Abstract: Aiming at the dredger fill with high clay content, a series of vacuum preloading model tests and microscopic tests were carried out in this study, to discuss the reinforcement effect and mechanism of the chemical modification combined with vacuum preloading method. The results show that the liquid limit and plasticity index of the dredger fill were both reduced notably, while the coefficient of permeability of the dredger fill was significantly increased; in addition, the microscopic tests results show that a series of complex chemical reactions happened between modified admixture and soil particles due to chemical modification, and it can be observed that a large amount of insoluble substance was attached to the surface of the dredger fill particles due to the chemical modification, which contributed to a typical aggregate structure and increasing the pore diameter, and leading to a significant improvement in the permeability of the dredger fill. Compared with traditional vacuum preloading method, the chemical modification combined with vacuum preloading method has greatly improved the reinforcement effect of the dredger fill. The maximum increases in vacuum preloading drainage and vane shear strength of the dredger fill reinforced were 17.6% and 69.0%, and the surface settlement increased significantly. This research provides a theoretical basis for improving the technical development of vacuum preloading method.

Key words: vacuum preloading, chemical modification, model test, reinforcement effect, mechanism analysis