Experimental And Theroctical Study On The Calculation Of Laterally Loaded Piles Near The Slope

Lateral loaded pile is a pile foundation which bears large horizontal force or moment(such as wind force,vibration force,ship impact force and braking force of driving).The calculation of internal force and displacement is one of the important contents in the field of pile foundation design and calculation.Recently,a lot of lateraly loaded piles have been widely used in structures near natural or artificial slopes,such as mountain bridges,transmission towers and offshore wharfs.At this time,due to the weakening of soil resistance on one side of the slope,its horizontal bearing capacity will be significantly reduced.How to consider the weakening effect becomes a key problem in calculating the horizontal bearing capacity of this kind of pile foundation.In order to solve this problem,the failure modes and loaded-bearing characteristics of horizontal loaded piles near slopes are deeply analyzed by means of model tests indoors and theoretical analysis,and a calculation method of internal force and displacement of piles considering pile-soil parameters,slope shape and slope distance is proposed.The specific work is as follows:(1)Indoor model tests of horizontal loaded side-slope piles and ground piles were carried out.The process of soil deformation to failure in front of side-slope piles was observed.At the same time,the displacement of pile top,the bending moment of pile body and the maximum bending moment of two test piles during loading were compared and analyzed.The results show that the failure mode of the soil near the front surface of the pile is wedge failure,which follows the process of soil uplift-crack development-irregular wedge sliding out.When the load is small,the displacement of the top of the pile and the maximum bending moment of the pile are almost the same.With the increase of the load,the displacement of the top of the pile and the maximum bending moment of the pile are larger and the bending moment of the pile is zero.The point is also deeper.(2)To simplify the test wedge reasonably,based on the passive wedge model of lateraly loaded piles on flat ground,a passive wedge model of soil for lateraly loaded piles on slopes is proposed.According to the different depth of wedge development,the shape of passive wedge of soil can be divided into three situations,so that the influence of slope shape and the distance between piles on the slope can be fully considered.On this basis,the concept of equivalent depth is put forward according to the difference between the horizontal loaded piles on the slope and on the flat ground.The equivalent depth is introduced into the traditional clay p-y curve equation,and then the internal force-displacement solution of the horizontal loaded piles considering the slope weakening effect is obtained.This method is used to predict the internal force and displacement of the pile in the model test and the field test.The calculated displacement of the pile top and the maximum bending moment of the pile body are within a reasonable range,which verifies the rationality of this method.(3)According to the theoretical calculation method in this paper,some main factors affecting the internal force and displacement of lateral loaded piles on the slope are analyzed,such as undrained shear strength of soil,inclination angle of slope and distance of slope.The calculation results show that the undrained shear strength of soil has a significant effect on the internal force and displacement of slope piles,and the internal force and displacement of slope piles do not change with the increase of the distance between slopes.Finally,a new method to define the critical critical distance between slopes is proposed based on the distribution law of the ultimate resistance of soil around piles,and the expression of the critical distance between slopes is derived,which can consider the influence of soil parameters on the critical distance between slopes.