摘要
To study the ground motion intensity measures(IMs)suitable for the design of seismic performance with a focus on longitudinal resistance in tunnel structures,21 different seismic intensity parameters are selected for nonlinear calculation and analysis of tunnel structures,in order to determine the optimal IM for the longitudinal seismic performance of tunnel structures under different site conditions.An improved nonlinear beam-spring model is developed to calculate the longitudinal seismic response of tunnels.The PQ-Fiber model is used to simulate the longitudinal nonlinear behavior of tunnel structures and the tangential interactions between the tunnel and the soil is realized by load in the form of moment.Five different site types are considered and 21 IMs is evaluated against four criteria:effectiveness,practicality,usefulness,and sufficiency.The results indicate that the optimal IMs are significantly influenced by the site conditions.Specifically,sustained maximum velocity(V_(SM))emerges as the optimal IM for circular tunnels in soft soil conditions(CaseⅠsites),peak ground velocity(V PG)is best suited for CaseⅡsites,sustained maximum acceleration(A_(SM))is ideal for both CaseⅢand CaseⅤsites,and peak ground acceleration(A PG)for CaseⅣsites.As site conditions transition from CaseⅠto CaseⅤ,from soft to hard,the applicability of acceleration-type intensity parameters gradually decreases,while the applicability of velocity-type intensity parameters gradually increases.
为研究适用于隧道结构纵向抗震性能设计的地震动强度参数(IMs),选取21个不同的地震动强度参数进行了隧道结构的非线性计算和分析,以确定不同场地条件下隧道结构纵向的最优IM.建立了改进非线性梁弹簧模型以计算隧道结构纵向的地震响应,其中采用了PQ-Fiber模型来模拟隧道结构纵向的非线性行为,以弯矩荷载作用在隧道结构上的形式模拟隧道与土之间的切向相互作用;选取了5种不同的场地类型,采用有效性、实用性、有益性和充分性4类评价准则对21个IMs进行优选.结果表明:场地条件对最佳IMs具有显著影响,持续最大速度V_(SM)是Ⅰ级场地圆形隧道的最佳IM;峰值速度V PG是Ⅱ级场地的最佳IM;持续最大加速度A_(SM)是Ⅲ级和Ⅴ级场地的最佳IM;峰值加速度A PG是Ⅳ级场地的最佳IM.可见,随着场地条件从Ⅰ类到Ⅴ类,从软到硬,加速度型强度参数适用性逐渐降低,而速度型强度参数适用性逐渐增强.
基金
National Key Research and Development Program of China(No.2022YFC3004300)
the National Natural Science Foundation of China(No.52378475).
