Instruments for Determining Stress Displacements in Soils: Fid-Bau Portal

Instruments for Determining Stress Displacements in Soils

K. A. Jackura

Section I of this report presents the basic theory, design and construction of a 10-inch diameter soil pressure cell. Finite element analytical techniques were used in assessing various cell geometric shapes that would minimize registration error regardless of cell orientation to the major principal stress. Approximately 170 cells of an optimum geometric shape were used in the evaluation of soil stresses around a buried culvert and its composite embankment. A discussion of their output data, and a comparison to three types of other commercially available soil and interface pressure cells installed in conjunction with this model is included. Calibration procedures are also discussed. Section II discusses the design and construction of a continuous settlement profile gage. The gage is composed of a transducer sensing head and a horizontally placed 2-inch diameter plastic pipe. The transducer is pulled through the pipe by means of a cable raceway. Water within the pipe provides the static reference head for all settlement measurements. Accuracy is plus or minus 0.05 ft of settlement. Field performance of the device is included.