Applications Of Roller Compacted Concrete In Rehabilitation And Replacement Of Hydraulic Structures

Although roller compacted concrete (RCC) was primarily developed for rapid, economical construction of new dams, the case histories reported herein show that it has been used extensively in remediation projects at existing hydraulic structures. These case histories were compiled to illustrate the versatility of RCC in repair, rehabilitation, and replacement of hydraulic structures. RCC applications include increasing existing spillway capacities; construction of new service, emergency, and combination spillways; repair of spillways, outlet tunnel, and lock floor; overtopping and scour protection for rock fill timber crib and embankment dams; seismic strengthening; increasing sliding stability; breach repair; and replacement of rock fill timber crib, earthfill embarkment, and concrete dams. The basic properties of RCC (high strength, low permeability, and high erosion resistance compared to nonstabilized materials) together with low cost, rapid and relatively simple construction methods, and proven performance make it particularly attractive for remediation of hydraulically deficient embankment dams. Depending on the complexity of placement and total quantity of material required, the cost or RCC typically ranges from 25 to 50 percent less than conventionally placed concrete. These savings are primarily the result of reduced costs for forming, placing, and compacting RCC. Also, the reduced construction time typical of RCC contributes significantly to its lower cost. Rapid construction is a major advantage in repair of hydraulic structures where delays and shutdowns can cause significant losses to the user. Also, rapid construction minimizes the impact of bad weather and reduces the potential for adverse environment impact in the vicinity of project sites.

Earthen levees are extensively used to protect the population and infrastructure from periodic floods and high water due to storm surges. The causes of failure of levees include overtopping, surface erosion, internal erosion, and slope instability. Overtopping may occur during periods of flooding due to insufficient freeboard. The most problematic situation involves the levee being overtopped by both surge and waves when the surge level exceeds the levee crest elevation with accompanying wave overtopping. Overtopping of levees produces fast-flowing, turbulent water velocities on the landward-side slope that can potentially damage the protective grass covering and expose the underlying soil to erosion. If overtopping continues long enough, the erosion may eventually result in loss of levee crest elevation and possibly breaching of the protective structure. Hence, protecting levees from erosion by surge overflow and wave overtopping is necessary to assure a viable and safe levee system. This book presents a cutting-edge approach to understanding overtopping hydraulics under negative free board of earthen levees, and to the study of levee reinforcing methods. Combining soil erosion test, full-scale laboratory overtopping hydraulics test, and numerical modeling for the turbulent overtopping hydraulics. It provides an analysis that integrates the mechanical and hydraulic processes governing levee overtopping occurrences and engineering approaches to reinforce overtopped levees. Topics covered: surge overflow, wave overtopping and their combination, full-scale hydraulic tests, erosion tests, overtopping hydraulics, overtopping discharge, and turbulent analysis. This is an invaluable resource for graduate students and researchers working on levee design, water resource engineering, hydraulic engineering, and coastal engineering, and for professionals in the field of civil and environmental engineering, and natural hazard analysis.

A book of broad interest to professionals, dam engineers and managers, and to organizations responsible for dam development and management, RCC Dams offers a topical account of the design and operation of roller compacted concrete dams, describing the latest developments and innovative technologies in the field. The book considers planning and design, materials and construction, as well as the operation and performance of RCC dams.