Research on the distribution and evolution of weathering failure of stacked wall and sandwich wall under freeze–thaw cycles. (May 2022) - Qin, Haiyang
Highlights: The capillary water rise height of a sandwich wall is higher than that of a stacked wall. The "drilling and filling" method ensures the stability of the sandwich wall during the freeze–thaw cycles. Distribution of moisture content and rebound strength in stacked wall are relatively even. However, all of these distribution in a sandwich wall are relatively uneven. Moisture content, strength increment, and crack density distribution curves are all seen as "concave" shapes in stacked walls. All of these distribution curves, however, are shown as "straight" shapes in the sandwich wall. There is a clear linear relationship between moisture content and strength increment, and the line slop in sandwich wall is bigger than that in stacked wall. Abstract: In order to reveal the impact of environmental vicissitudes on weathering failure of stacked wall and sandwich wall, the capillary water rise mechanism and its spatial distribution in these two types of walls are studied based on SF (Sharp Front) theory in this paper. The result shows that the horizontal bonded mortar and the vertical interlayer soil can block and promote the capillary rise process respectively. In the freeze–thaw experiment, 6 groups of walls with different freeze–thaw cycles are used to simulate stacked wall and sandwich wall with different weathering degrees. Then moisture meter and strength meter are used to extract data and further analyze the distribution and evolution of weathering performance of these walls. The result shows that with increasing freeze–thaw cycles, the moisture content of both the stacked and sandwich walls is increasing while the strength is decreasing. The moisture content curve, strength increment curve, and crack density curve of the stacked walls all show a "concave" form, with maximum values in the lowest two layers and then drops sharply with increasing height. However, these curves of sandwich walls are all viewed as a "straight" form, with all values decreasing nearly linearly as height increases. There is an obvious linear relationship between the moisture content and the strength increment, and the corresponding slopes are-5.556 for stacked walls and-8.8891 for sandwich walls, indicating that the strength attenuation problem faced by sandwich wall is more serious. Furthermore, compressive tests revealed that after 20 freeze–thaw cycles, the sandwich wall's strength decreased by an additional 11.7 percent as compared to the stacked wall.