开放系统预制混凝土梯形渠道冻胀破坏力学模型及验证

预制混凝土衬砌渠道在中国北方寒冷地区得到普遍应用，而其在高地下水位条件下的冻胀力学分析尚无简捷、可靠的方法。该文假定渠道基土服从Winkler假设，从而在特定地区相似的土质、气候条件下衬砌板各点的基土冻胀强度仅与相应点的水分补给强度有关，结合冻胀力、基土冻胀率和地下水埋深三者相互间的函数关系，提出了一种计算渠道衬砌冻胀受力分布的方法。将其应用到一类预制板尺寸适中的预制混凝土衬砌梯形渠道中，建立了冻胀破坏力学模型。结合力学分析和工程实践，对预制混凝土衬砌结构可能发生的冻胀破坏形式和原因进行了分类，并确定了相应的冻胀破坏验算控制截面，提出了相应的冻胀破坏判断准则。采用单位荷载法提出了一种对板间接缝处法向冻胀位移进行直接验算的方法。最后，结合工程实例进行了计算，结果表明，模型合理可靠，可为工程设计提供一定的参考和理论依据。

Mechanical model and validation of frost heave damage of precast concrete slab lining trapezoidal canal in open system

Abstract: The precast concrete slab lining trapezoidal canal is widely applied in cold regions of northern China, but the calculation method of frost heaving force distribution and the mechanics model of frost heaving damage under high groundwater level conditions have not yet been set up. Due to similar weather condition and soil texture in the specific region, the strength capacity of groundwater supply on each point of the concrete lining slab becomes the decisive factor of the strength of frost heaving on each point. Through Winkler assumption for mechanic characteristics of soil, the strength of frost heaving on each point of the concrete lining slab is only related to the capacity of water supply on the corresponding point; according to the functional relations between frost heaving force, frost heaving strength and groundwater depth, the article proposed a method to calculate the frost heaving force distribution on the concrete lining slab. By applying the idea to a type of precast concrete slab lining trapezoidal channel whose precast concrete slab size was moderate, a mechanics model of frost heaving damage in open system was established. The article divided precast concrete slab lining canal into 2 types. One had large precast concrete slabs, and as caulking material was cement mortar with weak bond strength, the integrality of the type was worse; the other had moderate precast concrete slab size and caulking material was usually flexible material with strong bond strength such as polyurethane, plastic waterproof ointment, so the integrality of the type was excellent and it was the main research object of this article. With the preceding model the distribution of axial-tension, shear force and moment in the canal slope lining plate can be calculated, respectively. Combining mechanical analysis with engineering practices, the manifestations and the reasons of frost heaving damage of precast concrete slab lining trapezoidal channel were classified as axial-crack, shear failure and bending rupture of joints between precast concrete slabs. According to different forms and reasons of frost heaving damage, the controlled sections for checking the possibility of frost heaving damage were confirmed, and the corresponding judge rules were proposed. The method to check normal displacement caused by frost heaving on joints between precast concrete slabs was put forward based on the unit-load method. The calculation method and the mechanics model discussed in the article were based on different groundwater supply intensity of different point on canal lining, so it had great commonality, and it could calculate the distribution of frost heaving force on concrete lining canal with different types of cross-section. Finally, an engineering example was carried out, and the results showed that the model was reasonable and reliable and can serve as reference and theoretical basis for engineering designs.