基于半圆弯拉试验的煤样抗拉及断裂性能研究

 为研究准静态加载条件下煤的抗拉及断裂性能，采用巴西圆盘劈裂法和半圆弯拉法对煤样进行抗拉性能对比测试；并开展不同切缝深度的半圆弯拉煤样断裂性能测试分析，探讨平面应变断裂韧度KIC和J积分断裂韧度对评价煤的断裂性能的适用性，研究切缝深度对半圆弯拉煤样的2种断裂韧度测定结果的影响；并结合受载过程中煤样表面应变监测和破坏后试样的工业CT扫描图像分别对煤样受载变形特征和破坏后裂纹展布规律进行分析。研究表明：半圆弯拉试验更适于测定煤的抗拉强度；当量纲一化的切缝深度 = 0.28时半圆弯拉煤样平面应变断裂韧度KIC离散度最小；煤样的J积分断裂韧度离散度更小，且更适用于评价煤的断裂性能。

Characteristics of tensile strength and fracture properties of coal#br# based on semi-circular bending tests#br#

Brazilian disc(BD) and semi-circular bending(SCB) tests were carried out to investigate the characteristics of tensile strength and fracture properties of coal under quasi-static loading. The SCB specimens with notches of various depths were tested to analyse the fracture properties of coal. The KIC fracture toughness and J-intergral fracture toughness of coal were calculated. The effects of notch depth on the fracture toughness were also discussed. The strain gauges were utilized to monitor the deformation features of specimens. The computed tomography scanning was also carried out on the failure specimens to figure out the crack distribution. Results show that SCB method is more suitable to obtain the tensile strength of coals than BD test. In the current testing situation，the coefficient of variation(CV) of KIC fracture toughness is the smallest as the dimensionless notch depth equal to 0.28. The KIC fracture toughness is easily affected by the notch depth and the dimensionless stress intensity factor(SIF). The results also indicate that the J-intergral fracture toughness is more suitable for evaluating the fracture properties of coals.