Abstract: The application of the hydraulic fracturing technique is more and more extensive in geotechnical engineering, but hydraulic fracturing may cause some geology disasters. Therefore, the mechanism of the hydraulic fracturing is a hot topic in geotechnical engineering. The fracture propagation is studied through the principles of the fracture mechanics, the computation formula of the cracking angle of fracture and the critical internal water pressure based on the maximum circumferential stress criterion are deduced. Then, the relation between the critical internal water pressure and the direction of the fracture are analyzed in detail; meanwhile, the fracture location where the hydraulic fracturing is mostly inclined to occur under the tension-shear complex model is obtained.

Key words: hydraulic fracturing, the maximum circumferential stress, tension-shear complex fracture, the critical internal water pressure

摘要： 水力劈裂技术在岩土工程中应用越来越广泛,但自然界中的水力劈裂可能会引发地质灾害,因此,水力劈裂 机理研究已成为岩土工程中的热点问题。通过利用断裂力学理论对水力劈裂时裂纹的扩展问题进行研究,推导了 基于最大周向应力理论的裂纹起裂角及临界水压的计算公式,分析了压剪复合断裂时临界水压力与裂纹面方向之 间的关系,在此基础上得出了压剪断裂时最易于发生水力劈裂的裂纹面位置。

关键词: 水力劈裂, 最大周向应力, 压剪裂纹, 临界水压