Characteristics of ground vibration induced by sand compaction pile driving in coal ash ground

The sand compaction pile method is frequently used for the improvement of soft ground. However, its driving process will induce ground vibration. In this study, in-situ measurement was conducted on the ground vibration induced by the sand pile driving at the coal ash filled ground at the ash pond in Taichung Thermal Power Plant. The peak ground velocity, the frequency content and the attenuation tendency of the ground vibration was investigated. Results show that during the three phases of sand pile driving, penetration, pull out and compaction, the maximum ground vibration was caused when the compaction was made near the ground surface. The predominant frequency of the induced ground vibration was exactly the operation frequency of vibratory pile driving equipment. The ground vibration during the compaction in the coal ash layer attenuated more rapidly than in the original soil layer. Moreover, the data were compared to the acceptance criteria in the vibration codes of different countries, and the ground vibration induced by the sand pile driving generally would cause hardly any damage on structures which locate beyond a distance of 20 m from the vibration source.