Renwick Dam RCC Stepped Spillway Research

摘要

A specific study utilizing a two-dimensional, 1:8 scale physical model was conducted to evaluate the hydraulic performance of a 4(H):1(V) chute slope, stepped spillway and the associated energy dissipating stilling basin. The model study came at the request of the North Dakota Natural Resources Conservation Service (NRCS) because of the limited design guidance available for flatter sloped stepped spillways (θ ≤ 22°). The steps from the spillway create tremendous energy dissipation resulting in flow bulking. As a result, higher training walls for stepped spillways as compared to smooth spillways are necessary to contain the design flow. According to literature, the increased energy dissipation in the stepped spillway chute allows for a reduction in the length of the energy dissipation stilling basin as compared to the stilling basin length required for a conventional smooth spillway chute. The riprap size expected to protect the downstream channel from scour has an approximate D_(50) of 14 cm (5.5 inches). The results of the study are presented in a format that will assist engineers in designing stepped spillways with similar design parameters.