Experimental Study On Electro-Osmotic Consolidation Of Marine Dredger Fill By Using Electric Vertical Drain

In recent years, people have carried out many hydraulic fill projects in the coastal regions of our country. Owing to bad engineering characteristics of dredger fill, the foundation must be pretreated before construction. Dealing with dredger fill by usual drainage consolidation methods always costs a lot of time and the methods are sometimes difficult to achieve satisfactory results. Electro-osmosis is suitable for foundation improvement of dredger fill because its performance is independent of the particle size and its dewatering has a high speed. High energy consumption and electrode corrosion of metal materials block the development of electro-osmosis. As a new material of electrokinetic geosynthetics, electric vertical drain(EVD) may change the current situation. Therefore, studies on its fundamental characteristics,laws of drainage and efficient utilization are very significant for engineering field application.Several tests are conducted to research the impacts of the drainage boundary conditions and power supply modes on electro-osmotic drainage of marine dredger fill by using electric vertical drain for electrodes. The main results are:1. Under the surface drainage condition, this paper shows the regularities of electro-osmotic consolidation when voltage or current is constant. Holding constant voltage has an advantage over constant current during electro-osmotic drainage.2. The influence of voltage on electro-osmotic drainage is studied in this paper when the bottom of soil is drainable. A moderate increase in voltage can lead a better result. Blindly increasing the voltage, however, cannot contribute to an obvious improvement in the electro-osmotic effect and it can waste a lot of energy. It can get a better result when the top of the boundary condition is drainable than that when the bottom of the boundary condition is drainable.3. Contrastive tests with different on-off time are conducted and compared with tests of which currents are continuous. The data shows that: short power period can improve water discharge and the efficiency; long power period contributes to reducing the difference of moisture content in soil after electro-osmotic consolidation.4. The electric vertical drain electrodes can keep intact during the experiments and it also has a productive drainage function. In engineering practice, it is very important to make full use of this advantage and combine electro-osmotic drainage with other methods to treat marine dredger fill comprehensively. All these can contribute to a better treatment effect.