Model Test And Theoretical Study Of Lateral Bearing Characteristics Of Non-circular Cross-section Piles In Soft Clay

In recent years,infrastructure construction has been quickly developed,which imposes lateral loading requirements on pile foundations.The construction of large infrastructures in areas with soft clay soils can be challenging,and pile foundations are often chosen as a solution to improve the bearing capacity of soft clay.Traditionally,pile foundations are usually designed with circular or annular cross-section,but to reduce the project cost while meeting the bearing capacity requirements,non-circular cross-section piles have been introduced in engineering practice in recent years.Compared to traditional circular piles,non-circular cross-section piles provide higher lateral bearing capacity with less material cost.In this paper,the lateral bearing characteristics of rectangular cross-section pile,cross-section pile and H-beam pile are studied by using lateral load model test,numerical calculation,and theoretical analysis.A theoretical model of p-y curve applicable to non-circular cross-section pile is established.The mechanism of the difference between non-circular section piles and circular section piles is shown.The main work of this paper is as follows:(1)The lateral load bearing characteristics model test of non-circular section pile is carried out.The pile moment and shear distribution,the p-y curve law of model piles with different pile types(rectangular,cross-shaped and H-beam)and different cross-sectional size ratios are obtained.(2)Based on the finite element limit analysis software Optum G2,a two-dimensional ultimate load analysis was carried out for non-circular section piles.The empirical formula of ultimate load carrying capacity coefficient Npu considering different loading angles β is obtained.(3)Based on the finite element software Plaxis 3D,a three-dimensional numerical analysis is carried out for non-circular section piles,and the stiffness distribution of noncircular section piles under different loading angles is obtained.The variation law of initial stiffness Ki of p-y curve with respect to each variable is obtained,and the empirical formula of initial stiffness Ki considering different loading angles β is proposed.(4)The variation law of the bearing capacity coefficient Np along the depth z direction is discussed in depth,and the theoretical model of p-y curve applicable to non-circular section piles is constructed based on the two-dimensional ultimate bearing capacity coefficient Npu and three-dimensional initial stiffness Ki.The reliability of the p-y curve theory is verified by comparing the theoretical p-y curve with the model test p-y curve.The analysis of p-y curve parameters is carried out to explore the variability of p-y curves under the effects of different pile types,different section size ratios and different loading angles.(5)Based on Winkler foundation beam equation and p-y curve,a theoretical calculation model for lateral loading of non-circular section piles is established,and the numerical solution of the theoretical model is obtained by using the numerical method of bvp4 c function solution in MATLAB.The distribution law of pile displacement,pile bending moment and pile shear force of each non-circular section pile were obtained.The reliability of the proposed theoretical calculation model is verified by using the 3D elasticplastic numerical analysis from Plaxis 3D.Through the analysis of pile internal force parameters,the variation law of pile internal force under different parameter conditions is discussed.