Classification T=200mm T=150mm T=100mm Remarks
Thickness   T=maximum 200mm 150mm 100mm  
t=average 150mm 100mm 70mm  
Standard   a=gab 300mm 300mm 200mm  
b=size 70∼90mm 60mm 60mm  
Range of filter 370∼390 300 200  
Mortal(㎥/㎡) 0.173 0.115 0.075  
Applicable scope Large river, harbor dam general river drainage canal