Experimental investigation on hole erosion behaviors of chemical stabilizer treated soil

Abstract

Soil erosion plays a vital role in the performance of hydraulic projections such as earth dams and embankments. To improve the erosion resistance of the soil is crucial for preventing the dam break and assuring the safety of the hydraulic projections. In this study, three chemical stabilizers, i.e., sodium silicate (SS) solution, lignosulfonate (LS) powder, and sodium polyacrylate (PAANa), are used to treat the sandy soil. A set of hole erosion tests to investigate the erosion behaviors in treated and untreated specimens. The experiments collect flux and the mass of eroded particles during the erosion process. These data then yield the relations between hydraulic shear stress and erosion rate. Erosion coefficients, i.e., the critical shear stress (CSS), and the erosion rate index (ERI), are acquired from linearly fitted relation curves between the hydraulic shear stress and the erosion rate. During the erosion experiments, we observe that the erosion continues in untreated specimens and leads to the collapse of the specimens if the experiment is not stopped. On the other hand, erosion in treated specimens stops automatically after a long erosion time, even if the hydraulic gradient is maintained. These results indicate that the stabilizers improve the anti-erosion capability of the soil specimen. The improvement becomes significantly noticeable if the stabilizer content and the curing time increase. Among the three stabilizers tested in the experiments, PAANa performs best in treating the sandy soil since the rate of increase in CSS and ERI reaches 214.4% and 85.4%, respectively, when 1.5% PAANa is added into the specimen. The rates of increase in CSS and ERI are 23.2% and 43.8%, respectively, for the specimens treated with lignosulfonate, given the same other conditions. Based on the results, the choice of the stabilizer is discussed and suggested.