基于隧道与断层破碎带距离因素的震害规律分析

Analysis of the Seismic Damage Rule Based on the Distance between the Tunnel and the Fractured Fault Zone

断层破碎带是引起隧道震害的关键因素之一,隧道破坏程度与断层的相对位置、距离等因素关系密切。文章通过对12种典型数值模型的模拟分析,研究了隧道与断层破碎带距离因素影响下隧道结构的地震破坏规律。为确定模型的加载方式,依据地震几何学原理与地震动衰减效应进行地震波传播的理论研究;以有限差分软件FLAC^(3D)的非线性动力分析模块为平台,将计算得到的地震波输入到隧道模型中;通过对计算结果的系统分析,探讨了隧道与断层不同距离对隧道结构的震害影响。研究结果表明:隧道结构的震害主要发生在边墙肩部和角部等位置,其破坏区域大致在共轭45°方向上;隧道与断层破碎带相交,衬砌的变形破坏主要发生在与破碎带接触的部位;隧道位于断层上盘,距离因素对震害影响显著,且距离约10 m时最严重;隧道位于断层下盘,距离因素对震害影响不明显。研究成果对跨断层隧道的震害风险评估及防震、减震设计有重要指导意义。

Considering that a fractured fault zone is one of the main factors to cause tunnel damage during an earth-quake, and that the relative position of and distance between the tunnel and fault affect the degree of damage, this paper discusses the seismic damage rule of tunnels influenced by the distance between the tunnel and the fractured fault zone based on the analysis of 12 typical numerical models. Specifically, theoretical research is carried out on seismic wave propagation combining the geometric principle and the attenuation effect of an earthquake to deter- mine the loading mode of the model, and the influence of the distance between the tunnel and fault on the tunnel damage is analyzed using the non-liner dynamic analysis module of FLAC3D software as the platform and inputting the calculated seismic wave into the model. The results show that tunnel damage mainly occurs at the areas between the spandrel and the corner of the sidewall with a conjugate angle of 45~; the lining damage occurs in the areas con- tacting the fractured zone in cases where the tunnel intersects with the fractured fauh; the distance has a significant effect on the seismic damage when the tunnel is located above a fault, with the most serious damage under a distance of about 10 m; the distance has little influence on seismic damage when the tunnel is located below a fault.