Analysis of the effect of air injection loading path on strengthening soft dredger fill by air-booster vacuum preloading method

When air-booster vacuum preloading method is used to reinforce soft dredger fill，the reinforcement effect will be affected by air injection pressure and air injection time. Indoor model tests with different combinations of injection pressure and injection time were used to investigate the effect of the air injection loading path on the reinforcement of soft dredger fill. Four air injection loading paths were considered：constant pressure-constant time，constant pressure-variable time，variable pressure-constant time and variable pressure-variable time. The test results show that the reinforcement effect of air-booster vacuum preloading method is always better than that of conventional vacuum preloading method. And when the air injection loading path of variable pressure-variable time is adopted，the soil reinforcement effect is the best. Compared with the air injection loading path of constant pressure-constant time，the air injection loading path of variable pressure-variable time can lead to an increase in soil surface settlement by 9.25%，an increase in drainage by 9.35%，a decrease in average water content by 13.91% and an increase in average vane-shear strength by 20.59%. The gradual increase of air injection pressure and air injection time can effectively prevent the accumulation of clay particles to the prefabricated vertical drains(PVDs)，and increase the number of soil pores between PVDs and the booster board. The permeability of soil and the reinforcement effect of deep soil can be improved by using the loading path of variable pressure-variable time. © 2023 Academia Sinica. All rights reserved.