Stone Columns in Civil Construction
Soils comprised of some amount of silt and clay fails to respond towards the deep vibratory compaction. For making improvements with these soils of cohesive nature for constructing heavy buildings, creating stiff reinforcing elements in the mass of the soil becomes important for what the stone column technique comes into context. This technique is also known as the vibro-displacement or vibro-replacement technique. It involves making significant improvement for the ground improvement in the vertical columns formed through the soils. These columns of the compacted aggregate require to be improved so that they can get the capacity of carrying considerable vertical load.
Specialized vibratory probes are used to install the stone columns. They generally vibrate in the horizontal mode. Diameters of the columns can be achieved within 2 to 5 feet on the basis of the conditions and requirements of the soil.
Initially, the vibrator penetrates to the required level of depth through vibration technique and water or air jetting or just through vibration. Then, gravel is added at the tip of the vibrator. Then, the gravel is being pushed into the surrounding soil through progressive raising and re-penetration of the vibrator. The matrix including soil columns depicts an overall mass comprising low compressibility and high shear strength.
If you ask about the degree of improvement, then it would depend upon the characteristics of soil as well as the columnsí» spacing. You can get the stone columns arranged for making them fit for the diverse soil conditions as well as requirements of the design. However, they generally differ from 5 to 10 feet, centrally. Making improvements with the old fill soils comprising of the rubble fills can be regarded as the largest application of the stone columns worldwide.
As the soil column system should essentially be considered as a unit involving shear strength as well as compressibility, the individual columns may often comprised of the capacities of carrying the axial load of 40 tons or more. Generally, the stone columns are used only beneath the foundation of the building during the construction process. Nearly in all types of building construction, stone columns are used. Civil construction projects in the USA include commercial, residential, and industrial buildings, storage tanks, dams, highways, power plants, liquefaction mitigation, landslide corrections, stabilization of cofferdams and other applications are the places where they are mostly used. These columns can be used next to the existing buildings without causing any damages from the vibrations.