Evaluation of the stiffness characteristics of rock joints from data of field observations at water-development projects

Rechitskii, V. I.

doi:10.1007/bf02905981

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“…Analysis of the test results obtained for fine-and medium-grained sandstones show that the average shear stiffness of joints in the slip zone amounted to the following consecutive normal stress ranges was: 320 MPa/m, 353 MPa/m and 418 MPa/m (Table 3). Generally, test results do not differ from the values presented for sandstones by Rechitskii (1998), and are of the same order of magnitude as the test results obtained by Wines & Lilly (2003). In turn, sandstones from Kangaroo Valley (Haque, 1999) provided results of approx.…”

Section: Authorssupporting

confidence: 57%

“…In turn, while analysing tests carried out on fractured rocks without filling, such as: granite, marble, Rechitskii (1998) the peak values of shear stiffness k si obtained equal to 1.8-4.3 GPa/m, and a stiffness within the slip zone of k slim = 160-430 MPa/m. For sandstone and tuffaceous sandstone, the author provides the above values in the ranges of k si = 1.2-1.3 GPa/m and k slim = 200-260 MPa/m, respectively.…”

Section: Authorsmentioning

confidence: 99%

“…In order to find the shear stiffness in sandstones Rechitskii (1998) approach has been employed, assuming that shear stiffness is a quotient of maximum shear stress and corresponding displacement. Analysis of the test results obtained for fine-and medium-grained sandstones show that the average shear stiffness of joints in the slip zone amounted to the following consecutive normal stress ranges was: 320 MPa/m, 353 MPa/m and 418 MPa/m (Table 3).…”

Section: Authorsmentioning

confidence: 99%

“…In this case, both stiffness types are equal. Yet another definition of stiffness was adopted by Rechitskii (1998). According to him, stiffness is the proportion between the stress and the resulting shift at the joint.…”

Section: Introductionmentioning

confidence: 99%

“…Such an approach to the issue causes the above stiffness types to differ by even an order of 10 2 Pa/m. According to Rechitskii, depending on height h and width m of the joint, stiffness K s50 is on average 6-times higher than stiffness K slim , considering the following empirical formulas (Rechitskii, 1998): describing the mechanical properties of a fracture, and this relation to the material generated at its joint, due to the friction caused by the adjacent rock layer are: shear stiffness K s and normal stiffness K n , expressed in MPa/m. The first time this was quantitatively described by Barton (1972), stating that:…”

Section: Introductionmentioning

confidence: 99%

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Behaviour of joints in sandstanes during the shear test

Małkowski¹

2015

Acta Geodynamica Et Geomaterialia

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In the case of soft rocks, with many beds, or subjected to tectonic tensions, fractures with the separation occur, which cause many problems to the quantitative assessment of their properties. Considering the fact that deformation properties are proportionate to the strength properties also in the case of rocks, measurement of shear stresses can become the basis for quantitative assessment of mechanical properties of rocks joints, in particular as regards their shear stiffness. In the article, the author has presented the results of laboratory studies of shear behaviour of rock joints in Carboniferous sandstones: fine-and medium grained during a shear test. He has presented the values of internal friction angle, cohesion, shear stiffness at the rock joints, as well as joint roughness coefficient. All the tests were carried out at low stresses with the help of direct shear test. The results show that the internal friction angle of fractured sandstones and of intact ones tested at low stress (up to 10 MPa) is similar. Shear stiffness K s of joints grows up with the normal stress and correspond with the shifting on the discontinuity. For the low normal stresses K s was obtained as follows: 320 MPa/m, 353 MPa/m and 418 MPa/m. The joint roughness coefficient (JRC) for the fine-grained sandstone amounts to 5 to 7, while for medium-grained sandstone-6 to 8. This conclusion can be very useful for geological or engineering designing (eg. mining workings support design, underground roadways stability assessment, rock mass classification) when evaluate the shear resistance between sandstone rock blocks.

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Section: Authorssupporting

confidence: 57%

Section: Authorsmentioning

confidence: 99%

Section: Authorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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