高陡横坡段桩柱式桥梁双桩基础模型试验

Model Tests of Double-pile Foundation for Pile-column Bridge in High and Steep Cross Slope

为探讨高陡横坡段桩柱式桥梁双桩基础的破坏模式及承载机理,根据相似理论,进行了复杂荷载作用下45°,60°及75°三种边坡坡度的桥梁双桩基础室内模型试验。试验结果表明:柱顶组合荷载对坡体的影响,仅限于浅层2～4倍桩径范围内;复杂荷载作用导致的边坡整体失稳为系统主要破坏模式;高陡横坡段前后桩柱的内力分布规律与陡坡单桩及双排抗滑桩差异显著,桩、柱顶端均存在较大负弯矩,柱顶及桩顶边界条件均非完全自由;桩柱内力与位移均随柱桩高度比(h/l)呈非线性增长,且重力二阶效应(P-Δ效应)显著;柱顶负弯矩随边坡坡度增加而增大,但柱底正弯矩随之减小;桩身最大正弯矩及桩顶水平位移均随边坡坡比的增加而呈非线性增长。

In order to study the failure mode and bearing mechanism of double-pile foundation for pile-column bridge in high and steep cross slope,on the basis of the similarity theory,this study designed and accomplished model tests under complex loads from slope angle of 45°,60° and 75°.The results indicate that the impacts of the combined loads at the column cap are only limited in 2~4 times of the pile diameter;the slope overall instability caused by complex loads is the main failure mode;there is significant difference in the internal force distribution between front and back pile,single pile and anti-slide double-pile in high and steep cross slope;there are greater negative moments at the top of the pile and the column and their boundary conditions are not totally free;parameters contrastive analysis shows that both the internal force and displacement of pile-columns are in a non-linear increase with the value of h/l,and their P-Δ effect is obvious;with the increase of the slope angle,the negative moment of column cap becomes larger,but the positive moment of column base becomes smaller;the maximum positive moment and horizontal displacement of pile are in a non-linear growth with the increase of tan（α）.