Numerical Study On Damage Mechanism Of Rock Strength Weakening And Its Application

Creep is one mechanical characteristic of rock, and many instability of rock engineering is closely related with creep of rock. Weakening of rock strength is an important factor of creep. Generally speaking, all materials are of different rheological property, but only under special conditions this behavior of numerous materials could become apparent. When geomaterials in engineering are subjected to long lasting load, this behavior will become very apparent under usual condition and can't be neglected. So it is necessary to study on the factors that influence this behavior of rock, such as creep characteristic, long-term strength, failure mode, structure of rock pillar, confined pressure and so on.In this thesis, the research content is stated as follows:1. Mechanical parameters of three kind of specimens which is sampled from Sijiaying iron mine of limited liability company in Luanxian County are tested in rock mechanical lab and the data of compression and shear are obtained. It is prepared for next simulation experiment;2. According to the mechanical parameters obtained in previous stage, numerical models under different axial pressure condition, same axial pressure and different confined pressure condition and same confined pressure and different axial pressure condition are established and simulated by using Rock Failure Process Analysis (abbreviated as RFPA^2D ). Simulation results are analyzed and the law of rock strength weakening is obtained. Three stages of rock creep are analyzed and the long-term strength of rock is determined;3. the mechanical model of Sijiaying Mine changing from open-pit to underground mining is established. Selecting typical sections and considering the pits with backfill or not, mining stope with intervening pillar or not, the thickness of roof and distance among intervening pillar, the instability of each design is simulated by RFPA^2D. Instable characteristic is analyzed and long-term strength and thickness of roof are determined, which provides science basis to the safe design for Sijiaying Mine.