基于矩阵位移法的桩锚结构分析方法
ANALYSIS METHOD FOR PILE-ANCHOR RETAINING STRUCTURES BASED ON THE DISPLACEMENT MATRIX METHOD
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摘要: 采用将桩锚结构视为荷载作用-侧向弹簧支承的连续梁模型,支护桩为直立的弹性地基梁,主动土体转换为土压力,锚杆简化成为可逐步施加的弹簧支承,而被动土体则用侧向支承的土体弹簧替代.土体弹簧的刚度K是通过半无限大弹性空间内部水平荷载作用下的Mindlin 解来确定,这种方法降低了因深度加深而带来弹簧刚度的增长率,更加符合实际情况.针对这种弹性地基梁模型,提出了以矩阵分析为手段的计算方法,该法优点在于将桩锚视为桩-锚-土三者协同作用的支护结构,同时在计算过程中充分考虑了基坑分步开挖的施工过程对支护桩、锚杆以及被动土体的变形影响.通过实例分析表明:矩阵位移法为桩锚结构设计提供了一种合理、有效的计算方法.Abstract: The pile-anchor retaining structures are simplified as a continuous beam in load-spring model. The pile is simplified as elastic foundation beam, while the active earth is converted to load system, and the anchors and the passive earth are simplified as a spring system. The spring stiffness has been determined by Mindlin's solution in semi-infinite elastic space under horizontal rectangular load, and the spring factor is closer to the actual situation because of reduced rate of increasement in spring stiffness with depth. According to this model, the matrix analysis method is presented, with the consideration of the effects of excavation process on pile deformation and internal forces of anchor. It proves the matrix analysis method to be convenient and feasible through a practical example.