Experimental and numerical study of collapsible soils treated by colloidal nanosilica

This paper presents findings from an experimental study examining the effects of colloidal nanosilica (CNS) grouting on the behaviour of collapsible soil under monotonic and cyclic loading conditions. Drained and undrained monotonic and cyclic triaxial tests were conducted on treated and untreated soil specimens. Results indicated that the injection of CNS enhanced shear strength, reduced excess pore water pressure, and increased the brittleness index of treated samples. In cyclic triaxial tests, untreated soil samples experienced liquefaction within initial cycles, while CNS grouted samples remained stable until the 300th cycle. An elastoplastic constitutive model was used to describe the mechanical behaviours of treated and untreated soil specimens, showing good agreement between calculated and experimental results. However, slight discrepancies were observed in the trends of pore water pressure and volume change for treated soil. Factors such as incomplete saturation during sample preparation, hydraulic gradients along the length of the sample, and CNS compressibility can lead to discrepancies between experimental and calculated values.