非埋式桩板结构路基水平承载试验研究

非埋式桩板结构广泛应用于我国高速铁路的建设工程中,尤其是山区陡坡段,但对该结构的水平承载特性缺乏相应的研究。以杭黄高铁陡坡段非埋式桩板结构路基为原型,通过水平承载模型试验,研究结构内力弯矩、土压力分布形式,分析结构变形规律以及路基破坏形式。研究表明:当非埋式桩板结构路基承受水平荷载时,结构内力变化以桩基为主,并且随着水平荷载的增加,桩基弯矩呈基本不变至稳步增长最后剧烈增大的趋势;结构变形以水平位移为主,最大水平位移达7.25 mm,承载板发生内高外低的翘曲变形;当水平荷载达到一定时,路基边坡发生浅层破坏与局部压溃破坏,桩板结构的桩基于桩顶处与滑动面附近产生裂缝。试验过程中,桩板结构整体稳定性良好,但在水平荷载超过一定范围时结构变形过大,因此在水平推力较大的地段应谨慎选用非埋式桩板结构路基。

Model Testing Study on Non-embedded Pile-Plank Structure Subgrade under Horizontal Load

Non-embedded pile-plank structure is widely used in the construction of high-speed railway in China, especially in steep slope section in mountainous area. However, there is no corresponding research on the horizontal bearing capacity of the structure. In order to study its behavior, a subgrade slope section of non-embedded pile-plank structure on Hangzhou-Huangshan high speed railway is researched with model test to analyze the bending moment of piles, soil pressure, structural distortion and the failure mode of subgrade. The results show that(1) When the subgrade of non-embedded pile-plate structure bears horizontal load, the change of internal force of the structure is concentrated mainly in pile, and with the increase of horizontal load, the bending moment of pile remains unchanged at first, then steadily increases and finally increases sharply.(2) The structure is mainly subjected to horizontal displacement, the maximum horizontal displacement is 7.25 mm, and the bearing plate has warped deformation of inner high and outer low.(3) When the horizontal load reaches a certain level, the roadbed slope is damaged in shallow layer with local crushing, and cracks appear at the pile top and near the sliding surface.(4) During the test, the pile-plank structure shows a good overall stability, but the structure deformation is too large when the horizontal load exceeds a certain range. Therefore, in places with large horizontal thrust, non-embedded pile-plank structure should be chosen carefully.