Study On Deformation Characteristics And Countermeasures Of Column Pile In Asymmetric Excavation Foundation Pit In Soft Soil Area

Based on the foundation pit project of Zhuhai Jinwan Aviation Urban Civil Art Center,this paper studies the deformation characteristics of the central pillars of asymmetric excavation foundation pits with deep silt soil layers with different excavation depths on both sides.The main research content is as follows:(1)Theoretical analysis of the force characteristics of the central column in the asymmetric excavation pit is carried out.According to the horizontally loaded pile and anti-slide pile theory,the Winkler elastic foundation beam theory is used to derive and establish the asymmetric excavation central column full pile.The long-range deflection differential equation is used to solve the deduced lateral resistance model of horizontally loaded piles in asymmetric excavation pits,and the internal force and displacement analysis of any position within the full-length range of the pile that can be used in matrix calculations is obtained.solution.(2)According to the mechanical properties of the silt soil layer within the site,the corresponding mechanical parameter laboratory test was carried out;and the modified Mohr Coulomb constitutive model was used to carry out the three-dimensional finite element numerical calculation and analysis of the actual asymmetric foundation pit excavation on site.The construction monitoring results were compared and analyzed,and the deformation characteristics of the soil around the asymmetric excavation pit,the retaining structure and the column piles were discussed.(3)The actual foundation pit model is appropriately simplified,focusing on the study of the difference in the excavation depth on both sides of the foundation pit,the depth of the enveloping structure,the reinforcement range in the pit,the stiffness of the column itself,and the depth of the column that affect the deformation of the lower middle column.Through calculation and analysis,it is found that the difference in the excavation depth on both sides of the foundation pit and the stiffness of the column itself have the most obvious influence on the deformation of the column in asymmetric excavation.(4)In view of the excessive horizontal offset of the column piles during the excavation and construction of the foundation pit,a detailed calculation and analysis were carried out,and two construction countermeasures were proposed for reinforcement of steel lattice columns and unloading outside the pit.Two options were analyzed.The effect produced is that the reinforcement of steel lattice column has obvious effect on controlling the displacement of the column,while the unloading scheme outside the pit mainly reduces the lateral displacement of the enclosure structure,and the effect of controlling the deformation of the column is not obvious.