CAUSES OF FAILURE OF FOUNDATIONS AND REMEDIAL MEASURES.

Rain and the sun are the main agents with the change of the seasons and may develop horizontal movement of the earth adjoining the structure. This is effective in the case of clayey soils and black cotton soils Such soils become soft and swell when wet loosing their bearing power considerably and shrink and crack when dry. Rise and fall of the sub soil water level, increasing or decreasing the moisture content which is especially effective when the underground water is near the surface, or in damp soils overlying a layer of porous materials like sand ;the sub -soil shrinks or expands causing cracks. Soakage of the rain water in the sub soil also produces a number of changes as mentioned above and some times bring in salts which react chemically on the lime and bricks in the foundation and cause them to disintegrate. Underground open drains should be provided to drain out the excess water when the sub soil water level rises. Deep foundations with sides (of the trenches) well filled and consolidated with good slope away from the walls given to the ground surface will help against rains. A plinth protection of about 60 to 90 cm width with concrete will give further protection. Cement or hydraulic lime should be used with stones up to the plinth level in such damp locations.