桩径对陡岩河岸墩式码头群桩基础竖向承载特性的影响

Influence of pile diameter on vertical bearing characteristics of group piles foundation of pier type wharf in steep rock bank of river

采用ABAQUS有限元软件模拟陡岩群桩(四边形四桩)竖向承载工况,建模过程考虑陡坡钻岩成孔、桩基和承台混凝土浇筑、群桩承载等流程,并考虑材料和桩岩接触非线性影响,建立陡岩群桩系统三维模型,通过改变桩径、桩嵌岩深度等参数,分析陡岩群桩(四边形四桩)的竖向承载特性。研究表明,不同桩径和桩嵌岩深度条件下陡岩群桩(四边形四桩)竖向承载能力是群桩径向膨胀与桩前岩体缺失效应、桩后岩体增强效应、承台刚度综合作用的体现。群桩竖向极限承载力和竖向承载群桩效应系数随桩径的增大分别呈"S"形和"∽"形规律变化。对于竖向荷载作用下的陡岩群桩(四边形四桩),在桩径较大时(D=2.2m),前排桩(桩1和桩2)的桩顶沉降与后排桩(桩3和桩4)的桩顶沉降仍有较明显的差异。

In this paper,the finite element software ABAQUS was used to simulate the vertical bearing condition of steep rock group piles(quadrilateral four piles).The modelled process incluled drilling hole in rock slope,pouring concrete of pile and platform,loading process of group piles foundation etc.The nonlinear effects of material and pile-rock contact were taken into consideration when three-dimensional models of steep rock group piles system were developed.The vertical bearing characteristics of steep rock group piles were analyzed by changing parameter of pile diameter and rock-socketed depth of pile etc.The research results showed that the vertical bearing capacity of steep rock group piles(quadrilateral four piles)under the condition of different pile diameter and rock-socketed depth was the embodiment of comprehensive effect of radial expansion of group piles and loss effect of the rock mass before pile,reinforcement effect of the rock mass behind pile and stiffness of the bearing platform.The vertical ultimate bearing capacity and coefficient of group piles effect varied with the increase of pile diameter in the“S”type and“∽”type.For steep rock group piles(quadrilateral four piles)under vertical load,the settlement of pile top settlement of the front row pile(Pile 1 and Pile 2)still had obvious difference with the pile top settlement of the back row pile(Pile 3 and Pile 4)even when pile diameter was large(D=2.2 m).