It is a ground improvement technique used to improve the load bearing capacity and reduce the settlement of the soil. It is also called as granular columns or granular piles. This technique is also known as vibro replacement. In this technique dense aggregate column (stone columns) is constructed by means of a crane-suspended downhole vibrator.
Installation of stone column improves ground by reducing soil settlement. Due to its higher modulus of elasticity than that of soil, it absorbs more load than soil and reduces overall settlement.
Since applied load distributes in between soil and stone column in the ratio of their stiffness, the load carrying capacity of soil also increases.
Stone aggregates are used to fill stone column. Water can easily pass into the stone column. So, stone column helps in excess pore water pressure mitigation and accelerates the consolidation process.