Study On Mechanical Properties Of Retaining Structures Considering Rheological Properties Of Soil

The word"rheology"comes from the ancient Greek philosopher Heractitus saying"????????",which means that everything flows.The rheological properties of soil can directly affect the long-term stress and deformation performance of retaining structures.Summarized based on the predecessors'research,and on the study of the rheological properties of soil on the basis of the mechanical performance of single row retaining structure,rheological properties of soil was established three row pile retaining structure of two-dimensional finite element model,the stress characteristics of combined retaining structure of three pile internal force and deformation of the retaining structure has carried on the comprehensive analysis and calculation,The influence of soil rheological material parameters and retaining structure design parameters on retaining structure mechanical properties was studied by orthogonal test.Finally,the secondary interface UPFS is developed based on ANSYS,and the compiled creep constitutive model is applied to engineering practice by writing and modifying the corresponding user subroutines.The main research work and conclusions are as follows:(1)A two-dimensional finite element model of single-row retaining structure considering rheological properties of soil was established,and the rheological mechanical parameters of the model were calibrated.Through numerical simulation,it is found that the horizontal displacement curve of retaining structure pile top with time can be divided into three stages after considering the rheological properties of soil,that is,the stage of rapid increase,the stage of stable development and the stage of stability.(2)A two-dimensional finite element model of three rows of pile retaining structure is established considering the rheological properties of soil.The calculation results show that the rheological properties of soil have significant effects on the internal forces and deformation of retaining structure,which are mainly shown as:a.Whether the rheological properties of soil are considered has no effect on the horizontal displacement and bending moment variation trend of each pile row.B.Relative to the retaining structure without considering rheological properties,under given rheological parameters,the maximum horizontal displacement and the maximum positive bending moment of the pile after considering rheological properties increase by 26.6%and 28.98%.(3)The orthogonal test was used to analyze the influence of soil material rheological parameters and retaining structure design parameters on the mechanical properties of three rows of micro-steel pipe piles.The results showed that:a.The creep parameter E1 is the significant factor affecting the maximum horizontal displacement of each row of piles,row spacing is the significant factor affecting the maximum positive bending moment of each row of piles,and creep parameter?1 is the significant factor affecting the stability time of each row of piles.B.The optimal design scheme of three rows of micro-steel tube piles is creep parameter E₁,creep parameter?₁,pile diameter,row spacing,and soil stiffness between piles are respectively 70.541MPa,0.436d·MPa,299mm,2m,K.(4)By writing and modifying usercreep user subroutines,we develop the Kelvin creep constitutive model of S-9 and 5 element extension,and verify the correctness of the compiled subroutines.Developed by subroutine was applied to underground garage in Shanghai cement mixing pile and slope supporting projects,horizontal displacement of retaining structure is analyzed with the time changing law,study the various parameters on the retaining structure of foundation pit retaining structure horizontal displacement and the effect of and from reducing the deformation of retaining structure,reduce the project cost and achieve better economic benefits,The optimal scheme of retaining structure of cement reinforced soil mixing pile is obtained.