... introduction and application of 3D drainage net and geotextiles:1.Compound drainage nets also called 3D geocomposite drainage, 3D geotechnique ... is convenient, shorten the construction period, lower cost. 5.Compound drainage nets is mainly used for railways, highways, tunnels, ... ≥0.39Complex hydraulic conductivitym2/s≥1.2×10-310Non-woven to permeability coefficientcm/s≥0.3 3D Compound Drainage Nets