Preliminary Study On Water Sensitivity Of The Porous Media

The saline-freshwater interface is a transition zone from saline water to freshwater. The existence of the water sensitivity at the interface has double significances: firstly, water sensitivity makes the restoration of the permeability of the porous media difficult due to simply injecting fresh water to flush saline water. Secondly, the existence of water sensitivity presents new methods to prevent saline water intrusion. Therefore, it has significant meaning and applied value to study the water sensitivity of the porous media at the saline-freshwater interface.Based on the geohydrological investigation in the fields, seawater, freshwater and sand samples from the saline water intrusion zone were taken to conduct the batch experiments and column experiments. The aims of these experiments were to discuss the dynamics of particle detachment, migration and redeposition under different water hydraulic and chemical conditions at saline-freshwater interface, learn the relationship between the permeability change and the migration and redeposition of the detached particles, supply the scientific dependence for the assessment and prevention of the saline water intrusion. The results show:(1) The faster the fluid velocity, the bigger the effect of the hydraulic is. Thus the fines can easily migrate. Under the same hydraulic conditions, the effect of hydraulic on permeability is related to the critical ionic strength of the solution. The higher the critical ionic strength, the more difficult the fines are released. In the batch experiment, the shaking frequency was not beyond 150 times/min in order to prevent hydrodynamiclly induced particles. In the column experiment the critical influent velocity was 21 mL/min.(2) In the batch experiment when the shading frequency was set in the 150 times/min, the critical salinity concentration caused the particles...