Studies On Propagating Rules Of Near-surface Vibration Caused By Urban Rail

Vibration problem caused by rail traffic is a complex cutting-edge issues, which involves multiple disciplines machinery, transportation, geotechnical, structural, earthquake mitigation, environmental engineering, needs to supplement the theoretical level, in engineering practice has its far-reaching research value. According to space considerations, vibration problems include:a vibration source issues; vibration wave propagation in free space in; vibration transmission in buildings; vibration and noise control. From the semi-infinite soil considerations, environmental issues related to the vibration problem of soil parameters, soil model selection problem, Boyuan problem, scattering problem, vibration control problems, boundary conditions, vibration isolation and so on. Taking into account the new prominence by leaps and bounds in today’s rail transportation system generated by the apparent complexity and uncertainty coupled with the environment itself has a vibration problem still requires a new perspective to continue our in-depth research, discussion and mining. Paper, theoretical analysis, numerical simulation and field data analysis method of combining, carry out research work.First, located some intercity railway Beijing-site testing, processing test data and drawing away curve acceleration. Description z direction of the vibration amplitude and attenuation of more comparable, and pointed out the existence of ground vibration amplification phenomenon in the communication process. Then, using the fast Fourier transform (FFT) processing acceleration data obtained, press 1/3 octave contemplated within 1～80Hz data spectrum analysis. From the perspective of the frequency of the enlarged area to verify the existence and prove the high frequency ground vibration attenuation fast, low-frequency attenuation slow decay near the track at the fast track at a far slower decay near the track at the ground-based high-frequency vibration, much track ground vibration at low frequency -based conclusions. Furthermore, with the vibration acceleration level, vibration level and cumulative percentage vibration level of vibration attenuation of three methods to analyze research trends vibration with distance and scaled according to the vibration intensity with "urban regional environmental vibration standards" (GBI10070-88) were compared. Finally, ABAQUS as a platform to achieve a combination of the finite element method and the transmission through the artificial boundaries of discrete and finite element displacement interpolation method to obtain compute node boundary displacement function of time (boundary conditions). By boundary conditions DISP subroutine implementation model boundary conditions and using the measured ground acceleration as point load input, three-dimensional finite element model of the soil, to calculate acceleration, vibration level and the corresponding frequency characteristics of the model measuring point. Through comparative analysis of simulation and measured values, indicating the scope of the model, zero frequency drift phenomenon is about 40m, the overall impact of vibration intensity in the range 1～4dB, Verify that the method adopted by the subject combination of transmitting boundary finite element method is feasible.