土工袋防渠道冻胀水-热-力耦合数值模拟

根据水-热-力耦合计算模型,编制相应的有限元计算程序,并结合寒冷地区渠道工程进行数值计算,分析渠道建成后2 a内渠坡的温度场、水分场及位移的分布规律。计算结果表明:渠坡在冻融过程中表现出显著的冻胀、融沉变形特性,且冻胀和融沉变形不可逆;土工袋处理渠道对冻土渠坡具有较好的防冻胀效果,土工袋具有较小的导热性,可以有效减小渠坡内部土体温度受大气温度的影响,从而减小渠坡发生冻胀融沉变化的可能性;土工袋可以抑制毛细水和薄膜水的上升,可减小土工袋层及下部土体中的水分迁移,从而保持渠道内较为稳定的含水量,减小渠坡表层的冻胀量;土工袋具有一定的强度且在自身袋子张力作用下能够抑制部分冻胀变形,从而减小渠道衬砌体由冻胀引起的破坏。同时,渠道表层用土工袋处理后,渠坡内部温度可以较快达到稳定状态,运行2 a后可在地基2 m以下位置形成较为稳定的常年冻结层。

Moisture-heat-stress coupled numerical simulation of soilbags preventing the frost heaving of channel

According to the numerical model of moisture-heat-stress coupled field, the finite element algorithm for soilbags was built, and then one canal engineering project in the cold area has been analyzed to obtain the distributions of temperature field, moisture field and displacement within two years after the completion of project. The results show that the canal slope encounters significant frost heaving and melting deformation during the freezing and thawing process, and both the frost heaving and the melting deformation are irreversible. The geotextile treated channel has a good performance in preventing frost heaving of frozen soil slope. It also has the advantage of small thermal conductivity that can effectively reduce the influence of atmosphere temperature on the soil temperature inside canal slope, so as to reduce the possibility of frost heaving and melting settlement. At the same time, soilbags can suppress the rise of capillary water and film water and reduce the water immigration of the geotextile bag layer and the lower part, so as to maintain a more stable water content within the channel to reduce the frost heaving of canal surface. In addition, the geotextile bag has a certain strength, and under the action of its tension stress, the frost heaving can be suppressed, thereby reducing the damage of frost heaving on the channel lining. At last, with the treated surface of channel using the geotextile bag, the internal temperature of slope can quickly reach a steady state, and after 2 years, a more stable and perennial frozen layer is formed below 2 m of the ground.