Experimental investigations on frost damage of canals caused by interaction between frozen soils and linings in cold regions

In cold regions, the safety and efficiency of water conveyance canals are threatened by freeze-thaw damage. This damage is caused together by the heave and settlement deformation of soils and the interaction between soils and lining structures during the deformation. The model tests on freeze-thaw of a lining canal are conducted using the method of circulation cold supply in low temperature chamber and water supply from sand gravel in model tank base. Through the tests, the dynamic coupling laws of soil temperature fields, moisture fields, deformation fields and lining displacements are studied, and the change of physical properties in different canal cross sections is observed. The results show that the migrating and freezing of moisture causing soil deformation is controlled by temperature gradient and freezing rate, and restricted by soil initial water content. The cross-section of the canal affects its temperature boundary and heat transfer process, leading to the difference of freezing rate and frost-heave distribution. The frost heave and compression occur inside the freezing soils at the same time, and the compression of soils is affected by the cross-section of the canal, which causes intricate internal stress of canal soils. The freezing heave of soils and displacement of linings are not coordinated, which forms the gap between them and causes eccentric tension in the linings. In addition, the touch segregated ice layer is formed and transmits the interaction between soils and linings during freezing, and during thawing, the ice layer melts and the strength of surface soils loses, which causes the canal slope to slide to induce instability and slump of lining structures in a large scale.