合理工期的确定对于指导和控制工程施工具有重要意义，但是合理工期本身具有相对性和模糊性，如何确定和评价工程合理工期是一个复杂的问题。导流隧洞施工合理工期与工程规模、开挖方法、围岩类别及分布、施工设备配置等诸多因素有关，而且其中某些因素本身具有不确定性。结合导流洞工程施工合理工期确定问题，提出了一种通过工程案例类比和基于因果聚类模糊预测和评价的导流隧洞工程施工工期预测方法，并以导流洞工程施工实例验证该方法的可行性。

The determination of reasonable construction period is of great significance for the  instruction and control of the project construction. However, since reasonable period in itself is of relativity and fuzziness, how to identify and assess a reasonable construction period is complex. The construction period of diversion tunnel will be affected by many factors like construction scale, excavation methods, surrounding rock type and distribution, and construction equipment configuration, among which some factors are uncertain. We present a method of forecasting the construction period of diversion tunnel based on project cases analogy and causal clustering fuzzy prediction. We applied the method to the prediction of ten diversion channels of three completed projects, and the prediction results are very close to or even coincide with the actual construction period, which verified the feasibility of the method.   