地铁高架桥列车振动荷载对邻近构筑物受力变形的影响分析

为分析新建地铁高架桥运营期列车振动荷载对近接敏感构筑物的影响，结合长沙地铁1号线北延线高架桥上跨既有高速公路与干线铁路，两侧紧邻既有桥台桩基和框架桥，建立列车振动荷载下高架桥-地层-既有结构的动力耦合数值模型，分析了地层与既有结构的不同深度动力响应随时间变化规律，以及列车运行速度、轴重、近接距离、地层加固模量、阻尼比分别对桥台桩基和框架桥的水平位移、速度和加速度的影响规律。结果表明：列车振动作用下地表沉降值约为水平位移的40%，地层变形以水平位移为主；框架桥的变形、速度、加速度变化趋势与桥台桩基类似，但其绝对值相对较小，而桩基和框架桥不同深度的动力响应特征明显不同，桩顶和框架桥顶板受影响较大；既有构筑物的动力响应随速度的增加先减小后增大，且在低速区变化幅值较小，80km/h为列车的最佳运行速度；既有结构的动力响应随列车轴重的增大近似呈线性增大的关系，轴重相对于速度对动力响应的影响明显；近接距离越小，框架桥的动力响应越大，高架桥新建桩基与框架桥水平距离小于桩径的4倍时，需采取加固措施；动力响应随加固区刚度增大而减小，地层模量达到300MPa后，继续提高加固强度对降低响应的效果不明显。研究成果可为类似工程的建设与运营提供有益借鉴。

Influence of vibration load of subway elevated train on the stress and deformation of adjacent structures

In order to analyze the influence of train load on the proximity-sensitive structures during the operation period of the newly built subway viaduct, the viaduct on the north extension line of Changsha Metro Line 1 spans the existing expressway and main railway, and is adjacent to the existing abutment pile foundation and frame bridge on both sides. The dynamic coupling numerical model of viaduct-strata-existing structure under train vibration load analyzes the variation law of the dynamic response of the stratum and the existing structure at different depths with time, as well as the train running speed, axle load, approach distance, and the modulus of the reinforcement reinforced stratum, and damping ratio. Influence law on horizontal displacement, velocity and acceleration of abutment pile foundation and frame bridge respectively. The results show that the surface settlement under the action of train vibration is about 40% of the horizontal displacement, and the stratum deformation is mainly horizontal displacement. The variation trend of deformation, velocity and acceleration of frame bridge is similar to that of abutment pile foundation, and its absolute value is relatively small, while the dynamic response of pile foundation and frame bridge at different depths is obviously different, and the pile top and frame bridge roof are greatly affected. The dynamic response of existing structures firstly decreases and then increases with the increase of speed, and the variation amplitude is small in the low-speed area, the best running speed of the train is 80km / h. The dynamic response of the existing structure approximately increases linearly with the increase of the axle load of the train, and the greater the axle load, the more obvious the influence. The smaller the approach distance, the greater the dynamic response of the frame bridge. When the horizontal distance between the new pile foundation of the viaduct and the frame bridge is less than 4 times the pile diameter, reinforcement measures should be taken; the dynamic response decreases with the increase of the stiffness of the reinforcement area, and the stratum modulus After reaching 300MPa, the effect of continuing to increase the reinforcement strength to reduce the response is not obvious. The research results can provide useful reference for the construction and operation of similar projects.