基于数值模拟的双层薄膜防渗衬砌渠道抗冻胀机理探讨

Exploration on anti-frost heave mechanism of lining canal with double films based on computer simulation

在渠道衬砌板下铺设双层塑料薄膜,使混凝土衬砌板与冻土层之间可滑移、不产生冻结约束,从而达到防治渠道衬砌冻胀破坏的目的,即为双层薄膜防渗衬砌渠道。为了探明其抗冻胀机理及削减冻胀效果,应用ADINA软件对双层薄膜防渗衬砌渠道冻胀进行数值模拟,研究衬砌板应力和变形规律。对比普通渠道,双层薄膜防渗衬砌渠道抗冻胀效果非常显著,自身受力状态得到显著改善,且冻胀变形、冻胀力分布更加均匀;其阴坡、渠底、阳坡切向冻结力极值及均方差降低幅度均大于法向冻胀力降低幅度,揭示了该种渠道通过削弱冻结约束来改善衬砌板冻胀受力及使冻胀量分布均匀的抗冻胀机理。对比梯形断面和弧底梯形,可知双层薄膜防渗衬砌渠道适用断面为弧底梯形,在实际工程中应对弧底板和渠坡板之间的伸缩缝加强管理,或采用整体现浇式结构,以防止渠坡板滑动失稳。这些工作为双层薄膜防渗衬砌渠道的深入研究和推广应用提供了参考。

To prevent frost heaving damage,double plastic films can be laid under lining plate which can unbind adfreezing constraint between lining and frozen soil. This kind of canal is just called lining canal with double films. In order to explore its effect and mechanism,finite element software ADINA was applied to simulate canal heaving process and the rules of stresses and deformations of lining plate were also analyzed. Compared with the normal lining canal,lining canal with double films can get an obvious effect of anti-frost heave,because it can make frost heaving distribution and force more uniform to reform stress states remarkably. For mean square deviation and extremum of tangential adfreezing force on shady slope,bottom and sunny slope,the decreasing amplitude is greater than that of normal frost-heave force. And this fact demonstrates that lining canal with double films can weaken the constraint to make frost heaving distribution uniform and reform stress states,which is the mechanism of anti-frost heave. Compared with trapezoidal section,the trapezoidal with arc-bottom is suitable section for lining canal with double films. And its elastic joints between arc-bottom plate and that on slope should be managed elaborately,or integral structure should be applied to avoid sliding instability of plates on slope. The results can provide scientific references for further research and extended application of lining canal with double films.