断层破碎带对场地地震动的影响

Effect of Fault Fracture Zone on Ground Motion of Fault Site

使用有限差分软件FLAC3D,建立均匀无限半空间中含断层破碎带场地模型,研究断层破碎带对场地地震动的影响情况,分析破碎带倾角、宽度以及输入地震动强度对断层场地地震动分布的影响。研究表明:断层破碎带对场地地震动具有放大效应,地表各监测点显示,断层上盘和破碎带中点附近放大显著。随破碎带倾角增加,峰值加速度曲线最大值减小,上盘放大作用减弱,下盘放大作用增强,具有不对称性,反应谱峰值在上盘和破碎带中点附近变化明显。随破碎带宽度增加,场地地震动放大效应增加。输入地震动越强,场地峰值加速度越大,且在断层上盘和破碎带中点附近放大显著,反应谱的面积中心前移。

Finite difference software FLAC3 Dis used and homogeneous infinitive half space fault site is established to investigate the influence of fault fracture zone on site＇s seismic ground motion. The influence of fault fracture zone＇s inclined angle,width,as well as the intensities of inputting waves on the distribution of seismic ground motion are investigated. The results show that： seismic ground motion on fault fracture zone can be amplified,especially on hanging wall and neighborhood of fracture zone center which are shown in ground points. As the inclined angle is increased,the maximal of PGA is decreased. Amplification weakens on hanging wall and increases on foot wall,which is asymmetry. The peak of response spectrum changes significantly on hanging wall and the neighborhood of fracture zone center. As the fracture zone width is increased,the ground motion amplification is increased. As the intensity of inputting wave is increased,PGA is greater. The amplification on hanging wall and neighborhood of fracture zone center is significant,at the same time,the response spectrum area center moves forward.