Shear failure of rocks and creating their shear plane

BERČÁKOVÁ, Andrea and Rostislav MELICHAR. Shear failure of rocks and creating their shear plane. In 13th Meeting of the Central European Tectonic Studies Group. 2015. ISBN 978-80-7075-880-9.

Basic information

Original name

Shear failure of rocks and creating their shear plane

Name in Czech

Střižné porušení hornin a vytvoření ploch usmýknutí

Authors

BERČÁKOVÁ, Andrea (703 Slovakia, guarantor, belonging to the institution) and Rostislav MELICHAR (203 Czech Republic, belonging to the institution)

Edition

13th Meeting of the Central European Tectonic Studies Group, 2015

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Other information

Language

English

Type of outcome

Konferenční abstrakt

Field of Study

10500 1.5. Earth and related environmental sciences

Country of publisher

Czech Republic

Confidentiality degree

není předmětem státního či obchodního tajemství

RIV identification code

RIV/00216224:14310/15:00082864

Organization unit

Faculty of Science

ISBN

978-80-7075-880-9

Keywords in English

anisotropy; shear strength; cleavage

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Abstract

V originále

The study was focused on exploration of the shear strength of slate with distinguish planes of weakness, i.e. cleavage. Slaty cleavage represents the ability of rock to split into more or less parallel planes and disturbs the rock massif. The presence of these planes of weakness affects the strength and deformational behaviors of rocks and indicates asymmetric fracture of rocks and unpredictable strength behaviour. Tests were carried out on the laminated slate with predetermined shear plane. This rock originates from „Bělá” quarry from the Moravo-Silesian Culm, Czech Republic. The oriented specimens were taken by manual drilling machine. The drilled specimens of slate were divided into five groups based on the different angle between shear plane and cleavage. Testing of each group was carried out in seven directions with an interval of 15°. The first direction which was called “zero” direction was perpendicular to the cleavage. Solids were tested at portable rock shear box assembly Matest A129. Specimens confirmed anisotropic strength behaviour. Large variability of measured values of the strength was caused mainly by various dip of cleavage and by the direction of shear but in lesser extent. Two types of mechanisms of shear failure of specimens and creating their shear planes were distinguished (sliding vs. splitting). The first type was recognized for groups 1 a 2. These groups were characterized by lower values of shear strength and smoothed newly-formed shear planes, which are parallel to cleavage. It might have been caused by the parallel position of phylosilicates. These minerals reduce the friction ability of rocks and allow them to split. The other type, splitting, was recognised for group 4. This group was characterized by high values of shear strength without visible newly-formed shear planes and the specimens were crushed during the test. It might be explained by dominant influence of friction ability of rock. The group 3 is considered to be a transitional group with lower values of shear strength and specimens were crushed during testing. Significant effect of the shear direction on the strength was demonstrated on the group 5, on the specimens with cleavage upright to the shear plane.