基于相似分析的季节性冻土区铁路桥墩—基础场地振动特性研究

Study on vibration characteristics of railway piers and foundation sites in seasonal frozen soil areas based on similarity analysis

为了研究季节性冻土区铁路桥墩及周围场地的振动特性,选取哈大(哈尔滨—大连)高速铁路沿线某桥墩及周围不同场地进行了现场测试,并利用相似分析定义了无量纲参数a/(v 2/L)(列车运行引起的场地加速度峰值a与列车速度v 2除以列车总长度L的比值)和R/L(场地到桥墩的距离R与列车总长度L的比值),同时结合数值模拟对不同场地在不同季节的振动衰减特性进行了分析。研究表明:桥墩与场地的振动特性明显不同,在桥墩两侧0.8 m范围内场地的振动特性不受冻结作用的影响;在堆积填土侧Y和Z方向的振动都出现了放大,而在未堆积人工填土侧仅Z方向的振动出现了放大;在冻结季振动衰减要小于非冻结季,且冻结作用对堆积填土侧振动的影响更加显著。

In order to study the vibration characteristics of railway piers and different foundation sites in seasonal frozen soil region,field tests were carried out on a pier of Harbin—Dalian high-speed railway and its surrounding sites.And the dimensionless parameters are defined by similarity analysis,which are a/(v 2/L)(the ratio of the base site peak acceleration a caused by the train operation to the train running speed v 2 divided by the total train length L)and R/L(The ratio of the distance from the foundation site to the bottom end of the pier to the total length L of the train).The vibration attenuation characteristics of different sites around piers in different seasons are analyzed by numerical simulation.The results show that the vibration characteristics of bridge pier and foundation site are obviously different.The vibration characteristics of site are not affected by freezing action in the range of 0.8 m on both sides of bridge pier.And the vibration of Y and Z directions on the side of piled fill appears amplification phenomenon,while that of only Z direction on the side of non-piled fill appears amplification phenomenon.The vibration attenuation velocity in the freezing season is smaller than that in the non-freezing season,and the influence of the freezing season on the vibration of the stacked artificial soil side is more obvious.