Free swelling of soil and its role in the formation of cracks on concrete slopes of canals Available to Purchase

Determining the free swelling properties of soil during the design and construction of large hydraulic structures, including for concrete lined irrigation canals, is important for predicting the effect of swelling pressure on concrete lining. If swelling value is clear, it is possible to calculate the thickness of concrete and take measures to prevent deformation of the concrete slope of the canal. The reconstruction of the Bustan canal in the south of Karakalpakstan has been implemented with the purpose of abandoning expensive irrigation pumps, transferring to gravity irrigation system and providing reliable water to command area of 100 thousand hectares. After completion of construction in the western part at PK47+20, PK202+80, PK218+00, longitudinal cracks appeared in the left slopes. To identify the causes of crack formation, it was decided to test with destructive method in these areas and the condition of the geotextile and geomembrane, the physical, mechanical and chemical properties of the soil, the salinity of the water for preparing concrete and the free swelling of the soil have been checked. This article presents the results of laboratory studies to determine the free swelling of soil. Soil samples were tested in a licensed laboratory of JSC Gidroproekt in accordance with standards. The loosened soil was compacted using the SOYUZDORNII PSU device. The studies were carried out on an automated ASIS device. Research has shown that the absolute swelling deformation did not exceed -1.13mm and the relative swelling deformation was 0.047. Soil moisture after swelling varied from 16.30% to 26.43%. Classification according to the degree of free swelling; soils are classified as weakly swelling soils when the relative swelling deformation is 0.04–0.08. Free swelling of the soil could not have a significant effect on the appearance of cracks in concrete.