To study the tensile and fracture properties of the specimen under the quasistatic loading, the Brazilian disc splitting method and the notched semicircular bend (NSCB) method were used to test the tensile properties of coal specimens, and the fracture properties of NSCB specimens with different notch depths were tested and analyzed. The applicability of plane strain fracture toughness K_IC and J-integral fracture toughness in evaluating the fracture properties of coal specimens was discussed. The influence of notch depth on the fracture toughness measurement of the NSCB specimen was studied. Combined with the surface strain monitoring of specimens during loading and the industrial CT scanning image of damaged specimens, the deformation characteristics of coal specimen under loads and the distribution law of crack after failure were analyzed. The results show that the NSCB test is suitable for measuring the tensile strength of a coal specimen; when the dimensionless notch depth is β = 0.28, the dispersion of plane strain fracture toughness K_IC of the NSCB specimen is the smallest. Besides, the plane strain fracture toughness of coal is obviously affected by the notch depth and dimensionless stress intensity factor. The J-integral fracture toughness can be used to effectively evaluate the fracture performance of specimens.

中文翻译：

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准静态条件下爆破煤的拉伸断裂性能的实验研究

为了研究准静态载荷下试样的拉伸和断裂性能，采用巴西圆盘劈裂法和缺口半圆弯曲法（NSCB）分别测试了煤试样的拉伸性能和不同缺口的NSCB试样的断裂性能。深度进行了测试和分析。平面应变断裂韧性K _IC和J的适用性讨论了在评估煤样品断裂特性时的-整体断裂韧性。研究了缺口深度对NSCB试样断裂韧性测量的影响。结合试件加载过程中的表面应变监测和损伤试件的工业CT扫描图像，分析了试件在载荷作用下的变形特性和破坏后的裂纹分布规律。结果表明，NSCB试验适用于测量煤样品的抗张强度。当无因次切口深度为β  = 0.28时，平面应变断裂韧性的色散K _ICNSCB标本的最小。此外，煤的平面应变断裂韧性明显受缺口深度和无因次应力强度因子的影响。所述Ĵ -积分断裂韧性可被用于有效地评估的试样的断裂性能。