Publication details

Regularities of failure of migmatized gneiss with metamorphic foliation



Year of publication 2018
Type Article in Periodical
Magazine / Source Geology, Geophysics & Enviroment
MU Faculty or unit

Faculty of Science

Keywords strength anisotropy; uniaxial compressive strength; metamorphic foliaiton
Description The research is focused on an exploration of the mechanical anisotropy and fracture process of a rock with planes of weakness. In this study, the strength behavior of migmatized gneiss with weakened planes, i.e. metamorphic foliation is evaluated. Metamorphic foliation with a specific orientation of rock grains may results that the mechanical behavior, and the mechanical properties, i.e. strength, are changed in different directions of loading. The strength anisotropy and the direction of weakening are in geomechanics not sufficiently clear until now. For these purposes, series of uniaxial compressive strength tests were carried out on the five groups of specimens of migmatized gneiss based on the different angle between foliation and loading. The measured results have shown that mechanical properties of the migmatized gneiss have different values concerning foliation. U-shaped anisotropy was obtained, in accordance to Ramamurthy distinguished curve of anisotropy (Ramamurthy, 1993) with the minimum average strength at anisotropy angle of 30 degree and the maximum average strength is reached when anisotropy angle is 90 degree. Next, an intensity of deformation, an orientation of new-created fractures due to foliation and a shape of fractured specimens were characterized. An extension failure parallel or subparallel to the loading and a shear failure were also recognized on the fractured rock specimens. The characterization should be a contribution to understanding of that, how an orientation of weakness planes influences the strength and the fracture formation of the rock. The knowledge of the problem is useful information for stability ensuring of underground construction, mine workings and for other geotechnical application.

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