圆形深基坑环梁径向等效刚度系数研究

Research on Radial Equivalent Stiffness Coefficient of Ring Beam in Cylindrical Deep Excavation

弹性支点法是我国现行规范推荐的深基坑支护结构计算方法。在弹性支点法基础上,针对圆形深基坑环梁作为支护桩弹性支点的刚度系数提出明确算法,达到更合理地计算支护结构内力和位移的目的。通过弹塑性力学厚壁圆筒理论,得到环梁径向位移公式,进而推导出环梁径向等效刚度系数和环梁换算截面的等效材料抗力计算公式。将径向等效刚度系数和等效材料抗力作为弹性支点的参数,计算支护结构内力和位移。采用此方法计算沈阳某圆形深基坑支护结构的内力和位移。结果表明:采用等效刚度系数的二维弹性支点法计算得到的支护结构的内力与位移,与现场监测数据比较吻合,比三维有限元计算结果更安全,比常规刚度系数计算结果更经济合理。

The flexibility fulcrum method is the calculation method of the retaining structures of deep excavations,which is recommended by Chinese current codes.Based on the flexibility fulcrum method,a definite calculation method is proposed for calculating the fulcrum coefficients of ring beams as the flexibility fulcrum of retaining piles in cylindrical deep excavations.The purpose of this method is to calculate the displacement and the inner force of the retaining structures more reasonably.According to the thick-walled cylinder theory of plastoelasticity,the radial displacement formula of the ring beam is obtained.Then the radial equivalent stiffness coefficient of the ring beam is obtained by using the radial displacement formula based on the definition of the stiffness coefficient.The radial equivalent stiffness coefficient and equivalent compressive capacity of the ring beam are using as parameters of flexibility fulcrums to calculate the displacement and inner force of retaining structures.This method is used to calculate some cylindrical deep excavation project in Shenyang,China.The results indicate that:the results calculated by using the radial equivalent stiffness coefficient of 2d flexibility fulcrum method are in good agreement with the field monitoring data,safer than the 3D finite element calculation results,and more reasonable and economical than the usual stiffness coefficient results.