Reverse vacuum preloading method of blown silt foundation overlying backfill soil experimental study

In order to solve the problem of poor reinforcement effect of deep soil caused by backfilling when the traditional vacuum preloading is used to strengthen the pumped silt foundation, the reverse vacuum preloading method is proposed. This method uses the reverse drainage plate to directly apply the vacuum load to the deep soil, which effectively reduces the vacuum pressure loss along the road. Through laboratory model test, the influence of backfill thickness on the reinforcement effect of reverse vacuum preloading method was investigated. The test results show that compared with the traditional vacuum preloading method, the displacement increases by 16.46%, the average cross plate shear strength of silt layer increases by 9.60%, and the cross plate shear strength of deep soil increases by 20.50%, and the overall reinforcement effect of soil is significantly improved. With the increase of the backfill thickness, the shear strength of the cross plate of silt layer decreases significantly along the depth direction, and the treatment effect is more uniform. In addition, the field comparison test between the reverse vacuum preloading method and the traditional vacuum preloading method found that the surface settlement of the soil increased by 15.70% after the reverse vacuum preloading method, the pore pressure dissipation value at the depth of 12m increased by 26.20%, and the average shear strength of the cross plate increased by 21.12%. The reverse vacuum preloading method can improve the soil reinforcement effect and solve the problem of poor reinforcement effect in deep soil effectively.