中文摘要：

近年来，随着铁路建设规模的扩大、路网加密，出现许多新建线路与既有线交叉、并行情况，紧邻既有线施工的安全问题引起人们的关注。本文分别建立桥墩一承台一桩基础一地基土层三维空间数值分析模型、桥梁上部结构一桥墩有限元数值分析模型、车辆一桥梁动力相互作用模型，针对紧邻既有铁路桥的基础施工对行车的影响进行计算分析，将安全指标的计算值与规范值相比较进而做出预评价，并结合算例得出结论：紧邻既有线进行基坑开挖会对既有线产生明显的影响；当桥墩发生不同程度的不均匀沉降时，桥梁最大挠度出现在跨中，总体趋势为随列车速度的增加而增加，并在共振车速附近出现较大峰值；桥墩横向位移对列车运行平稳性的影响要大于不均匀沉降产生的影响；对于高速列车，必须严格限制桥墩的不均匀沉降和横向位移，提出了相应的限值建议。

英文摘要：

In recent years, foundation construction near existing railway lines has been brought into focus because many planned new railway lines may run parallel with and across existing railway lines. In this paper, the numerical 3-dimensional pier--bearing platform--pile foundation--foundation stratum model, the numerical FM bridge superstructure-pier model and the train-bridge interaction model were established. The impact of foundation construction on trafficn on an existing line was evaluated by comparing the calculated values with the safety criteria specified in specifications. Combining with an engineering example, conclusions are drawn as follows： Excavating a foundation pit adjacent to an existing line has obvious influence on operation of the existing line; when differential settlements occur with piers, the maximum deflection appears in mid-spans and tends to increase with increase of train speeds, however, the deflection reaches peak values around the resonant train speed; lateral displacements of pier has more influence on traffic comfort than differential settlements; for high-speed trains, differential settlements and lateral displacements of piers should be strictly limited, and the related allowances of pier of ballasted railway lines are recommended.