Study On The Influence Of Culvert Foundation Pit Construction On Plain Concrete Pile Composite Foundation In Soft Soil Area

Compound foundations in the culvert pit construction caused by engineering accidents are not uncommon,and the culvert pit construction process in the compound foundation deformation and the mechanism of internal force change is not yet perfect.In this paper,based on the previous research combined with actual engineering cases,the case of culvert engineering construction caused by rigid pile composite foundation in the engineering accident of fractured vegetative concrete pile is analyzed.First,MIDAS-GTS finite element software was used to simulate the actual project and analyze the causes of the fracture of the vegetative concrete piles on site.Subsequently,the influence of the length and stiffness of the steel plate pile enclosure structure on the internal force and deformation of the vegetative concrete pile was analyzed in depth;the influence of the pile cap,pile length,pile diameter and stiffness of the vegetative concrete pile was analyzed;finally,the construction of the culvert project was optimized and an optimized construction plan was proposed,which showed that(1)The fracture of the plain concrete pile in the soft soil area is due to the excessive bending moment of the vegetative concrete pile,and the vegetative concrete pile on the outside of the pit may also have broken.The reason why the pile body is subjected to excessive bending moments may be related to the fact that the pile cap has not been constructed.(2)Increasing the pile length and rigidity of steel plate piles cannot effectively reduce the stress and bending moment in vegetative concrete piles,so increasing the length of steel plate piles to prevent vegetative concrete piles from being broken is not an effective method for this project.(3)Increase the length of the plain concrete pile(1.5L is recommended),pile diameter(1.25 R is recommended)and stiffness in this project to prevent the pile from breaking duringconstruction,and increasing the pile diameter is the most effective measure.(4)In the xcavation of actual composite foundation pit,the roadbed stacking distance can be appropriately increased and internal support can be set to reduce the pile body bending moment,so as to prevent the plain concrete pile from being broken.In summary,the actual project can be prevented by construction pile cap,increasing the pile length,pile diameter and stiffness of vegetative concrete piles,increasing the pile loading distance on the side of the pit and imposing built-in methods to prevent the vegetative concrete piles from being broken in the construction process.