Long-Term Changes in the Properties of Soil Linings for Canal Seepage Control

摘要

Field and laboratory test data on typical soils in selected Bureau compacted soil (earth) canal linings show long-term physical changes in the linings. These data are indicative of lining performance. The physical properties (particularly unit weight) of the lining soil that affect permeability and canal seepage were tested at various intervals after lining construction. Unit weight was found to vary significantly from one test site to another from year to year. Although there was a general tendency for unit weight to decrease from the top of the lining to the bottom, in some cases it increased. Based on results of laboratory freezing tests, changes in unit weight for linings in cold climates were largely attributed to frost action. Generally, there appeared to be less (average) change in unit weight in fine-grained soils of low plasticity without gravel than in soils containing a significant gravel fraction. In one heavy clay lining, loss of unit weight was attributed to wetting and expansion of the soil. Based on field tests of permeability and seepage and on observations of seepage adjacent to the canals, it was concluded that the soil changes found did not significantly affect the expected performance of the canals in controlling seepage.