Landslide mechanisms in Hong Kong
Published:January 01, 2010
This paper reviews the nature and mechanics of landslides in the weathered terrain of Hong Kong. The vast majority of landslides are very shallow (a few metres depth) and occur during intense rainstorms. Deeper-seated landslides, in contrast, may occur days or weeks after intense rainstorms. The time of occurrence of landslides can be linked to hydrological and hydrogeological factors, and a hydrogeological grouping of landslide mechanisms is introduced related to timing in a storm. A relationship is presented that links intensity of landsliding to 24 h rainfall. The gradual deterioration and internal erosion of slopes prior to detachment is discussed and allows some realistic opportunity for identifying progressive major landslides. In particular, the growth of natural piping systems and infilling of dilated fracture networks are recommended as important indicators of landslide development. The conclusions are supported by case examples of slope failures, the study of some of which has been taken to a forensic level.
Figures & Tables
Weathering as a Predisposing Factor to Slope Movements
This volume is intended to provide an up-to-date overview of the approaches, methodologies and techniques devoted to better understanding of the weathering conditions of rock masses on slopes. According to the local conditions, a variety of slope movements may take place and involve weathered rock masses. Shallow and rapid soil slips evolving to debris flows are probably the most common type of slope movement. At the same time, deep-seated, intermittent landslides can also affect large volumes of weathered rocks and soils. Despite the high frequency of landslides in weathered materials, and the damage and casualties they repeatedly cause, little is known about the relationship between weathering and slope movements. This book presents worldwide case studies, where a variety of geological and geomorphological settings are discussed. The content is divided into three sections: the first is devoted to broad aspects of the weathering/landslide processes; the second and third sections include papers dealing with igneous/metamorphic and sedimentary weathered rocks, respectively.