基坑双排桩失稳加固最优方案分析

Optimal Scheme Analysis for Reinforcement of Double-row Piles in Foundation Excavation

分析了某基坑双排桩失稳原因,结合现场实际情况,提出3种加固方案,采用有限元法分析了桩身弯矩和变形,确定各加固方案最优截面尺寸。有限元计算结果表明:超过最优尺寸后,进一步增加加固深度并不能继续减小桩身弯矩,根据各加固方案对弯矩和变形的影响程度,提出2种方案联合加固思路,经计算分析,联合加固方案中桩身弯矩和变形均比单一加固大为减小,完全满足桩身弯矩承载力设计要求。结合现场开挖监测结果,该方案综合性价比最优。

The cause of instability of double-row piles in foundation excavation is analyzed. Three reinforcement schemes are proposed according to the actual situation in site. The finite element method is used to analyze the the bending moment and deformation of the piles and the optimum section size parameters of each reinforcement scheme are found out. According to the results of finite element calculation, the bending moment of the piles can not continue to decrease with further increase in reinforcement depth beyond the optimal size. According to the degree of influence on bending moment and deformation of each reinforcement schemes, the combined reinforcement of two schemes is put forward. After the further calculation and analysis, the bending moment and deformation greatly reduced by the combined reinforcement scheme, compared with the single reinforcement scheme. And it fully meets the bending moment bearing capacity of pile. According to the excavation monitoring results in site, it is shown that the combined reinforcement scheme has the best comprehensive cost performance.