双排桩开挖过程的改进有限元分析方法

MODIFIED FINITE ELEMENT ANALYSIS METHOD OF DOUBLE-ROW PILES WITH CONSIDERATION OF THE EFFECT OF STAGED EXCAVATION

在现有的双排桩计算模型上,提出了改进有限元计算方法。在该法中,将被动区的土压力视为弹簧反力,考虑地基反力系数的变化,并将弹簧反力转化成等效结点力且表示成单元结点位移的函数,由此得到弹性地基梁单元矩阵,最后建立平衡方程求解内力和位移;按改进方法,分步开挖考虑了开挖过程中桩体内力和位移的连续性,采用增量法来计算开挖过程的荷载增量。

In this passage,a modified finite element method is proposed based on the existing model of double- row piles. The passive earth pressure is treated as equivalent springs＇ resistance that is equivalently transformed into node load and expressed as a function of element nodes＇ displacement considering change of the groundsill＇ resistance coefficient. Therefore the elastic - groundsill - beam rigid matrix is obtained. Finally the matrix equation can be established to solve the internal force and displacement of piles. Continuity is considered during the course of staged excavation with the modified method, so the increment method is adopted to calculate the increment of the load. Analysis of an example indicates that results can well agree with expectation with reasonable parameters.