Experiment On The Creep Starting Stress And Long-term Strength Of Granite

Rock creep is one of the important reasons to produced large deformation even lose on tunnel and underground engineering,the building foundation. So the study of rock creep under different confining pressure initiation stress and long-term strength range has an important guiding significance for the design and construction of rock engineering.This paper mainly adopts the method of combining theory and experiment to analysis the obtained curves of creep.To find the conditions of creep starting stress and axial radial yield threshold stress range under different confining pressure.In this paper, the partly explain the micro mechanism of rock creep mechanism,and the nonlinear creep of rock, make use of the different confining pressures compression experiment to study the rock strength and deformation. And obtained the granite compressive strength, elastic modulus, Poisson's ratio and the basic mechanics of friction angle and cohesion parameters under different confining pressure.According to the different confining pressures compressive strength using single step loading to do the single axis and three axis creep experiment for obtained a series of experimental curves. By using data processing into many different forms of the axial and radial deformation, axial and radial creep rate curve, axial and radial isochrounous stress-strain curve to compare the axial and radial creep characteristics.And determine the rock creep starting stress, axial radial creep strength of long term stress range under different confining pressure. And comparative analysis the axial creep starting stress and long-term strength under different confining pressures. It was found that the creep initial stress, long-term strength change with confining pressure, its strength value and instantaneous maximum deviatoric stress ratio basically will be fixed in a certain range. At the same time we find that the radial long-term strength of rock creep is lower than the axial long-term strength axial. And the long-term strength of rock should be determined by the radial steady creep threshold.