Experimental research on release characteristics of deposited particles in porous media

The experimental research on the release characteristics of deposited particles in porous media plays an important role in the blocking process of the WSHP recharge. The release characteristics of deposited particles in porous media are studied by using the self-development sand deposition and release equipment. Two factors are taken into consideration, one is increasing the flow velocity, the other is changing the flow direction. The study shows that as the flow velocity increases, deposited particles are easier to release from the surface of porous media and it takes less time to reach the second peak of relative concentration, meanwhile, the water injected is almost of the same amount. Compared with the way of increasing the flow velocity, the way of changing the flow direction is more effective in the releasing process of deposited particles, and it takes less time and water to reach the second peak of relative concentration. With the increase of time, blocking will appear in porous media and change as it is before the flow direction. The initial phase after the flow condition changes plays an important role in the release of deposited particles. The research lays foundation for further studies on the deposition and release characteristics that suspended particles transport in layer, especially in the recharge process of WSHP.