针对地震错断后穿越活动断裂带隧道的快速抢通与线路重拟合问题，建立典型错动几何模型，以拟合段落总长度与超高时变率为目标，缓和曲线长、圆曲线长、夹直线长与圆曲线半径为决策变量，并加以基于欧拉螺线与圆弧参数方程构建的几何闭合约束，通过迭代使拟合线路末端的横向坐标与方位角满足预设容差，以保证工程可实施性。采用NSGA-Ⅱ算法进行多目标进化求解，利用非支配排序与拥挤度保持机制在目标空间获得分布均匀且收敛良好的Pareto解集，并引入线路偏移面积指标I量化评价各方案的横向扩挖规模与工程量指标；基于所得方案评估超高时变率、拟合长度、抗震设防影响及工程规模代价，筛选出若干代表性方案以匹配不同的安全与成本偏好，并提出基于拟合条件的抗震设防范围与断面扩挖建议。以某铁路隧道为例，选取最大突发位错作为最不利工况开展研究。研究结果表明，基于NSGA-Ⅱ多目标优化的线路拟合方法能够在快速抢通需求、工程量指标与运行舒适度、安全性之间提供可操作的折中方案，可为穿越活动断裂带铁路隧道的应急技术预案储备与震后快速抢修决策提供量化依据。
In this study, a typical geometric model for fault dislocation is established. The model uses total fitting length and superelevation change rate as dual objectives, and the lengths of transition curves, circular curves, and intermediate straight segments, along with the circular curve radius, as decision variables. The geometric closure constraints, based on Euler spirals and parametric equations for circular arcs, ensure engineering feasibility by iteratively aligning the transverse coordinates and azimuth at the end of the fitted line within preset tolerances. The nondominated sorting genetic algorithm Ⅱ (NSGA-Ⅱ) is used for multiobjective evolutionary computation to obtain a wellconverged Pareto solution set in the objective space, and a line offset area index I is introduced to quantitatively evaluate the scale of lateral overexcavation and the engineering volume of various schemes. Based on the resulting solutions, factors such as the rate of superelevation change, fitting length, seismic fortification impacts, and project costs are evaluated to screen representative schemes and recommend seismic fortification ranges and cross-sectional overexcavation. Using a railway tunnel as a case study, the maximum sudden displacement is selected as the most unfavorable condition. The results indicate that the line-fitting method based on NSGA-Ⅱ multiobjective optimization provides operable tradeoff solutions among rapid restoration, engineering volume, and safety, offering a quantitative basis for the technical reserve in emergency plans and decision-making for rapid post-earthquake repairs.
