Experimental Study On Effective Bearing Capacity Of Skewed Cast-in-place Piles Caused By Excavation Of Deep Soft Soil Foundation Pit

Pile foundation is one of the widely used foundation forms in current engineering construction,especially for buildings and structures on soft soil foundation,which has significant advantages in controlling uneven settlement of upper structures and supporting upper loads.After the construction of the cast-in-place pile foundation on soft soil site,it is often affected by the lateral pressure of the excavation of the foundation pit,which frequently leads to varying degrees of deviation of the already constructed vertical cast-in-place pile foundation.This phenomenon is common in engineering construction;however,the performance research on the bearing capacity of single and group piles of skewed cast-in-place piles in soft soil areas is relatively scarce,and how to accurately evaluate the effective bearing capacity and working characteristics of skewed cast-in-place pile foundations is currently a hot and difficult issue in engineering construction.Based on extensive reading of research materials on the working characteristics of skewed bored pile foundations at home and abroad,this paper further investigates the vertical load transfer mechanism and failure mode of skewed bored piles,and proposes a calculation method for the effective bearing capacity of skewed bored piles.Using the finite element numerical analysis software Midas GTS,a mechanical model is established to simulate the effect of excavation-induced skewing of bored pile foundations in soft soil sites and comprehensively analyze the factors affecting the effective bearing capacity of skewed bored piles,providing guidance for accident handling of skewed bored pile foundations.Finally,based on the three-dimensional finite element simulation analysis results and relevant measured data of bored piles in the Zhuhai Hengqin Macau New Neighborhood project,this paper analyzes in detail the reasons for the skewing of bored piles in soft soil sites and the factors affecting the bearing capacity of skewed bored piles,and provides reasonable suggestions for handling bored pile foundation accidents.The main research content and results are as follows:(1)This article introduces the basic characteristics of deformation and stress of pile foundations in excavated pits during the excavation process,as well as the bearing mechanism of deep soft soil ground injection piles.It is recognized that the use of the Midas GTS three-dimensional finite element numerical analysis method in the experimental research on the deviation of injection pile foundations and effective bearing capacity caused by excavation of pits in soft soil sites is more reflective of reality and computationally convenient,providing a theoretical basis for this study.(2)Through the comparative analysis of the three-dimensional finite element simulation analysis results of the cast-in-place pile foundation of the Zhuhai Hengqin Macau New Neighborhood Project and the relevant measured data,the rationality and correctness of the determination of the effective bearing capacity of the inclined grouting pile in the soft soil site proposed in this paper are verified.(3)Based on the applicability of finite element analysis software Midas GTS in geotechnical engineering,this study simulated the influence of different factors such as pile deflection rate,pile diameter,and silt thickness on the bearing capacity of skewed cast-in-place piles in soft soil sites,and proposed reinforcement measures for skewed cast-in-place pile foundations.