Use of calibration chamber as a large triaxial apparatus

A segment of a gravel column, 1 m high and 0.53 m in diameter, was modelled in a calibration chamber. The reconstituted sample was consolidated at a given confining pressure and then subjected to axial load exerted by the upper and lower membranes. Volumetric changes in both membranes and in internal chamber were measured. Up to 2% vertical strain was reached and internal friction angle was evaluated. Secant modulus of deformation was determined at considerable strains and at intermediate strain level in the unloading–reloading cycle. For the latter several times higher modulus was found.