盾构地铁隧道区间在地震作用下的三维动力时程响应分析

地铁已成为城市地下空间结构和轨道交通网络的重要组成部分。为预估和降低地震灾害的影响,以西安盾构地铁区间隧道为例,建立了地铁隧道区间三维计算模型,进行三维抗震时程响应分析。采用粘弹性局部人工边界模拟地基结构的半无限性,利用不同超越概率水平下的地震动参数作为参考,考虑相位随机性影响,拟合地震动时程样本,建立了地基与结构相互作用的三维有限元模型。计算结果表明,地震发生时,顶部、底面、侧面、以及联络通道处虽产生变形影响,但均在规范规定范围内;位移时程曲线、位移分布云图、拉压应力云图清楚显示区间结构在地震持续时的抗震情况,数据表明结构最不利位置在联络通道处,而内力和变形均满足规范安全要求。

Three-dimensional seismic response analysis of a shield-shaped subway tunnel

Subways has become an important part of the urban underground transportation networks as well as underground space structure. In order to forecast and reduce the impact of earthquake hazard, using a subway shield-shaped tunnel as an example, this work establishes a three-dimensional calculation model to analyze seismic response. In the calculation, a viscoelastic artificial boundary is employed to simulate the half infinite feature of the foundation. Several earthquake ground motion parameters under different exceeding probability levels are adopted for reference. Considering the random phase affects to fit the seismic ground motion time history samples, a three-dimensional finite element modeling for soil-structure interaction is carried out. The results show that the deformation amounts of the top, bottom, sides and the connecting passage are all deformed caused by the earthquake are all within the allowed range of the relevant codes . The displacement time history curves and tensile and compressive stress distributions clearly show the performance of the subway tunnel anti-earthquake structure. The most vulnerable position is the connecting passage, but its inner stress and deformation still satisfies the safety requirement of the codes.