Experimental Study On Effect Of Surcharge Gradient And Multistage Vacuum On Consolidation Of Dredged Silt By Vacuum Coned With Surcharge Preloading Method

In order to deepen the reform and development,Wenzhou proposed to optimize the urban spatial structure and layout,and vigorously develop coastal reclamation projects.Although vacuum combined with surcharge preloading technology is widely used in the engineering practice of treating mudflats in large areas in order to shorten the construction period,save the cost,and have good treatment effect,However,there are still some problems such as uncertainty of surcharge gradient and the accumulation of fine particles in the periphery of the PVD under vacuum suction to cause membrane blockage.In this paper,the dredging silt in Wenzhou area of Zhejiang Province is taken as the research object.The above problems are discussed and studied through the model test in the design room.The main contents are as follows:(1)Three kinds of surcharge gradients are designed for indoor test.The data analysis show that the reinforcement effect is related to the surcharge gradient and the surcharge time.Reasonable control of the surcharge gradient can effectively reduce the horizontal displacement,reduce the impact on the surrounding structures,and avoid unnecessary economic losses and casualties.(2)The effect of multistage vacuum on the consolidation of dredged silt by vacuum combined with surcharge preloading method is studied.The experimental results show that multistage vacuum has more obvious effect on consolidation of draught flow mud by vacuum combined with surcharge preloading,and the settlement and strength of three-stage vacuum loading are the largest,and the reinforcement effect is the best.(3)On the basis of three-stage vacuum loading,the optimum surcharge gradient suitable for Wenzhou dredged silt is discussed,and the experimental analysis shows that the method has better treatment effect in improving the bearing capacity of foundation.Moreover,the uniformity of technology is improved at different depth of foundation,and it is concluded that the gradient of surcharge load should be controlled reasonably in engineering practice,otherwise,the instability of foundation will occur,resulting in economic loss and casualties.