Experimental study on transport process of electro-osmosis based on Hangzhou soft soil

To study transport process of electro-osmosis and reveal electro-osmotic mechanism, laboratory electro-osmotic tests were conducted using a self-made model box and Hangzhou soft soil, with ferrum and graphite being the electrode materials. Mass concentrations of selected elements in the electro-osmotic drainage, gravity drainage as well as soil mass were monitored. Current and electro-osmotic dewatering were also monitored during the experiments to calculate electro-osmotic water transport per unit charge. The results show that mass concentrations of Na and K ions are much higher in electro-osmotic drainage than those in gravity drainage, while opposite results are obtained for Mg and Ca ions, which indicates that electro-osmosis technique has a dependency on the transferring of water by counters of low order and small atomic mass. Double layer constitutes the primary refection of the influence of soil physical and mechanical properties on electro-osmotic process. Sensitivity of the electro-osmotic water transport per unit charge to water content is closely related to the soil type, while for a given type of soil, this sensitivity may differ for varied range of water content. Under the potential of 1.58 V/cm, the ultimate water content of the deposed Hangzhou soft soil is 35%, indicating that the electro-osmosis technique is ineffective for Hangzhou clay with water content below 35%. It is thus not recommended to adopt the above technique to dispose Hangzhou clay with water content lower than 35%. © 2018, Central South University Press. All right reserved.