Study On Load Bearing Characteristic Of Cast-in-Situ DX Piles With Model Tests And Numerical Analysis

ABSTRACT:DX pile, a new type of pile, is being widely used in recent years. It is based on general straight pile, and is formed with several bearing plates made by extruding device. The bearing plates are distributed along the pile on hard soil layer. It has more advantages than general pile such as higher bearing capacity, lower settlement. This paper focuses its study on DX single pile and group-pile's bearing capacity and DX single pile's tension resistance by field tests of large scale model piles and numerical analysisThis paper studied DX pile's bearing mechanism and group pile-effect by DX model pile. The model piles are 2m and 4m long and diameter is 0.15m, and the group-pile contains 4 piles.This paper analyzes 4 types of group-pile which contains 4 piles with spacing 1.5D,2D,2.5D and 3D (D is diameter of the bearing plate) by numerical analysis, and draws some conclusions. By field tests and numerical analysis, this paper's main conclusions are as follows:DX pile's bearing capacity and tension resistance are increased to 2-2.3 times of general piles. The ratio of DX pile's end resistance is very low, about 10% of the total load. The low percentage can reduce the adverse effect to DX pile's bearing capacity when removing the soil of pole.Group pile's effect of DX pile increases sharply when pile spacing decreases. The bearing capacity of 3D-spacing group-pile is 1.32 times 1.5D-spacing group-pile. Effect coefficient of group-pile increases from 0.59 to 0.78 when spacing increases from 1.5D to 3D. The maximum value of settlement of soil among group-pile occurres between two bearing plates, and it decreases when the spacing of pile increases.