Method and apparatus for lifting, leveling, amd underpinning a building foundation

Abstract

A method and apparatus for leveling a building foundation including excavating a cavity below the portion of the foundation to be raised at regular intervals and using and an oversized screw anchor driven under the foundation at approximately 15 degrees relative to the foundation edge at each of the excavated cavities, the anchor having relatively large helical screw flighting or auger plate to insure support at relatively shallow depths. Each excavated cavity is provided with a bed of dry cement mix. The method includes the steps of installing an anchor jack-plate upon said bed of dry cement the jack plate having a collar and gusset attached thereto slidable upon the screw anchor shaft, providing a pair of hydraulic jacks atop the anchor plate, taking a portion of the foundation load on each jack, thereby directing the load at each jack in axial alignment with the helical screw anchor flighting or auger plate, setting the cement by wetting and welding the collar of the anchor jack-plate to the screw anchor shaft only when the foundation is considered level, installing a screw jack at each lifting point and removing the hydraulic jacks and pumping cement into any voids detected below the foundation footing.

Description

[0001] 1. Field of the Invention[0002] This invention relates generally to a method and apparatus for lifting, leveling, and underpinning a building foundation where such foundation has fallen out of plumb as a result of soil movement below the foundation and more particularly to foundation leveling apparatus that utilizes screw anchors as an integral part of a support column.[0003] 2. General Background[0004] The prior art teaches various methods for raising, leveling, and underpinning foundations that have dropped or cracked as a result of movement of the supporting soil on which the foundation was laid. These concepts include the process of excavating a portion of the soil from below the foundation and constructing some form of underpinning in the form of columns which serve as a new footing for the foundation at strategic points and using these columns as a base for supporting screw jacks to bring the building foundation back into a level plane. Others teach the use of screw anc...

AI Technical Summary

Benefits of technology

0006] The present invention teaches a method and apparatus for leveling a building foundation. The method including excavating a cavity below the portion of the foundation to be raised at regular intervals and using and an over-sized screw anchor driven under the foundation at approximately 15 degrees relative to the foundation edge at each of the excavated cavities, the anchor having relatively large helical screw flighting or auger plate to insure support at relatively shallow depths, providing a bed of dry cement mix at each of the excavated cavities, installing an anchor jack-plate having a

Problems solved by technology

Several problems occur when these procedures are implemented.

In some case the screw anchor is not driven to a sufficient depth to insure stability or the angle of penetration is improper.

Therefore, when the jack is loaded, the anchor bends or excessive stress is placed on the foundation due to improper point loading.

Where cement piers are used they are often not level, thereby causing the jacks to stress the foundation by improper point loading.

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