Study On The Clogging Mechanism Of Newly-dredged Mud Under Vacuum Preloading By Experiment And DEM Simulation

In recent years,the vacuum preloading method is widely used in reclamation project in the coastal areas.With the continuous improvement of vacuum preloading method,direct drainage vacuum preloading method with no sand gradually replaces the traditional vacuum preloading method.Comparing with the conventional vacuum preloading method,this method not only improves the construction speed of foundation reinforcement,but also solves the high cost problem caused by the purchase of sand material.However,engineering practice shows that this method does not effectively solve the problem of clogging in the drainage process,especially for the treatment of the newly-dredged mud with high content of clay particles.To solve the problem of clogging,it is necessary to study the formation mechanism,formation process and prevention of clogging.Many scholars have studied it by the macro-model test in the lab,while the study on the micro-level is still very defective.In this paper,the clogging mechanism and influence factors of vacuum preloading are studied from both the macro and micro perspective.Through the model test,the variation law of drainage rate,pore pressure and porosity ratio is summarized,and the correctness of particle flow simulation is validated.Combining the macroscopic test results and the microscopic numerical results,the relationship among the drainage rate,particle migration and the clogging behavior are established to explain the mechanism of clogging behavior.Based on the simulation of the vacuum preloading process under different particle compositions and loading conditions,the influencing characteristics of clogging formation and consolidat ion deformation are summarized.Accordingly,the method of particle flocculation and air-injection are proposed to improve the effect of vacuum preloading method.Finally the validity of these methods is proved by the method of particle flow simulation.