Numerical Simulation Of Residual Stress Of Jacked Pile And It's Effect On The Behavior Of Pile

In recent years, with the rapid development of city infrastructure, high buildings are increasing and intensive, the pile foundation is becoming main form of high building. People attach importance to jacked pile because of it's merit of little quiver, loud noise and good to environment. The jacked piles are widely used in southeast of China and big cities like Tianjin and Shanghai, and make good effect. It is a potential development technology.When the pile is pressed in, there is residual stress around the pile. When testing the pile the test instrument is set to zero, so the result of the test ignores the influence of the residual stress. The problem is very complicated because a lot of basic problems are involved. Although different methods have been adopted by many researchers, no satisfactory results have been obtained until today. This paper is on the basic of the fruit of the experts at home and abroad and takes the residual stress of the jacked pile as an object. A rational finite element model that accorded with the actual process of jacked pile was put forward by using the commonly used software. The penetration process of this model which used finite deformation theory and adaptive mesh technique was simulated through the contact between pile and soil and displacement loading. The effects of the pile bearing capacity caused by residual stress were given.The results show that the residual stress doesn't affect the total ultimate bearing capacity of the jacked pile, but there are some influences on the bearing capacity of the pile. The results show that the residual stress leads to higher measured shaft resistance and lower toe resistance. The share scale of the shaft bearing capacity is estimated highly or the toe bearing capacity is estimated lowly. The shaft resistance is measured highly on the top parts of the pile and lowly on the bottom.The skin friction coefficient of pile, diameter and stiffness of the pile and modulus of deformation of the soil influence the residual stress. The larger the skin friction coefficient of pile is,the location of the neutral surface is near the top of the pile more and more. With the skin friction coefficient of pile becomes large, the residual stress and residual axis stress are larger. With the diameter of the pile becomes large, the residual stress and residual axis stress are larger, but the distribution of the shaft resistance along the pile dose not change. The larger the stiffness of the pile is, the smaller the residual stress and residual axis stress are and the location of the neutral surface is near the top of the pile more and more. The residual shaft resistance of the pile increases with the accretion of the modulus of deformation of the soil, but the distribution of the shaft resistance along the pile is not equal more and more. The situation of the shaft resistance accords with the above rules, but the distribution along the pile is basically alike.