The quality of a structure, whether it is a house, apartment building, or commercial building, is inextricably tied to its foundation. If the structure is not built on a proper foundation, the rest of the structure, even if properly constructed, is likely to show defects over time. When foundations are constructed directly on ground soils, it often creates an unstable environment for the foundation. In addition, if these soils are active or expansive, the environment may be especially problematic. For example, in regions where the soil has a high percentage of active clay, expansion and contraction of the clay subjects the foundations to significant loads (e.g., forces) and potential movement.
Structures built on soils in certain regions may have had their slab foundations and walls displaced and damaged (e.g., cracked foundations and walls) as a result of differential expansion and/or contraction of the soil. Over time, engineers have developed systems and methods for designing foundations in an attempt to minimize damage due to soil movement. Some of these systems and methods include isolating heavy slab foundations from the active soils by suspending the slab above the ground using structural supports (e.g., helical piers, drilled shaft piers, pressed concrete or steel pilings, spread footings, natural rock, etc.) and lifting assemblies (e.g., lifting bolts, hydraulic jacks, air-inflatable jacks, electrical scissor jacks, etc.). For example, U.S. Pat. No. 7,823,341, HEIGHT-ADJUST ABLE, STRUCTURALLY SUSPENDED SLABS FOR A STRUCTURAL FOUNDATION, issued on Nov. 2, 2010, which is incorporated by reference herein, discloses a method of lifting a slab foundation using structural supports and lifting assemblies. The installation of supports and lifts to raise the slab foundation creates a protective void between the soil and the slab foundation, such as may permit the vertical expansion of the soil without subjecting the slab foundation to varying forces associated with the dynamic nature of soil.
Many of the existing systems and methods for providing a slab foundation suspended over the ground surface require the foundation to be formed in the final suspended position, and thus often require relatively expensive concrete forming materials (e.g., void material, such as waterproofed honeycombed box structures, sacrificed in the area between the ground surface and a poured concrete slab foundation) and may prevent the typically more labor efficient foundation construction techniques used in forming slab foundations on the ground surface. Existing systems and methods for lifting heavy slab foundations after their being formed on the ground surface to isolate the foundation from active soils are often relatively costly with respect to the materials consumed by the process (e.g., the components, such as lifting mechanisms and associated components, that remain to hold the foundation in its lifted position) and labor intensive to implement (e.g., requiring an appreciable number of workers to manually manipulate tens to over one hundred lifting mechanisms distributed throughout a slab foundation).
USPTO Backgrounds
USPTO Backgrounds