STRENGTHENING THE BASE WAREHOUSE CAPACITY 26,000 TONS OF OIL IN MARIUPO

Building area of the oil storage locates in the coastal zone of the Azov Sea. It is composed from heterogeneous soils, which includes liquid mud. Water saturation of the building area leads to the high level seismic magnitude ? 7 points, which are additionally complicated building conditions. Oil storage complex consists of five tanks for oil storage with capacity of 6,500 tons. Tanks are thin-walled steel containers, which has cylinder form. All the tanks locate on the same reinforced-concrete slab, also protective concrete wall 6,4 m height have been constructed. Features of the structures, which are being designed and complicated soil conditions are caused necessity use of pile foundations or artificial bases. Design load on the pile, which are cutting weak layers of soil base, is about 600-800 kN on each one. Such load value is proved by dependence that the use of piles with a higher design load will cause a significant increase of the transverse forces in plate grillage. It causes increasing of the grillage thickness, weight, concrete and reinforcement consumption. Follow foundation solutions have been considered: 1) monolithic concrete bored 14 m piles, which are manufactured under protection of the steel pipe with 600 mm diameter. Such manufacturing method provides pile high quality and reliability; also process occurs without dynamic action on the border buildings; 2) precast concrete prismatic piles with section 400x400 mm, length 14 m. Hydraulic hammers are possibly to use, it is significant reduce dynamic load of the surrounding buildings; 3) root monolithic concrete piles with 600 mm diameter and 14 m length. Such piles are performed with replacement of a drill soil by concrete mixture; it is supplied to the hole through the auger under pressure. Performing of the root monolithic concrete piles in the water saturated soils is conducted without use of protecting pipe or clay mixture. It allows reducing the cost and accelerating process of piles arranging compared to the bored method with help of protection of the steel pipe. But presence of weak layers in the soil base can lead to increased concrete consumption, which increase building cost. Also there is presence problem of the reinforcing cage immersing in piles fresh concrete. If we take root piles production cost by 1.0, so relative cost of bored will be 4,8. Precast concrete prismatic piles with section 400x400 mm, length 14 m has cost 1,25. 4) Concrete slab with soil base reinforcement by soil-cement elements by drilling-mixing technology is another foundation variant. So, weak soil thickness is cut by soil-cement elements with 400 mm diameter and 7 m length, distance between its centers are 1,5 m. Relative cost of the last variant is 0,48 of the root variant.