Investigation of physical and mechanical properties of ijolite-urtite under uniaxial and triaxial compression

The study of deformation and failure processes in rock masses is often carried out in laboratory conditions on samples. Widely used test equipment is used for this purpose, which makes it possible to create loading conditions similar to those inside the rock mass. Basically, the loading mode is implemented when forces are applied only to one side of the sample (along one axis), that is, uniaxial compression or tension. Test equipment that allows creation of loading along three axes, i.e. triaxial compression, is used less frequently. Such equipment is often very expensive, and testing requires a lot of time and resources. Nevertheless, this loading mode is one of the most interesting, since it is close to real conditions in the rock mass. This paper presents the results of experimental studies of ijolite-urtite samples (rocks from the Khibiny massif, the Kola Region) in conditions of uniaxial and triaxial compression. The purpose of the research is to establish how the values of the compressive strength of this rock change, to assess the critical values of the specific strain energy, as well as the tendency to dynamic destruction during the transition from the uniaxial loading mode to the triaxial one. The experimental studies revealed that there exists a sharper increase in the values of compressive strength and the critical values of specific strain energy of the ijolite-urtite samples in conditions of triaxial compression than under uniaxial compression. It has been established that the studied rock is prone to dynamic failure under uniaxial compression and preserve its tendency to this type of failure under triaxial compression.