Laboratory Investigation the Effects of sheet pile on Seepage Control and sand ‎boiling through Alluvial Foundation of hydraulic structures

The sheet piles are used below hydraulic structures to reduce seepage flow rate and hydraulic gradient at the ýoutlet of such structures rested on permeable foundations.ýþ þSo far, for analysis of seepage under hydraulic ýstructures much research work has been conducted in the form of numerical models. However, less field and ýlaboratory works have been done to study boiling phenomena for evaluating of the numerical models. In the ýpresent research work, a laboratory model was made to simulate seepage and its controlling measures under ýcoastal dikes. The model consist of a flume 2.2m long, 0.8m deep and 0.4m wide, in which vertical sheet pile ýwere provided by Perspex sheets. The flume was made of steel frame and Perspex as well as thick glass ýsheets. The foundation material was made of clean, fine sand, compacted to a uniform density and covered ýthe bottom 40cm of flume. Perspex sheets were employed sheet pile variable depth. The piezometric heads at ýthe both downstream and upstream side of dike were measured using small diameter clear plastic tubes. The ýeffect of position and depth of the sheet pile on the seepage flow and exit gradient have been demonstrated in ýform of dimensionless curves. The results show that the depth of the sheet piles d/D=0.46 with the maximum ýupstream water level h/hm=1.0 boiling phenomenon does not occur and the seepage rate and hydraulic ýgradient in the area are favorable.ý