methods of improving bearing capacity of soil

1. Increasing the depth of the footing is the simplest method of improve the bearing capacity of
soil, This method is restricted to sites where the sub-soil water level is much below and deep
excavations do not increase the cost of foundations disproportionately.
2. Drainage is a well known method to improve the bearing capacity of certain soils . Drains (with
open joints) are laid in trenches just at the footing base. The sub-soil water thus collected is
drained out through a system of pipe drains provided outside the external walls of the building.
3. By blending granular material, like sand, gravel or crushed stone into the natural soil by
ramming. The layer of soil thus formed is much stronger and is of improved bearing capacity.
4. By confining the soil in an enclosed area with the help of sheet piles. This method is used with
advantage in shallow foundations in sandy soils.
5. By driving sand piles. This method is based on the principle of reducing the void volume of the
natural soil. Holes are made in the soft soil with the help of wooden piles or other means and
then sand is filled in the holes and rammed. These are called sand piles. Bearing capacity of soft
soil can be appreciably improved by driving sand piles at close spacing.