Multi-capillary Columns MCC
Geologic profile in the area of oxbow lakes and the coastal area is often shaped so that under the layer of non-cohesive soils (sands) there are weak and non-bearing soils. MCC column technology was designed for such places. This technical method of improvement significantly improves strength and deformation parameters of the ground, combining the advantages of concrete columns, when the core of the column is made at the depth of non-bearing soils and compaction using vibroflotation method, when the column is carried out in a layer of load bearing soil.
MCC Columns are carried out in several following stages:
• Piling section – depending on the characteristic of the ground and surrounding buildings, a vibratory probe is used, that is a vibroflot for vibro compaction or CFA auger, which allows us to obtain the planned depth;
• Concreting – when the device reaches the planned depth, there begins concrete mix injection process in areas of organic or cohesive soils. The load-carrying medium is injected under high pressure through vibroflot nozzles previously attached to the vibroflot. Cementing process in non-bearing soils is accompanied by the compression of soil through injected cement mixture;
• Compaction - sandy soil lying over the organic or cohesive soil layer are compacted with vibroflot with an extra soil gradation improvement.
The application of MCC usually depends on the same geological profile, therefore it is recommended to perform in-depth assessment of geological profile before the decision to apply MCC method is made. This technology can be successfully applied to organic soils (aggregate mud, peats), but also to soft-cohesive soils (loams, dusts) as well as to non-cohesive soils (sands). They are often used as reinforcement for road embankments and other infrastructure facilities, and also have applications under the foundations of different structures (buildings and halls).
Depending on the soil parameters (particularly, lateral resistance of soft soils) and the pressure of concrete mix, concrete columns reach diameters ranging from 0.4-1.2 m, whereas, in non-bearing soil layer they are larger in diameter in proportion to columns in load-bearing soils. MCC columns are arranged on a square or triangular grid, reaching a depth uo to 30 m.