针对一些高水头电站中镇墩混凝土开裂比较严重的情况，结合某水电站的工程实际，采用ANSYS程序中的钢筋混凝土非线性计算模块，对钢岔管和外包镇墩混凝土结构进行了三维非线性有限元计算。通过2种控制工况的计算分析和明钢岔管应力的比较，认为：在镇墩混凝土中布置适当的受力钢筋，考虑镇墩钢筋混凝土与钢岔管联合承载，按钢衬钢筋混凝土分岔管的形式进行设计，不仅可以减小钢岔管管壁厚度和加强梁尺寸，达到简化岔管制造工艺和降低工程造价的目的，而且可以提高镇墩的整体性，避免由于高内水压力造成的镇墩混凝土严重开裂现象，保证钢岔管和镇墩混凝土的长期安全运行。因此，外包钢筋混凝土的分岔管是一种比较有发展前途的岔管结构型式。

In accordance with the cracking seriousness of anchor block of some high water head hydropower stations, a 3D FEM analysis on jointly bearingload of the steel bifurcation and outer reinforced concrete was carried out by means of the nonlinear analysis module in ANSYS software. On the basis of the analysis results of the two control conditions and by comparison with the exposed steel bifurcation, the calculated results are concluded that the steel linedreinforced concrete bifurcation and outer reinforced concrete, in which some reinforcing bars are arranged in the anchor block and considered to bear internal water pressure with the steel bifurcation jointly, can reduce the thickness of pipe shell and the dimension of the strengthening beam so as to simplify the technology and reduce the cost of the project. Furthermore, this kind of structure? can enhance the integrity of the anchor block, avoid the serious cracking in concrete caused from the high water pressure, and, thereby, guarantee the long term safe operation of the steel bifurcation and anchor block. So this type of bifurcation will have a better development in future.