关键词: 质点振动峰值速度, 冲孔灌注桩, FLAC3D, 冲程

Abstract: This paper presents a case history of the vibration influence of the proposed magnetic levitation bridge under passing the existing Shanghai-Kunming railway viaduct. The peak particle velocity (PPV) of the target soil was selected as the target of the vibration control. The shaft of the cast-in-place reinforced concrete pile was installed by impact punching method in this project. To study the pile construction induced vibration on the adjacent existing bridge piers, vibrations from three typical installation impact conditions, namely, shallow layer punching, mid layer punching and deep layer punching, were numerically investigated by using FLAC3D software. The PPV values generated from different stroke and installation depth were evaluated. The results showed that the stroke had a great influence on the PPV values. With the increase of the stroke, the PPV in the radial, tangential and vertical directions gradually increased. During construction, the impact of construction vibration on the existing railway bridge piers could be reduced by reducing the stroke. The overlying soil had less effect on the transmission of vibration and the induced PPV at the ground surface was reduced with the deeper punching position. As the impact depth increased, the horizontal vibration of the soil was stronger than the vertical vibration. The research results will provide a scientific basis for the impact assessment of vibration safety in the construction of cast-in-place piles near the railway line and the optimization of pile installation procedures.

Key words: peak particle velocity, cast-in-place reinforced concrete pile installed by impact method, FLAC3D, hammer stroke