Effect of loading rate on Mode I fracture toughness, roughness and micromechanics of sandstone

摘要

From this study the following conclusions are drawn: The fracture toughness (K_(IC) and K_(IC)~C, the fracture roughness (D and A) and the height deviation of the generated fracture stay constant irrespective of crack opening rate between 5 X 10~(-6) to 5 X 10~(-10)m/s in the Chevron-Bend Test. The range of published experimental data on rate dependency of Mode I fracture toughness has been extended by three orders of magnitude to lower rates. The correction factor for the plasticity, p, increases with decreasing loading rate. There is evidence for an increase of fracture density with increased loading rate. Crack propagation in Flechtinger Bausandstein at fracture velocities of 10~(-2)-10~(-6) m/s shows no evidence for a contribution of subcritical crack growth.