Nonlinear modulus of rock is function of strain level and strain amplitude.The modulus decays exponentially with ascending of strain amplitude, while increases with strain level increasing.

• 岩石非线性模量既是所受应变水平的函数，也是应变振幅的函数，模量随应变振幅的增加以指数形式下降，随应变水平增加以指数形式上升。