Study On Range Of Expanding Bottom Effect Of Uplift Piles With Enlarged Bottom

With the rapid development of new urbanization in China,the development and utilization of underground structure presents a good state of development.The construction of underground space structure is increasing gradually,which makes the requirements for the stability of the building(construction)foundation more stringent.The enlarged-base uplift pile is widely used in this background.The research method of finite element method is adopted in this paper,which is to obtain the ideal numerical solution of the enlarged-base uplift pile by numerical method of the physical parameters of the pile and the change of the geometric structure of the pile.In this paper,the theoretical analysis of enlarged-base uplift pile is carried out,and the finite element method is used to calculate the bearing capacity of the belled pile and to determine the influence range of the belled pile.The work carried out is as follows:(1)Using the ABAQUS finite element software commonly used in geotechnical engineering,a three-dimensional pile-soil model is established.The interaction of pile-soil contact,boundary conditions and initial stress field are considered comprehensively.The working mechanism of pile can be obtained by applying load method or displacement control method.(2)Numerical analysis is beneficial to the study of the common law of the bottom pile.In this paper,it is found that the diameter of the bottom(D),the angle of internal friction of soil(?)and the elastic modulus of the soil(E_s)have a great influence on the ultimate bearing capacity of the pile,and the range of the influence on the bottom is proportional to that of the pile.(3)Generally speaking,the ratio of expansion to diameter recommended by engineering is 2,with the increase of pile length L,the bearing capacity of the pile is increased,and the influence range of bottom expansion tends to be stable.(4)According to the finite element method,the critical depth of the enlarged-base uplift pile tends to be stable with the change of pile length,and based on the slip line theory,the numerical calculation of the enlarged bottom pile under the critical depth is carried out,and the calculation formula of the bearing capacity of the enlarged bottom long pile is deduced,and the formula is verified numerically.