铁道建筑

现行规范对悬索桥吊索加工长度提出±2 mm的严苛制造精度要求，但测量过程存在显著不确定度，导致传统判定方法难以客观评价测量可靠性。针对这一问题，本文基于测量不确定度表示指南(GUM)框架，建立涵盖12项输入变量的吊索长度测量不确定度评定模型，并引入随机森林(RF)算法对影响因素进行重要性排序，筛选出测力、测距、测温3项关键能力变量。据此提出“分而治之”控制策略：对关键变量实施精度强化控制，对非关键因素仅维持现行规范质量稳定性要求，并构建仅依赖设计长度与设计荷载的简化预测模型(调整决定系数R²=0.974，预测平均绝对偏差0.01 mm)。以五峰山长江大桥为工程实例，全桥312根吊索加工长度的测量不确定度均控制在1.09 mm以内，制造误差低于2 mm，实现免调索安装，并借助同步张拉仅以48次作业完成全部测量。结果表明，该协同模型可有效量化与控制吊索长度不确定度，为现行标准引入测量不确定度评估提供了可操作的实现路径，并为大跨铁路悬索桥的高精度制造与施工控制提供理论支撑。

Current standards impose a stringent manufacturing accuracy requirement of ±2 mm for the suspender fabrication length of suspension bridges， yet the measurement involves significant uncertainty， making it difficult for traditional methods to objectively assess measurement reliability. To address this issue， this study establishes a measurement uncertainty evaluation model for suspender based on the Guide to the Expression of Uncertainty in Measurement (GUM) framework， incorporating 12 input variables. The Random Forest (RF) algorithm is introduced to rank the importance of influencing factors， thereby identifying three key capability variables: force measurement， distance measurement， and temperature measurement. Accordingly， a “divide and conquer” control strategy is proposed: enhanced precision control is applied to the critical variables， while only the current quality stability requirements of the specifications are maintained for non critical factors. A simplified prediction model relying solely on design length and design load is constructed， achieving an adjusted coefficient of determination R²=0.974 and a mean absolute deviation of prediction of 0.01 mm. Taking the Wufengshan Yangtze River Bridge as an engineering example， the measurement uncertainties for the fabricated lengths of all 312 suspenders are controlled within 1.09 mm， and the manufacturing errors are below 2 mm， enabling "adjustment-free" installation， synchronous tensioning further completes all measurements in only 48 operations.. The results demonstrate that this collaborative model can effectively quantify and control the length uncertainty of suspenders， providing a practicable implementation path for introducing measurement uncertainty evaluation into current standards， and offering theoretical support for the high precision manufacturing and construction control of long span railway suspension bridges.