山区地形条件下高架轨道交通引起地面振动实测研究?

考虑地形对轨道交通振动衰减的影响,对重庆轻轨6号线经过典型斜坡及陡崖地形的高架段进行现场测试。分析了振动频谱特性以及振动速度级沿轨道中心线及45°、90°三个方向的衰减规律。研究结果表明:列车引起地面振动主要频率分布在50 Hz两侧附近,各距离处频率分布不受地形影响;地表振动从桥墩承台传至周围土体中会出现较大的放大;振动沿斜坡和陡崖衰减速度慢于平面,在平面上衰减先快后慢,在斜坡方向则先慢后快,同时地面振动随距离衰减呈现出波动性,在90°方向距轨道中心线13 m附近出现了振动放大区;列车运行具有明显的偏载效应,近轨列车引起振动在承台上随距离增大,远轨列车引起振动随距离减小。

Field Tests on Ground Vibration Caused by Viaduct Rail Transit under Mountainous Terrain Conditions

Considering the influence of terrain on the vibration attenuation of rail transit,field tests were carried out on the viaduct section of Chongqing Light Rail Line 6 passing through typical slopes and cliffs.The vibration Spectrum characteristics and the attenuation of vibration velocity level in three directions are analyzed,including 0,45,and 90 degrees from the track center line.The results show that the main frequencies of ground vibration caused by trains are distributed around 50 Hz and the frequency distribution at various distance is not affected by terrain.Ground vibration will be amplified greatly when it is transmitted from the pier cap to the surrounding soil.The decrease of vibration is slower along slope and steep cliff than that on the plane,which decays obviously and then slowly on the plane.However,it decays slowly and then quickly on the slope.At the same time,the ground vibration shows fluctuation with distance attenuation.There is a vibration amplification zone near the distance of 13 m in the direction of 90 degrees from track center line.The train operation has obvious eccentric load effect and the vibration on the pier cap caused by the near-track train increases with the distance,while the vibration caused by the remote-track train decreases with the distance.