Different Analysis Strategies for Roller Compacted Concrete Dam Design

Abstract

This study presents the results of numerical simulations of the 56 m high Kocak concrete gravity dam planned to be constructed in Giresun, Turkey. A three stage analysis procedure was employed, namely rigid block stability analysis, two-dimensional finite element analysis both in frequency and time domain and three-dimensional dynamic analysis. The preliminary dimensions of the dam cross section were determined from stability analysis following recommendations in [1] and [2]. Afterwards, a time history analysis was conducted by following the procedure of [3] that accounts for foundation flexibility and dam-reservoir interaction using the finite element method. In order to estimate the crack lengths and distances, a nonlinear time history analysis was conducted for the two-dimensional model using Westergaard’s [4] added mass approach including concrete cracking based on a smeared rotating crack approach. In the 3D linear spectrum analysis, the importance of modeling the exact geometry and complete soil-dam interaction and the influence of earthquake induced effects were investigated. It was found that the preliminary design section based on rigid body equilibrium is susceptible to cracking. However, the locations of expected cracks are highly dependent on the 2D versus 3D idealization of the dam geometry. Considering the fact that the length to height ratio of the dam is around 3, detailed three-dimensional simulations was found to be necessary to determine potential damage locations after an earthquake. The analysis results shed light on the locations of grout curtain to reduce uplift pressures without sustaining severe damage under operational based earthquake hazard, and stability of the structure under maximum design and maximum credible earthquake hazard levels.