| The nonlinear fracture characteristics of rocks,such as the crack tip opening displacement,the length of the fracture process zone,and the tensile strength of cohesive cracks,need to be considered in unconventional reservoir engineering problems.Based on the test of nonlinear fracture characteristics of granite,the horizontal displacement field of granite and the size characteristics of fracture process zone are obtained by digital image correlation from room temperature to 200 ?,and it is available to analyse the influence of the tip opening displacement,the tensile strength of the cohesive crack and the slope of the load-COD softening curve and make corrections of the model of the rock cohesive crack under the temperature field.It is shown that with the increase of temperature,(1)the internal stress state of the rock sample changes from single tension to local compression or tension,and the fracture morphology of the rock changes from single to multiple cracks above 80 ?.(2)Moreover,the critical crack tip opening displacement increases significantly above 100 ?.(3)The slope of the COD softening curve is obviously slow after the peak load,which demeonstrates the brittleness of rock decreases.(4)Furthermore,the crack process zone increases significantly above 80 ?. |
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