城市轨道交通临近建筑的隔振分析

VIBRATION ANALYSIS OF BASE-ISOLATED BUILDING NEAR URBAN RAIL TRANSIT

基于车辆-轨道垂向耦合模型获得的地铁轨道路基振动激励,建立了采用粘弹性边界平面有限元地层模型,分析了地面振动响应特点;分析了叠层橡胶垫、圆柱形螺旋港弹簧和碟形弹簧三种隔振元件的力学性能,讨论了建筑基础隔震技术在城市轨道交通领域减振应用的可能性;采用一四层框架作为研究模型,分析了基础隔振框架随结构竖向自振特性变化的振动响应规律,并提出设计建议。分析结果表明:地铁路基荷载一般在10Hz以下,集中在5Hz以内,主要表现在低频段;水平与竖向结构动力响应均应考虑;现有隔振元件竖向刚度经过适当调整,或者采用适当的组合形式,是可以满足对城市轨道交通引起的建筑结构振动控制的要求;隔振结构竖向第一自振频率控制在3Hz-5Hz范围内,并在隔振层附加5%-10%的阻尼,可以获得70%竖向减振效果。

Obtain the dynamic metro-roadbed force based on vehicle-track vertical coupling dynamics model and build the 2D FEM ground model with viscoelastic artificial boundary condition to analyze the vibration-response character- istics of ground surface.Compare the mechanical performances of three types of isolating elements,namely,laminated rubber isolator,cylindrical helix steel spring and disk spring and discuss the application feasibility of base-solated technol- ogy in the field of urban rail transit.Employ a 4-floor frame model to analyze the vibration-responses of base-isolated struc- ture with various vertical natural vibration characteristics,and propose the isolation design suggestions.The analysis re- sults show that the load-frequency band is mainly within 10Hz,special 5Hz,which can induce the resonance of building structure and may fall into the sensitive range to human body.The horizontal and vertical dynamic responses should be taken into account simultaneously.The existing isolation elements and the bi-isolator proposed can be applied to decrease the vibration responses of buildings,if their vertical stiffnesses are adjusted appropriately or they are constructed in some proper compound forms.The vibration responses will be decreased about 70%,if the 1 st natural frequency of base-isola- ted building is controlled to be less than 3Hz～5Hz and the structure is attached with a damping of 5%～10% damping ratio.