After slope excavation of expansive soil canal, the soil body at slope surface would suffer weathering destruction of different degree due to the long-time exposure. If the protection and treatment for weathered canal slope are not taken in time, the destruction will expand and the stability of canal slope will be threatened. In view of the practical situation of deep excavation of slope of expansive soil canal of Middle Route Project of South-to-North Water Diversion, the weathering characteristics of the slope surface are analyzed, and the suggestions for its construction and excavation, protection and treatment are put forward. It is pointed out that after the excavation, modified soil should be backfilled in time. If it can not be sealed timely, the measures such as surface protection by waterproof material, setting drainage ditches and changing excavation mode should be adopted, so as to reduce or avoid the destruction of the slope surface by weathering.%膨胀土渠道边坡开挖后，若裸露时间过长，渠坡坡面土体会遭受不同程度的风化破坏。若不及时采取防护或处理，风化渠坡的破坏范围会不断扩大，很有可能会危及到渠坡的稳定。结合南水北调中线深挖方膨胀土渠道开挖所揭露的实际情况，对渠坡坡面风化特征进行了分析，并提出了膨胀土渠坡施工开挖、防护及处理措施。着重指出，渠道开挖后应及时回填改性土封闭，对于不能及时封闭的坡面，可采取防雨材料覆盖、设置排水沟、改变开挖方式等，避免或减小坡面土体遭受风化破坏的风险。
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