Numerical Simulation Study On The Influence Of Different Setting Of Anti-slide Piles On The Mechanical Characteristics Of Pier Foundation

As the main type of bridge foundation,pile foundation inevitably located in the high and steep slope.On the one hand,it bears the combined load transferred from the superstructure,and on the other hand,it also bears the side soil pressure of pile caused by the deformation of the slope,which is caused by the construction or rainfall.That stress condition is more complex than the inclined pile on the plain and the common anti-slide piles.And when the slope needs to be supported by a retaining structure,the interaction between the pile and the retaining structure should be considered.At present,the study on the optimal placement of the pier foundation pile is generally attention to the stability of slope.But the force characteristics of pier foundation and the influence of the retaining structure is not considered enough.It is necessary to carry out further research on the force characteristics of the pier foundation and its influencing factors.In this paper,combined with a static model test,the three-dimensional simulation calculation of FLAC 3D software is used to analyze the mechanical and deformation characteristics of the pier foundation as well as its influencing factors.1.The smaller the cumulative landslide force of pier foundation,the smaller the internal force and horizontal deformation.The pile foundation with lower caps can control horizontal displacement better than elevated caps.It is suggested that the pile foundation with lower caps should be adopted in the pier foundation and the pier foundation should be selected on the basis of the cumulative landslide force smaller.2.The horizontal displacement of the pier foundation increases with the increase of the buried depth of the front row anti-slide pile,and it is basically unchanged with the increase of the buried depth of the subsequent row anti-slide pile,and then increases sharply when the buried depth of the subsequent row anti-slide pile is lower than the pile cap.When the anchorage section of the anti-slide pile is a high strength bedrock,the length of the anchorage section has little influence on the internal force and deformation of the pier foundation.It is suggested that the front row anti-slide pile do not use the buried pile,the subsequent row anti-slide pile can use the buried pile which is above the pier cap and the length of the anchorage section can be appropriately reduced in combination with economic factors.3.Compared with the anti-sliding piles in the front row,the anti-slide piles in the rear row can better exert its reinforcing effect on the bridge foundation.The influence of the sectional dimension of anti-slide pile,the pile spacing and the strength of the pile on the stress and deformation values of the foundation piles decreases in turn.The force and deformation of foundation piles can be reduced by increasing the section size and the strength of concrete or reducing the spacing between piles.4.The smaller the distance between the front anti-slide pile and the pier foundation,the more obvious the support effect of the anti-slide pile to the pier foundation.The horizontal deformation of the pier foundation decreases first and then increases with the increase of the distance between the rear anti-slide pile and the pier foundation.And with the increase of the shear strength parameter reduction,the distance between the optimal pile position and the pier foundation decreases.It is suggested that the choice of piles for the front row of anti-slide piles should be close to the pier foundation.And the distance between the rear anti slide pile and the pier foundation should be 3~5 times the cross section length of the anti-slide pile.