Geogrid has a role in suppressing rutting:
Let's take a look at how ruts are formed. Due to the rheological properties of asphalt concrete at high temperature, the asphalt road surface in summer becomes soft and sticky; under the action of vehicle load, the stressed area is dented, and the asphalt surface layer cannot be completely restored to the pre-load state after the vehicle load is removed. Under the action of repeated rolling by the vehicle, the plastic deformation accumulates continuously, and finally a rut is formed.
Therefore, we know that asphalt concrete itself has rheological properties at high temperature. When it is under load, even under super load, there is no mechanism in the surface layer that can inhibit the movement of aggregates in asphalt concrete, resulting in asphalt surface layer , eventually forming a rut. So if there is an inhibitory force that stops the movement of the asphalt concrete, will the rutting be improved?
If we use polyester geogrid in the asphalt overlay, it can reduce the rutting phenomenon in the road very well. Because the geogrid has the characteristics of high tensile strength, low elongation and high temperature resistance, and it has good compatibility with asphalt mixture, when the aggregate in the asphalt concrete penetrates between the grids, a composite mechanical interlock is formed. The system will limit the aggregate movement and increase the lateral restraint in the asphalt surface layer, and the various parts of the asphalt surface layer will restrain each other, prevent the asphalt surface layer from moving, and finally play a role in resisting rutting.
The coordination relationship between the upper and lower layers of the geogrid, the tensile strength of the upper and lower layers of the two-layer geogrid is different, or the deformation is inconsistent. In general, the tensile strengths of the upper and lower geogrids are not fully developed at the same time with the increase of the embankment filling height and the differential settlement of the embankment cross-section. In short, there is some kind of coordination between the two.
As far as the same layer of geogrid is concerned, the effect of geogrids in different parts is significantly different with different filling heights. It is related to the change of stress distribution in embankment under soil height. The geogrid significantly changes the stress field of the soft soil foundation, and homogenizes the foundation stress through its unique net pocket effect, thereby improving the deformation characteristics and stress characteristics of the foundation.
The role of geogrids is very extensive. We understand the application of node anchoring of geogrids. Geogrids are embedded in soil, gravel and asphalt layers. The load bearing and node anchoring of geogrids are mainly It is realized through its own nodes or ribs. The geogrid is affected and acted by the relevant media, and a large stress can be obtained only through a small displacement, rather than relying only on the relationship between the geogrid and the medium. The frictional force is used to provide the required stress, and the geogrid is similar to the interaction between the mesh and the relevant medium to obtain greater force requirements.
This geogrid constitutes an efficient stress transfer and good response system, which effectively exerts the super reinforcement effect of the geogrid itself, and can minimize the length of the anchor ingot.
The interfacial characteristics of the geogrid and soil directly affect the safety and stability of the reinforced earth retaining wall. Therefore, the interface technical index between geogrid and filler is very important in the design of reinforced earth retaining wall. In this paper, on the basis of analyzing the influencing factors of the interfacial friction characteristics of the geogrid from the aspects of test method, loading method, boundary effect and size effect of the side wall of the test box, filler thickness, compaction and reinforcement holding conditions, the geogrid interface friction characteristics are analyzed. Pull-out and direct-shear tests of gratings in gravel and cohesive soils.
The test results show that the shear strength of the contact surface between the steel-plastic geogrid and the sand-gravel material is high, while the shear strength of the contact surface with the clay is very low. The geogrid and gravel material are used as fillers. The direct shear friction test is not suitable for determining the shear strength of the contact surface of the geogrid. The test results have important reference value for the design of geogrid-reinforced earth retaining wall.
As a tie bar, the friction characteristics of the geogrid and the filler have an important influence on the properties of the reinforced soil structure. In this paper, on the basis of analyzing the influencing factors of the interfacial friction characteristics of the geogrid, the pull-out test and the direct shear test of the geogrid in sand-gravel and cohesive soil are carried out. The test results can provide important reference value for the design of geogrid-reinforced earth retaining wall.
Analysis of factors affecting the friction characteristics of geogrid interface At present, various test equipment and test methods for testing the direct shear and pull-out friction characteristics of the interface between geogrid and filler are not unified, and the factors considered by the test equipment are also different. In engineering applications, the friction characteristics of tie bars and fillers are generally determined by indoor friction (shear) tests, pull-out tests or field full-scale tests.