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本文提出了一个水压致裂测量地应力的新的断裂力学方法.该方法改进了 Abou-Sayed 等人(1 978)提出的断裂力学方法.因为当裂隙长度小于某一临界值时,岩石的断裂韧度 K_(1 c)与裂隙长度相关.另外,精确地确定岩石中原生裂隙长度 L 是非常困难的。因此,在计算最大水平主应力时,用一个新参数 U(U=K_(1 c)π~(1/2)L)代替 K_(1 c)和 L,将显著地提高最大水平主应力的精确度.此外,这个参数可以通过一个简单的空心圆柱破裂实验直接来测定.基于岩石断裂韧度最近的实验结果,当裂隙长度小于某一临界值时,新参数 U 近似为岩石材料常量.同时,参量2~(1/2)U 可以取做为含有随机分布较小裂隙的岩石抗拉强度.
This paper proposes a new fracture mechanics method for measuring hydraulic stress-induced fracture stress. This method improves the fracture mechanics method proposed by Abou-Sayed et al. (1978). Because the fracture length is less than a certain critical value, the rock The fracture toughness K_(1 c) is related to the fracture length. In addition, it is very difficult to accurately determine the primary fracture length L in the rock. Therefore, when calculating the maximum horizontal principal stress, using a new parameter U (U=K_(1 c)π~(1/2)L) instead of K_(1 c) and L, will significantly increase the maximum horizontal principal stress. Accuracy. In addition, this parameter can be directly determined by a simple hollow-cylindrical fracture experiment. Based on the recent experimental results of rock fracture toughness, when the fracture length is less than a critical value, the new parameter U approximates the rock material constant. The parameter 2~(1/2)U can be taken as the tensile strength of a rock containing randomly distributed fractures.