弧底梯形复合衬砌渠道冻胀破坏力学模型及其求解

Research on mechanics models of frost-heaving damage on composite lining trapezoidal canal with arc-bottom

针对弧底梯形断面渠道,考虑复合土工膜和渠基土壤的摩擦力,通过分析复合衬砌渠道的冻胀破坏机理,指出弧底梯形复合衬砌渠道坡板可简化为在冻胀力、冻结力、摩擦力共同作用下的悬臂梁,整个衬砌体属于压弯组合变形结构。通过适当的假设和简化,建立了弧底梯形复合衬砌渠道冻胀破坏力学模型,分别求出渠道坡板和弧形底板内力表达式,并对衬砌板的厚度进行验算。对比混凝土渠道,加入复合土工膜后,衬砌体产生允许范围内的冻胀位移量,使渠基土壤对衬砌体的有效冻胀力和有效冻结力减小,改善了衬砌体本身的受力状态,起到防冻胀破坏的作用,揭示了复合衬砌渠道防冻胀破坏的机理;对比梯形渠道,认为弧底梯形渠道坡板与底板整体结构性更强,反拱作用明显,更有利于渠道的防冻胀破坏。

The composite lining canal is a kind of lining form which combine compound geomembrane and concrete lining structure. In order to improve the performance of the canal of anti-freezing expansion damage, aimed at the lining trapezoidal canal with arc-bottom, the friction of the compound geomembrane and the concrete lining structure are considered. By analyzing the damage mechanism of frost-heaving on the concrete lining of the channel with arc-bottom section, it has been indicated that the slope lining is seen as a cantilever beam under the function of frost-heaving force, frozen force and the friction. Further, it has been found that the slope lining plate and the bottom lining plate are combined deformation members under the loads of bending and compressing. The mechanics models of frost-heaving damage of composite lining canal with arc-bottom are built. The internal forces of the canal slope lining plate and the canal bottom lining plate with arc-bottom are solved and the thickness of the lining plates are assessed. Compared with the concrete canal, the tangential force of constraint of the lining canal is reduced by adding the compound geomembrane because of a number of allowable displacements of frost heave. The stress condition of the lining structure itself is improved, and the distribution of the frost-heave capacity is more balanced. These have played an important role in anti-freezing expansion damage and have disclosed the mechanism of frost-heaving damage. Compared with the trapezoidal canal, the integration of the lining canal with arc-bottom combined with the slope lining plate and the bottom lining plate is better because of its anti-arching effect is obvious and it' s of more benefit to anti-freezing expansion damage. To sum up, this study provides some theory basis for the technology of anti-freezing expansion damage of the compound lining canal.