Comparative Study on Mineral-Scale Microcrack Propagation of Shale under Different Loading Methods

Figure 3

Six different loading methods. (a) Loading method I: a displacement load of X = -0.2 mm is applied to the left boundary L and the right boundary R is fixed. (b) Loading method II: a displacement load of X = −0.2 mm is applied to the left boundary L; a displacement load of Y = 0.2 mm is applied to the lower left boundary LD, and the right boundary R is fixed. (c) Loading method III: the left boundary L is applied with X = 0.2 mm, Y = 0.2 mm displacement load, the left lower boundary LD is applied with Y = 0.2 mm displacement load, and the right boundary R is fixed. (d) Loading method IV: Y = 0.2 mm displacement load is applied to the lower left boundary LD, and the right boundary R and the upper right boundary RU are fixed. (e) Loading method V: a pressure load of X = 10 MPa is applied to the left boundary L; a displacement load of Y = 0.2 mm is applied to the lower left boundary LD, and the right boundary R and upper right boundary RU are fixed. (f) Loading method VI: the left boundary L is applied with a pressure load of X = 20 MPa, the left lower boundary LD is applied with a displacement load of Y = 0.2 mm, and the right boundary R and the upper right boundary RU are fixed.

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