Silty sand has the characteristic of being rich in micro pores， which makes it more difficult to reinforce it by grouting. Based on the traditional grouting reinforcement material， nano-silica sol was introduced to analyze the feasibility for reinforcement of silty sand. In this paper， the physical and mechanical properties of reinforced soil under different conditions were compared by using laboratory test methods such as comparative test of grouting effect of different materials， unconfined compression strength experiment， permeation experiment and SEM scanning electron microscope analysis. The results showed that the nano-silica sol grouting can quickly and effectively penetrate into the soil to cement the soil particles and seal the pores compared with traditional grouting materials. After the curing in both dry air and water environments， the mechanical experiments and seepage scouring experiments were carried out. When the filling rate was 25%， the strength of nano-silica sol reinforced soil increased to 280—290 kPa， and the seepage resistance time was extended to 340 h under continuous water scouring. By comparing the compositions and structural characteristics of reinforced soils in different curing environments and ages， it found that the structure of reinforced soils was more complete and less porous under water curing， so the nano-silica sol had a greater advantage in water-rich areas.
