复合荷载作用下坡顶面双排桩设计要素数值模拟

Numerical simulation of design elements of double-row piles on slope top under composite load

【目的】研究坡顶面承重、阻滑双排桩的受力变形特性,分析桩间距、连梁高度、桩身嵌固深度等因素对桩身受力变形特性的一般影响规律,尤其是反映竖向荷载及桩身自由段长度对桩身水平位移及最大弯矩的影响。【方法】借助ABAQUS有限元软件,通过单变量的变化,模拟双排桩在不同影响因素下的受力变形特性。【结果】滑动面的存在使桩身水平位移及弯矩在桩间距为1d~2d(d为桩径)时发生突变,故在确定桩间距时应注意滑动面产生的影响;连梁高度对桩身受力变形特性的影响微乎其微,按标准取值即可;在滑动面位置桩身嵌固深度对桩身水平位移及弯矩有较大影响,但继续增大桩身嵌固深度后,影响变小,在工程设计中桩身嵌固深度适当超过滑动面即可;当增大桩身自由段长度时,P-Δ效应也更加显著,对于不同的自由段长度,前后排桩桩身的最大弯矩近乎相等。【结论】位于坡顶面的双排桩须承受轴、横向复合荷载,可起到承重、阻滑的双重作用,其承载机理及受力形式较护坡桩更为复杂。本文研究成果可为相关工程设计要素的取值提供一定参考。

[Purposes]The stress and deformation characteristics of load-bearing and anti-slide double-row piles on slope top were studied.The impact of pile spacing,coupling beam height,pile embedded depth and other factors on deformation characteristic of pile was analyzed.In particular,the influence of the vertical load and the length of the free section on the horizontal displacement and the maximum bending moment was reflected.[Methods]Based on the finite element software ABAQUS,controlling the single variable,the deformation characteristics of double-row piles under different factors were simulated.[Findings]Due to the sliding surface,the horizontal displacement and bending moment of the pile change suddenly,when the pile spacing is 1d-2d(d is pile diameter).Therefore,the influences of sliding surface should be considered,when the pile spacing is designed.The value of the couple beams height had tiny impact on the function of piles,which can be selected according to the standard.The embedded depth had significant effect on the deformation and the moment of the piles in the location of the sliding surface.However,the effect will decrease as the increase of the depth.The embedded depth should exceed the sliding surface properly in project design.When the length of piles free section increases,the P-Δeffect change to more remarkable.The maximum bending moment of the front and back piles almost equal under different lengths of free section.[Conclusions]The double-row piles located on the top surface of the slope must bear the axial and transverse composite loads,the bearing mechanism and stress form are more complicated than those of slope protection piles.The research results can be used for the design of related engineering.