考虑预制混凝土“设缝”作用的梯形渠道冻胀机制影响研究

Frost heave mechanism of trapezoidal canals considering the effect of joint setting in precast concrete

寒区衬砌渠道输水能力下降主要是由常年冻融作用下衬砌结构发生冻胀破坏所致,针对渠道衬砌结构冻胀破坏问题提出渠坡板纵向设缝的抗冻措施与数值分析方法。本文通过将渠道衬砌板与冻土视为整体处理的方法构建混凝土衬砌渠道热力耦合冻胀模型,以甘肃省景泰灌区某混凝土衬砌渠道为研究对象,考虑不同设缝措施与纵缝填充的接触本构对3种工况进行抗冻影响因素分析。结果表明:渠底深部基本不受渠道整体几何边界的影响,但渠道边界尺寸和基土热流分布均对基土上部温度场变化具有显著影响。渠道阴坡、渠底和阳坡最大冻深分别为86.3、67.5、58.2 cm。通过合理设缝措施可使渠道阴坡法向冻胀力降低40.7%、底板冻胀量减小63.5%、切向冻胀力降低43.8%,使渠道断面冻胀分布趋于均匀,且模型分析与实测结果相符,表明本文构建模型的合理性。研究结果可为长距离输水渠道数值计算提供理论依据。

The decrease of water transport capacity of lined canals in cold regions is mainly caused by frost heave failure of lining structure under freeze-thaw action.In view of this problem,the control measure of longitudinal joint setting in the canal plate was proposed and the numerical analysis was conducted.A thermal coupling frost heave model of concrete lined channel was constructed by treating the canal lining plate and frozen soil as a whole.Taking a concrete lined canal in Jingtai Irrigation District of Gansu Province as the research object,the influencing factors of frost resistance under three conditions were analyzed based on the contact constitutive of different joint construction measures and longitudinal joint filling.The results show that the depth of the bottom of the channel is not affected by the overall geometric boundary of the canal,but both the size of the canal boundary and the heat flow distribution of the subsoil have significant effects on the temperature field of the upper subsoil.The maximum freezing depth of the shady,bottom and sunny slopes of the canal are 86.3,67.5 and 58.2 cm,respectively.Reasonable joint arrangement can reduce the normal frost heave force of the shady slope by up to 40.7%,the frost heave quantity of the bottom plate by up to 63.5%,and the tangential frost heave force by up to 43.8%,so that the frost heave distribution of the canal section tends to be uniform,and the model analysis is consistent with the measured results,indicating that the model established in this paper is reasonable.The results can provide a basis for the numerical calculation of long-distance water conveyance canals.