The concept of safety factor has long been proposed to evaluate the uplift triggering of underground structure induced by soil liquefaction, and it is well known that it should be unity when the underground structure raises up. However, a close-unity value has been rarely obtained in experiments, especially for vulnerable cases. This is due to the difficulties of an accurate measurement during testing; thus, the sidewall friction below groundwater table is always ignored for simplicity. In this study, a close-unity safety factor during the seismic shaking was acquired for a variety of manhole uplift cases, being stable in ground or suffering significant uplift. More importantly, a complete time history showing the safety factor degradation was acquired for each case. It was found that the safety factor before earthquake shaking (termed as ‘prior safety factor’ subsequently) shows good correlation with the final manhole uplift displacement based on the presented centrifuge testing data both in this study and in the literature. This prior safety factor shows good potential to predict final uplift displacement for conventional manholes.

安全系数的概念早已被提出来评价土壤液化引起的地下结构抬升触发，众所周知，地下结构抬升时应统一。然而，在实验中很少获得接近统一的值，特别是对于易受攻击的情况。这是由于在测试过程中难以准确测量；因此，为简单起见，始终忽略地下水位以下的侧壁摩擦。在这项研究中，对于在地面稳定或遭受显着抬升的各种人孔抬升情况，获得了地震震动过程中的紧密统一安全系数。更重要的是，每个案例都获得了显示安全系数退化的完整时间历史记录。根据本研究和文献中提供的离心机测试数据，发现地震前的安全系数（以下称为“先验安全系数”）与最终人孔抬升位移显示出良好的相关性。该先验安全系数显示出预测传统检修孔最终提升位移的良好潜力。