What is geogrid mesh?
Geogrid mesh structure reinforcement material made of high molecular polymer materials (such as polypropylene PP, polyester PET or high-density polyethylene HDPE). It has high tensile strength, low elongation, strong chemical stability, anti-ultraviolet aging and other properties. It is mainly used to improve soil structure and increase soil shear strength and bearing capacity.
Main types of geogrids
Geogrids can be divided into the following categories according to their structural form and stretching direction:
It is stretched in only one direction (usually longitudinally), with high longitudinal tensile strength and low elongation. It is often used in structures such as retaining walls and embankment slopes that require longitudinal force.
It is stretched in both longitudinal and transverse directions to form a regular rectangular grid, with relatively balanced longitudinal and transverse strength. It is suitable for projects such as road and railway subgrade reinforcement and foundation load distribution.
It is a high-temperature resistant grid formed by alkali-free glass fiber coated with resin, with excellent tensile properties and strong aging resistance, and is particularly suitable for asphalt pavement reinforcement and crack prevention.
It is formed by a special process to form a triaxial equal strength structure, with tensile strength evenly distributed in multiple directions, which is suitable for reinforcement needs under complex stress conditions.
Main functions of geogrids
The core function of geogrids is to enhance and stabilize soil structure, which is mainly reflected in the following aspects:
Enhance bearing capacity: disperse foundation load, prevent settlement and slip;
Control soil deformation: inhibit lateral displacement, stabilize slope structure;
Improve construction efficiency: reduce foundation treatment work and reduce construction cost;
Anti-fatigue and anti-cracking: prevent reflective cracks in road projects;
Eco-friendly: when used on vegetation slopes, it can work with soil to facilitate vegetation growth.
Working principle of geogrid
Interlocking effect between grid structure and soil
The most notable feature of geogrid is its regular open grid structure. These grid holes are usually rectangular or triangular. By laying in loose soil, the grid ribs can penetrate into the soil particles. When the filler is compacted, the soil particles are "embedded" in the grid, forming a mechanical locking effect (Interlocking).
This structural interlocking effect has two key meanings:
Improving the overall stability of the soil: After the filler and the grid form a composite, the overall shear strength is significantly improved, which can better resist lateral displacement.
Forming friction resistance transmission: There is interface friction between the grid and the soil, which can disperse the external load through the grid to a wider range of soil layers, reducing local stress concentration.
Force transfer and reinforcement effect
Under load (such as vehicle pressure, foundation deadweight, slope thrust, etc.), the soil is prone to shear deformation, settlement or slippage. At this time, the geogrid, as a reinforcement material, bears part of the tensile stress, converting the "shear stress" in the soil into "tensile stress", thereby delaying or inhibiting the occurrence of damage.
Its specific force process is as follows:
The load is transferred to the filler → the soil tends to deform → the grid bears tensile force → hinders deformation → the structure is stable.
Therefore, the working mechanism of the geogrid can be summarized as: changing the force mode of the soil, dispersing the load through tensile action, and building a more stable structural system.
Disperse stress and prevent damage
In addition to enhancing the integrity of the structure, geogrids also have good stress dispersion capabilities. When there is a local weak layer or settlement trend in the foundation or slope, the grid can effectively diffuse the stress to the surrounding soil, forming an "isobaric curve" to avoid local settlement causing global structural instability.
Preventing road surface reflection cracks: Especially using fiberglass grids in asphalt pavement can alleviate the development of thermal shrinkage cracks;
Control the development of slope sliding surfaces: By setting up multiple layers of geogrids, the distance between sliding surfaces is increased and the safety factor is improved;
Limiting fill deformation: If used in dams or embankment slopes, it can effectively reduce lateral deformation caused by loads.
Comparison Between Geogrid Mesh and Other Geosynthetics
Geogrid vs. Geotextile
Feature | Geogrid Mesh | Geotextile (Woven / Nonwoven) |
---|---|---|
Structure | Stiff or semi-rigid grid | Flexible fabric (woven or nonwoven) |
Main Function | Reinforcement and load distribution | Separation, filtration, drainage, some reinforcement |
Tensile Strength | High, especially in a specific direction | Moderate, evenly distributed |
Deformation Control | Excellent, restricts lateral displacement | Good flexibility, less structural control |
Typical Applications | Base reinforcement, retaining walls, slopes | Soil separation, filtration under roads, drainage layers |
Interlocking Effect | Strong interlock with aggregate | No mechanical interlocking, relies on friction |
Geogrid vs. Geomembrane
Feature | Geogrid Mesh | Geomembrane (HDPE, LLDPE) |
---|---|---|
Structure | Open grid mesh | Continuous, impermeable sheet |
Function | Reinforcement and stabilization | Seepage and barrier control |
Typical Use | Roads, slopes, embankments | Landfills, ponds, reservoirs |
Physical Behavior | Load-bearing, tensile reinforcement | Waterproofing, gas containment |
Combination Use | Often layered over/under membranes | Needs reinforcement in structural areas |
Geogrid vs. GCL (Geosynthetic Clay Liner)
Feature | Geogrid Mesh | GCL (Bentonite + Geotextile/Membrane) |
---|---|---|
Structure | Polymer mesh structure | Bentonite clay layer sandwiched in geotextiles |
Function | Reinforcement, stress distribution | Self-sealing, impermeable liner |
Working Principle | Load transfer, tensile reinforcement | Bentonite swelling to block fluid |
Installation | Easy, needs tensioning | Fast, conforms to terrain |
Applications | Slopes, roads, foundations | Landfill liners, ponds, canals |
Frequently Asked Questions
1. In what types of projects is geogrid suitable for use?
Answer: Geogrids are widely used in projects such as highways, railways, airport runways, dams, slope reinforcement, port terminals, retaining walls, landfills, parking lots, etc. It is especially suitable for projects such as soft foundation reinforcement, slope stabilization and structural enhancement, which can effectively extend the service life of the project and improve the bearing capacity.
2. How much tension or load can geogrid withstand?
Answer: Different types of geogrids have different tensile strengths, generally ranging from 20kN/m to 400kN/m. Uniaxial grids usually have particularly high tensile strength in one direction, while biaxial grids provide balanced support in two directions. The specific value should be selected according to the project load requirements.
3. Can geogrids be laid directly on untreated soft soil foundations?
Answer: It is not recommended to lay directly on untreated extremely soft foundations. Usually, preliminary foundation treatment is required, such as replacement, compaction, laying of isolation layer, etc., and then combined with geogrid construction to achieve the best reinforcement effect. In some high-humidity or flooded areas, it can also be used in combination with geotextile and crushed stone layer.
4. How long is the service life of geogrid?
Answer: Geogrid made of high-quality polymer materials (such as HDPE, PP, PET) has good acid and alkali resistance, corrosion resistance, and aging resistance. It can usually be used underground for more than 30 years, and products exposed to ultraviolet rays need to be surface stabilized. The lifespan is different under different working conditions. It is recommended to consult the manufacturer and check the product warranty instructions.