foundation pit are clarified.Through the above research,the main conclusions obtained in this paper are as follows:(1)Based on the achievements of domestic and foreign research scholars,the deformation forms and failure modes of the enclosure structure and support system are studied,and the uplift mechanism and enclosure structure of the foundation pit are studied.Deformation mechanism and surrounding surface subsidence deformation mechanism,analysis of pit bottom uplift deformation,envelope structure deformation and surface subsidence change law;analysis of deep foundation pit surrounding surface subsidence,envelope structure horizontal displacement and deformation calculation method of pit bottom uplift,The deformation calculation method suitable for the deep foundation pit of this silty clay layer is determined.(2)Based on the open excavation of deep foundation pit project on the southern bank of the Yellow River Tunnel inJinan,a monitoring plan suitable for the project was developed,and the acquired monitoring data was used to analyze and obtain the deep layer of the ground connection wall during the deep foundation pit excavation of the silty clay layer The horizontal displacement changes in an Ctarch shape55.The horizontal displacement of the top of the wall and the vertical displacement of the top of the wall gradually increase,and the change in the short-side direction is smaller than thechange in the long-side direction.The supporting axial force also increases continuously.The supporting axial force value is obviously smaller than the concrete supporting axial force value,and the surrounding surface settlement deformation curve is gradually showing a “scoop-shaped”trend.The maximum surfece settlement change eimount appears at a distance of 10 m from the edge of the foundation pit,and various monitoring data are within the control value range within.(3)Through the use of Midas / GTS NX numerical simulation software,the deformation law of the enclosing structure deformation,the uplift of the pit bottom and the surface settlement of the deep foundation pit project of the silty clay layer under different working conditions were simulated and studied The comparative analysis of on-site monitoring data shows that the simulation results are basically consistent with the actual deformation law on site.(4)By studying the thickness of the envelope structure,the embedded depth of the envelope structure,and the degree of influence of the soil elastic modulus on the excavation of the foundation pit,it is obtained that the envelope structure increases the thickness of the ground connection wall and increases the depth of the ground connection wall.As well as increasing the soil elastic modulus,the horizontal displacement and deformation of the deep layer of the envelope,the surroxmding surface settlement and the change of the uplift of the pit bottom are all reduced.Control measures.