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岩石断裂韧度表征其抵抗裂纹起裂和扩展的能力,作为其力学性能的一个重要指标,在岩石力学理论研究与岩体工程应用中有着不可替代的作用。由于岩石结构的复杂性,其破坏形式大多呈现为复合型断裂破坏,研究复合型加载条件下岩石断裂韧度具有重要的意义。为了研究锈岩的断裂力学性能,以便其在建筑工业中得到更为广泛的应用,通过18个中心裂纹圆盘(CSTBD)试件径向受压试验,进行了复合型加载条件下锈岩断裂韧度的试验研究。测得了锈岩在纯I型,纯II型以及复合型加载时的断裂韧度,并将试验结果与基于广义最大周向应力(GMTS)准则的理论值进行了对比分析,结果表明:锈岩的纯I型断裂韧度为1.01 MPa·m~(0.5),而纯II型断裂韧度为1.51 MPa·m~(0.5),是纯I型断裂韧度的1.49倍,这与基于GMTS准则的理论值1.34非常接近,而比基于最大周向应力(MTS)准则的理论值0.87大很多。裂纹尖端附近的T应力及断裂过程区裂纹尖端的临界距离r_c对岩石类材料的开裂路径以及复合型断裂韧度都有较大的影响。考虑了T应力的广义最大周向应力(GMTS)准则能很好的预测试验结果。
Rock fracture toughness characterizes its ability to resist crack initiation and propagation as an important indicator of its mechanical properties, which plays an irreplaceable role in rock mechanics research and rock engineering application. Due to the complexity of rock structure, most of the failure modes are complex fracture failure. It is of great significance to study the fracture toughness of rock under complex loading conditions. In order to study the fracture mechanics properties of the rust rock so that it can be more widely used in the construction industry, the radial compression tests of 18 central cracked disk specimens (CSTBD) Toughness of the experimental study. The fracture toughness of rusty rock under pure type I, pure type II and composite loading was measured. The experimental results were contrasted with the theoretical values based on GMTS. The results show that: The pure type I fracture toughness is 1.01 MPa · m ~ (0.5), while the pure type II fracture toughness is 1.51 MPa · m ~ (0.5), which is 1.49 times of pure type I fracture toughness, Is very close to the theoretical value of 1.34 and much larger than the theoretical value of 0.87 based on the maximum circumferential stress (MTS) criterion. The T stress near the crack tip and the critical distance r_c at the crack tip in the fracture zone have a great influence on the cracking path and the fracture toughness of composite rock. The generalized maximum circumferential stress (GMTS) criterion, which takes into account T stress, can well predict the experimental results.