Study on the Creep Mechanical Properties of Phyllite Under the Coupling Effect of Excavation Unloading and Pore Water Pressure
Excavation disturbances induce high stress concentrations and stress redistribution within the mine rock body.Additionally,hydraulic factors diminish the rock body's strength.Mines situated in the southern region of China are particularly susceptible to disasters during the rainy season due to the influence of rainfall.Therefore,investigating the combined effects of these factors on the mechanical properties of mine rock is of significant importance for ensuring the long-term stability of mine side slopes.The study utilized a slope rock body from the Yinshan Mine in Jiangxi Province as a sample and conducted a graded loading creep test based on a triaxial compression test to investigate the mechanical properties of millimeter-scale rock under the combined effects of excavation unloading and pore water pressure.The results indicate that,with increasing excavation unloading and pore water pressure,the short-term peak strength and elastic modulus of the saturated millimeter-scale rock progressively decrease.Under identical excavation unloading conditions,an increase in pore water pressure leads to a reduction in the strength of saturated millimeters due to the influence of the pore water pressure.This results in an increase in transient strain,a decrease in the transient elasticity modulus,and a reduction in resistance to deformation.Additionally,both creep strain and steady-state creep plasticity exhibit exponential growth with the increase in axial stress up to a certain threshold.Under identical pore water pressure conditions,the instantaneous strain and instantaneous elastic modulus of the excavation-disturbed specimen are lower than those of the undisturbed specimen.Additionally,the creep strain and creep rate escalate with the increasing degree of unloading due to excavation.This observation suggests that excavation-induced disturbances diminish the rock strength,rendering the rock body more susceptible to deformation.The findings indicate that the rock strength of phyllite is diminished due to excavation disturbances,rendering the rock mass more susceptible to creep damage.The study further reveals that the combined effects of excavation unloading and pore water pressure exacerbate this reduction in strength.Consequently,the rock mass becomes increasingly prone to creep damage,thereby compromising the stability of slopes.
excavation unloadingpore water pressurephyllitemechanical propertycreep testcoupling effect
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