Repair, Evaluation, Maintenance and Rehabilitation Research Program: Evaluatingthe Stability of Existing Massive Concrete Gravity Structures Founded on Rock

摘要

The U.S. Army Corps of Engineers is responsible for designing and maintaining alarge number of navigation and flood control structures. Many of the older massive concrete gravity hydraulic structures are being examined to determine if rehabilitation is required to meet stability criteria. The procedures currently used for evaluating the safety of existing massive hydraulic structures are the conventional equilibrium methods, which are the same general methods used in the design of these structures. Because the conditions of equilibrium are insufficient for a complete analysis of all aspects of structure foundation interaction involved in the stability and performance of these structures (soil structure foundation interaction in the case of earth retaining structures), these conventional equilibrium methods necessarily involve assumptions regarding aspects of the loading forces and the resisting forces that act on the hydraulic structures. Differences between actual field performance and calculations from conventional analysis have been noted for some existing hydraulic structures. Conventional design methods were developed based largely on classical limit equilibrium analysis without regard to deformation related concepts. Today, analytical tools such as the finite element method (FEM) are available which consider the manner in which the loads and resistance are developed as a function of the stiffnesses of the foundation rock, the structure foundation interface, and rock joints within the foundation. These analytical tools provide a means to evaluate the conventional equilibrium-based design methods used to evaluate the safety of existing hydraulic structures, and specifically, to identify and investigate key assumptions used in safety calculations from the conventional analysis.