In landscape design, architecture and construction in general, today, composites and synthetic materials are widely used. They organically enter both natural and artificial structures, performing the tasks of strengthening and correcting various forms. One of the most common materials of this type can be called a geogrid to strengthen slopes on steep slopes.
What is a geogrid?
Until recently, engineering tools for solving the problems of isolation or strengthening of open ground were mainly limited to variations of geotextiles. At least, this was the situation in the areas of mass service for plots for various purposes. Improving the design of geosynthetics has significantly expanded the range of engineering tasks of this type, which has formed a demand for the creation of an ergonomic formation with a flexible but strong structure. This is how it is possible to imagine a geogrid for strengthening slopes, which performs the function of external reinforcement of soils, gravel and sand surfaces. This type of synthetic lattice is made of plastic tapes that are fastened together by welding, forming a cellular structure. During operation after laying, this synthetics creates erosion protection of slopes and embankments in conditions of high slope steepness. Such tasks are relevant in the construction of roads, bridges, railway tracks, crossings through highways, etc.
Volumetric geogrids
The most popular type of geogrid, which is caused by the three-dimensional structure of its cells. The area of such a coating, depending on the form of release in briquettes, varies from 10 to 25 m 2 . As for the material of manufacture, the volumetric geogrid for reinforcing slopes is made from the following raw materials:
- Polymers Inexpensive and practical synthetics, which allows you to produce the product in small sizes, but with high strength properties. Both continuous and perforated tapes are made of polymers, which makes it possible to provide the drainage function.
- Textile canvas. The optimal solution for zoning layers, reducing the negative effects of frost heaving and reinforcing slopes.
- Concrete. A special kind of geogrid, due to which a general framework for reinforcing the problem area is formed. As part of the concrete structure, the above-mentioned geosynthetics can be used.
Flat geogrids
Also a latticed variation of geotextiles, but with flat cells of a rectangular or square shape. As such, the reinforcement of slopes with this material is rarely performed, but with its help, without increasing the height of the landscape, the following tasks can be more effectively realized:
- Fixation of structural layers.
- Uniform distribution over the area of dynamic and static loads. In other words, indirect reinforcement of slopes by a geogrid with a flat structure is realized.
- Increase the bearing capacity of the base.
- Reduce the risk of rutting and road crashes.
- Retention of crushed stone and gravel on the necessary technological layer without its departure into the soil.
Flat geogrid is more often used where, in principle, it is not justified or technically impossible to use volumetric reinforcing cells. This can be the device of access roads, laying of tracks, installation of heavy floor coverings, etc.
General technology for reinforcing slopes with a geogrid
Directly for reinforcing complex landscape areas along the ground, the following geogrid device technology is used:
- Measurements and planning of the target site. To do this, use measuring equipment, as well as manual devices like levels and levels.
- In the case of loose slopes, compaction is mandatory. This problem is solved by manual cutters or a vibrating plate.
- The material is rolled out according to the marked and prepared area. As the instruction on reinforcing slopes with geogrids notes, regardless of the angle of the slope, the upper part of the coating should capture a horizontal plane of at least 50 cm.
- The material is fixed with special fasteners in accordance with the tension force that is optimal for the particular case.
- A control measurement is carried out and the physical state of the stacked geogrid is evaluated.
- The honeycomb structure is filled with bulk material.
Used fasteners
Geogrid laying can be performed both in single and in multiple order. That is, it is not necessary for one site to strive to be limited to one module - the possibilities for coupling and the formation of strong joints eliminate the problems of the destruction of a single reinforcing fabric. Another thing is that each module must be fixed at the edges in a separate order, regardless of whether an adjacent module is paired with it. From this we should proceed, determining the number of fasteners.
The installation of geogrids to strengthen the slopes can be carried out by various technical means, but more often they use pins, plastic or metal anchors, as well as brackets made of steel reinforcement. Mounting is carried out both along the edges and along the central axis. Moreover, it is not recommended to place the latches in a straight line. The greatest reinforcing effect is provided by the configuration of the arrangement of fasteners in a checkerboard pattern. To fasten the individual modules together, an air stapler is additionally used. According to average estimates, about 2,000 fasteners are spent on fixing 1 km 2 of a continuous geogrid.
What material to use as a filler?
After installing the geocarkas, you can begin to fill its honeycombs with bulk material. In this capacity, ordinary soil and sand-gravel mixtures can also act. The choice is determined by the requirements for strengthening and the appearance of the coating. And if in the case of road embankments, reinforcing slopes with a geogrid does not focus on decorative tasks at all and can be supplemented with concrete supports, then in landscape design, on the contrary, a water supply infrastructure for irrigation of vegetation is created. In this case, filling is carried out using fruitful soil or a sand-peat mixture, after which seeds of ornamental plants or a lawn are planted.
Tips for Strengthening Smooth Slopes
The simplest type of terrain with a slope, for which two reinforcement schemes can be applied:
- The technique is suitable for loosely bonded and clay soils. A geogrid is laid along the entire slope to strengthen the slope with subsequent fixation. In the upper part of the boundary of the modules should go under the stone emphasis, which will prevent the erosion of the slope during heavy rainfall.
- From the top and bottom, the coverage of the geoframe with aggregate should completely cover the slope. At the same time, a tight ditch is organized in the lower region, forwarding the sewage to the nearest catchment or sewer.
Technique for strengthening flooded slopes
Regularly flooded slopes are subject to both their own erosion and destruction, as well as deformation of the external reinforcing layers. In this regard, additional measures should be taken to protect the geo-frame. Firstly, only a volumetric grate should be used, and secondly, an effective drainage material should be used as a filler - for example, granite crushed stone with a diameter of 20-40 mm. If an intensive flow of water is expected, then it is advisable to fill the surface of the grate with concrete mortar. A protective layer with reverse filtration based on the same geotextile is laid under the reinforcing layer itself.
Conclusion
Against the background of the active process of urbanization and the rapid pace of urban life, interest in natural objects with all the attributes of landscape design is growing. Along with this, there is a need to solve problems associated with the protection of the natural soil massif from erosion by water and erosion. To prevent the negative consequences of such phenomena on the slopes, geogrids are used. This is a simple and effective solution, which is quite attractive for financial expenses. For example, the Geospan geogrid for strengthening slopes in the basic version costs about 150 rubles / m 2 . This is a structure with a volumetric honeycomb structure based on polyethylene tapes, the cells of which can be filled with crushed stone, soil and sand. There are also more functional modifications, including those designed for operation in a wide temperature range from -60 to 70 ° C.