摘要
依托某磁浮线下穿沪昆高铁桥梁的工程建设项目,以周围土体质点振动峰值速度为控制指标,设计了浅层冲孔施工、中层冲孔施工、深层冲孔施工这三种不同工况,采用FLAC^(3D)模拟冲孔灌注桩施工对既有桥梁墩台的振动影响,重点分析了不同冲程、冲孔深度对周围土体质点振动速度的影响,得到了质点振动速度变化规律。分析结果表明,冲程对土体质点振动速率的影响较大,随着冲程的增大,径向、切向和竖向的质点振动峰值速度均逐渐增大,在施工时可通过减小冲程的方法来降低施工振动对既有铁路桥梁的影响;上覆土体对振动的传播有削弱的作用,冲孔位置越深,引起的地表振动速度越小;随着冲击作用深度的增加,土体的水平振动强于竖向振动;研究成果为临近铁路线冲孔灌注桩施工振动安全影响评价及冲孔施工方案优化提供科学依据。
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 FLAC^(3D) 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.
作者
陈军州
CHEN Junzhou(Xinjiang Natural Gas Transportation Co.Ltd.,State Power Grid Group Co.,Beijing 100020)
出处
《土工基础》
2021年第6期712-717,共6页
Soil Engineering and Foundation
关键词
质点振动峰值速度
冲孔灌注桩
FLAC^(3D)
冲程
peak particle velocity
cast-in-place reinforced concrete pile installed by impact method
FLAC^(3D)
hammer stroke
