| Summary: | 碩士 === 中原大學 === 土木工程研究所 === 94 === Abstract
A pounder impacting ground surface causes stress waves that make sand particles rearrange and improve density to modify engineering properties and decrease liquefaction probability.
This study uses numerical method to simulate the dynamic compaction. The objectives include discussing ground vibration caused by dynamic compaction and comparing the efficiency of modification with different types of pounder base.
The results of analysis indicate that the modification by conical-bottom pounder with 90o apex angle is better than flat bottom pounder. For the simulation of impact once, the influence range of stress caused by the conical-bottom pounder is wider than the flat bottom pounder. After impact, the value of Ko is greater than 1 in shallow soil layer. The results show that the volume of crater is almost the same, irrespective of the type of pounder. The spacing of impaction point with 36 cm get better modification than 18 cm. Comparing the simulation value with the measured field value, the maximum amplitude of accelerations at ground surface 10 m from the impact point are both about 1 g.
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