Ground improvement refers to the technique that improves the engineering properties of the soil mass treated. Usually, the properties that are modified are shear strength, stiffness, and permeability. Ground improvement has developed into a sophisticated tool to support foundations for a wide variety of structures.
Some of the methods for ground improvement technique are as follows;
- Vibro compaction :- This method is rapid densification technique which could be used effectively in saturated cohesive less soil(sand). In such loose deposits, vibration or shock waves caused localized spontaneous liquefaction followed by densification and settlement. The load due to shock is temporarily transferred to the liquid and the soil particles take a much denser pattern aided by the soil particles. Even dry soils due to shock and vibration, the particle moves from the original position and take a more compact pattern. Once the particles are loosened due to the shock, the effectiveness of this method decreases with the increase in the percentage of fines in the soil, more than 20% of silt or 5% of clay may reduce the effectiveness of this method.
- Vibro-displacement compaction:- It is also known as Vibro-floatation which is a technique in which the density of granular soils or cohesive fewer soils is increased by the insertion of a heavy vibrating poker to the desired depth.
- Stone column technique :- It is also called as granular columns or granular piles. This technique is also known as Vibro replacement. In this technique, a dense aggregate column is constructed by means of a crane-suspended downhole vibrator. The installation of a stone column improves ground by reducing soil settlement.
- Dynamic compaction of soil:- It is a technique in which a drop weight is used to densify the soils and fill materials. The drop weight is typically made of steel and is lifted by a crane and repeatedly dropped on to the ground surface. The vibrations that are resulted from the repeated drops are transmitted below the surfaces which improve the soil at depth. These drop locations are generally located on a grid pattern.
We cannot determine the best method. According to the soil, the methods to be applied is selected.