A Computational Analysis Of The Influences Of Structural Defects On The Working Behavior Of Retaining Structures For Foundation Pits

The retaining structures for foundation pits are very important to control the deformation and stability of the foundation pits.In actual engineering,due to the complexity of geological conditions,geological exploration,unreasonable design,construction techniques and processes,the retaining structures will inevitably have various defects,resulting in foundation pit accidents.However,at present,there is a lack of quantitative analysis of the working behavior of retaining structures with defects in service at home and abroad.Therefore,on the basis of reading the relevant literature,this paper studies the working behavior of the defective retaining structures through numerical simulation.This paper mainly has done the following research work:(1)Based on the research methods in this paper,the basic methods of internal force and deformation analysis of foundation pit retaining structures were reviewed.(2)A three-dimensional finite element model of the foundation pits was established by using the Venus computing software FRWS and BSC-3D,while the deformation,bending moment,shear force and axial force of the retaining structures under different defect structures were calculated.By comparing with the working behavior of normal retaining structures,the effects of the retaining pile structural defects on the working behavior of the pile itself,the structural defects of the retaining pile on the working behavior of the internal support system,and the internal supporting system defects on the working behaviors of the internal supporting system were studied.The general laws of internal force and deformation of the retaining structures under different structural defects were summarized.Through the above work,the main conclusions were obtained.(1)Stem shrinkage will have an adverse impact on its working behavior.Stem enlargement will increase its bending stiffness and reduce the deformation of the retaining piles.The effect of the length of the bored piles on the working behavior of the pile body is obvious,and the working behavior of the pile is less affected when the pile length is within a reasonable range.When the pile length is less than the minimum embedding depth,the pile will overturn and fail.(2)The stem shrinkage and stem enlargement of the diameter will cause the deformation of the internal support structure to increase,and as the diameter of the defective pile decreases,the internal support will gradually move outside the pit.The effect of bored piles on the internal support structures is not obvious within a certain length range,and bored piles below this length will significantly increase the internal support deformation.(3)When the support is mainly affected by the axial force,the joint defects have little influence on the internal support;Defects in the crown and beam joints will seriously reduce the overall stiffness of the internal support structure,which is most destructive to the foundation pits.Partial concrete segregation will reduce the strength of the supporting structure and increase the deformation of the segregated part.The research results reveal the general laws of the working behavior of the retaining structures in the case of structural defects,and provide a reference for the future working behavior of the retaining structure and related research.