Performance of landslide debris-resisting baffles

Abstract

© 2015 The Hong Kong Institution of Engineers. Arrays of landslide debris baffles are commonly installed upstream of rigid barriers in Hong Kong to dissipate flow energy impacting a rigid barrier. Currently, baffles are installed using prescriptive and empirical approaches in Hong Kong without design recommendations. Given the engineering value of baffles, an improved understanding of their interaction mechanisms is warranted. Flume modelling and numerical back analysis using the discrete element method (DEM) were adopted to study the influence of landslide debris baffles on impact on a downstream terminal rigid barrier. Froude scaling was used to dynamically characterise the flow. The optimum geometrical configuration was examined. The results revealed that an array of baffles is effective in reducing the peak dynamic impact induced by debris on a rigid barrier and that overflow processes need to be controlled. Baffle heights exceeding 1.5 times the approach flow depth (h) exhibited little incremental influence on reducing the peak dynamic impact forces induced on the rigid barrier. At least two staggered rows are required to effectively intercept discharge from the first row and reduce the frontal debris impact force. The optimum spacing between successive rows (L) and transverse blockage is L/D = 3 (D is the slit opening) and 30%, respectively.