Experimental research on a grid device for the kinetic energy charge dissipation of mud-flows

A particular grid device for kinetic energy dissipation of a mud-flow is proposed, which is already usefully employed for stilling work to service dam drainages. In this paper, the results of experimental research on a prototype realized in the Laboratory of the Department of Hydraulic and Environmental Engineering G. Ippolito are presented, with the aim of also investigating the employment of the aforesaid grid device for the dissipation of the kinetic charge of a fast mud-flow, which is a natural extreme event. The experimental installation consists of a steel pond, equipped with a particular pump group made for the purpose, and is able to raise mud-flows up to 30 l/s up to a maximum height of approximately 12 m and the aforesaid flows, by means of a slide, are directed to the device. The fast mud-flow has been reproduced by means of a mixture of water and carbonate, which is insoluble in water, characterized from a d50 equal to 0.0013 mm. During the tests different values of volume concentration have been adopted of between 50 and 70, and it has been possible to control the mixture by means of continuous measures of specific weight and viscosity. The results have shown the effectiveness of the device in the presence of flows characterized with elevated Froude numbers in particular, and a beneficial effect has been induced from an obstruction wall positioned on the extremity of the grid and also by varying the full bend behind the wall (and so the empty-full ratio of the device is between 0.20-0.30), evidencing rollers that increase the total dissipative capacity of the device, which has turned out to be equal to approximately 85 in terms of kinetic charge.