ABSTRACT
The primary causes include the necessity of increasing the load on footings, destruction of masonry or deterioration of its watertightness, worsening of foundation stability and increase in soil deformability, or continuous growth of unacceptable displacements. Hence, if loading on footing increases, the foundation soil can resist the increased load in many cases, which cannot however be said about the footing itself. The stress condition of foundation soil can also vary, so that the stability conditions of footings and the part of foundation can change. Deformability of foundation soil can increase upon mechanical or chemical suffosion, intensive softening of organic matter in soil, additional moistening of subsiding loess, and thawing of permafrost soil. The conditions of pressure transfer vary if a foot is enlarged to one or two sides, or if its depth of founding is changed and the footing is reconstructed as a piled one.
