水对亚临界裂纹扩展的影响

利用Instron1342型电液伺服材料试验机，采用双扭常位移松弛法对花岗岩试件在空气中及饱和水两种条件下进行了亚临界裂纹扩展试验研究，获得了相应的裂纹扩展速率V与应力强度因子KI的关系（KI -V曲线）及亚临界裂纹扩展参数，讨论了两种环境下裂纹亚临界扩展的规律，并对两种环境下亚临界裂纹扩展参数进行了对比分析。研究表明：采用常位移松弛法所测试的两种条件下的lgKI -lgV关系都有很好的线性规律。在双对数坐标空间中，含饱和水试件的lgKI -lgV曲线位于空气中试件lgKI -lgV曲线的左上角，曲线斜率减小，而截距增加。在同一应力强度因子水平上，含饱和水试件的裂纹扩展速度大，说明水能加速亚临界裂纹扩展，与实际相一致。

Effects of water on subcritical crack growth

Subcritical crack growth of double torsion specimens made of granite is studied by using Instron1342 type electro hydraulic servo test machine in air and in saturated water. The relations of mode-I stress intensity factor KI and subcritical crack growth velocity V are tested by double torsion constant displacement load relaxation method, and the subcritical crack growth parameters are obtained. The behavior of subcritical crack growth law is discussed under two conditions, and the subcritical crack growth parameters are compared. The results show that lgKI -lgV relations accord with linear rule under two conditions. The lgKI -lgV curves of saturated water specimens locate top left corner of those of air specimens. The slope of curve is smaller, and the intercept is bigger. The subcritical crack growth velocity of saturated water specimen is speeded at same stress intensity factor of air specimens, which implies that water speeds up the subcritical crack growth. The results correspond to practice.