基于向量地震动强度指标的海底沉管隧道地震易损性分析

Seismic Fragility Analysis of Submarine Immersed Tunnel Based on Vector-valued Intensity Measure

为了合理评估海底沉管隧道的抗震性能,基于向量地震动强度指标进行了地震易损性分析,建立了以最大层间位移角和能量比为损伤性能指标的沉管隧道地震易损性曲面.以港珠澳沉管隧道为研究对象,根据地震动强度指标的评价特性(有效性、实用性和效益性)对4个典型的地震动强度指标进行了综合评价,并选取地面峰值加速度和结构基本周期谱加速度作为向量地震动强度指标(IM).考虑地震动的不确定性,对沉管隧道进行了增量动力分析,采用回归分析方法获得了概率地震需求模型,进而构建了不同损伤性能指标的沉管隧道地震易损性曲面,并对向量IM和标量IM的沉管隧道地震易损性分析效率进行了比较分析.研究结果表明:基于向量IM进行地震易损性分析,可以合理地反映两个地震动强度指标对沉管隧道失效概率的影响;基于向量IM进行地震易损性分析的效率更高,向量IM能更好地降低沉管隧道响应预测的离散度,提高沉管隧道抗震性能预测的精度.

In order to reasonably evaluate the seismic performance of the submarine immersed tunnel,the seismic fragility analysis of immersed tunnel based on vector-valued intensity measure is carried out,and fragility surfaces of immersed tunnel are established with the maximum inter-story drift ratio and energy ratio as damage measures.Taking the Hong Kong-Zhuhai-Macao immersed tunnel as the research object,and 4 typical intensity measures are comprehensively evaluated by using three methods:efficiency,practicability and proficiency.Considering the uncertainty of earthquake,the incremental dynamic analysis of immersed tunnel is carried out.The probabilistic seismic demand model is obtained by using regression analysis method,and then the seismic fragility surfaces of immersed tunnel with different damage measures are established.The efficiency of vector-valued intensity measures and scalar-valued intensity measures are compared and analyzed.The results show that the seismic fragility analysis based on vector-valued intensity measures can reasonably reflect the influence of two intensity measures on the failure probability of immersed tunnel.The efficiency of seismic fragility analysis based on vector-valued intensity measures is higher.Vector-valued intensity measures can better reduce the dispersion of response prediction of immersed tunnel and improve the prediction accuracy of seismic performance of immersed tunnel.