Earthquakes generally consist of one mainshock and subsequent aftershocks. Although effects of aftershocks following the mainshock on surface structures has been studied extensively, similar studies on underground structures are rarely reported in the literature. With the fast advances in underground space development, robustness of remediation measures against underground structures uplift induced by soil liquefaction shall be examined to ensure their functioning subject to not only the mainshock but also the subsequent aftershocks. This paper studies the uplift behaviour of a conventional manhole subjected to the mainshock-aftershock sequence. It was found that, in the ground that becomes liquefied during the mainshock, manholes become more vulnerable when faced with aftershocks. Due to this reason, some of the previously proposed remediation measures, such as increasing the manholes’ self-weight, roughening the sidewalls, were examined using centrifuge modeling in this study. It was found that such measures had little effect in the aftershocks despite their effectiveness in the precedent mainshock. In contrast, the methods that mitigates manhole uplift by enhancing the manhole’s base permeability, demonstrated better performance in the aftershock than in the mainshock, indicating its promising application potential in future mitigation design.

中文翻译：

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主余震序列下液化引起的井盖隆起修复措施的稳健性

地震通常由一次主震和随后的余震组成。尽管主震后余震对地表结构的影响已被广泛研究，但对地下结构的类似研究在文献中却很少报道。随着地下空间开发的快速推进，需要检验针对土壤液化引起的地下结构隆起修复措施的稳健性，以确保其在主震和后续余震的影响下发挥作用。本文研究了主震-余震序列作用下常规检修孔的隆起行为。研究发现，在主震期间液化的地面中，沙井在面对余震时变得更加脆弱。因此，本研究使用离心机模型对之前提出的一些修复措施（例如增加沙井自重、粗糙侧壁）进行了检验。结果发现，尽管这些措施在前次主震中有效，但在余震中收效甚微。相比之下，通过提高井底渗透性来缓解井盖隆起的方法在余震中表现出比主震更好的性能，表明其在未来缓解设计中具有广阔的应用潜力。