Macro-micro experimental study of rock static and dynamic fracture toughness
MAN Ke1, LIU Xiaoli2, SONG Zhifei1, GUO Zhanfeng3, LIU Zongxu1, YU Yunhe1
1. College of Civil Engineering, North China University of Technology, Beijing 100144, China; 2. State Key Laboratory of Hydroscience and Hydraulic Engineering, Tsinghua University, Beijing 100084, China; 3. Urban and Rural Construction and Designing Institute of Henan Province Co., Ltd., Zhengzhou 450002, China
Abstract：The notched semi-circle bend (NSCB) specimen and fracture toughness test method was used to measure the static and dynamic fracture toughness of Beijing Fangshan granite samples. The results showed the dynamic fracture toughness is generally 1.3~2.6 times the static fracture toughness for medium and high strain rates. The surface morphologies of the damaged rock samples were then characterized using SEM and a laser confocal microscope for three-dimensional reconstructions of the fractures and surface roughnesses. The static and dynamic fracture modes were both mode I crack tensile failures. The difference between the dynamic and static crack growth was that the stress wave in the dynamic tests reflected back and forth at the internal interface of rock sample which induced micro-cracks and accelerated the convergence and penetration of existing and new cracks. The crack propagation had acceleration and deceleration stages with the changes in the rock crack propagation speed consistent with the relative height of the reconstructed three-dimensional rock surface morphology, which also corresponded to the rock surface roughness variations. The key difference between the static and dynamic behavior is that the rate effect (inertia effect) during dynamic loading tends to counteract the structural effects of the physical and geometric properties of the rock material itself.
满轲, 刘晓丽, 宋志飞, 郭占峰, 柳宗旭, 于云鹤. 岩石静态与动态断裂韧性的宏细观试验[J]. 清华大学学报（自然科学版）, 2021, 61(8): 799-808.
MAN Ke, LIU Xiaoli, SONG Zhifei, GUO Zhanfeng, LIU Zongxu, YU Yunhe. Macro-micro experimental study of rock static and dynamic fracture toughness. Journal of Tsinghua University(Science and Technology), 2021, 61(8): 799-808.
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