Experimental tests were conducted on the composite rock-concrete specimens with four roughness profiles to investigate the propagation process of interfacial cracks under three-point bending and four-point shear conditions. By measuring the initial fracture loads, various combinations of interfacial stress intensity factors (SIFs) of modes I and II corresponding to the initial fracture conditions were determined. Based on these results, an expression for classifying the initiation of interfacial cracks under the mixed mode I-II fracture was derived by normalization, which could eliminate the effect of interfacial roughness. Furthermore, a criterion for specifying the propagation of the interfacial crack by considering the nonlinear interfacial characteristics was proposed, which indicates that the crack would start to propagate along the interface when the SIFs caused by the external loads and the cohesive stresses satisfied this criterion. The numerical simulations on the interfacial fracture process were also conducted by introducing the crack propagation criterion to predict the load versus crack mouth opening displacement (P-CMOD) curves, and a fairly good agreement with the experimental results could be obtained. Finally, by combining the criterion for the maximum circumferential stress with the proposed criterion for crack propagation, the interfacial crack propagation mode was assessed. The results indicated that once the initial fracture toughnesses for the rock, concrete and interface from experimental work were obtained, the propagation process of the interfacial cracks and the corresponding fracture modes including nonlinear characteristics of the materials and interface could be predicted by using the method derived in this study.
|Journal||Journal of Engineering Mechanics|
|Early online date||13 Apr 2018|
|Publication status||Published - Jun 2018|
- rock-concrete interface; interface fracture; fracture mode; crack propagation criterion; initial fracture toughness