Ground Vibration Attenuation Law of Dynamic Compaction Reinforcing in Loess Region

[Purposes] This work is carried out to explore the ground vibration effect of dynamic compaction in loess area. [Methods] Field tests of three-direction surface vibration velocity with and without isolation trench were carried out to analyze the influences of parameters such as tamping point distance, tamping times, and isolation trench size on vibration velocity in different directions. Comparison with the theoretical value of vibration attenuation was also made. [Results] Results show that: vibration velocities in x and z directions are much higher than that in y direction under different measured conditions, and vibration velocity in x direction is the largest. According to the peak amplitude of typical vibration waveform, the energy of Love wave (y direction) is only 7.8% of that of Rayleigh wave (x and z direction). In isolation trench condition, the ground vibrations in three directions are subject to exponential attenuation, in which the z direction velocity is the fastest, the x direction velocity is slightly second, and the y direction velocity is the slowest. The vibration velocity of the same tamping point increases with the increase of tamping times, but the sensitivities of the three directions to the tamping times are different, and the tamping time has the greatest influence on the z direction vibration velocity. For measure points behind the isolation trench, vibration velocities of lines 1 and 2 in x direction decrease by 33.9% and 6.4%, respectively on average, which is due to the energy attenuation at the inflection point of the trench wall and the path increase of surface wave propagation along the trench wall. The x direction vibration velocity for lines 1 and 2 of each measuring point in front of the isolation trench increases 34.6% and 15.8%, respectively, which is due to the superposition of the reflected energy of the trench wall and the transmitted energy of the tamping point. The increase of trench size significantly improves the vibration isolation effect of Rayleigh wave (x and z direction), but has little effect on Love wave (y direction).