岩石-混凝土界面I-II型断裂及声发射特征

通过对岩石-混凝土复合试件进行三点弯曲和四点剪切断裂试验，研究了界面I-II复合型断裂力学行为及声发射特征。结果表明：（1）岩石-混凝土界面裂纹主要有三种破坏模式。模态比越高，界面粗糙度越大，界面裂缝出现非界面扩展复杂模式的可能性越大。（2）利用声发射特征参量的突变能够有效判断起裂和失稳临界状态，利用平均频率（AF）、上升时间与幅值之比（RA）两参数比值可量化分析断裂过程的拉剪破裂机制，利用AE事件聚积的方向可预测界面裂缝的扩展方向，从而揭示界面断裂损伤演化规律。（3）试件失稳破坏前夕，声发射信号主频变化明显，低幅低频信号大量剧增且突现不少低幅高频信号，主频有由离散发展为连续的趋势。高模态比时，主频分布的范围相对较大。

Mixed mode I-II fracture and acoustic emission characteristics of rock-concrete interfaces

Mechanical behaviors and acoustic emission (AE) characteristics of mixed mode I-II fractures at rock-concrete interfaces are studied through three-point bending tests and four-point shear fracture tests on composite rock-concrete specimens. The results show the failure modes can be divided into three categories. A higher modal ratio or a rougher interface results in higher possibility of the occurrence of non-interfacial complex failure modes. Incipient cracking and unstable failure can be identified by abrupt changes in AE parameters; microcracks be classified into tensile and shear cracks byaverage frequency (AF) and the ratio of rising time to amplitude (RA value). Fracture damage evolution can be revealed by predicting the propagation direction of interface cracks using the space distribution of AE events. When the final overall destruction of the specimens is imminent, the dominant frequencies of AE signals change significantly, manifesting a sharp increase in both the number and amplitude of low-amplitude, low-frequency AE signals and sudden emergence of a few low-amplitude, high-frequency AE signals. Meanwhile, the dominant frequencies are shifting from discrete to continuous and their distributions span a relatively large range under the condition of high modal ratios.