A Case Study On In Situ Testing Of Rock Mass Deformability

Parallel deformability tests: three rigid Plate Loading (PLT) and one extra Large Flat Jack (LFJ) were performed side by side in slightly jointed marlstone in order to compare their results. Pressure-displacement data obtained from LFJ and PLT tests are presented and processed using different formulas to determine overall (by the least-squares method), instant and interval moduli. Different moduli interpreted from PLTs are compared to moduli from the LFJ test data. The case shows typical problems encountered in PLT data interpretation.