基础埋深对碎石桩复合地基桩体破坏模式的影响

针对碎石桩复合地基中桩体性能,通过有限差分数值模拟与模型试验对比分析,验证了数值模型的可靠性,进而通过变化饱和黏土中碎石桩复合地基的埋置深度,分析了复合基础下单桩与群桩的承载特性和破坏模式。研究结果表明:增加复合地基的基础埋深,单桩复合地基的基础外土体围压增强,桩体侧向约束增加,桩体的最大径向位移减小,桩体破坏位置沿桩体向下移动;群桩复合地基桩体的破坏模式主要由桩体所在位置决定,中心桩破坏位置位于桩体较深处,边桩的破坏位置发生在桩顶附近,基础埋深对边桩的侧向约束作用较明显;摩擦型群桩复合地基破坏模式随埋置深度发生转变,并导致桩体破坏模式由最初沿水平方向鼓胀(剪切)破坏转变成为向下的刺入破坏。

Influence of composite foundation embedded depth on the failure modes of stone columns

Performance of stone columns in composite foundation was investigated through finite difference method(FDM) that was verified by published experimental results of model tests, and then the effect of embedded depth of composite foundation on failure mode of single column and group columns in saturated clay soil was analyzed. The research results show that with the increase of the embedded depth of composite foundation, the surrounding pressure of the single column increases, the lateral constrains function is enhanced, the horizontal maximum deformation along stone columns reduces, and the failure location move down gradually along stone column. In the cases of a group of stone columns, the failure mode of columns is determined by the location of columns under composite foundation. Compared with side stone columns whose failure location is near to the top of the columns, the failure of the central column is located in the deeper parts of the columns. The lateral restraint effect of the foundation embedded depth on the side column is obvious. The failure mechanism of the friction columns transforms from the initial bulging(shearing)along the horizonal direction to downward penetration when the embedment depth becomes large.