Study on the mechanical properties and consolidation mechanism of dispersive soil modified with nano-clay

Dispersive soils are characterized by low resistance to water erosion, low shear strength, and poor hydraulic performance, making them prone to engineering disasters such as dike piping, channel collapse, and slope instability. This study investigates the modification of dispersive soil using nano-montmorillonite and attapulgite. Through identification, permeability, and unconfined compressive strength (UCS) tests, the effects of additive dosage, dry density, and curing time on the dispersibility and mechanical properties of the soil were analyzed. Furthermore, XRD, FTIR, and SEM characterizations were conducted to examine the microstructure and elucidate the modification mechanisms. By integrating macroscopic and microscopic results, a macro–micro correlation model was established. The results indicate that to transition dispersive soil from dispersive to transitional and finally to non-dispersive states, the critical dosages are 7% and 9% for nano-montmorillonite, and 8% and 10% for attapulgite, respectively. Increasing the dry density, curing time, and additive dosage led to a gradual decrease in permeability and a corresponding increase in UCS for both modified soils. Microstructural analysis revealed that while the additives did not alter the fundamental crystal structure of the original clay minerals, they created a denser mineral framework through filling and bonding effects. Additionally, a predictive model for UCS was developed using shape factor and fractal dimension as independent variables. This model demonstrated high accuracy, proving effective for evaluating the UCS of attapulgite-modified dispersive soil. These findings offer a theoretical basis and technical guidance for the solidification and engineering application of dispersive soils.