USING OF BORING AND MIXING TECHNOLOGY TO STRENGTHEN SUBFOUNDATION OF THE FACILITIES POLTAVA MINING AND PROCESSING PLANT

The pile bases, which cut all weak thickness and lean in suitable soil, often apply at construction in the engineering-geological conditions presented by soil with special characteristics (for example, loessial collapsible soil, water-saturated clay, peat, il, dusty sand, etc.). The device of the bases on previously strengthened basis is also quite popular in such conditions. Today in many countries of the world actively apply boring&mixing and jet technology of cementation of soil. In Ukraine the most widespread is the boring&mixing technology of strengthening of soil. One of the main advantages of use of this technology is that soil-cement elements can suit lower than a level of ground waters. For production the soil-cement elements use the boring machine, a mixer to solution and the pump for solution. The Poltava mining and processing plant carries out a full production cycle ? from production of crude ore before production of iron ore pellets ? the prepared raw materials for steel works. Ore processing, production of a concentrate, crushed stone and pellets is carried out on the overworking complex consisting of crushing, concentrating factory and shop on production of pellets. The geological structure of a platform of building is presented by alluvial sand, from dusty to average fineness which from a surface up to the depth of 0,6 ? 3,1 m are blocked by a bulk layer (sand small, with inclusion of construction garbage, crushed stone, fragments of solid rocks), and up to the depth of 5,0 ? 5,7 m ? small alluvial sand. Within a platform treat adverse engineering-geological processes: flooding of the territory; dynamic impact on sandy soil from the movement of railway transport, works of the production equipment, and also explosive works on career that can lead to their dynamic depression; manifestation of a mechanical suffosion at operation of the water bearing communications. The shallow foundations on the strengthened basis are accepted as the most economic in these engineering-geological conditions. Value of necessary settlement resistance of the strengthened basis of R=350 ? 450 kPas was provided by regulation of a step of elements from 1х1 m to 1,5х1,5 m. For uniform distribution of loading from the base on the strengthened massif between a sole of the bases and the top sawn-off shotgun of elements is arranged a crushed-stone pillow 400 mm thick. Thus, positive experience of application the vertical soil-cement elements for strengthening of the bases of objects of mining and processing works is presented in article. Thanks to boring&mixing technology it was possible in adverse engineering-geological conditions to execute the shallow foundations instead of expensive pile bases.