MOORE & TABER                     

 

 

Soil Grouting and Ground Improvement Specialists

 

         

Relative elevation surveys are commonly performed on residential floor slabs or foundation elements as an effective means of determining magnitude and direction of relative elevation differential. A manometer device used for this purpose consists of a stationary reservoir and graduated portable probe, connected with a length of flexible tubing. The reservoir is filled with water, which fills the tubing and portable probe. The water level in the stationary reservoir maintains a constant level, which is constant at the portable probe by definition. The base of the probe is placed on the surface to be measured, and relative elevation readings are obtained by comparing the position of the probe’s graduations to the stationary water level. Manometer devices in use today are typically graduated in 0.1-inch increments.

An initial reading is obtained at a reference point on the surface to be surveyed. All other readings obtained throughout the residence are referenced from this point. Readings are then recorded on a copy of the residence floor plan. The collection of relative elevation readings can then be contoured. Contours are lines that connect points of equal elevation. A plan showing relative elevation contours for a structure can provide valuable information for contractors and engineers involved in the development of remedial repair options.

The image shown above is a comparison of relative floor elevation contours with superimposed buried canyon topography.  In this case, floor deformation patterns resulted directly from settlement of underlying deep canyon fill.

Moore & Taber has performed several thousand relative floor elevation surveys, using manometers of our own design and manufacture.  This type of survey data has proven to be an indispensable diagnostic tool in the field of remedial construction.

Laser scanning techniques can provide a higher order of detail, as a 3-dimensional point cloud of the structure itself is generated.  The image below shows a laser scanner being used to collect point cloud data for a freeway bridge abutment, alongside an image of the scanned point cloud.  Successive scans may be compared to evaluate deformation, as was done during a recent highway project.