地铁运行引发临近建筑群低频微振动及传递规律研究

Low-frequency microvibration and its transfer law of nearby building group caused by running metro train

随着城市建筑群的飞速建设,由地铁运行引起的建筑群低频微振动问题越来越突出。本研究依托成都某建筑群项目,研究地铁运行对土体及建筑群振动的影响。考虑轮轨非线性动力相互作用、土体分层特性、土体‑建筑相互作用关系等因素,建立地铁列车‑轨道‑隧道‑土体‑建筑群耦合动力学模型;通过现场测试掌握地铁振动源强特征,并对模型进行验证;在此基础上研究地铁动荷载下土体振动的空间传播规律及不同土层界面处的局部振动特性;评估地铁运行对建筑群的影响。研究表明:建立的动力学模型可有效用于研究地铁运行下建筑群低频微振动问题;实测隧道壁加速度卓越频率为31.5~80 Hz,实测隧道壁VL_(zmax)(最大z振级)主要在70.3~71 dB,实测道床VL_(zmax)则在94.3~125 dB;随着振动波在土体中向上传递,振动能量逐渐衰减,但是在地表附近存在一定的振动放大;土体对80 Hz以上的振动具有较强的吸收能力,随着振动横向传播距离的增大,VL_(zmax)近似线性减小;该建筑群中的住宅楼和商业楼均未出现振动超标。

With the rapid development of building groups,the low-frequency microvibration caused by running metro train has become a serious problem.Aiming at a practical building group in Chengdu,the influences of running train on soil vibration and building vibration are investigated.A detailed train-track-tunnel-soil-building group coupled dynamic model is established by considering the nonlinear wheel-rail dynamic interaction,the layered structure of soil and the soil-building interaction.A field test is conducted to study the source strength of metro system,which is also adopted to validate the dynamic model.On this basis,the train-induced soil vibration and local vibration at interface of different layers are studied.The influence of running train on building group is evaluated.Results show that,the established dynamic model is effective to solve low-frequency microvibration caused by running train.The predominant frequency of tested tunnel acceleration is 31.5~80 Hz,the VL_(zmax)of tunnel wall is 70.3~71 dB,and the VL_(zmax)of track bed is 94.3~125 dB.When the wave travels upwards in soil,the energy is absorbed while vibration nearby earth surface is amplified.Soil can absorb vibration above 80 Hz,and with the lateral distance increases,VL_(zmax)decreases linearly.The train-induced building vibration is not beyond the limit values.Conclusions provide vibration control theory for building groups.