Impact of Extruded Curb Misalignment and Temperature Stress on Slab Cracking of CFRDs: A Case Study of the Pankou Dam

Abstract

Slab cracking is one of the major issues in the safe operation of a concrete-faced rockfill dam (CFRD). At the Pankou Reservoir Hub, a 124 m high CFRD, slab cracks were observed after only three days of concrete pouring. These cracks were characterized by mostly occurring on the surface, developing nearly horizontally, and spreading throughout the whole slab. It is of great significance to investigate the underlying causes to improve safety in similar projects. Through a detailed analysis of design documents, construction practices, and health monitoring data, the study identifies extruded curb misalignment and cement hydration heat as primary contributors to early shallow slab cracking. A series of numerical simulations were performed to assess the combined effect of extruded curb misalignment and temperature stress, and the results showed that the misalignment of the extruded curbs resulted in an uneven thickness of the concrete slab, where the temperature stress is concentrated and led to tensile stresses exceeding the allowable values and consequent slab cracking, so to alleviate the issue of slab cracking, the construction quality of the extruded curb should be strictly controlled. This study also provides a reference for avoiding and repairing slab cracking in similar projects.