Below ground walls, such as those which provide for the walls of the basement, must be able to support the weight of a structure resting thereon and to resist lateral forces associated with the surrounding soil and hydrostatic pressure from water in the soil.
Particularly when a basement wall is constructed of masonry block, lateral pressure may cause the wall to deflect inwardly and cracks to appear on the inner surface of the wall as mortar joints yield to a tensile force component. If such deflection continues unabated, the entire wall may buckle and collapse with damage to the supporting structure.
A number of methods of straightening walls experiencing initial stages of deflection employ applying a counterbalancing force on the inner surface of the basement wall by means of cables or a threaded rod passing from a plate on the inner surface of the basement wall through the wall and anchored at a position outside the wall, for example, in a trench. Tightening the cable or threaded rod may then pull the wall back into alignment. A system of this type is taught by U.S. Pat. No. 4,189,891.
In a different approach, U.S. Pat. No. 4,353,194 teaches applying force by means of an ellis jack braced between the floor of the basement and the wall suffering from deflection.