倾斜桩基与竖直桩基竖向承载特性比较研究

以厦深客运专线韩江特大桥潮安县段桩基选型工程为研究背景,通过室内静载模型试验,对承受竖向荷载时低承台倾斜桩基与竖直桩基的荷载-沉降曲线、桩体荷载分担比等工作特性进行了研究。结果表明:在荷载-沉降曲线特征方面,倾斜桩基较竖直桩基率先呈现非线性变化,承台顶部荷载达到8 kN之前倾斜桩基的沉降量小于竖直桩基的相应值,随上部荷载的增大倾斜桩基的沉降量逐渐大于竖直桩基的相应值;在桩体荷载分担量方面,竖直桩基和倾斜桩基的相应值都随上部荷载增大而逐渐增大;但在桩体荷载分担比方面,与竖直桩基单调增加不同,倾斜桩基呈现出先增大后减小的特征。受桩间距由上到下逐渐增大的影响,倾斜桩基承台下侧桩间土体的随深度遮拦作用逐渐减小,由此引发土体绕桩滑动作用的增强,从而造成中桩与桩间土体承载能力的不同发挥,成为引起2种不同类型桩基承载特性不同的主要原因。

COMPARISON STUDY ON THE VERTICAL CAPACITY OF THE VERTICAL PILE FOUNDATION AND INCLINED PILE FOUNDATION

Taking the Hanjiang Bridge pile foundation project of Xiamen-Shenzhen Passenger Dedicated Line as the background,static load model test was adopted to study the load-settlement and pile’s stress ratio characteristics of vertical pile foundation and inclined pile foundation.The results showed that the load-settlement curve of the inclined pile foundation showed non-linear prior to the vertical pile foundation,and settlement of the inclined pile foundation was smaller than that of the vertical pile foundation at the early load phase.The pile’s load sharing amount of the vertical pile foundation and the inclined pile foundation was increasing with the upper-load’s adding,but the pile’s load sharing ratio of the vertical pile foundation increased monotonically while that of the inclined pile foundation turned increasing first and then reducing.Affected by the pile spacing that increased from top to bottom,the masking effect of pile decreased at the lower part of the inclined pile foundation then the extrusion effect of soil was enhanced,which is the main reason of the different load-bearing characteristics of two sorts of different pile foundations.