大直径扩底灌注桩的抗震性能研究
Seismic Performance of Large-diameter Belled Piles

深入分析土-大直径扩底灌注桩体系动力相互作用机理是地震工程的重要研究内容。本文采用快速拉格朗日FLAC3D有限差分程序建立地震荷载作用下扩底桩-土和等直径桩-土动力相互作用体的三维数值模型，分析大直径扩底桩与普通等直径桩地震反应的差异。桩周土采用Mohr-Coulomb弹性模型以考虑土体的非线性，桩体采用线弹性模型，桩与桩周土之间采用"切割模型"法设置桩土间接触面。输入5·12汶川地震波，对两种桩基的地震反应进行了数值计算与分析。结果表明：扩底桩的抗震性能优于等直径桩；与具有显著差异的加速度时程曲线相比，扩底桩对位移动力响应并不敏感。
The dynamic interaction mechanism of soil and large-diameter belled piles is an important factor in earthquake engineering research. Based on the Lagrangian FLAC3D program, we established three-dimensional numerical models of the dynamic belled pile-soil interaction and dynamic equal-diameter pile-soil interaction under seismic loading to investigate the difference in the seismic responses of the large-diameter belled pile and conventional equal-diameter pile. We used the Mohr-Coulomb elastic model to consider the nonlinear characteristics of the soil around the pile and the linear elastic model to simulate the pile itself. We then used the model cutting method to set the interface between the pile and its surrounding soil. Under the input of a 5·12 Wenchuan seismic wave, we performed a numerical calculation and analysis of the seismic responses of the two pile foundations. The results show that the anti-seismic performance of the large-diameter belled pile is better than that of the conventional equal-diameter pile. A comparison of the acceleration time history curves with a dramatic difference shows that the belled pile is not sensitive to the dynamic displacement response