岩石亚临界裂纹扩展试验及门槛值研究

利用Instron1342型电液伺服材料试验机,采用常位移松弛法对大理岩、花岗岩双扭试件进行了亚临界裂纹扩展试验研究,获得了其裂纹扩展速率V与应力强度因子KI的关系(KI-V曲线)及I型断裂韧度,分析了不同岩石中裂纹亚临界扩展的规律,确定了岩石亚临界裂纹扩展的停滞速度和门槛值K0。研究表明:采用常位移松弛法所测岩石的lgKI-lgV关系都有很好的线性规律,即岩石的亚临界裂纹扩展速率与裂纹尖端应力强度因子服从幂函数关系,这与Charles理论相符。二种岩石的K0/KIC值的变化在0.706～0.870之间。所测数据为岩土工程稳定的时间相依性研究提供了基本数据。

Study on subcritical crack growth and thresholds of rocks

Subcritical crack growth of specimens made of marble and granite was studied in double torsion test using Instron1342 type electro hydraulic servo test machine. The relations of the stress intensity factor K1 versus the subcritical crack growth velocity V and the fracture toughness K1c were obtained by the load relaxation method under constant displacement. The behavior of subcritical crack growth was analyzed. The threshold values of subcritical crack growth in rocks were obtained. It was shown that 1gK1-1gV relations of rocks measured by this method accorded with linear rules, i.e. the relations between subcriticai crack growth velocity V and stress intensity factor K1 conformed to power law, which was in good agreement with the Charles theory. The range of Ko/K1c for these two kinds of rocks was from 0.706 to 0.870. The test results would provide the basis for studying time-deoendency of rock stability.