RIPRAP Design for Towboat-Induced Forces in Lock Approaches
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS HYDRAULICS LAB
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Commercial towboats in navigable waterways, particularly in confined reaches, generate waves and currents which can be of significant magnitude such that stabilization of the banks with riprap is warranted. This paper focuses on stable riprap design for tows under way here referring to those whose sailing line is parallel to the banks and whose speed is constant. Therefore, return current, wave characteristics, and channel geometry are the governing parameters for sizing the stone. Propeller jet impacts due to maneuvering tows are not addressed. Most of the existing guidance on sizing the riprap on the banks for waves has been based on coastal waves. The riprap design guidance pertaining to waves produced by typical commercial towboats found on US waterways is limited. Based on site-specific needs to address stone sizes due to towboat-induced forces, several studies have been conducted at the US Army Engineer Waterways Experiment Station WES, Vicksburg, Mississippi. The physical model studies include the Tennessee-Tombigbee Waterway, the Gallipolis Lock approach on the Ohio River, and some general navigation research regarding stone slope stability in confined waterways. Although these studies have been primarily devoted to the evaluation of specific stone sizes and gradations subjected to specific towboat operations, the study results lend themselves to use as general riprap design guidance.
- Hydrology, Limnology and Potamology