Abstract: As a new pile installation method introduced from abroad, the high-frequency resonance-free hydraulic pressed pile driving has received increasing popularity and applied in many large-scale construction projects in China in recent years due to the continuous improvement of equipment performance and the increasing maturity of technology. The principles of pile installation are based on the high frequency vibration destroys the soil around the pile and reduces the lateral friction of the pile to achieve rapid pile penetration, but the destroy of the soil will reduce the axial capacity of the pile and recovers slowly, which makes it difficult to meet the design requirements in a short period of waiting time. In this paper, the engineering case history of high-frequency resonance free hydraulic pressed pile driving in an urban viaduct in Shanghai and its surrounding areas is presented. Through the test results of high-frequency resonance-free hydraulic pressed pile driving, the axial capacities in different set-up period are load tested. The variation trend of the pile axial capacity with time is analyzed and presented.

Key words: resonant-free pile installation, set-up effect, axial capacity, steel pipe pile