The Changeable Interaction betweeen Soils and Pressure Cells; Tests and Reviews at the Waterways Experiment Station

Abstract
The principal subjects of the report are the often neglected changes in the interaction of soil and pressure cells with consequent changes in relative errors in cell registrations. The report contains (a) a brief account of the development and use of soil pressure cells; (b) a review of proposed theories for soil-cell interaction; (c) a delayed account of tests with Waterways Experiment Station pressure cells placed in a large triaxial device; and (d) tentative conclusions plus suggestions for calibration, installation, and measuring procedures. Early theories may yield acceptable explanations of the action of soil pressure cells, but corresponding numerical data are not reliable because these theories were based on the Boussinesq equations for forces on the free soil surface, whereas the Mindlin equations should be used for forces acting in the interior of a soil mass. Theory and experiments show lateral stresses may increase or decrease the axial stresses, normal to the faces of a cell, that is, the calibration factor of a soil pressure cell is not a constant but varies with the configuration of the cell, with the magnitude and direction of the principal soil stresses, and with the value of the Poisson ratio in addition to the moduli of deformation of cell and soil. Registration of soil pressure cells may become quite variable and unreliable when the stress conditions in the soil approach those of failure with corresponding changes in soil deformations and properties.

This publication has 0 references indexed in Scilit: