公路隧道箱型预制仰拱变形破坏的模型试验研究

Model test research on deformation and failure of box-shaped prefabricated inverted arch structure of highway tunnel

基于自主设计的新型箱型预制仰拱结构,采用室内物理模型试验,结合数字照相量测技术,研究该箱型预制仰拱的力学特性及破坏模式,通过数值模拟研究实际工况中衬砌与仰拱共同作用的受力规律.结果表明:竖向荷载作用下产生的拉张效应是预制仰拱裂纹产生及发展的主要原因,水平压力对预制仰拱的裂纹发展作用不明显.预制块接缝处以及各个预制块中柱转角处是预制仰拱结构的最薄弱部位,接缝处和转角处影响预制仰拱结构的安全.预制仰拱位移变化关于中轴部位呈对称分布,位移由大到小依次为中间预制块、左1预制块、左2预制块、左3预制块.箱型预制仰拱破坏可以分为加载压密、弹塑性变形和塑性破坏3个阶段.当仰拱与衬砌共同作用时,仰拱的上部主要承受拉应力,仰拱的下部主要承受压应力.试验结果表明,所设计仰拱结构具有良好的受力性能.

A new box-shaped prefabricated inverted arch structure was designed.The mechanical characteristics and failure mode of the box-shaped prefabricated inverted arch were studied by indoor physical model test combined with digital photographic measurement technology,and the stress law of the lining and invert were studied by numerical simulation in actual working conditions.Results show that the tensile effect generated under vertical load is the main reason for the crack generation and development of the prefabricated inverted arch,while the horizontal pressure has no obvious effect on the crack development of the prefabricated inverted arch.The joints of prefabricated blocks and the corners of columns in each prefabricated block are the weakest parts of the prefabricated inverted arch structure,and the joints and corners affect the safety of the prefabricated inverted arch structure.The displacement of the prefabricated inverted arch is symmetrically distributed with respect to the central axis,and the displacement is the middle prefabricated block,the left 1 prefabricated block,the left 2 prefabricated block and the left 3 prefabricated block in order from large to small.The failure of the box-shaped prefabricated inverted arch can be divided into 3 stages:loading compaction,elastoplastic deformation and plastic failure.When acting with the lining,the upper part of the inverted arch is mainly subjected to tensile stress,while the lower part is mainly subjected to pressure.Experimental results show that the self-designed inverted arch structure has good mechanical performance.