水平荷载下扩底楔形桩承载力特性透明土模型试验

Experimental study on lateral bearing capacity of enlarged wedge-shaped pile using transparent soil

通过改变纵向截面形式以提高单位材料利用率、提高桩侧摩阻力或桩端阻力的异形桩在工程界逐步得到推广应用;然而,针对纵向截面形式改变对基桩水平向承载力特性影响的研究却相对较少。为分析纵向截面形式改变对水平向承载特性影响规律及桩-土相互作用机理;基于透明土材料和PIV(particle image velocimetry)技术,采用非插入式测试方法开展水平荷载作用下扩底楔形桩的承载力特性模型试验,测得水平荷载下基桩H0-y0曲线、基桩变形、以及桩周土体扰动位移场等规律特性,继而探讨水平荷载下扩底楔形桩的极限承载力、基桩变形对桩周土体位移场的扰动规律以及桩-土相互作用机理;同时进行等截面桩、楔形桩的水平向承载力特性透明土模型试验作为对比分析。试验结果表明,文中试验条件下,由于扩大头的存在,扩底楔形桩的水平向承载力约为楔形桩的2.0倍;水平荷载下,桩周土体的竖向位移略比水平向位移要大,桩端附近土体水平向位移变化比竖向位移变化要更明显;水平极限荷载下桩端略有一点向上拔出。

By changing its longitudinal section for improving the material usage,the special-shaped piles with the improved pile side resistance and pile tip resistance,have been widely applied to engineering practice.However,the researches on the lateral bearing capacity of special-shaped pile were relatively absent.Based on the transparent soil material and PIV( particle image velocimetry) technique,experiments on the lateral bearing capacity of enlarged wedgeshaped pile were carried out,and the H0-y0 curves and deformation of pile under the horizontal load as well as the displacement field of disturbed surrounding soil were investigated.In a comparative analysis,the experiments on the pile with constant cross-section and wedge-shaped pile with the same concrete usage were also conducted.The research results show that the lateral bearing capacity of enlarged wedge-shaped pile is nearly 2.0 times of that of wedge-shaped pile because of the existence of enlarged pile tip.The vertical displacement of surrounding soil of pile is slightly larger than the horizontal displacement,while the vertical displacement of soil near the pile tip is slightly smaller than the horizontal one.In addition,under the ultimate lateral load,the pile tip is slightly pulled out.