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亚临界裂纹扩展是岩体工程时间相依性的主要原因之一。采用常位移松弛法,对饱水和干燥两种状态下的大理岩、花岗岩双扭试件进行了亚临界裂纹扩展试验研究,获得了两种岩石在两种状态下的亚临界裂纹扩展速率V与应力强度因子KΙ的关系,分析了两种岩石在两种状态下亚临界裂纹扩展的规律,并确定了两种岩石在两种状态下的门槛值(干燥状态):大理岩0K为1.365,花岗岩0K为2.305;(饱水状态):大理岩0K为1.118,花岗岩0K为1.490。研究表明,两种岩石的IlgK与lgV关系有较好的线性规律,但由于岩石本身矿物成分等的不均匀性,同种岩石的IlgK与lgV关系离散性较大,饱水状态下离散性更大;水能加速岩石亚临界裂纹的扩展,且对不同的岩石,其影响程度也不一样;水可以使岩石亚临界裂纹扩展的门槛值有较大幅度降低,不同岩石其降低的程度也不一样。
The subcritical crack propagation is one of the main reasons for the time dependency of rock mass engineering. Using the constant displacement relaxation relaxation method, the subcritical crack propagation of marble and granite under both saturated and dry conditions was studied, and the subcritical crack growth rate V And the stress intensity factor KI, the laws of subcritical crack propagation of the two rocks are analyzed and the threshold values (dry state) of the two rocks are determined in two states: 0K for marble is 1.365, 0K of granite is 2.305; (full water state): 0K of marble is 1.118 and granite 0K is 1.490. The results show that there is a good linear relationship between IlgK and lgV in both rocks. However, due to the inhomogeneity of rock composition, the relationship between IlgK and lgV of the same kind of rock is more discrete, Large; water can accelerate the expansion of rock subcritical cracks, and for different rocks, the impact is not the same; water can make the threshold of rock subcritical crack growth is significantly reduced, the extent of rock reduction is not the same same.