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Abstract Based on the shear test with variable angle for pressure punch of mudstone samples in natural moisture condition，the fracture evolutionary rule and fractal characteristics of fracture blocks distribution of mudstone under compression and shear loading are studied by using nonlinear fractal theory. The research results are as follows：(1) The cohesion and friction angle parameters of rock samples are achieved by draw Mohr’s strength envelope according to the test date of shear test with variable angle for pressure punch. (2) The shape of load-load point displacement curves of rock sample under compression and shear loading is similar to complete stress-strain curve of rock sample under uniaxial compression，can be divided into compaction，elastic，plastic and fracture etc four stages，and faithfully represent the failure process of rock samples under coupled compression and shear. (3) Compression and shear failure is the nonlinear energy dissipation dynamics process，fracture blocks distribution has self-similarity obviously，and can use fractal dimension characterization its size distribution character. (4) Fractal dimension of fracture blocks distribution decrease logarithm with shear angle increase because of dominate fracture type transformed from splitting fracture into shear fracture.
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Received: 29 November 2010
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2011, Vol. 30 
