岩石Ⅰ型断裂韧度估算及其影响因素分析

Estimation of mode Ⅰ fracture toughness of rock and its impact factors analysis

岩石的I型断裂韧度K_(IC)与抗压强度σ_c之间存在相关性,可根据二者之间的经验关系通过σ_c估算岩石的K_(IC)值,但其估算结果会因测试方法和岩性的不同而有所差异。为了获得更合理准确的岩石K_(IC)估算值,在试验数据统计回归的基础上,建立了不同K_(IC)测试方法和岩性条件下的K_(IC)与σ_c经验关系,并分析了其差异和适用性。结果表明,4种K_(IC)推荐测试方法均可获得良好的K_(IC)与σ_c线性关系,但差异明显,建议使用"V"形切槽巴西圆盘(CCNBD)方法所得经验关系估算岩石的K_(IC)值;结果还表明,利用经验关系估算K_(IC)值的方法更适用于均质各向同性岩石。需要说明的是,估算方法并不能代替实验室测试,并且通过实验室测试建立经验关系是间接获取K_(IC)值的必要前提。

The relationship between mode I fracture toughness KICand compressive strength σcof rock makes it possible to estimate KICvalues from σcbased on empirical relationship between KICand σc. However,the estimates are influenced by the KICtest methods and lithology. In order to obtain more reasonable and accurate KICvalues of rock,the authors established empirical relationships between KICand σcunder different KICtest methods and lithology based on the statistical regression of test data collected from literature,and then the authors analyzed their differences and applicability. Results indicated that the empirical relationships between KICand σcobtained from the four different suggested KICtest methods were all in good but obviously different linear relationship,in which the relationship obtained from cracked chevron notch Brazilian disc（ CCNBD） specimens was proposed to estimate the KICvalues of rock. Meanwhile,the results also showed that it was more applicable for homogeneous and isotropic rocks to estimate KICvalues from empirical relationships. It should be pointed out that the estimates obtained from empirical relationships can never replace the lab tests,and the empirical relationships established by lab tests is a necessary premise for all indirect estimations.