基于桩基自平衡试验数据生成等效桩基静载测试曲线的智能反分析方法

Intelligent back analysis using clonal selection algorithm in calculating equivalent top loading curve using O-cell test data

采用桩基础洞桩法建造地铁站时,大直径桩的承载性能会对洞桩法变形控制有较大影响。本文提出了一种采用克隆选择算法进行优化的数值仿真反分析方法,以实现由自平衡测试数据建立等效荷载曲线,并通过现场测试数据对所提方法进行验证。采用所提方法对大直径桩的力学行为进行分析,在依托工程条件下的桩自平衡点的位置在距桩底0.1到0.25倍桩长范围。此外,研究了桩的直径、长度和埋深对经验系数、自平衡系数和极限承载力的影响,发现桩侧阻力受加载方向的影响较小。桩总侧摩阻力占极限承载力的比值随着桩长和埋深的增加而增大,但随着桩径的增加而减小。

The bearing behaviour of larger-diameter piles significantly influences the performance of subway station construction using the pile foundation pile-beam-arch(PBA)approach.This paper proposes a numerical method combined with back analysis optimized by the clonal selection algorithm(CSA)to construct an equivalent top-loading(ETL)curve using the field O-cell test data.The test data are used to verify the proposed method.The behaviour of largediameter piles is analysed based on the test data.In the specific conditions of this study,the optimal positioning of the self-equilibrium point is determined to be within a range of 0.10 to 0.25 times the pile length from the bottom of the pile.In addition,the effects of pile diameter,length,and buried depth on the empirical factor,self-equilibrium factor,and ultimate bearing capacity of the original pile are investigated.The influence of the loading direction on the side friction resistance is minimal.The ratio of the total skin friction to the ultimate bearing capacity increase as the pile length and buried depth,but decrease when the pile diameter increases.