为满足合肥地铁新建轨道交通线路适用于管片外径6 200 mm的盾构区间施工要求，采用原适用于管片外径6 000 mm的某常规土压平衡盾构进行扩径改造设计。首先，设计了该盾构复合刀盘的扩径改造方案，开挖直径由原6 280 mm扩径至6 470 mm。然后，在分析计算盾构刀盘受力组成的基础上，利用Solidworks软件建立刀盘扩径改造后的三维模型。最后，通过ANSYS有限元仿真软件对扩径改造后的刀盘进行静力学和模态分析验证。结果表明，扩径改造设计后的复合刀盘满足强度、刚度使用要求。目前，该盾构刀盘已完成工厂内的扩径改造并运抵项目，后续将在合肥地铁建设中得到实际应用。

The construction shield section for the new rail transit line of Hefei metro requires to apply to the shield segment outer diameter of 6 200 mm. In order to meet the requirement, an EPB shield with the shield tunnel segment outer diameter of 6 000 mm is studied. First, an expansion modification scheme for composite cutterhead of shiled machine is proposed, the excavation diameter of which is modified from 6 280 mm to 6 470 mm. Then, on the basis of analyzing and calculating the force composition of shield cutterhead, a 3D model is established by using Solidworks. Last, the modified cutterhead is validated by ANSYS software for static and modal analysis, the results show that the modified composite cutterhead meets the requirements of strength and stiffness. At present, the cutterhead of the shield machine has completed the modification design in the factory and arrived at the project, and will be practically applied in the construction of Hefei metro.