Definition

Drainage geocomposite (also known as dimple drainage board or drainage board) is a prefabricated drainage system composed of a polymer core laminated with a filtration geotextile. The core structure features regular dimples (or cusps) forming a three-dimensional network, creating a "drainage-filtration-protection" integrated functional layer

Drainage geocomposite serves as an ideal alternative to traditional granular drainage layers, providing rapid water collection and transmission while preventing soil particle intrusion and clogging

1. Functional Principles

1 Drainage Mechanism

The drainage function operates in three stages:

Collection: Water permeates through the geotextile into the core cavities; the geotextile filters out soil particles

Transmission: Water flows within the three-dimensional channels along the plane direction

Discharge: Water is directed to preset outlets (drainage ditches, catch basins, downspouts)

2 Additional Functions

Protection: Acts as a protective layer for waterproofing membranes against sharp objects in backfill

Capillary Break: The air gap interrupts capillary rise, providing vapor/gas barrier functions

Water Retention: Perforated cores can store water for sustained plant growth on green roofs

2. Main Applications

1 Building Construction

Basement Waterproofing:

Green Roofs / Roof Gardens:

Interior Moisture Protection:

2 Transportation Engineering

Highway/Railway Subgrade Drainage:

Tunnel Lining Drainage:

Retaining Wall Drainage:

3 Hydraulic and Environmental Engineering

Dam Drainage:

Landfills:

Athletic Fields:

4 Special Applications

Saline/Expansive Soils:

Permafrost Regions:

5. Installation Precautions

5.1 Material Storage and Protection

Store drainage boards in dry, ventilated areas, away from direct sunlight and fire sources

Stack vertically or flat, do not tilt or cross-stack; stacking height ≤3 layers

Cover promptly after installation to prevent mechanical damage and UV exposure

5.2 Substrate Preparation

Ensure substrate is smooth, compact, dry, and free of sharp debris

Verify waterproofing membrane (if present) is accepted before drainage board installation

Substrate slope shall meet design requirements for proper drainage

Connect drainage boards reliably to drainage ditches, catch basins, downspouts, etc.

At drain pipe connections, remove geotextile from core backside, wrap and fix board to pipe