Abstract

An Mw6.6 earthquake occurred at 3a.m. on September 6, 2018, in the eastern part of Iburi, Hokkaido. This earthquake killed 41 people, caused a series of service interruptions in Sapporo city. Soil liquefaction and approximately 6000 landslides were triggered. A field investigation was conducted on liquefaction and typical landslides during September 18 to 24, 2018. The liquefaction disaster exhibited soil flow, subgrade collapse, uneven settlement, earthquake subsidence, and deformation of buildings. After investigation of typical landslides, it was found that owing to the continuous heavy rainfall and typhoon, the surface soil had a high-water content. A layered loam of approximately 2 m below ground surface developed into a weak surface. Based on the analysis of sliding morphology, the landslides were classified into translational earth slides and earth flow. To clarify the mechanism of regional landslides, the stability and permanent displacement of slopes considering effect of continuous heavy rainfall and seismic motion was analyzed. Limit equilibrium analysis was applied based on the pseudo-static method. Then Newmark displacement calculation was conducted based on the seismic acceleration record. The distribution range of analysis results showed agreement with actual landslides disasters. The results verified the contribution of continuous rainfall and strong motion to the failure of regional slopes.

摘要

凌晨3点发生了Mw6.6地震。2018年9月6日，在北海道伊武里东部。这次地震造成41人死亡，在札幌市造成了一系列服务中断。引发了土壤液化和大约6000次滑坡。2018年9月18日至24日对液化和典型滑坡进行了实地调查。液化灾害表现为土流，路基倒塌，沉降不均匀，地震沉降和建筑物变形。对典型的滑坡进行调查后，发现由于持续的强降雨和台风，表层土壤含水量很高。地表以下约2 m的分层壤土发展成弱表面。根据滑动形态的分析，滑坡分为平移滑坡和土流。为了阐明区域性滑坡的机理，分析了考虑到连续暴雨和地震运动影响的边坡的稳定性和永久位移。基于伪静态方法进行极限平衡分析。然后根据地震加速度记录进行Newmark位移计算。分析结果的分布范围与实际的滑坡灾害相吻合。结果证实了连续降雨和强运动对区域性斜坡破坏的贡献。基于伪静态方法进行极限平衡分析。然后根据地震加速度记录进行Newmark位移计算。分析结果的分布范围与实际的滑坡灾害相吻合。结果证实了连续降雨和强运动对区域性斜坡破坏的贡献。基于伪静态方法进行极限平衡分析。然后根据地震加速度记录进行Newmark位移计算。分析结果的分布范围与实际的滑坡灾害相吻合。结果证实了连续降雨和强运动对区域性斜坡破坏的贡献。