抗滑桩对桥梁桩基受力变形影响的模型试验研究

Influence of Anti-slide Pile on the Stress-Deformation of Pile Foundation based on Model Test

通过室内模型试验研究了加载过程中桥梁桩基与抗滑桩桩顶位移、桩身应变、桥梁桩基前后土压力、抗滑桩桩前土压力的变化,得到两者的受力变形特性,并确定了模型试验中桥梁桩基和抗滑桩的破坏模式。研究表明,两者桩身弯矩分布均为抛物线形式分布,抗滑桩与桥梁桩基最大弯矩均位于岩土交界面与滑动面之间;两者桩基破坏面也均位于岩土交界面与滑动面之间;抗滑桩与桥梁桩基滑动面以上段桩前土压力分布均为倒三角形分布形态,在滑动面处土压力基本为0,桥桩桩后土压力分布成“S”形分布,压力峰值位于滑动面下方及桩顶处;抗滑桩先于桥梁桩基发生破坏,下滑力主要由抗滑桩承担,随着下滑力的增加,抗滑桩承担荷载比例增大;抗滑桩与桥梁桩基桩顶水平位移变化规律基本保持一致,在加载初期桥梁桩顶水平位移变化幅度小,随着荷载的增加其变化幅度逐渐增大,两桩之间相互作用越加显著。

The indoor model test is conducted to study the displacement of pile foundation and that at top of anti-slide pile,pile shaft strain,earth pressure distribution in front of and behind of anti-slide pile during loading process,and the behavior of stress and deformation are obtained,and the failure mode of bridge pile foundation and of the anti-slide pile in the model test are obtained.It is found that,the bending moments of the two piles are distributed in the form of a parabola,and the maximum bending moments and failure point of the piles are located at a certain distance above the rock-soil interface.In addition,the distribution of soil pressure in front of the piles above the sliding surface of the two piles is triangular,and the soil pressure at the sliding surface is almost zero.The earth pressure is distributed in the shape of"S"behind the bridge piles,and the peak value of pressure locates under the slide surface and at the top of pile.The anti-slide pile fails before the pile foundation,the most of the driving force is taken by the anti-slide pile,and with the increase of the sliding force,the load-sharing ratio of the anti-slide pile gradually increase.The horizontal displacement of the anti-slide pile and the pile foundation of the bridge are basically the same.At the initial stage of loading,the horizontal displacement of the bridge pile has a small change,and the change gradually increases with the increase of the load,and the interaction between the two piles becomes more significant.