Study On Proliferation Mechanism And Model About Dredged Sediment In The Process Of Cutter-suction

In dredging engineering,due to mechanical disturbance,sediment diffusing rapidly into the water body makes the pollutants in the sediment particles released which will caused the water secondary pollution,and influence the environment and ecological balance.The key to solve the problem is how to reduce or stop the spread of sediment dredging engineering,in order to reduce the secondary pollution of water.This paper is based on the secondary pollution problem caused by the sediment diffusion in the process of dredging.According to the features of dredged sediment,suitable and environmental protection proliferation agents were chosen to be used in the dredged sediment.And the effect mechanism of proliferation agent and model were studied.Dredging process as the research object,a set of cutter-suction simulator was designed,and the proliferation effect of the proliferation agents was explored through the simulation experiments.And through CFD model to predict the fluid flow condition and sediment diffusion distribution.The results of the study are as follows:(1)According to the actual situation in dredging engineering,a set of cutter-suction device which contains drag system,dosing system and monitoring system was designed to explore the sediment diffusion performance.And to stability test of the device,through the online turbidity in overlying water,the SS,COD before and after the dredging,and the sediment diffusion scope were used to characterize the proliferation effect of sediment in the dredging process and the stability of the device.Results showed that the dredging device can simulate the dredging process,and no matter the reamer rotating speed is 90 r/min,120 r/min or 180 r/min,the sediment diffusion has the similar rule.(2)The key influence factors in the process of cutter-suction were studied by changing the reamer rotating speed,drag power and reamer ground movement speed of the simulation device.And analysis it's the overlying online turbidity of the water,SS and COD before and after the drag,and the sediment diffusion scope of the sediment were studied to explore the proliferation effect and the law of diffusion of sediment.(3)According to the characteristics of dredged sediment,the polysilicic ferric(PSF)and cationic polyacrylamide(CPAM)and their blends with reagent of were chosen to study the proliferation effect of sediment in the cutter-suction process by the analysis of the diffusion of sediment diffusion radius and height,the overlying water turbidity,sediment system of particle size and Zeta potential.The result shows that the method of adding non-proliferation agent can reduce the spread of the sediment which includes diffusion radius and height,decrease the overlying water turbidity,increase the sediment particle size,increase the Zeta potential of water body,and have certain proliferation of sediment diffusion effect.(4)Using the computer fluid dynamics(CFD)model for computer simulation of cutter-suction process to predict the spread of the fluid flow condition and sediment distribution.