Some implications of empiricism and assumptions in laboratory testing

Abstract

The implications of approximation s, introduced by empiricism and/or assumptions, in laboratory assessment of rock are brought out with the help of discussions on three topics - correlation between uniaxial compressive strength and point load strength index; triaxial compression test data's use for assessment of c,Φ , m and s parameters; and evaluation of dynamic elastic parameters (based on compression and shear waves' velocities). The objective is to highlight that in certain cases the theories, practices, and/or the empirical relationships, normally adopted, may not be applicable when the underlying assumptions do not hold good; and unacceptable distortions are introduced if these are used. The paper presents suggestions to deal with the discussed atypical situations. The submission is that ingenuity is called for to assess a rock; and the assessment must be holistic. Two things need to be made mandatory - one, to communicate the tests data to a centralised place, so that suggested relationships can be re-examined; and, two, to declare the data-base on which any relationship is based.