A kind of drainage material consisting of a white polypropylene channel-shaped core surrounded by a gray long-fiber hot-bonded non-woven filter fabric, with metal conductor inside for measuring the driven depth.

• 灰色长纤维热粘无纺布滤膜包裹（通过粘合）白色聚丙烯槽型芯板组成的排水材料，内装配金属电子导线用于测量打设深度。