Study of the Efficiency of Downstream Blanket in Heading-Up Structures

Abstract

In this research, an electrolytic tank is used to study the effect of using a perforated blanket downstream the aprons of heading-up structures on the safety against piping through making different scenarios for length of blanket, intensity of perforations and presence of cutoffs. The study lead to conclude that when a blanket is added downstream the apron of the heading up structure, it acts as if the apron is extended, the uplift head increases at the critical section because the blanket blocks partially the pores of the soil downstream the apron and changes the distribution of the uplift diagram under the apron, so it is needed to increase the perforation ratio of the blanket in order to dissipate the increase in the uplift head at the end of apron due to the addition of the blanket. The conclusions also include determining the optimum length and perforation ratio for the downstream blanket with and without cutoffs.