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The recognition, repetition and prediction of the post-failure motion process of long-runout landslides are key scientific problems in the prevention and mitigation of geological disasters. In this study, a new numerical method involving LPF3D based on a multialgorithm and multiconstitutive model was proposed to simulate long-runout landslides with high precision and efficiency. The following results were obtained: (a) The motion process of landslides showed a steric effect with mobility, including gradual disintegration and spreading. The sliding mass can be divided into three states (dense, dilute and ultradilute) in the motion process, which can be solved by three dynamic regimes (friction, collision, and inertial); (b) Coupling simulation between the solid grain and liquid phases was achieved, focusing on drag force influences; (c) Different algorithms and constitutive models were employed in phase-state simulations. The volume fraction is an important indicator to distinguish different state types and solid‒liquid ratios. The flume experimental results were favorably validated against long-runout landslide case data; and (d) In this method, matched dynamic numerical modeling was developed to better capture the realistic motion process of long-runout landslides, and the advantages of continuum media and discrete media were combined to improve the computational accuracy and efficiency. This new method can reflect the realistic physical and mechanical processes in long-runout landslide motion and provide a suitable method for risk assessment and pre-failure prediction.

Background: This study aimed to characterize and compare the demographics, clinical profile, and COVID-19 outcomes between healthcare workers (HCWs) and non-HCWs COVID-19 patients diagnosed in different phases of the pandemic defined by the vaccine rollout policy and different variants that circulated in South Carolina (SC). Methods: Extracted from the statewide electronic health record data, we analyzed the clinical outcome of 34,502 HCWs and 1,071,020 non-HCWs adults diagnosed with SARS-CoV-2 between March 2, 2020 to April 14, 2022. Logistic regression models were used to explore the association between different pandemic phases and COVID-19 severity-related outcomes. Results: Substantial reductions in mortality were observed following the vaccine rollout in non-HCWs and HCWs. Compared to the pre-vaccination period, non-HCWs patients diagnosed during post-vaccination with Alpha predominance (adjusted odds ratio [aOR]: 1.10; 95%CI: 1.04–1.16) were more likely to be hospitalized, but the reduced mortality rates were observed in all post-vaccination periods. Regarding HCWs, a reduced mortality rate was only observed in the pre-Alpha (aOR: 0.33; 95%CI: 0.13–0.84) and Omicron periods (aOR: 0.21; 95%CI: 0.05–0.89). Conclusions: The declining protection effect of vaccines informs the importance of early promotion of the booster dose of the COVID-19 vaccine for HCWs who have more occupational exposure.