PREDICTION METHOD FOR METRO ENVIRONMENTAL VIBRATIONS BASED ON MEASURED FREQUENCY RESPONSE FUNCTIONS

For the prediction of metro environmental vibrations in its construction design stage, a prediction method based on a measured ground frequency response function is presented. The problem of ground vibration prediction is transferred into two parts: a coupled train-track model is used to calculate the forces on the base; pulse tests in a tunnel are used to measure frequency response functions of a tunnel-soil system. Superposition technique in a frequency domain of two parts is used to calculate ground vibration responses. A standard prediction procedure is presented and programmed by MATLAB. Frequency response functions are measured by pulse tests in an 18m depth tunnel to predict ground vibration responses. Comparative verification is done using the measurement data at Beijing Metro Line 15. The results show that: the peaks of responses are both around 0.02m/s²; main vibration frequencies are both at 30Hz~80Hz; one-third octave spectrums and Z vibration levels are similar. It is implied that the prediction method has good accuracy and spectral distribution property.