钢支撑轴向预加压力对支护结构力学性状影响分析

Effect of axial preloading in struts on mechanics properties of retaining system

利用连续介质有限元数值模型分析某深基坑支护结构在支撑轴向预加压力作用下的变形和内力,支撑刚度根据现场压缩试验确定,预加力大小通过位移监测数据反分析得到,地基土采用HS模型。分析结果表明:预加压力可减小支护桩的侧向变形和内力,可使各道支撑轴力相当,有助于材料循环利用和装配式作业。其后利用分析结果证明预加压力对支撑刚度的提高主要通过土方开挖前压缩支撑。支撑刚度和轴向预加压力的关系被定量研究,支撑刚度可提高一倍以上。轴向预加压力的作用可通过适当放大支撑刚度的方法引入到平面杆系结构弹性法中。

Lateral displacement and internal forces of retaining system in a deep excavation while axial load was applied in struts were investigated by means of numerical simulation of a continuous medium FEM model.In the model,support stiffness was based load test in site,axial load was determined by back analysis to monitoring data,hardening soil model was selected.It was proved that axial load could help retaining wall in the lateral displacement,bend moment and shear force.Axial forces of different struts could be keep in the same level by axial load was also shown.Then analysis data was used to reveal the relationship between axial load and support stiffness.Support stiffness could be increased in two times at least by compress the strut before excavation.The effect of axial load could be introduced to elastic supporting method by increased support stiffness properly.