Deformability of rock mass and a comparison between plate jacking and Goodman jack tests

Research highlights
► Deformability of rock mass by Goodman jack is 2 to 3 times lower than plate jacking test.
► Average deformation modulus of Goodman jack may be multiplied by a factor of 2.5.
► Plate jacking tests must be conducted to arrive at the realistic multiplication factor.
► The modulus must be compared only with mean value of Q and not with RQD.
► The average value of modulus of deformation increases with increase in applied pressure.