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近几年来西北地区修建了一些混凝土衬砌的渠道,力图最大限度的减少渗漏,节约水量,提高渠系水的有效利用系数,扩大灌溉面积。但由于西北地区气候严寒,最低温度达零下30℃左右,且冰冻期长达四、五个月之久。因此,就给混凝土渠道带来了严重的“冻害”问题,特别是在土质基础上修建的混凝土渠道,因排水不良引起的冻害为更甚。甘肃在1957年修建的昌马河总干渠,干渠均有冻胀断裂现象,进入灌区的甘新公路桥附近及北干渠的某些建筑物,系土质基础,护底因冻胀隆起10余厘米。近年来修建的几条混凝土渠道,如金塔东干渠、永昌二坝渠等均出现了“冻害”。发生纵横向裂缝,使渠道破坏,尤
In recent years, a number of concrete lining channels have been constructed in the northwestern region in an attempt to minimize leakage, save water, raise the effective utilization coefficient of canal water and expand the irrigated area. However, due to the cold climate in northwest China, the minimum temperature reaches minus 30 ℃, and the freezing period lasts for four or five months. As a result, serious “frost damage” problems have been brought to the concrete channels, especially the concrete channels built on the soil foundation. The frost damage due to poor drainage is even worse. In 1957, Gansu’s Changma River main canal and main canal were all frost heaved and fractured. Some buildings near the Gansu Highway Bridge and the Northern Main Canal of the irrigation area were soil foundation and the bottom of the embankment was swept up by more than 10 centimeters . In recent years, the construction of several concrete channels, such as the Golden East trunk canal, dam Yongchang two dikes appeared “frozen damage.” Occurrence of vertical and horizontal cracks, the channel destruction, especially