ABSTRACT
The investigation of horizontal pressures in full size retaining structures by means of built-in pressure cells requires the development of methods for calibrating the pressure cells. Three different calibration methods are described and their drawbacks and advantages analysed. In the first method, the pressure cell, covered by the calibration material, is loaded by means of a rigid platen pressing onto the calibration material. In the second method, the pressure cell, covered by the calibration material, is loaded by means of an air bag, and in the third method the pressure cell is loaded directly by the air bag, without any covering material. The calibrations obtained for a single pressure cell in conjunction with the three methods of calibration, are compared and the most important factors affecting the calibrations are analyzed. A comparison is made with an ealier theory that indicates that the registration of a pressure cell depends on the ratio of the compressibilities of the calibration material and the cell itself. While the theory is valid, it is shown here that the calibration depends primarily on the compressibility of the pressure cell.
