Study on the small strain dynamic characteristics and microscopic mechanism of nano-silica modified lime soil

Abstract

Nano-silica (NS) possesses the characteristics of high specific surface area, high chemical activity and nanoscale dimensions. Incorporating an appropriate amount of NS into lime soil not only enhances its mechanical properties, but also contributes to resource conservation and environmental protection. This study investigates the small strain dynamic characteristics of nano-silica modified lime soil (NSLS) through resonant column test and examines its microscopic mechanism and pore changes by SEM, EDS, XRD, FTIR and MIP. The research findings indicate that with increasing confining pressure and curing age, the dynamic shear modulus G of NSLS gradually increases, while the damping ratio D gradually decreases. Furthermore, the fitting results from the Hardin-Drnevich model demonstrate that under different confining pressures, adding 0.4 % NS to lime soil yields the most significant improvement in stiffness, with the maximum dynamic shear modulus G_max increasing by 34 %–45 % and the maximum damping ratio D_max decreasing by 20 %–30 %. Additionally, SEM, EDS, XRD, FTIR and MIP test results reveal that NS promotes the generation of more hydration products in NSLS, which helps to reduce its porosity. In summary, this study illustrates how NS can enhance both mechanical properties and microstructure of lime soil while providing scientific evidence for its application in practical engineering.