Failure mechanism and treatment measures for expansive soil canals in cold regions: A case study of the Xinjiang Water Conveyance Canal in China

The stability of the expansive soil slope of the Northern Xinjiang Water Conveyance Canal is considered crucial for its normal operation. In this study, the causes of failures in the expansive soil slope of the canal were investigated by means of field instability section monitoring and laboratory triaxial tests. It is indicated by the results that landslides, frost heaving, and uplift damage are significantly impacted by the cyclic action of wet-dry-freeze-thaw (WDFT). The mechanical properties of the foundation's expansive soil are found to deteriorate due to the WDFT cycles, particularly in the first cycle, before being stabilized after three cycles. A trend of deterioration and instability of the expansive soil canal slope is observed, commencing from the largest tensile crack at the top of the canal, but no significant local instability is found to occurs. In this study, treatment measures are proposed to maintain the safe operation of water conveyance expansive soil canals in cold regions, such as the reduction of the water level behind the geomembrane, to improve the normal operation of the canal and water transfer time. This research can be utilized by engineers and decision-makers in making informed decisions regarding the design and construction of expansive soil canal slopes in cold regions thereby assisting in the prevention of similar failures in the future.