饱和地基中单排孔近场隔振的现场试验与数值分析

Field test and analysis of vibration isolation of machine foundation by a row of holes in saturated soil

针对饱和地基中明置动力机器基础的环境振动影响问题,进行单排孔近场隔振的现场试验和三维边界元数值分析。对现场试验结果进行无量纲化分析;基于饱和土三维半解析边界元法,分别推导动力机器基础环境振动影响和单排孔近场隔振的边界元方程;详细研究单排孔对动力机器基础振动影响的隔振效果,分析单排孔几何参数和单排孔距振源距离对隔振效果的影响。结果表明:单排孔能够降低动力机器基础的环境振动影响;增加排孔孔径和孔深、降低孔间净距均能取得更好的隔振效果,工程设计时,建议排孔孔径取0.1~0.15λR(Rayleigh波波长)、孔深不超过1.0λR,孔间净距不大于0.1λR;单排孔距振源距离对其隔振效果也有较大影响,距离越近则隔振效果越好。单排孔孔数对其平均隔振效果影响很小,但更多的排孔可获得更大的屏蔽区域面积。

The investigation was focused on the effects of using a row of holes for the reduction of nearby vibration response generated by the motion of a machine foundation on saturated soil.The analysis was accomplished with the aid of a series of field experiments and numerical simulation.3D semi-analytical BE models were established to use a row of holes as active wave barrier to isolate the ground vibrations generated by the machine foundation laid on the surface of saturated soil foundation,and the effects of the model parameters on screening effectiveness were investigated and discussed in detail.The results showed that a row of holes could isolate the ground vibrations successfully.Increasing the radius and the depth,decreasing the net spacing between two successive holes increase the screening effectiveness.According to the results,it was suggested in the design that the hole radius should take the value of 0.1-0.15λR,and the hole depth and the net spacing between two successive holes should take the value no more than 1.0λR and 0.1λR,respectively.Moreover,the distance between the machine foundation and wave barriers affect the screening effectiveness,and the the distance was,the the screening effectiveness was.The number of holes in a row had less effect on the screening effectiveness.However,the bigger the number of holes in a row was,the larger the screening zone behind barriers was.