# Improvement Methods for Reduction of the High Stress of Ultra-High Asphal Concrete Core Dams
## 3 Investigation on the Tensile Stress Feasibility of UACC
### Reasonable Value Ranges of the Curvatures of UACC  
#### 3.4.1 Tensile Characteristics of UACC  
According to Section 3.2, the flexural deformation of ACC is the fundamental reason that the UACC generates high tensile stress. Thus, the flexural deformation and tensile stress of SACC are only discussed in the following section. The flexural deformation of SACC toward upstream is negative, and the flexural deformation of UACC toward downstream is positive. The compressive stress is negative, and the tensile stress is positive. Figure 18 shows that the flexural deformation of SACC is circularly distributed. The flexural deformation maximum at the center of SACC is 0.687 m. The deflection to span ratio is 0.2% and less than 1%. Figure 19 shows that the major principle stress of SACC is hierarchically distributed. It should be noted that tensile stress regions appear in the major principle stress of SACC. The tensile stress maximum at the steeper end of SACC is 0.349 MPa. Figures 20-22 and Table 7 show that the flexural deformation, tensile stress, and tensile stress area of SACC increase sharply with dam height. When \(h=100\) m, the flexural deformation of SACC is 0.197 m. The tensile stress of SACC is 0.078 MPa (the tensile safety factor is 3.85), which is far less than the YTFCS. The SACC is safe and will not experience tensile failure. The tensile stress area of SACC is 307 m\({}^{2}\). When \(h=150\) m, the settlements of SACC are 0.408 m. The tensile stress of SACC is 0.232 MPa (the tensile safety factors is 1.29), which is more than the YTFCS and far less than the UTFCS. The SACC has the probability that experiences tensile failure. The tensile stress area of SACC is 681 m\({}^{2}\). When \(h=200\) m and \(h=250\) m, the settlements of SACC are 0.687 m and 1.042 m. The tensile stresses SACC are 0.349 MPa and 0.522 MPa (the tensile safety factors are 0.86 and 0.57), which are far more than the UTFCS. The SACC experiences tensile failure. The tensile stress areas of SACC are 1335 m\({}^{2}\) and 2097 m\({}^{2}\). Figure 17: Mechanical diagram of curved asphalt concrete core (CACC) (completion period and operation period). Figure 19: Major principal stress contours of SACC (\(h\) = 200 m). Figure 20: Relationship between flexural deformation maximum of SACC and dam height. Figure 18: Flexural deformation contours of SACC (\(h\) = 200 m). Figure 23-25 and Table 8 show that the flexural deformation of SACC deceases with valley slope ratio and the tensile stress and tensile stress area of SACC increases sharply with valley slope ratio. When the valley slope ratio is 0.5:1.0, the flexural deformation of SACC is 0.750 m. The tensile stress of SACC is 0.126 MPa (the tensile safety factor is 2.38), which is far more than the YTFCS. The SACC is safe and will not experience tensile failure. The tensile stress area of SACC is 1013 m\({}^{2}\). When the valley slope ratio is 2.5:1.0, the flexural deformation of SACC is 0.640 m. The tensile stress of SACC is 0.737 MPa (the tensile safety factor is 0.41), which is far more than the UTFCS. The SACC experiences tensile failure. The tensile stress area of SACC is 1334 m\({}^{2}\). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Dam Height (m)** & **100** & **125** & **150** & **175** & **200** & **225** & **250** \\ \hline Flexural deformation (m) & 0.197 & 0.297 & 0.408 & 0.538 & 0.687 & 0.862 & 1.042 \\ Tensile stress (MPa) & 0.078 & 0.138 & 0.232 & 0.298 & 0.349 & 0.445 & 0.522 \\ Tensile stress area (\(10^{3}\) m\({}^{2}\)) & 0.307 & 0.450 & 0.681 & 0.927 & 1.335 & 1.704 & 2.097 \\ Tensile safety factor & 3.85 & 2.17 & 1.29 & 1.01 & 0.86 & 0.67 & 0.57 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Flexural deformation, tensile stress, tensile stress area, and tensile safety factor of SACC with different dam heights. Figure 21: Relationship between tensile stress maximum of SACC and dam height. Figure 22: Relationship between tensile stress area maximum of SACC and dam height.