考虑太阳辐射的寒区衬砌渠道水-热-力耦合冻胀模型与应用

Frost heave modeling with thermos-hydro-mechanical coupling for lined canal in coldregions considering solar radiation and its application

寒区渠道走向导致的太阳光遮蔽产生了阴阳坡效应,引起了渠道水、热、变形的非对称分布。为探明其对渠道冻胀破坏的影响规律,本文提出了渠道阴影计算方法,采用HOTTEL晴空辐射模型,基于辐射度算法建立了考虑太阳辐射时空变化的渠道热辐射边界方程,并结合冻土水-热-力耦合理论构建了“环境-冻土-工程”相互作用的耦合冻胀模型。基于寒区“E-W”走向大型输水渠道现场监测数据验证了该模型的准确性,并系统分析了渠道温度场、水分场及变形场的耦合作用及发展变化的不对称、不同步规律。仿真结果表明:太阳辐射和阴坡遮蔽导致阴阳坡热边界差异显著,其日均温差最大为3.5℃,阴坡早于阳坡15 d冻结,晚于阳坡1 d融化,冻深最大差值为31 cm;冻结期内阴坡冰含量明显高于阳坡,而融化期阳坡冰融化较快,水分场呈条带状分布;坡板和底板最大冻胀变形分别发生在1/4~1/3坡长处和偏阳坡处,阴阳坡冻胀变形差值最大为4.0 cm。上述不对称、不同步冻结特征的宏观表现均是由阴阳坡太阳辐射的空间效应和昼夜温差的时间效应引起的温度梯度和冻结速率差异所致,就此给出了冻胀数值模拟热边界合理选取的建议,为寒旱区大型渠道防冻胀设计、复核及修复提供理论依据。

The sun shading caused by the canal orientation leads to the sunny-shady slope effect,which brings about the asymmetrical distribution of moisture,heat and deformation of a canal in cold regions.In order to explore the influence of solar radiation on canal frost heave damage,a shadow calculation method of canal was proposed and thermal boundary balance equation was established based on radiation algorithm,using HOTTEL clear sky model.Next,a coupled thermo-hydro-mechanical model was proposed based on the frost heave theory of frozen soil,considering the interaction of“environment-frozen soil-engineering”.Based on the on-site monitoring data of large-scale canal going from"E-W"in cold regions,the simula⁃tion method is verified and the coupled effect of temperature field,moisture field and deformation field and the asymmetry&asynchrony development are systematically analyzed.The simulation results show that solar radiation and shady slope shading cause obvious differences in the thermal boundary between the shady and sunny slopes.The difference in daily average temperature can reach 3.5℃,causing the shady slope to freeze 15 days earlier than the sunny slope and 1 day later to melt with the maximum difference of 31 cm in freezing depth.The ice content of the shady slope during the freezing period is significantly higher than that of the sunny slope,while the ice melting on the sunny slope during the melting period is faster,and the moisture field is distributed in strips.The maximum frost heave deformation of the slope slab and bot⁃tom slab occurs at 1/4~1/3 slope and near the sunny slope respectively,and the development of frost heave deformation between the shady and sunny slopes is obvious with the maximum difference of 4.0 cm.The above characteristics of asymmetric and asynchrony freezing all arise from the difference of temperature gradient and freezing rate caused by space effect of solar radiation and time effect of diurnal temperature difference.Therefore,reasonable suggestions for the selection of the thermal boundary of the frost heave nu⁃merical simulation are given.The results can provide a theoretical basis for the design of anti-frost heave,review and repair of the large-scale canal in cold-arid regions.