Study on the influence of stress and water content on creep characteristics of fractured granite
To investigate the effects of stress and water content on the creep characteristics of fractured granite,a series of creep tests were carried out using the high temperature triaxial rheological test system for rock.The experiment mainly consists of the multi-stress creep tests under different confining pressures,and uniaxial creep tests under different water content.The test samples were intact granite and granite with different inclinational fractures,which were taken from Beishan pre-selected area of Gansu Province for geological disposal of high-level radioactive waste in China.The experimental results indicates that,the lateral deformation of fractured granite presents more significant creep characteristics,and the lateral steady creep strain rate is slightly higher than axial steady creep strain rate.With the increase of the stress level,the axial strain presents a linear growth relationship,while the lateral strain and the axial and lateral steady creep strain rates all show an exponential function growth relationship.Under the condition of the same confining pressure and the same deviatoric stress,the larger the fracture inclination angle is,the larger the axial and lateral strains are,and the higher the axial and lateral steady creep rates are.Under saturated state,the steady creep rate of granite is significantly increased,and the rock mass is more prone to deformation under the same stress,resulting in the failure of granite under lower creep load or shorter creep duration.When the inclination angle θ is 45° or 60°,the failure time of saturated sample is only 1.05‰ or 0.84‰of the failure time of dry sample.The failure modes of fractured granite can be divided into three types:causing new fractures which cut across the pre-made fracture(θ=30°),slipping of the pre-made fracture(θ=60°)and the compound failure of the first two forms(θ=45°).The confining pressure of 10 MPa,and the dry or saturated state have no significant influence on the creep failure form of fractured granite.
rock mechanicsgranitecreepfracture inclination anglewater contentfailure mode
万方数据
维普
