Characteristics and causes of crest cracking on a high core-wall rockfill dam: A case study

Abstract

Avoiding and controlling dam crest cracking is one of the most difficult problems facing high core rockfill dams of more than 100 m. However, few studies have been conducted on the characteristics and causes of dam crest cracking based on long-term measurement data. In this study, a real case of a dam suffering cracking at the crest was studied. The dam has a maximum height of 186 m and has been in service for 10 years. The spatiotemporal characteristics of the dam crest cracking were determined based on monitoring data obtained using crack monitoring instruments, radar detection, seismic refraction tomography, and pit exploration. The causes of dam cracking were analyzed based on the deformation inclination and strain index. The factors controlling the cracking (such as the dam structure, geological structure, and materials' properties) were investigated. The results show the following. 1) The cracks mainly occurred at the interface between the core wall and the downstream dam shell. 2) The cracks mainly developed during the impoundment and operation periods with high water levels, and there was no convergence trend within the 10 years of operation. 3) Uneven settlement and uneven horizontal displacement were the main reasons for the crack formation. 4) The factors influencing the cracking include dam zoning, the geological structure, wetting, and the rheological properties of the rockfill materials, and the reservoir level. The results of this study provide an important engineering reference for the prevention and control of dam crest cracking in high rockfill dams.