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<p>Railway embankments must be stable during earthquakes to prevent track deformation and minimize accident risks. The vertical component of near-fault pulse-like ground motions can significantly increase the risk of damage to railway embankments. Therefore, accurately assessing the effects of near-fault vertical ground motions (VGMs) on the seismic demand of railway embankments is crucial to ensuring their structural safety. This study addresses this problem from a probabilistic perspective, developing a probabilistic seismic demand model for railway embankments under pulse-like horizontal ground motions (HGMs) and VGMs to identify the optimal intensity measures (IMs). The amplification coefficient, denoted as <i>β</i>, quantified the increased seismic demand of railway embankments under the combined effects of near-fault pulse-like HGMs and VGMs, as opposed to that under pulse-like HGMs only. Analysis of near-fault ground motions indicated that the vertical-to-horizontal peak acceleration ratio increased as source distance decreased, averaging 0.88 and exceeding the empirical 2/3 ratio. The velocity spectral intensity (VSI) of the HGMs was identified as the optimal IM. Statistical analysis revealed average values of <i>β</i> ranging from 1.1 to 3.6 under various ground motions. <i>β</i> followed a normal distribution; its mean and standard deviation decreased as the VSI increased and increased in proportion to the VSI ratio of vertical-to-horizontal ground motions (V/H). A mathematical model for <i>β</i>, incorporating multilevel seismic safety reserve levels of 50%, 84%, and 98%, was established using VSI and V/H to assess the impact of random VGM on railway embankment, ensuring cost-effective yet reliable seismic resilience for railway infrastructure.</p>

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Multilevel prediction model for seismic safety reserves: impact assessment of near-fault vertical ground motions on railway embankment seismic demand

  • 期刊论文

  • 发表日期：

    2025年6月30日

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  • Pan Si,
  • Shuang Tian,
  • Liang Tang,
  • Yanfang Liu,
  • Xianzhang Ling

摘要

Railway embankments must be stable during earthquakes to prevent track deformation and minimize accident risks. The vertical component of near-fault pulse-like ground motions can significantly increase the risk of damage to railway embankments. Therefore, accurately assessing the effects of near-fault vertical ground motions (VGMs) on the seismic demand of railway embankments is crucial to ensuring their structural safety. This study addresses this problem from a probabilistic perspective, developing a probabilistic seismic demand model for railway embankments under pulse-like horizontal ground motions (HGMs) and VGMs to identify the optimal intensity measures (IMs). The amplification coefficient, denoted as β, quantified the increased seismic demand of railway embankments under the combined effects of near-fault pulse-like HGMs and VGMs, as opposed to that under pulse-like HGMs only. Analysis of near-fault ground motions indicated that the vertical-to-horizontal peak acceleration ratio increased as source distance decreased, averaging 0.88 and exceeding the empirical 2/3 ratio. The velocity spectral intensity (VSI) of the HGMs was identified as the optimal IM. Statistical analysis revealed average values of β ranging from 1.1 to 3.6 under various ground motions. β followed a normal distribution; its mean and standard deviation decreased as the VSI increased and increased in proportion to the VSI ratio of vertical-to-horizontal ground motions (V/H). A mathematical model for β, incorporating multilevel seismic safety reserve levels of 50%, 84%, and 98%, was established using VSI and V/H to assess the impact of random VGM on railway embankment, ensuring cost-effective yet reliable seismic resilience for railway infrastructure.