What properties of ground are improved by stone column? Discuss the ground improvement technique by stone column with neat sketch stating diameter, depth, spacing and materials of column.

Soil Stabilization is the alteration of soils to enhance their physical properties. Stabilization can increase the shear strength of a soil and control the shrink-swell properties of a soil, thus improving the load bearing capacity of a sub-grade to support pavements and foundations.

Properties of ground improved by stone column are:

• The low bearing capacity of clayed soils and soft cohesive soils are improved.
• The post construction settlement is also reduced.
• The sub soil building embankments are improved.

The following is one of the ground improvement technique by stone column:

Bearing and Ramming Method:

• The float bailer is used to bore the holes of required size.
• Stones are back filled inside the casting after boring is crushed completed.
• The granular fill is compacted by rammer's and the casing is withdrawn at the short pass.
• Adding of additional granular charge and repeating the stages till full length of column.

• Stone Column usually has dia of 0.5 to 0.90 m. They are spaced at about 1.5m to3m.The gravel used for stone column has a size range of 6m to 40m.

• Below is the diagram of Bearing and ramming method: