Studyon Horizontal Ultimate Bearing Capacityof Single Pile Basedonthe Finite Element Strength Reduction Method

Pile foundation is widely used in modern engineering construction,because it has the advantages of high bearing capacity,large stiffness,and small settlement.The pile foundation can transfer the load from the superstructure to the deep foundation,improved the bearing capacity of the foundation and reduced the settlement of the building.The ultimate bearing capacity of the pile under horizontal load is determined by the properties of the soil around the pile,the material of the pile,the pile top and the constraint condition of the pile end,the bending rigidity of the pile and the depth of the pile.The method of determining the horizontal bearing capacity of pile foundation is mainly based on logarithmic increment method.In recent years,with the development of the strong reduction principle,it has been used to determine the ultimate bearing capacity of pile foundation.The ultimate bearing capacity of the pile is determined by this method,and the ultimate bearing capacity of the pile is not very large,but the latter has its unique physical and mechanical significance.The principle of strength reduction is a kind of finite element method used to calculate slope stability coefficient F in slope engineering.The method has been successfully applied to slope stability analysis.However,the application of ground foundation and tunnel engineering began to enter the initial stage.At present,many scholars try to calculate the bearing capacity and stability of tunnel by strength reduction method.Some scholars have successfully simulated the ultimate bearing capacity of vertically loaded piles by the strength reduction principle.At present,no scholars have studied the principle of strength reduction in horizontal loading pile,which has a great relationship with the calculation of the horizontal ultimate bearing capacity of piles.In this paper,the strength reduction method is used to study the horizontal bearing capacity of pile foundation.First of all,this paper gives a review on the basic theory of pile foundation,and systematically introduces the horizontal bearing capacity of pile foundation theory and development,as well as their respective advantages.Then list a little classical theory of pile foundation.This paper systematically introduces the horizontal bearing capacity of pile foundation theory and their respective advantages.Afterwards describes the principle and application of strength reduction method,and discusses the feasibility and necessity of strength reduction method in pile foundation calculation.In the next place,give an account of the use of numerical calculation and the simple application of finite element software MIDAS/GTS.Finally,combined with the engineering example(artificial filling pile),and using the method of strength reduction and MIDAS/GTS software,to simulate the pile foundation bearing capacity.Validating the calculation of bearing capacity of pile foundation by strength reduction method is feasible.The strength reduction method is used to analyze the ultimate bearing capacity of pile foundation.The horizontal deformation characteristics of pile foundation are simulated,and the ultimate bearing capacity of pile foundation based on strength reduction method is studied.Through the simulation of pile foundation,the following conclusions are obtained:(1)The model of horizontal loading pile is solved by MIDAS/GTSNX software.Pile and soil element types are made of solid element,the pile soil contact is simulated by the plane contact element,pile top horizontal concentrated load applied 10 step loading,the surrounding soil applied with unilateral constraints,the underlying soil applied to the constraint three.Finally,the load characteristics are analyzed successfully.According to the results of calculation,this paper extracts the load displacement value of pile foundation,and draws the horizontal displacement curve of the top of pile foundation under horizontal load,and the curve has certain nonlinear.The curve is basically consistent with the measured N0 2pile foundation curve,and the simulation results can basically reflect the stress condition of the pile foundation in the field.(2)The load displacement curve of laterally loaded pile foundation is collated,and the logarithmic load displacement curve of pile under horizontal loading is obtained.Determine the limit value of 862 kN bearing capacity of the pile horizontal horizontal displacement curve of the logarithm of the load level simulation of pile foundation with load increment method,the horizontal displacement of the corresponding close to 50 mm,when the maximum horizontal displacement of 46 mm simulation load of 800 kN.(3)Strength reduction of several soil layers is carried out by strength reduction factor,and the horizontal displacement value of corresponding reduction coefficient is solved.Using strength reduction principle to draw the displacement reduction curve,the curve of the inflection point,and in accordance with the inflection point and ultimately determine the bearing capacity of pile limit is 880 kN,and the level of the ultimate bearing capacity determination and the logarithm of 862 kN or less,the relative error is 2%,has its unique physical meaning but use strength reduction.(4)Further discussed(near the pile top displacement node near)relationship unit stress increases with the reduction of the curve,the pile top stress of X and ZX as well as the tau unit and the displacement stress reduction coefficient curve also appeared inflection point phenomenon,but the stress of Z in the complex of small changes the range appeared two inflection point,but in a large range is also showing an inflection point phenomenon,which shows that the strength reduction of stress has certain effect.