Simulation of Construction of RCC Dams. I: Temperature and Aging

Abstract

The increasing number of roller compacted concrete (RCC) dams being built around the world demands accurate methodologies for the realistic short- and long-term evaluations of the risk of thermally induced cracking in these constructions. In this work a numerical procedure for the simulation of the construction process of RCC dams is presented. It takes into account the more relevant features of the behavior of concrete at early ages, such as hydration, aging, creep, and damage. A 2D model of the Urugua-iRCC Dam, built in Argentina, is used to perform the corresponding analyses. In this first part only the thermochemical aspects of the simulation of the construction process are presented. The temperature distribution and evolution inside the dam are obtained before and after the completion of the dam. The evolution of the compressive and tensile strengths and elastic moduli and their final distribution inside the dam can also be predicted. Results from 2D and simplified vertical 1D models are compared to assess the validity of the latter, and several parametric studies are carried out. The simulation and discussion of the mechanical aspects of the construction process are relegated to a companion paper that follows. INTRODUCTION AND MOTIVATION During the last 30 years great effort has been made to find an alternative to embankment dams for large gravity construc- tions that would, on one hand, overcome the risk of failure due to overtopping or internal erosion (piping) and, on the other hand, be economically competitive. Currently, the an- swer to this technological challenge is roller compacted con- crete (RCC) dams. RCC is a relatively lean no-slump concrete that can be spread horizontally and compacted using earth- working machinery such as dozers and vibratory rollers. The first evaluations on place-in unit costs for several RCC dams built in the United States showed that these represented sav- ings ranging from 30 to 70% of the cost of conventional con- crete dams (Schrader and Naminas 1988). RCC dam construction has the following features: • The dam body is constructed by placing concrete, in the same placing cycle, over a wide area encompassing sev- eral blocks. • Transverse joints are cut after the placement of concrete. • No longitudinal joints are made. • Pipe cooling is not (generally) used.