THE USE OF MINIATURE SOIL STRESS MEASURING CELLS IN LABORATORY APPLICATIONS INVOLVING STRESS REVERSALS

Abstract

This paper describes the potential use of miniature soil stress measuring cells in model pile tests where normal stresses up to several MPa may be expected, accompanied by unloading and multiple substantial stress reversals. Devices rated in the 0.5 to 7 MPa range are considered and it is shown that they can develop marked cell-action effects, including strong non-linearity and hysteresis. A new approach to cell calibration and characteristic modelling is presented. It is shown that measurement errors may only be kept within tolerable limits through complex calibrations involving cells with suitable boundary conditions combined with a multi-stage loading history dependent, data reduction procedure.