Study on mechanical characteristics of deep engineering rock materials

According to the characteristics of deep diversion tunnel of Jinping II Hydropower Station located in the high field stress condition, for its surrounding rock, i.e. marble, the conventional triaxial test and pre-peak unloading test are carried out.Then study on its mechanical characteristics through the comparative analysis.The results show that: The peak strength increases according to the initial confining pressure increases, and even if the stress path and initial confining pressure is different, but as long as the real-time confining pressure, the peak strength is equal.Further, the change rule of mechanics parameters is the same under different stress paths.These conclusions have revealed the difference of mechanical properties of marble under loading and unloading conditions and provided reliable theoretical reference for the numerical simulation about excavation, designing and stability analysis of deep diversion tunnel in West China.