Book Description

Flexible linings provide a means of stabilizing roadside channels. Flexible linings are able to conform to changes in channel shape while maintaining the overall lining integrity. Permanent flexible lining such as riprap, gravel, or vegetation reinforced with synthetic mat are suitable for hydraulic conditions similar to those requiring rigid linings. Vegetation or temporary linings are suited to hydraulic condition where uniform flow exists and shear stresses are moderate. Design procedures are given for rock riprap, wire-enclosed riprap, gravel riprap, woven paper net, jute net, fiberglass roving, curled wood mat, synthetic mat, and straw with net. Special design procedures are presented for composite channels and channels with steep gradients. The design procedures are based on the concept of maximum permissible tractive force. Methods for determination of hydraulic resistance and permissible shear stress for individual linings are presented. Nomographs are provided for solution of uniform flow conditions in trapezoidal channels. Nomographs are also provided for determination of resistance characteristics for vegetation and permissible shear stress for soils. (fr).