The Drainage Effect of Three-position Composite Drainage Network in Road Foundation

The three-dimensional composite drainage network is composed of two sides of the three-dimensional structure of plastic mesh bonded to permeable geotextiles. It can replace the traditional sand and gravel layer. It is mainly used for drainage of landfill, roadbed and tunnel inner wall.

Three-dimensional composite drainage network is a new type of geotechnical material for drainage. The core in the middle is made of high density polyethylene (HDPE) as raw material, processed by special extrusion molding process, and has a special three-dimensional structure. The middle core is rigid and vertically arranged to form a drainage channel. The core of the mesh is formed by the upper and lower cross-arranged bars, which support to prevent the geotextile from embedding in the drainage channel. This enables the three-dimensional composite drainage network to maintain high drainage performance even under high loads. 

The two-sided adhesive permeable geotextile composite of the three-position composite drainage network has the comprehensive performance of "filtration - drainage - air permeability - protection", which is the most ideal drainage material at present.

The principle of three-position composite drainage network：

1. The three-position composite drainage network is laid between the foundation and the subfoundation, which is used to discharge the water between the foundation and the subfoundation, block the water siphon effect and effectively integrate into the edge drainage system. This structure automatically shortens the drainage path of the foundation, and the drainage time is greatly shortened. And it can reduce the use of selected foundation materials. It can extend the service life of the road.

2. Laying a three-dimensional composite drainage network on the base can prevent the fine material in the base from entering the base (that is, playing an isolation role). The aggregate base will enter the upper part of the geonet to a limited extent. In this way, the composite geotechnical drainage network also has a potential role in limiting the lateral movement of the aggregate base. At this level, its role is similar to the reinforcement of the geoglery. In general, the tensile strength and rigidity of the composite geodrainage network will be better than many geogrid used for foundation reinforcement. This limiting effect will improve the supporting capacity of the foundation.

3. After the road is aging and cracks are formed, most of the rainwater will enter the section. In this case, the three-dimensional composite drainage network is directly laid under the road instead of the drainage foundation. The drainage network can collect water before it enters the foundation/substructure. In addition, the bottom end of the drainage network can be covered with a layer of film to further prevent water from entering the foundation. Another advantage of this structure is that it may allow the concrete to hydrate more evenly. Whether it is a rigid road or a flexible road system, this structure can extend the life of the road.

4. In the northern climate, laying three-dimensional composite drainage network can help reduce the impact of thermal expansion and contraction. If the freezing depth is very deep, the geomesh can be laid in a shallow position in the base, as a capillary action blocking. In addition, it is often necessary to replace with a granular base that is not easy to frost heave. Freezing-prone backfill can be filled directly onto the surface of the drainage network until the ground line of the foundation. This could potentially limit the development of ice crystals, eliminating the need to limit traffic loads during spring ice melt in cold regions.