两拼式U形渠道混凝土衬砌结构冻胀破坏力学模型

Mechanics Model of Frost-heaving Damage of Concrete Lining U-shaped Canals with Splicing Two Arc-plates

两拼式小型U形渠道混凝土衬砌属薄壳拱形结构。通过对两拼式小型U形渠道混凝土衬砌冻胀破坏机理及破坏特征的力学分析,确定了在法向冻胀力、法向冻结力及切向冻结力和重力共同作用下混凝土衬砌整体结构的计算简图,建立了该衬砌结构冻胀破坏的力学模型并推导出冻胀控制内力及最大拉应力的计算公式。结合混凝土板抗裂条件,给出了胀裂部位、衬砌板厚及抗冻胀破坏验算的方法。结果表明,与三拼式U形渠道相比,两拼式U形渠道衬砌结构法向冻胀力小、分布均匀、恢复力大、整体适应变形及抗冻胀能力强。

Small concrete lining U-shaped canal with splicing two arc-plates can be regarded as thin-shell arc structure. The calculating diagram of the entire structure under the all loads of normal frost heaving force, outside the normal freezing, tangential freezing force and gravity was determined based on the damage mechanism and damage characteristic of the frost-heaving of the small concrete lining of U-shaped canal with splicing two arc-plates in this paper. Then the frost-heaving mechanics model was given and the calculat- ing formula of the frost heaving control internal and the maximal tensile stresses were worked out. According to the anti-crack re- quired term for the concrete plates, the calculation methods including determining the position of expansion cracks, lining plate thick- ness and anti-frost heaving destruction checking were obtained. The results show that the normal frost heaving pressure of the concrete lining structure of U-shaped canal with splicing two arc-plates was smaller, more equally distributed with good resilience and stronger ability of adapting entire deformation and anti-frost heaving compared with the U-shaped canal with splicing three arcplates.