高拱坝表孔闸墩侧面拉应力影响因素分析

Study of Influencing Factors on Tensile Stress for Sides of Surface Hole’s Piers in High Arch Dams

高拱坝泄洪能力大,泄洪表孔尺寸大,结构复杂,荷载作用下闸墩内侧面往往会出现很大的拉应力。为此,采用ANSYS有限元方法计算研究温度荷载、弧门推力、坝体上游静水压力等因素对高拱坝泄洪表孔闸墩侧面拉应力的影响,通过改变闸墩厚度及在坝体上游与闸墩外侧交接处增设局部放大体来研究其对闸墩侧面拉应力的影响。结果表明,温度荷载及弧门推力对闸墩侧面拉应力影响不大,坝体上游面静水压力引起拱坝由两岸向坝顶泄水表孔变形是引起闸墩内侧面拉应力大的主要原因;增加闸墩厚度和增设局部放大体两种方法均可有效减小闸墩内侧面的拉应力,且后者混凝土用量少,节约材料。

The high arch dams have large spillway capacity and large-sized surface holes to discharge flood. The structure of surface holes are complicated. The inner sides of the piers have strong tensile stress under the action of loads. The ANSYS finite element method was used to calculate the effects of temperature load, arc gate thrust and hydrostatic pressure on the tensile stress of the sides of surface hole,s piers. The tensile stress of the piers' sides was studied by changing the thickness of the piers and adding partial magnification structures between upstream of dam and outside of piers. The results show that the temperature load and the arc gate thrust are not the main causes of large tensile stress on piers' sides. Under the action of hydrostatic pressure on the upstream surface of the dam, the arch dam is deformed from the two sides of the dam to the surface hole in the middle of dam crest, resulting in the large tensile stress on the inner sides of the piers. To reduce the tensile stress effectively, such methods can be used as increasing the thickness of the piers and adding local enlargement structures. Moreover, the latter has the characteristics of less concrete consumption and material saving.