介绍了裂纹亚临界扩展的试验方法及原理 ,应用双扭试件试验 ,研究了三峡船闸花岗岩亚临界裂纹的扩展 ,并得到了岩石的断裂力学参数 . The test method and principle of subcritical crack propagation are introduced. With the double torsional test, the extension of the subcritical crack of the granite in the Three Gorges Project is studied and the fracture mechanics parameters of the rock are obtained.