Spillway and Outlet Works, Shelbyville Dam, Kaskaskia River, Illinois. Hydraulic Model Investigation.

Tests were conducted on a 1:40-scale model reproducing the spillway for Shelbyville Dam, a combination concrete and earth structure rising 108 ft above the bed of the Kaskaskia River. The spillway consists of an ogee crest controlled by three tainter gates 45.33 ft wide and 36.92 ft high; a 156-ft-wide, 206-ft-long chute sloped 1 on 4; and a conventional hydraulic jump type stilling basin. The design flood, 162,500 cfs, will be passed at pool elevation 638.2 by combined operation: 157,500 cfs over the spillway and 5000 cfs through two 11-ft-high by 5.5-ft-wide sluices through the spillway section beneath the piers. Flow conditions in the approach, discharge characteristics of the spillway, hydrostatic pressures on the ogee weir crest, performance of the conventional stilling basin, and the height of the training walls were investigated. The limits of two exit channel protection plans involving the use of various sizes and gradations of stone and concrete paving were developed with and without berms behind the training walls. (Author)