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High stresses are expected in deep mines, and it is perhaps unusual for rock failure due to high stresses to be
observed in shallow mining. In this paper, stress-induced failures of competent rock are described in three
shallow mining situations. Two of the rock failures occurred with considerable violence, both involving
significant strain bursting seismicity. Rock failures in the third case often occurred with some violence and
were preceded by audible noises. The first situation is failure of very competent granite in a dimension stone
quarry, in which the depth of the “vertical cut slope” was about 3 m. The second situation is failure of the
roof in a coal mine at a depth of about 50 m below surface. The third situation is also failure of the roof in a
coal mine, but at a depth of about 25 m below surface. None of these failures can be explained using
commonly-used rock strength criteria.
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Dynamic Rock Failures Due to “High” Stress at Shallow Depth T.R. Stacey, et al.
204 Deep Mining 07, Perth, Australia