A composite 3D drainage net (also known as a three-dimensional geotechnical drainage board, tunnel drainage board, or drainage board) is composed of a three-dimensional plastic mesh with double-sided bonding water seepage geotextiles, which can replace the traditional sand and gravel layers. The mesh double-sided bonding water seepage geotextile makes up a drainage tool, which is used for the drainage of landfills, roadbeds, and inner walls of tunnels.
A composite drainage net is a new type of drainage geotechnical material. Using high-density polyethylene (HDPE) as raw material, it is processed by a special extrusion molding process and has a three-layer special structure. The middle rib has high rigidity and is arranged to form a drainage channel. The upper and lower ribs form support to prevent the geotextile from being embedded in the drainage channel and can maintain high drainage performance even under high load. Double-sided bonded water-seepage geotextile composite use, with “reverse filtration-drainage-breathable-protection” comprehensive performance, is currently the most ideal drainage material.
used in railways, highways, tunnels, municipal engineering, reservoirs, slope protection, and other drainage projects with remarkable effect.
1. Strong drainage (equal to one-meter thick gravel drainage).
2. High tensile strength.
3. Reduce the probability of geotextiles embedded in the mesh core and maintain long-term stable drainage.
4. Long-term withstand high-pressure load (can withstand a compressive load of about 3000Ka).
5. Corrosion resistance, acid and alkali resistance, and long service life.
6. Convenient construction, shorten the construction period, and reduce cost
In transportation infrastructures such as railways and highways, the safety and service life of the project are related to its own drainage system, of which geosynthetics are an important part of the drainage system.
Ⅲ）Characteristics of three-dimensional composite drainage network
1. When the load is 720kPa and the gradient is 2%, the permeability is 2500m/d and the flow rate is 13 pm/m.
2. The creep test retains more than 60% of the thickness after bearing a load of 1200kPa for 10,000 hours.
3. The carbon black content of the three-rib drainage mesh core is not less than 2%, the density is 0.94g/cm3, the tensile strength is not less than 36.5kN/m, and the melt index is 1.0 g/10min, and the thickness is 7.6mm.
4. The clear pore size of the non-woven geotextile is 0.18mm, the water permeability is 0.26 Sec-1, the permeability is 0.2cm/sec, the puncture strength is 580N, the trapezoidal tear strength is 356N, the holding tensile strength is 900N, and the holding extension strength is 50%, burst strength 2750kPa.
With the development of modern industry, the requirements for environmental cleanliness are getting higher and higher, so the need for a composite drainage network is more urgent. The composite drainage net requires a small drainage force and high drainage efficiency. Generally, the anti-seepage membrane is used as the material of the composite drainage net, and non-woven geotextile is also used. The composite drainage net is arranged in the fiber orientation, the yarn itself is too tight, the warp and weft cross structure is added, and there is a large gap between the yarns. Generally, the fabric structure is required to be tight, but the filtration resistance increases. As for the filter paper, due to the tight organization, small and few voids, a slight increase in the accumulation of filtrated substances will increase the filtration resistance, reduce the filtration efficiency, and at the same time its resistance The creasing ability is poor, which affects its service life. The non-composite drainage net has the advantages of a chaotic arrangement of fibers and no warp and weft crossing. The melt-blown nonwoven fabric has the advantages of fine fibers, fluffy structure, many inter-fiber gaps, small pore size, and good wrinkle resistance. The composite drainage net can be retracted. It has the effect of high filtration efficiency, small filtration resistance, and long service life of the composite drainage net. At the same time, due to the large capacity between fibers, even if a certain amount of filtration material is accumulated, it can still maintain a low filtration resistance. For example, if polypropylene fibers are used, Due to the fine fiber size, large specific surface area, and good chemical corrosion resistance, the composite drainage net is suitable for industrial filter materials. filter paper.
Ⅳ）The functional characteristics of the 3D composite drainage network
1. It is laid between the foundation and the sub-base to drain the accumulated water between the foundation and the sub-base, block the capillary water and combine it into the edge drainage system. This structure shortens the drainage path of the foundation, the drainage time is reduced, and the amount of selected foundation material can be reduced (ie, the material with more fines and lower permeability can be used). Extend the life of the road.
2. Laying a drainage net on the sub-base can prevent the sub-base fines from entering the sub-base (that is, it plays a role in isolation). The total base layer will enter the upper part of the geonet to a limited extent. In this way, the composite geotechnical drainage net also has the potential effect of limiting the lateral movement of the total base, in this way, its effect is like the reinforcement effect of the geogrid. Generally speaking, the tensile strength and rigidity of composite drainage mesh are better than that of many geogrids used for foundation reinforcement, and this restriction will improve the support 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 drainage net is laid under the road surface, instead of a drainable foundation. Drainage nets can collect moisture before it enters the foundation/subbase. Moreover, the bottom end of the drainage net can be wrapped with a layer of film to further prevent moisture from entering the foundation. For rigid road systems, this structure allows the road to be designed with a higher drainage coefficient Cd. Another advantage of this structure is the possibility of more uniform hydration of the concrete (studies on the extent of this advantage are ongoing). Whether for rigid roads or flexible road systems, this structure can extend the service life of the road.
4. In northern climates, laying drainage nets can help reduce the impact of frost heave. If the freezing depth is deep, the geonet can be laid at a shallower position in the sub-base to act as a capillary blockage. It is also often necessary to replace it with a granular subbase that is less prone to frost heave, extending down to freezing depths. The backfill soil that is prone to frost heave can be filled above the drainage net to the ground line. In this case, the system can be connected to a drain outlet so that the water table is at or below this depth. This could limit the development of ice crystals without limiting traffic loads when the ice melts in spring in cold regions.
5. Seams and laps of three-dimensional composite drainage nets:
1. Adjust the direction of the geosynthetic material so that the length direction of the material roll is perpendicular to the road.
Ⅴ）Welding quality requirements of composite drainage mesh:
1. For the double seam inflation length of 30-60mm, the inflation pressure between the double seams reaches 0.15-0.2MPa, and the pressure is maintained for 1-5min, and the pressure does not drop.
2. For a single weld seam and T-shaped joint and repair point, a 50㎝×50㎝ square should be used for vacuum detection, the vacuum pressure is greater than or equal to 0.005MPa, and it is qualified for the 30s, and the soap liquid does not foam.
3. Indoor test. The tensile strength of the weld should be greater than that of the base metal.
4. Quality inspection should be carried out with the progress of construction.
5. Reference basis: “Waterproof Board Application Technology Engineering CTTT/T238-1998”
6. Matters needing attention:
Ⅵ）Note 1. Adjust the direction of the geosynthetic material so that the length direction of the material roll is perpendicular to the road.
2. The composite geotechnical drainage net must be terminated, and the geotextiles on the adjacent geonet cores are overlapped along the material roll.
3. Connect the geonet cores of adjacent geomaterial rolls with white or yellow plastic buckles or polymer tapes to connect the material rolls. Tape every 3 feet along the length of the roll of material.
4. The direction of the overlapped geotextile should be consistent with the direction of the packing. If the geotextile is laid between the foundation/base layer and the sub-base, continuous wedge welding, flat head welding or stitching will be carried out to fix the overlapping geotextile upper layer. If stitched, a flat stitch or general stitch is recommended to achieve the least stitch length.
Ⅶ）Geocomposite drainage network structure and performance
Double-ribbed geotechnical drainage net The double-ribbed drainage geonet is made of high-density polyethylene as raw material, carbon black is added as an anti-ultraviolet aging agent, and the network structure is extruded through a special machine head. Two intersecting ribs form drainage channels with high longitudinal and lateral drainage capacity. The double-ribbed geotechnical drainage net also has high vertical and horizontal tensile strength and can withstand high tensile stress and compressive stress.
Ⅷ）Geocomposite drainage network for landfill
In landfills, geocomposite drainage nets can be used to:
1. Groundwater drainage layer
2. Leak detection layer
3. Leachate collection guide layer
4. Closure gas collection guide layer
5. Collection and drainage of surface water at the closure site
Ⅸ）Leachate drainage layer and leakage detection layer of landfill
To prevent the leakage of the lining system and ensure the safety of the landfill, the leachate drainage system must have reliable drainage performance, discharge the leachate collected by the lining system, and ensure that the saturated head of the lining leachate is less than the thickness of the drainage layer. Traditional natural drainage materials such as sand and gravel are used for leachate collection and drainage in landfills, which will occupy a lot of landfill space. For slope leachate diversion, it will be difficult to stack with sand and gravel. The use of a geocomposite drainage network is not limited by the slope of the slope. Gravel is used as a leachate collection guide layer, which will cause damage to the anti-seepage geomembrane. According to statistics, the laying of gravel on the geomembrane is the biggest cause of damage to the geomembrane, accounting for more than 70% of the total damage.
The three-dimensional geocomposite drainage network has a three-dimensional space three-dimensional guide structure. It is composited with high-permeability geotextiles, which can maintain long-term guide performance under high loads. It is used for the main leachate collection guide layer (LCRS), which can The leachate of the anti-seepage membrane is discharged in time, so that the water head is smaller than the thickness of the geotechnical drainage material, and the leakage of the geomembrane caused by the excessive water head is reduced.
Shandong Dajin people will escort your project and provide you with a high-quality composite drainage network based on the core values of making customers safe, secure, and loving.