超长桩荷载传递机理有限元分析

在对试桩实测资料进行分析的基础上,采用数值分析方法,研究了深厚软土地区单桩在竖向荷载作用下由短桩至超长桩随桩长增加时的荷载传递性状.结果表明:非嵌岩超长桩Q-s曲线仍可能发生陡降;由于超长桩的桩身压缩量较大,超长桩侧阻与端阻不同步发挥的现象较桩长不大时显著得多,极限荷载和承载力特征值下的端阻比通常均小于10%;在工作荷载下,短桩过渡到超长桩时,轴力主要承担部分由桩身下部逐渐转为桩身中上部,侧阻由三角形分布转为单驼峰分布;超长桩沉降计算中将侧阻简化为三角形分布可能会导致较大的计算误差.

Finite Element Analysis on Load Transfer Mechanism of Overlength Piles

Based on the analysis of field measured data of test piles, the load transfer mechanism from short piles to overlength piles in deep soft soil was analyzed by numerical analysis. The results show that Q-s curves of non-socked overlength piles are possibly steep. Non synchronous phenomena in shaft and tip resistance of overlength piles are more outstanding than shorter piles due to compression of pile shaft. The tip resistance ratios are not more than 10% under ultimate loads and characteristic value of the vertical bearing capacity. Moreover, under working loads, the load of short piles is mainly undertaken on the lower piles shaft, while that of long piles is carried by middle and upper piles shaft. Besides, the shaft resistance distributes in a triangle pattern and a single-hump pattern for short and long piles, respectively. The assumption of triangle-patterned distribution of shafc resistance may result in error in settlement cal culation of overlength piles.