椅式桩板结构变形破坏特征模型试验研究分析

Model Test Study on Deformation and Failure Characteristics of Chair-shaped Pile-sheet Structure

山区地形艰险、地质复杂,修建铁路遇到了大量的陡坡路基,出现边坡直立的高填方车站路基越来越多,传统的单一支挡结构在此类边坡上应用无法满足多种需求,因此提出了一种兼有承重、阻滑及支挡功能的高悬臂陡坡椅式桩板结构。由于陡坡高悬臂椅式桩板结构是一种新型超静定结构,有必要揭示并掌握其变形和破坏特征,以利于该结构的设计和推广应用。通过模型试验研究分析,得出以下结论:(1)变形极值出现于主桩桩顶;(2)悬臂段变形为主控因素;(3)裂纹多出现于桩梁交界处的桩体上和横梁中部;(4)椅式桩破坏模式一般为某构件形成塑性铰使结构丧失正常使用功能;(5)坡体破坏缓于结构破坏,软质岩边坡主要发生主桩外侧的浅层坡体挤压破坏和高荷载条件下主副桩间的岩体挤压破坏。

In mountainous areas, especially in Southwest China, the terrain is very difficult and the geology is complicated. Under the difficult and complicated conditions, many steep slopes have been encountered in the railway construction, and more and more high filling stations with upright slopes have appeared. The traditional single retaining structure cannot meet the different demands on such type of slope. Therefore , a high cantilever steep - slope chair - shaped sheet-pile structure with load bearing , sliding resistance and retaining function is proposed. Because chairshaped pile-sheet structure with high cantilever constructed on rock slope is a new type of statically indeterminate structure , it is necessary to reveal and master its deformation and failure characteristics so as to facilitate the design , popularization and application of the structure. Through the model test analysis , the following conclusions are drawn :(1) The extreme deformation occurs at the top of the main pile;(2) The cantilevers deformation is the main controlling factor;(3) The cracks occur mostly on the pile body and the middle of the crossbeam at the junction of the pile and beam;(4) The failure mode of the chair-shaped pile is that a component forms a plastic hinge, which makes the structure lose its normal function;(5) The failure of the slope is lower than that of the structure, and the extrusion failure of the shallow slope body outside the main pile and the extrusion failure of the rock mass between the main and auxiliary piles under high load conditions occur mainly on the soft rock slope.