Results of experimental study of friction effect on mechanical properties of salt rocks
The purpose of the work is to study influence of friction between samples and press plates on mechanical parameters of salt rocks. The main source of information for determining values of mechanical parameters of salt rocks is laboratory tests of rock samples for compression. It is known that values of mechanical parameters determined from results of compression of samples essentially depend on magnitude of frictional force between fronts and plates of a press. Wherein, empirical coefficients of shape used in calculation of values of mechanical parameters corresponding to uniaxial compression do not take into account specific frontal conditions. This leads to a known inaccuracy in formulation of an experiment and interpretation of its results. Thus, relevant studies correspond to more detailed study of influence of friction between samples and press plates on mechanical properties of salt rocks. During experimental studies 75 samples of fine to medium grained rock salt from Verkhnekamsk deposit of potassium salts were tested. The paper presents results of experimental studies directed to determine coefficient of friction of salt rocks according to a scheme "shear with compression" over various surfaces. Studies were carried out on compression of samples of different heights under known contact conditions. The necessary friction value was modeled using manufactured gaskets placed between fronts of samples to be tested for compression and press plates. A full diagram of deformation was build from the compression results of each sample and a set of mechanical parameters was determined. Dependences that reflect an effect of frictional forces between fronts of samples and press plates under compression on values of strength limit, destructive deformation and specific energy consumption of rock salt deformation are determined. Results of the study are intended to improve a method of testing rocks for compression.