Evaluation of small strain stiffness characteristics of soft clay treated with lime and nanosilica and correlation with UCS (q_u)

Improving the strength and stiffness properties of soils using non-conventional materials has been extensively performed in the past decade. In recent years, many nanotechnology-based materials have been used in different civil engineering projects. Unlike the static properties, dynamic characteristics of stabilized soils, which are of great significance in the seismic analysis of geostructures in earthquake-prone areas, have not been extensively explored throughout the literature. In this study, the influence of the addition of nano-SiO₂ and lime on the shear wave velocity (V_s), small strain shear modulus (G_max), and unconfined compressive strength of the stabilized clay is investigated. Adopting nano-SiO₂ and lime contents and curing time of the mixtures as testing variables, several series of bender element (BE) tests and unconfined compressive strength tests are performed on soft clay samples stabilized with the variable percentages of lime and nano-SiO₂. The experimental results demonstrate that the simultaneous addition of the nano-SiO₂ and lime contents to the mixture up to a certain level (7% lime and 1% nano-SiO₂) leads to a considerable increase in the small strain characteristics and unconfined compressive strength of soft clay. A typical correlation between the small strain properties and unconfined compressive strength (q_u) is also developed for the mixture used in this study, which could be an alternative approach for the evaluation of shear stiffness. Such correlation could serve as a quick, convenient reference without having to prepare numerous specimens for the dynamic experiments.