深基坑双排桩支护结构地震响应分析

Seismic Response Analysis of Double Row Piles Supporting Structure in Deep Foundation Pit

文中基于某深基坑项目,结合黏弹性人工边界条件,建立了深基坑双排桩支护体系的三维实体仿真模型,对深基坑双排桩支护结构分别进行不同地震波类型、不同地震波幅值及单双向地震波作用下的响应分析.结果表明:①不同类型地震动荷载作用下,桩身峰值动弯矩沿深度方向上的分布规律大体一致,均呈现出S形分布;剪力的最大值在桩的中下部,其中Northridge波作用下产生的峰值剪力最大,为50.36 kN,El-Centro波作用下产生的峰值剪力为Northridge波的82.6%,Kobe波作用下产生的峰值剪力为Northridge波的72.7%;②地震波幅值从0.1 g增大到0.3 g时,桩身峰值动弯矩、剪力和位移都急剧增大,动弯矩达到1010.2 kN·m,剪力峰值达到450.8 kN,位移达到12.8 cm;③当水平加速度幅值小于0.1 g时,单向地震和双向地震的作用下的桩顶位移时程基本一致,大于该值时,其位移值相差较大;双向地震作用时,当竖向地震动峰值加速度大于2/3的水平地震动峰值加速度时,竖向地震动对结构的影响不能被忽略.

Based on a deep foundation pit project in Wuhan Times Square,combined with viscoelastic artificial boundary conditions,a three-dimensional solid simulation model of deep foundation pit double-row pile supporting system was established,and the response analysis of deep foundation pit double-row pile supporting structure under different seismic wave types,different seismic wave amplitudes and single and two-way seismic waves was carried out.The results show that:①Under different types of ground motion loads,the distribution law of peak dynamic bending moment of pile body along the depth direction is generally the same,showing an"S"type distribution.The maximum shear force is in the middle and lower part of the pile,and the peak shear force generated by Northridge wave is 50.36kN,the peak shear force generated by El-Centro wave is 82.6%of that of Northridge wave,and the peak shear force generated by Kobe wave is 72.7%of that of Northridge wave.②When the amplitude of earthquake wave increases from 0.1g to 0.3g,the peak dynamic bending moment,shear force and displacement of pile body all increase sharply,with the dynamic bending moment reaching 1010.2 kN.m,the peak shear force reaching 450.8 kN and the displacement reaching 12.8cm③When the amplitude of horizontal acceleration is less than 0.1g,the displacement time history of pile top under the action of one-way earthquake and two-way earthquake is basically the same,but when it is greater than this value,the displacement value is quite different.When the peak acceleration of vertical ground motion is greater than 2/3 of the peak acceleration of horizontal ground motion under bidirectional earthquake,the influence of vertical ground motion on the structure can not be ignored.