注浆支盘式锚杆拉拔荷载传递非线性分析

Nonlinear analysis of load transfer of grouting branch-type anchor

基于支盘式锚杆室内模型拉拔试验,探究荷载–位移曲线的变化特征和轴力传递特性,然后在此基础上探讨支盘式锚杆的力学模型,推导出盘端阻力的理论计算公式,结合锚-土界面的双曲线非线性模型,采用分段变形协调迭代算法建立荷载传递计算模型,并与实测数据进行对比验证,最后对极限扩孔压力分布、支盘挤扩角等参数进行敏感性分析。研究结果表明,荷载–位移曲线可划分为三阶段,轴力分布沿锚固体深度呈减小趋势且在支盘处发生台阶状突变,荷载比也不断增长;计算模型所得结果与室内实测数据基本一致,验证了本模型的有效性;支盘的极限扩孔压力沿支盘径向先快速非线性增长后缓慢减小,其峰值随着位移增大而增大并以支盘中心为圆点径向外移,整体分布由"锥台状"发展为"圆柱状";挤扩角大于50°时,对锚杆承载性状影响显著。研究结果对支盘式锚杆的受力分析和设计具有重要的理论及实际意义。

Based on the indoor model pull-out tests on the branch-type anchor,the variation characteristics of the load-displacement curve and the axial force transmission characteristics are studied.Then,the mechanical model for the anchor is discussed,and the theoretical formula for the end resistance of disc is derived.Combined with the hyperbolic nonlinear model for the anchor-soil interface,the load transfer model is established by using the sectional deformation coordinated iterative algorithm.Finally,the sensitivity analysis of the parameters such as the ultimate pressure of cavity expansion distribution and the squeezing angle of the branch disc is performed.The results show that the load displacement curve can be divided into three stages.The axial force distribution decreases along the anchor depth and the step mutation occurs at the branch disc,and the load ratio also increases continuously.The calculated results are basically consistent with the indoor measured data,which verifies the validity of the model.The ultimate pressure of cavity expansion increases rapidly and nonlinearly along the radial direction of the branch disc and then decreases slowly.The peak value increases with the displacement and moves radially outward with the center of the branch disc as the circular point.The overall distribution changes from"cone platform"to"cylinder".When the squeezing angle is greater than 50°,the ultimate drawing force significantly increases.The research results are of important theoretical and practical significance for the analysis and design of the force of the branch-type anchor.