砂土地基强夯振动特性与安全距离预估的实验研究

Experimental study on vibration characteristics and safety distance prediction of dynamic compaction of sandy soil foundation

针对砂土地基强夯振动问题,通过现场试验田实验,分析了砂土地基强夯振动的波形特征、振动速度与频率的衰减规律,根据量纲分析法建立了一种强夯振动安全距离的数学计算模型。研究表明:强夯振动以水平径向波为主导波,波动持续时间在2 s之内,0~1 s是由夯锤夯击地面时产生的振动波,对周围建筑物影响较大,1~2 s为夯锤夯击地面后余震产生的振动波,对周围建筑物影响较小;强夯振动速度峰值随与夯击点距离的增加基本呈现幂指函数的衰减规律,在距离夯击点10~40 m范围内,强夯振动速度峰值随距离的增加而快速减小,在距离夯击点40~100 m范围内,强夯振动速度峰值有微小的波动。强夯振动主频率峰值受距离的影响较大。两组数据显示,所建立的强夯振动安全距离计算模型,比非线性曲线法模型分别减少19.46%和14.50%。

This paper is aimed at addressing the dynamic compaction vibration of sandy soil foundation.The study building on the field experiments is focused on analyzing the waveform characteristics behind dynamic compaction vibration of sandy soil foundation and the attenuation law underlying vibration velocity and frequency and developing a mathematical calculation model for safety distance of dynamic compaction vibration using the dimensional analysis method.The results show that dynamic compaction vibration is dominated by the horizontal radial wave,whose fluctuation duration lasting 2 s,during 0-1 s of which,the vibration waves are produced by rammers ramming the ground,with a great impact on the surrounding buildings;during 1-2 s,the vibration wave are generated by the aftershock after the rammers ram the ground,with little impact on the surrounding buildings.The peak value of dynamic compaction vibration velocity basically presents the attenuation law of power exponential function with the increase of distance from the compaction point,as is exemplified by a rapid decrease occurring in the peak value of dynamic compaction vibration velocity with the increase of distance within the range of 10-40 m from the compaction point;and a slight fluctuation observed in the peak value of dynamic compaction vibration velocity within 40-100 m from the compaction point.The main frequency peak of dynamic compaction vibration is subjected to a greater influence of distance.The calculation model for vibration safety distance of dynamic compaction based on the dimensional analysis method boasts a higher calculation accuracy and a lower average error by 19.46%and 14.50%respectively in two sets of data than the model based on the nonlinear curve method.