Geoglage is a kind of three-dimensional grid structure material which adopts high strength polyethylene sheet and is connected by ultrasonic welding and so on. It is a kind of special geosynthetic material. In rock engineering, it is combined with soil, sand, stone and other fillers to form different apparent cohesion, different reinforcement strength and different depth of cushion. These cushion layers can be placed in the required position according to the requirements of the project to strengthen the roadbed, slope protection, construction of retaining walls, etc. Its biggest feature is that it can complete a variety of difficult problems that are difficult to be dealt with by conventional methods in rock engineering, such as bridge head jumping, soft foundation subsidence, grouting, collapse and so on. It has the characteristics of light material, wear resistance, aging resistance, chemical corrosion resistance, wide applicable temperature range, high tensile strength, rigidity, toughness, strong impact resistance, relatively stable size, convenient transportation and so on. In the construction, the connection is simple and the construction method is simple, thus simplifying the construction process and improving the construction speed; And can be used repeatedly.
The basic principles of geogrid
The reason why the geoglage has excellent effect and has been concerned by the engineering field should also start from its basic principle. In the foreign literature describing its principle, it is called “a honeycomb three-dimensional limitation system that can significantly improve the performance of ordinary filling materials in load-bearing and insect-erosion control applications in a large range.” Its key principle is three-dimensional restriction. Everyone knows that when a car drives in the desert, it makes two deep ruts, the part that is pressed down deeply, and the sides of the ruts rise high. If the vehicle behind continues to follow the ruts, the sunken part will sink further, and the hump will rise further, until the hump ruts against the chassis of the car, and the sunk ruts have buried most of the wheels, and can not move forward. The reason for this is that when the external load acts on the foundation surface, according to Prandtl theory and Taylor theory, under the action of concentrated load, the active zone 1 is compressed and sinks, and the force is decomposed to both sides and transmitted to the transition zone 2, and the transition zone 2 is transmitted to the passive zone 3, and the passive zone will be deformed and uplifted without restriction. That is to say, once the load acts on the subgrade, the active area of the formation will be formed under the load, and it will squeeze through the transition area, so that the passive area will bulge. In other words, the load bearing capacity of the foundation is determined by the shear force along the slip line and the forces in the three regions of active, transitional and passive movement. Not only can the real process of the above principle be very clearly experienced on the sand base, but such a template can also be found on the soft foundation highway, but the rate of formation is slower than the change on the sand. Even better roadbed materials can not avoid its lateral movement. The general highway subgrade is several meters higher than the ground, and it is not easy to absorb water and turn pulp, but long-term settlement still exists. Some of the reasons are rainwater infiltration, material loss and base subsidence. The lateral displacement of materials to both sides of the subgrade section is undeniably another very important reason under the long-term rolling and vibration force of the wheel load. Taking highways at all levels in our province as an example, there are obvious feelings on the main carriageway of the road that the road has been pressed out of an “S” trench belt. Some expressways are no exception, and the turbulence of the car driving on the carriageway is obviously stronger than the feeling of driving on the overtaking belt, especially in the road and bridge connection section (commonly known as “bridge jump”). This kind of ditch subgrade settlement is the typical transverse slip of subgrade materials.