SAFETY OF EXISTING STRUCTURES AND CAUSES OF FAILURE OF THE FOUNDATIONS

Causes of failure of foundations may take affect because of unequal settlement of the sub -soil , so masonry should be raised uniformly over the whole area and unequal distribution of the weight of the structure on the foundation due to eccentricity of load it may abrupt change in magnitude of load or variation in ground support. Rain and sun are the main agents with the change of the seasons. 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 soil. Transpiration of trees and shrubs are superimposed on the seasonal conditions and the root system of isolated generally spread to a radius of greater than the height of the tree which may affect adverse. For overcoming the damaging effects of shrinkage the foundations should be taken sufficiently deep and a depth of 90 cm is necessary to avoid cracking in normal bricks from the growing trees. Safety of the existing structures may be affected by (1) Excavation in the immediate vicinity which may cause a reduction in support to the structure. (2) Mining or tunneling operations in the neighborhood (3) Adjacent structures which may impose additional loads on the foundation strata or additional stresses in earth work and supporting structures. (4) Vibrations and group movements resulting from the traffic, piling or explosions in the immediate Vicinity. (5) Shrinkage of clay soils due to weather, transpiration of plants (6) Lowering of the ground water level by pumping from wells may cause settlement of the ground surface over a wide area. (7) A rise in the ground water level may cause movement of the foundation strata:-- Er Fateh chand Guleria, RTI welfare Association registered number HPCD, 3552 , Bilaspur Himachal pradesh phone number, 9459334377