中文摘要：

结合某导流底孔工程，针对封堵期结构的受力特征，采用三维有限单元法对导流底孔坝段结构和坝上游面的应力分布情况进行计算分析。结果表明：导流底孔进水口段和坝内孔身段的分缝布置于坝面上游时，坝上游面将出现较大范围的横河向拉应力，当考虑大坝两侧分缝内填充材料作用或将导流底孔进水口段与坝内孔身段的分缝位置下移至与大坝上游面平齐时，能够有效地减小坝上游面拉应力的数值与范围，降低坝上游面混凝土受拉开裂的可能性。

英文摘要：

Based on a bottom outlet project, with regard to the characteristics of forces acting on the structure during the blocking period, the stress distributions of the structure and upstream dam surface were studied by means of the 3D finite element method. The results show that a wide range of tensile stress along the dam axis will appear at the upstream dam surface when the position of the seam which links the orifice of the bottom outlet and the dam is arranged in front of the upstream dam surface. In order to reduce the tensile stress along the dam axis efficiently, measures of filling materials in the seams at both sides of the dam or moving the position of the seam which links the orifice and the dam to the parallel position of the upstream dam surface should be taken. In this way, the possibility of concrete crack on the upstream dam surface during the construction, operation and blocking periods may be reduced.