Study on the ground vibrations laws and influential parameters subjected to impact load

Usually the study of environmental vibration subjected to impact load is limited to strong impact load such as blasting, while lack of concerns of other styles of impact loads. A field impact test on ground surface was carried our by a heavy hammer, in which the accelerations of ground vibration were achieved. The time history curves of the accelerations are typical pulse property. Through Fourier Transformation on the measured data shows that the main frequency of ground vibrations ranges in 10-100 Hz, and most of them concentrated in several key points. The accelerations were analyzed according to the ISO2631 and the vibration levels were found to be 68-92 dB. In addition, an FEM model was established to simulate the ground vibrations subjected to impact load and the calculated results agree well with the test ones. In the analysis, such influential parameters as soil elastic modulus, density and weight of hammer were considered. The results show that the ground acceleration levels increase monotonously with impact load, attenuate with the distance to the impact point, and decrease with soil elastic modulus increasing, while they are not obviously influenced by soil density variation. These conclusions have important significance for further study on the environment vibration.