Identification and Stabilization of Dispersive Soils: Case Study of Water Transfer Canal of Simindasht-Garmsar

The existence of salts in certain types of fine-grained clayey soils leads to soil dispersion. Structural damage might occur if dispersive clays are not properly identified since, under certain conditions, the particles in these clays are dispersed and can be rapidly washed away. Certain hydraulic structures in Simin Dasht (a region in Semnan Province, Iran) have suffered severe damage as a result of being erected on dispersive soils. Soil types around the water transfer canal in Simin Dasht were studied in the present article and their degree of dispersion (divergence) evaluated. Subsequently, methods were proposed for soil treatment. To this end, soil samples were taken from the area and, upon determining their specifications, were subjected to the crumb test, the double hydrometer test, and other chemical tests. The results revealed that soils in this region, particularly around the water transfer canal, were dispersive. To determine if adding cement, lime, and aluminum nitrate would reduce soil dispersion, the collected samples were thus treated and subsequently subjected to the pinhole test. The test results showed that adding 5% cement, 5% lime (without complete removal of scouring), or 3% aluminum nitrate to highly dispersive soils; and adding 3% cement, 5% lime, or 3% aluminum nitrate to dispersive soils would stabilize the dispersive soil in the region.