桩板式挡土墙桩-板土压力传递特性的试验研究

Experimental Study on Transfer Behavior of Earth Pressure on the Retaining Wall Slab in the Pile-sheet Retaining Wall

广泛应用于路堑、路堤以及滑坡等特殊路基支挡工程的桩板式挡土墙目前多采用桩后搭设直板的结构形式,致使设计严重偏于保守。为明确不同挡土板布设位置下桩板式挡土墙桩–板土压力的传递特性及其分布规律,基于相似原理采用室内物理模型试验,开展桩前置板、桩后置板以及桩间无挡板3种典型工况的室内模型试验研究,获取桩–板后填土在水平推力作用下的整体变形及其典型破裂面特征,监测并确定抗滑桩两侧、桩间挡土板背侧以及填土跨中土压力的分布规律。试验结果表明:在水平推力作用下,桩前置板、桩后置板以及桩间无挡板3种典型工况的桩–板后填土均产生一条横跨加载面的整体裂缝。抗滑桩和桩间挡土板的背侧土压力大致分别呈"勺子型"和"梯形"分布,且相较于桩后置板工况而言,尽管桩前置板工况下抗滑桩所承担的土压力较大,但桩间挡土板所对应的土压力则显著降低。由于桩间挡土板的存在,尤其是桩后置板工况,在一定程度上削弱了桩–板后填土的土拱效应,但桩前置板工况仍为桩–板后侧填土土拱效应的形成和发展提供了空间;相较而言,桩前置板工况可利用桩–板后填土土拱效应的发挥显著减少作用于挡土板上的土压力,设计时宜采用桩前挂板或板搭设在桩翼缘板上的结构形式。研究成果可为桩板式挡土墙的合理设计提供参考。

Pile-sheet retaining wall is widely used in the cutting slope, embankment engineering and landslide treatment. The slab located at the behind of stabilizing piles, for example, is one of the most popular structural form in the engineering design, leading to some conservatism in the design. In order to investigate the transfer behavior of earth pressure and the regularities of distribution considering different setting location of retaining wall slab in the Pile-sheet retaining wall, three typical laboratory model tests(slab located in front of piles, slab located behind of piles and without slab) were conducted. The overall deformation and the fracture surface of the filling soil were observed, and the earth pressure on the stabilizing pile and retaining slab were also monitored. The experimental results showed that under the action of horizontal thrust, the retaining wall slab backfill of the three typical working conditions all generated an overall crack across the loading surface. The distribution of earth pressure on piles and retaining slab were "spoon-shaped" and "trapezoidal shaped" respectively. Compared to the case of slab located behind of piles, the earth pressure undertook by the stabilizing piles was much larger for the case of slab located front of piles, and the earth pressure undertook by the retaining slab was smaller instead. Soil arching effects of the filling soil was weakened because of the existence of retaining slab, especially for the case of retaining slab located behind of the piles. However, soil arcing still had the formation conditions and development space for the case of retaining slab located in front of the piles. In comparison, the slab located in front of piles could effectively reduce the earth pressure acting on the retaining slab because of the development of soil arching effect, and reduce the earth pressure acting on the retaining slab. Therefore, it was recommended to use the structure of slab located front of piles or the flange of pile. The research results can provide reference for the reasonable design of pile-sheet retaining wall.