Researchers from South Ural State University have developed a unique technology for deep soil compaction that could radically improve the condition of our roads. This new development aims to address one of the main problems the Russian road system is facing: rapid deterioration of road surfaces and frequent repairs.
A poorly prepared subgrade begins to subside under load, and the asphalt covering first deforms and then collapses. Waves, ruts, deep subsidence, and localized potholes appear. Currently, soil preparation before road construction is carried out using heavy equipment: rollers that repeatedly pass over the site, "ironing" the earth. Because rollers cannot compact the subgrade to a sufficient depth, compaction is carried out layer by layer with additional backfill. The Chelyabinsk scientists have proposed an original device designed for installation on excavators. Like a drill, it penetrates the soil and compacts it to a depth of up to three meters, ensuring high road subgrade strength.
"The design consists of a cone-shaped metal body and a special planetary mechanism, including rollers and bearings, which generate additional pressure and vibration. Rotation is driven by a hydraulic motor," explains Marat Asfandiyarov, Associate Professor of the SUSU Department of Hydraulics and Hydropneumatic Systems. "The operating principle is as follows: the excavator lowers the device into a pre-prepared area, the cone begins to rotate, "wedging" the soil and compacting it in all directions across the entire depth of the working element. This method allows for significant compaction depths (up to three meters or more), which is impossible to achieve with standard roller compaction technologies."
The researchers conducted a series of experiments on various soils, including sandy loams, sands, and clays. It is important to note that dry, loose materials like sand exhibit low compaction capacity. However, wetting significantly improves the situation: the compaction coefficient increases from 0.8 to almost 0.99. This means that the use of wetting devices (such as nozzles) can significantly increase the effectiveness of the procedure.
Experiments have confirmed that the new compaction method can ensure a long service life for roads − up to 25 years without major repairs. The new mechanism is also applicable to the construction of hydraulic structures, embankment reinforcement, and building foundations of any scale.
"Another advantage of this technology is the uniform compaction across the entire depth, which allows us to use our invention for the construction of new and the reinforcement of existing hydraulic structures, such as dams, weirs, embankments, and other engineering structures," comments Kirill Gundarev, engineer at the SUSU Department of Hydraulics and Hydropneumatic Systems. "A couple of years ago, heavy rainfall caused serious problems in our country, including dam failures and subsequent flooding of populated areas. The cause was the insufficient strength of the protective structures. Our method allows us to create not only a dense supporting foundation, but also a strong retaining frame. To achieve this, we simply fill the craters formed by compaction with concrete. This ensures the structure will withstand any extreme natural loads."
A unique technology developed by the Chelyabinsk scientists will also make it possible to build particularly strong foundations for residential buildings. The compaction unit itself is mobile, requires no utility lines, and can replace several types of construction equipment. All materials and components are Russian-made.
The scientists have been working on this new technology for seven years. Similar solutions currently do not exist either in Russia, or anywhere else. A patent for the invention has been obtained. The researchers are ready to begin large-scale testing with the participation of industrial partners.