Influences of filling replacement and drainage modification on stability of water conveyance canals in North Xinjiang

The leakage of canals in North Xinjiang is serious, and the behavior of expansive canal soil deteriorates rapidly, leading to frequent canal slides. In order to solve this problem, the canals are refilled and rebuilt, and a drainage system is set up at the bottom of the canals. Laboratory tests and numerical calculation are conducted to analyze the influences of reconstruction measures of canal slopes on their stability. The following conclusions are drawn: (1) The properties of white sandstone for filling replacement are relatively stable, and the shear strength indexes c and φ are basically not affected by the drying-wetting cycle and the freeze-thaw cycle. (2) The slide circle extends from the bottom to the top of the canals, mainly through the inner expansive soil layer. However, the properties of expansive soil will deteriorate with the drying-wetting cycle, and only 0.5 m- thick gravel and 1.5 m-thick white sandstone replacement layer on the surface of the canal slope shows a low resistance effect. (3) After canal reconstruction, the amount of landslide decreases, and the stability of canal slopes is improved, which is mainly due to the function of drainage system. The drainage system reduces the post-membrane water level, which ensures that the expansive soil inside the canals will not deteriorate, and significantly improves the stability of the canals. (4) In order to ensure the long-term stability of the canals, it is suggested to carry out continuous drainage operation for water seepage in the canals, and control the post-membrane water level within 2 m.