摘要 |
A complete, three-dimensional stress state of underground rock is determined by a method which includes the steps of: drilling a rock to form a borehole with a substantially spherical bottom; deforming the borehole either by releasing the rock from the stresses by overcoring or by applying an external static pressure to the rock; and measuring displacements of the spherical bottom in at least xx, yy, zz, xy, yz and zx radial directions during the deformation of the borehole.
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