可液化场地大直径扩底桩的动力p-y曲线特征研究

Characteristics of Dynamic p-y Curves for Large-DiameterBelled Piles in Liquefiable Sites

摘要:

可液化场地大直径扩底桩-土动力相互作用p-y曲线研究对扩底桩抗震设计具有重要意义。基于有限差分程序FLAC^3D，分别建立扩底桩和等直径桩的三维有限差分模型，通过在模型底部输入正弦波，得到可液化场地中不同埋深下扩底桩与等直径桩的桩-土动力相互作用p-y曲线，对两者的动力p-y曲线特征进行对比分析。结果表明：正弦波输入下扩底桩动力p-y曲线多呈倒"S"形，随着埋深增加，动力p-y曲线滞回圈面积及面积增长速度逐渐减小，斜率逐渐增大；扩底桩与等直径桩动力p-y曲线所围成的图形相似，两者动力p-y曲线斜率均随埋深增加逐渐增大，扩底桩动力p-y曲线滞回圈面积及面积增长速度在各埋深处均大于等直径桩，利于能量耗散，抗震性能更好。

Abstract:

The p-y curve of the dynamic pile-soil interaction of large-diameter belled piles in liquefiable sites is of great significance for seismic design. Based on the finite-difference program FLAC^3D, a three-dimensional finite-difference model of the large-diameter belled pile and the equal-diameter pile is established. By inputting a sine wave at the bottom of the model, the p-y curve of pile-soil dynamic interaction between the large-diameter belled pile and the conventional equal-diameter pile in the liquefiable site is obtained. The dynamic p-y curve characteristics of the large-diameter pile are analyzed, and the characteristics of the dynamic p-y curve are compared between the large-diameter pile and the conventional equal-diameter pile under different buried depths. The results show that the p-y curve of the belled pile under the sinusoidal input is mostly an inverted "S" shape. With the increase of the burial depth, the hysteresis loop area and the area growth rate of the dynamic p-y curve gradually decrease, and the slope gradually increases. The large-diameter belled piles are similar to the dynamic p-y curves of the equal-diameter piles. The slopes of both p-y curves gradually increase with the increase of buried depth. The hysteresis loop area and the area growth rate of the dynamic p-y curve of the large-diameter belled pile are larger than those of the equal-diameter pile in each buried depth, which is conducive to energy dissipation and better seismic performance.