考虑氯离子侵蚀的深层隧道地震易损性分析

Seismic vulnerability of deep tunnels influenced by chloride ion corrosion

氯离子侵蚀对隧道的抗震性能产生不利影响,研究隧道在侵蚀环境下的地震易损性对全寿命周期的抗震评估至关重要.为了量化分析隧道长期在氯离子侵蚀作用下抗震性能的退化趋势,基于地震易损性理论,结合考虑氯离子侵蚀影响的混凝土和钢筋强度时变模型,分别选取峰值地面加速度和隧道直径变形率作为地震动强度指标和结构损伤指标,通过采用增量动力分析(incremental dynamic analysis,IDA)方法进行时程分析,深入探讨了深层隧道的地震易损性,得到了不同服役时间及不同损伤状态下的地震易损性曲线.结果表明:在相同的服役时间和地震动强度下,轻微损伤的发生概率最高,其次是中等和严重损伤;在相同的损伤状态和地震动强度下,随着服役时间的延长,氯离子侵蚀导致隧道抗震性能下降,损伤概率上升;在轻微损伤状态下,当峰值地面加速度为0.30g且服役达100 a时,损伤概率是服役初期的2.39倍.研究结果可为深层隧道的抗震设计提供科学依据.

Chloride ion erosion adversely affects the seismic performance of tunnels,making it essential to study the seismic vulnerability of tunnels in corrosive environments for a comprehensive seismic assessment over their entire lifecycle.To quantify the degradation trend in seismic performance of tunnels exposed to long-term chloride ion erosion,a seismic vulnerability analysis is conducted based on seismic vulnerability theory.A time-varying model accounting for the effects of chloride ion erosion on concrete and steel strength is employed.Peak ground acceleration and tunnel diameter deformation rate are selected as indicators for seismic intensity and structural damage,respectively.Through incremental dynamic analysis(IDA),the seismic vulnerability of deep tunnels is thoroughly investigated.Seismic vulnerability curves are obtained for various service periods and damage states.The results indicate that for the same service duration and seismic intensity,the probability of minor damage is the highest,followed by moderate and severe damage.For the same damage state and seismic intensity,as the service time increases,chloride ion erosion leads to a decline in tunnel seismic performance and a rise in damage probability.In the state of minor damage,when the peak ground acceleration is 0.30g and the service life reaches 100 years,the damage probability is 2.39 times higher than that in the initial service period.The research results provide a scientific basis for the seismic design of deep tunnels.