基于拱梁分载法的高薄拱坝水平拱圈曲折稳定评价
BUCKLING STABILITY ANALYSIS OF HORIZONTAL ARCH RINGS OF HIGH-THIN ARCH DAMS BASED ON ARCH-CANTILEVER METHOD
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摘要: 该文针对深山峡谷中高拱坝半径较小且截面尺寸较大, 曲率和剪切变形对临界荷载的影响较为明显的特点, 基于大曲率深拱问题在拱坝中应用的理论和经典的拱梁分载理论, 对《拱坝抗曲折稳定分析再探》中的算例重新校核, 重新定义拱坝水平拱圈的抗曲折稳定系数, 并结合柔度系数绘制两者关系曲线, 更直观的判定水平拱圈的稳定性。结果表明:对于拱坝的中上部, 拱圈起主要承载作用, 拱圈的稳定性较弱, 曲率和剪切变形的影响不明显, 容易发生失稳, 故在校核稳定时应当给予重视;对于中下部, 拱圈的稳定性较强, 但剪切与曲率的影响较为明显, 并且剪切变形的影响大于曲率的影响;高拱坝的柔度系数越大则拱圈曲折失稳范围越大, 柔度系数为10时坝高全范围拱圈将不曲折失稳。Abstract: High arch dams in canyon areas are normally featured with small radiuses and large cross-sections, and the curvature and shearing deformation of high arch dams impose great influence on the critical load. Based on the experience in analyzing high arch dams of large curvature and using the arch-cantilever method, this study re-examined the examples in “Further discussions on the stability of arch dams regarding elastic buckling”. The buckling stability factor was reformulated, and its relationship with the slenderness coefficient of high arch dams was derived. Results show for the middle-upper part of high arch dams, arch rings bear a large portion of loads and are vulnerable to collapse. The influence of curvature and shear deformation is insignificant. On the other hand, for the middle-lower part, the stability condition is relatively better. The influence of curvature and shear deformation is noticeable, and that of shear deformation is greater than that of curvature. It is also noted that a bigger slenderness coefficient is associated with a bigger area of bulking instability of arch rings. A slenderness coefficient of 10 signifies no bulking collapse throughout the dam.