The highways circumnavigating Viti Levu play a pivotal role in Fiji's socioeconomic development, and are a crucial link to transport aid during disasters. Slope failures triggered by heavy rainfall and tropical cyclones have led to considerable damage and fatalities along Viti Levu's main roads in the past. Knowledge of slope instability mechanisms is key for the successful identification and management of slope failure hazards, however, there is a paucity of such information for Fiji's main roads. Severe Tropical Cyclone (STC) Winston was the strongest cyclone on record to make landfall in Fiji and affected the Fiji Islands from the early hours of 20 February until 3 am, 21 February, 2016. We present a field reconnaissance examining the characteristics and mechanisms of slope failures induced by STC Winston along a 35 km stretch of the northern part of the Viti Levu's ring road, “Kings Road”. Approximately 61 distinct shallow, small‐scale slope failures were identified most of which were of a complex type and included earth and debris slides (planar and rotational) with a minor flow component. The trigger for the slope failures was the ~258 mm of rainfall in 24 hours after 30‐days of antecedent rainfall totalling 482 mm. This caused rapid increases in porewater pressures, especially at the contact of residual soils and the underlying weathered basement rock. Evidence of recurring slips along Kings Road indicates that contemporary slope instability is likely caused by elevated porewater pressure during high intensity rainfall events in clay‐dominated soils.

中文翻译：

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2016年2月热带气旋温斯顿引发的斐济维提岛东北部斜坡破坏的地貌特征

环绕维提岛的高速公路在斐济的社会经济发展中起着举足轻重的作用，并且是灾难期间与运输援助的重要纽带。过去，由于暴雨和热带气旋引发的斜坡失灵已经在维提岛的主要道路上造成了相当大的破坏和死亡。边坡失稳机制的知识是成功识别和管理边坡破坏危险的关键，但是，斐济主要道路的此类信息很少。从2月20日凌晨至2016年2月21日凌晨3点，严重热带气旋（STC）温斯顿是有史以来最强的飓风，登陆斐济，并影响了斐济群岛。我们提供了一个现场勘测，研究了由STC Winston沿维提岛环城公路“国王路”北部35公里延伸段引起的边坡破坏的特征和机理。确定了大约61种不同的浅层，小规模边坡破坏，其中大多数为复杂类型，包括土流和碎屑滑坡（平面滑坡和旋转滑坡），流量分量较小。斜坡失稳的诱因是在30天的前期降雨总量482 mm之后的24小时内，降雨量约为258 mm。这导致孔隙水压力迅速增加，尤其是在残留土壤与下面的风化基底岩石接触时。