采用四点剪切型试件进行岩石－混凝土界面断裂试验，研究不同加载方式、缝高比、偏缝率下界面裂缝的扩展过程。采用界面断裂力学的方法计算裂缝尖端应力强度因子，提出了能预测裂缝发展不同模式的界面裂缝扩展准则，结合岩石－混凝土界面的拉伸软化本构曲线，通过有限元方法对四点剪切加载条件下界面裂缝扩展过程进行模拟，数值结果与试验结果吻合良好。结果表明：在得到界面、混凝土与岩石的抗拉强度、断裂能和起裂断裂韧度后，可以采用数值的方法预测裂缝扩展的不同模式，求解岩石－混凝土界面裂缝在Ⅰ－Ⅱ复合型应力场下的起裂荷载、极限荷载、裂缝扩展长度等断裂参数，模拟裂缝扩展全过程。%An experimental study on crack propagation in rock-concrete interface was carried out using four-point shearing beam to investigate the effects of different loading methods ,ratio of initial crack length to beam height and offset of pre-crack on crack propagation trajectory .The results suggest that there are two modes for pre-crack propagation under four-point shearing loading condition ,i .e .,along the rock-concrete interface and towards the rock .Based on interface frac-ture mechanics theory ,the stress intensity factor at the tip of a crack was calculated and a crack propagation criterion was proposed ,which can determine the crack propagation in different materials .Combined with the tension softening constitu-tive relationship obtained from the previous study ,the interface crack propagation under four-point shearing condition was simulated ,the simulation results showed a reasonable agreement with those of the experiments .It indicates that the pro-posed method can be used to determine the interface crack propagation mode subjected to the mixed mode of Ⅰ - Ⅱstress filed .Meanwhile ,the whole fracture process can be simulated and these fracture parameters including initial crack-ing load ,ultimate load and crack propagation length can be calculated numerically if tensile strength ,fracture energy and the initial fracture toughness of the interface ,concrete and rock are obtained .
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