盾构施工中地表振动的传播与衰减特性

摘要

为探讨盾构施工引起的地表振动的传播特性,对兰州地铁1号线某典型区段砂卵石地层盾构施工现场进行地表振动实测,从时域、频域和加速度振级角度分析盾构施工过程中地表振动的传播与衰减规律.结果表明,盾构掘进过程中,振源三向加速度幅值相当,z、x、y三个方向的加速度峰值依次减小.受洞内振动影响的范围约为两倍洞径区域.地表自由场地加速度传播随距隧道中心线距离的增加呈现先放大后急剧衰减的趋势,x向振动加速度有效值随距隧道中心线距离增加呈现双峰衰减规律.地表振动在距隧道中心线不同位置处发生反弹.该结果为盾构施工诱发地表振动机理及减振措施研究提供了基础.%This paper is concerned with investigating the propagation characteristics behind surface vibration resulting from shield construction.The investigation is performed by measuring the surface vi-bration of a typical section of a typical section of Lanzhou metro line 1,and thereby analyzing the propa-gation and attenuation law underlying surface vibration during shield construction in terms of time do-main,frequency domain and acceleration vibration level.The results demonstrate that shield tunneling involves the equivalent amplitude occurring in the three direction acceleration of the vibration source, with the acceleration peak varying from large to small in the order of z direction,x direction,and y direc-tion;and the inner vibration has an influence range of about twice the tunnel diameter;the acceleration of surface free field shows the tendency to zoom in and out rapidly following the increasing distance from the center line of the tunnel;the effective value of x to the vibration acceleration shows the law behind bi-modal attenuation; and the surface vibration rebound in different vibration source distance.The study may provide a basis for an insight into the mechanism behind the surface vibration induced by shield con-struction and contribute to the vibration reduction measures.