Debris flow drainage canal based on cascade antiscour notched sill group and application thereof

Abstract

A system of debris-flow drainage canal with cascaded sills is provided, which allows a high-efficient and low-cost realization of debris flow drainage and scour prevention. The canal contains two converging walls and a series of scour prevention sills, which are laid between the two converging walls. The sills are embedded to a certain depth and are evenly spaced and symmetrical to the centre line of the canal to form a cascaded structure for scour prevention. The drainage canal's width is 2 times wider than the sill's horizontal length along the cross-section. Compared with the prior art, this system can drain off a wide variety of flows from debris flow to flood and prevent debris-flow siltation even on a gentle slope. This system has a much higher stability and longer life of service. Moreover, this system can maintain the aquatic habitat in gullies and contribute to ecological restoration.

1 . A debris flow drainage canal based on scour-prevention cascaded sills comprises:
 two flow-converging walls; and   a plurality of sills with a predetermined embedded depth, the plurality of sills being disposed between and connected to the walls,   wherein the sills are evenly spaced and symmetrical with respect to the centre line of the canal, and the width D of canal is at least 2 times wider than the length B of the sills, meeting the requirement of D>2 B.   
     
     
         2 . The debris flow drainage canal according to  claim 1 , wherein the horizontal length B of the sills along the vertical direction of the walls is 1/10˜½ of the drainage canal's width D, meeting the requirement of 1/10 D≦B<½ D. 
     
     
         3 . The debris flow drainage canal according to  claim 1 , wherein an angle is formed between the walls and one end of the sills connected to the walls, and the other end of the sills inclines to a downstream direction. 
     
     
         4 . The debris flow drainage canal according to any one of  claims 1 - 3 , wherein along the vertical direction of the walls, the sills presents lower at the center and higher near the walls. 
     
     
         5 . The debris flow drainage canal according to any one of  claims 1 - 3 , wherein along the longitudinal direction of the walls the top width b 1  of the sills is smaller than the bottom width b 2  of the sills, and the downstream side is vertical, while the upstream side is inclined. 
     
     
         6 . The debris flow drainage canal according to  claim 3 , wherein the angle is within the range of 45° to 75°. 
     
     
         7 . The debris flow drainage canal according to  claim 4 , wherein along the vertical direction of the walls, the horizontal slope  1 :n, which is the sills' height difference h divides the sills' sill( 1 )'s horizontal length B along the vertical direction of the walls, is between 1:4 and 1:20. 
     
     
         8 . The debris flow drainage canal according to  claim 5 , wherein the top width b 1  is within the range of 0.6-1.5 m, and the bottom width b 2  is within the range of 1.0˜2.0 m, and the upstream side's slope  1 :m, which is upstream slope's height H 1  divides (b 2 −b 1 ), is between 1:0.4 and 1:1. 
     
     
         9 . The debris flow drainage canal according to any one of  claims 1 - 3 , wherein the space L between each two steps of the sills is within the range of 8.0˜25.0 m, and the embedded depth H of the sills is within the range of 1.5˜2.5 m. 
     
     
         10 . A method of using the debris flow drainage canal based on scour prevention cascaded sills according to  claim 1 , comprising using the drainage canal to prevent and control diluted debris flow, water-rock flow and flash floods with longitudinal slope of 3%-12%.