软弱复杂矿岩亚临界裂纹扩展机制分析

Mechanism Analysis for Subcritical Crack Growth of Flabby and Intricate Ore

采用双扭试件常位移松弛法,对某矿软弱复杂矿岩进行了亚临界裂纹扩展试验研究,测得其断裂韧度值和应力腐蚀下限值,并按Charles理论与Hillig&Charles理论对试验结果进行了线性回归,确定了采场矿岩亚临界裂纹扩展速度与应力强度因子之间的关系,试验复相关系数分别为0.9254和0.9247,均在显著性水平0.01上。试验结果表明,该矿软弱复杂矿岩的应力腐蚀亚临界裂纹扩展是拉应力和裂纹尖端物质与环境中的腐蚀介质发生化学反应,使化学键断裂这两种机制联合作用的结果;应力强度因子与亚临界裂纹扩展速度对数关系能很好地呈线性。

The constant-displacement-relax method of double-torsion specimen was applied to study subcritical crack growth of the flabby and intricate ore-rock at a mine. The fracture toughness and the lower limit of stress corrosion were obtained. According to the Charles theory and the Hillig ＆ Charles theory, the experimental data were regressed linearly, getting to know the relationship between the subcritical crack velocity and the stress intensity factor. And multiple correlation coefficients from test were 0. 9254 and 0. 9247 respectively, all above the significance levels of 0.01. Results show that subcritical crack growth of the flabby and intricate ore-rock at the mine under stress corrosion condition results from both tensile stress and the chemical reaction between materials at crack tip and the corrosion medium in the environment which results in the chemical bond breaking. In addition, the logarithmic relationship between the stress intensity factor and the subcritical crack velocity appears to be linear.