基于层状土推覆方法的盾构隧道抗震性能分析

当前对于地铁盾构隧道进行抗震分析时多基于弹性假设的简化设计方法,难以体现土体和结构的非线性特征;而动力时程分析具有耗时长,工作量大,考虑因素多等缺点使其在工程设计中的广泛应用受到限制。地下结构静力推覆方法具有概念清晰,考虑土体与结构相互作用,相比动力方法耗时大大减少等优点。而自适应层状土推覆分析可以改善地下结构静力推覆法的地震荷载加载模式,使之在含软弱夹层的场地中同样具有较高的精度。通过建立二维的土体-结构相互作用模型,采用自适应层状土推覆分析法对实际的单线地铁盾构隧道横断面进行拟静力弹塑性分析。绘制了其抗震性能曲线并发现了相对薄弱处的位置,并与动力时程的分析结果进行了比较,证明该方法有良好的精度。同时采用该方法对地铁盾构隧道抗震响应做了参数分析,给出了管片混凝土标号和土体模量的改变对隧道薄弱点受力的影响。

Seismic Resistance of Shield Tunnel based on Pseudo-StaticAdaptive Pushover Analysis

A majority of seismic design methods for shield tunnels are simplistic approaches based on elastic assumption, which cannot reflect the nonlinearity of soil and underground structures. Dynamic time-history analysis technique can''t be widely applied in engineering design due to many drawbacks such as long computing time, massive post-processing work, and so on. The pushover method can avoid the complex problem in dynamic analysis and needs less computing time to obtain the similar results. This study optimized the loading pattern in pushover analysis using an adaptive pushover analysis method. The presented method can consider the influence of layered soil ground. A two-dimensional soil-structure finite element model was established. The seismic response of a shield tunnel was analyzed by the improved pushover method and by dynamic time-history analysis. A comparison of the results between the two methods validated the applicability of the improved pushover method. Afterwards, the influences of concrete and soil modulus parameters on lining stress at weak points were investigated using the improved pushover method.