Sheeting joints are extensive fractures that typically develop parallel to natural slopes. Embryonic sheeting joints initially constitute channels for water flow and then become the focus for weathering and sediment infill accompanied by progressive deterioration and dilation. Slabs of rock fail along them periodically because of their adverse orientation and long persistence. They are however rough and wavy and these characteristics contribute highly to their shear strength and improve their stability. This paper reviews several landslide case histories and on the basis of these provides guidelines for characterising sheeting joints and determining their shear strength. Engineering options for stabilising sheeting joints in natural and cut slope configurations are then examined with reference to case examples.

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.

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