Study on the horizontal cracking mechanism of concrete dams overwintering surface in high cold regions

Abstract

The combination of winter surface layers and crack prevention is a key and difficult point in the construction of concrete dams in high cold areas. Based on the monitoring data and observation result, through three-dimensional finite element numerical simulation analysis, the influence of different factors on the normal stress of the interface between new and old concrete after overwintering is explored. Through simulation result, the interlayer stress state under different factors such as temperature difference between upper and lower layers, self generated volume deformation, and interlayer bonding strength is elucidated. The analysis result indicate that the opening, closing, and bonding state of the winter layer in high-altitude cold regions depend on three key factors: temperature difference between new and old concrete, self generated volume deformation, and interlayer bonding strength during construction. The temperature difference between new and old concrete and the self generated volume deformation will result in a larger normal stress as the driving force to prevent interlayer bonding, while the interlayer bonding strength will serve as the resistance force to prevent interlayer cracking. According to the analysis result, it can be concluded that the key control indicators for newly poured concrete in high cold areas after overwintering are the temperature difference between new and old concrete, as well as the strengthening of interlayer bonding through special interlayer construction techniques. The interlayer surface stress caused by the difference in self generated volume deformation caused by the temperature difference between upper and lower layers is relatively large, especially under the effect of end constraints. Therefore, increasing interlayer bonding strength while ensuring temperature control measures is also a key construction focus for newly poured concrete after overwintering.

Keywords

high cold areas / overwintering surfaces / interlayer stress / new and old concrete