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中文摘要：
采用高灵敏度传感器,测试正常运营的地铁和地面车辆引起的地面垂向振动加速度。将地面振动时程转换为频域内1/3倍频程频谱,研究正常运营的地铁和地面车辆引起的地面振动特性;同时,参考电子显微镜Tecnai30的环境振动标准,探讨地面振动对精密仪器的影响规律。研究结果表明,地面振动存在一个“等振频率”,在小于“等振频率”范围,地面振动主要受背景振动制约,而距离的影响很微弱;在大于“等振频率”范围,地面振动主要受距离的影响,背景振动的作用仅次于距离。小于“等振频率”的低频地面振动对精密仪器影响较大,其影响程度主要受背景振动的影响;而在大于“等振频率”范围,地面振动对精密仪器的影响随着距线路中心线距离的增加而减弱。地铁与地面车辆的地面振动的叠加,在6～30 Hz频段容易对精密仪器产生影响。
英文摘要：
Precision instrument is very sensitive to environmental ground vibrations,which may not be felt by human being but can cause malfunction of precision instrument.Four measure sections were chosen along metro line,where in-situ tests of metro and ground traffic induced vertical ground vibrations were carried out by using high sensitive accelerometers.The 350 ground vibration time-history curves of 94 records were transformed into 1/3 octave band frequency spectrum.Based on the transformationt,he characteristics of ground vibrations induced by the normal operation of metro and ground traffic were investigated.Finally,the law of impacts of ground vibrations on precision instrument was discussed with reference to an electron microscope Tecnai30 for analyzing environmental vibration impacts on precision instrument.It is found that there exists an ＂equal vibration frequency＂ for ground vibrations.When the frequencies of ground vibrations are smaller than the ＂equal vibration frequency＂,ground vibrations are mainly dominated by background vibrations,while the effect of distance is very weak;however,when bigger than the ＂equal vibration frequency＂,it is mainly governed by distance,but the effect of background vibration is only inferior to the distance.Ground vibrations with frequency smaller than ＂equal vibration frequency＂ have higher impacts on precision instrument affected by background vibrations.When vibration frequency is bigger than ＂equal vibration frequency＂i,mpacts on precision instrument decrease with increasing distance form line center.Superposition of metro induced ground vibrations and ground traffic causes the response within 6–30 Hz is found to be prone to affect precision instrument.＂Equal vibration frequency＂ is first found in this experiment and its implication needs to be further studied.
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Solution of Moving-load Induced Soil Vibrations Based on the Betti-Rayleigh Dynamic Reciprocal Theor
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