Development of a laboratory-scale pressuremeter

This paper presents details of the design, fabrication and operation of a laboratory-scale pressuremeter recently built at the University of Western Australia. The device is significantly different to any previously built miniature pressuremeter in that it uses air as the pressurising fluid and the membrane displacement is measured using strain-gauged 'feeler-arm' transducers, rather than inferring displacements from measured volume changes in the pressuring fluid. It is believed that the direct measurement of radial cavity displacement removes a number of potential sources of error inherent in the inference of displacement from the volume of hydraulic fluid applied. The requirement for system de-airing is also removed. Preliminary results from stress chamber testing are presented and basic interpretation of results indicates that the device is capable of producing high-quality stress-strain data.