Indoor Experiment And Numerical Simulation Study On The Creep Characteristics Of The Red Shale In Shabatu Mine

As the major engineering materials for the underground construction, rocks play an important role in the stability of projects. The material composition and complex geographical environments of rocks make them evidently timesensitive. At present, experiment research is an indispensable and fundamental work in the research of rock rheological propertites,whose results can provide the relevant rheology parameters to reveal the rheology attributes,build the rheological models,and analyse the data of engineering rocks.In this paper, laboratory tests and numerical simulation were conducted to research the red shale rock of Shabatu Mine. Following results were obtained:(1) The red shale rocks in Shabatu640roadway were sampled and processed into standard specimens and such basic tests as uniaxial compression, uniaxial tensile, shear were performed to gain the basic mechanical parameters of the red shale like compressive strength, tensile strength, elastic modulus, poisson’s ratio, cohesion and internal friction angle. Softening testing results show that the uniaxial compressive strength of the red shale gradually decreased with the increase of moisture content, indicating the easy partial disintegration under mandatory saturated state. From the expansion test, the expansion coefficient of the red shale was determined and the red shale exibited more obvious deformation in the first two hours when water was added into the red shale.(2) Creep experiments on red shale rock samples were conducted using multi-step incremental loading method. The results show the long-term strength of red shale specimens was only70%-80%of the instantaneous uniaxial compressive strength. And according to the creep test curves and data, creep parameters of the red shale rock were gotten by analyzing and calculating the recoverable instantaneous elastic strain, hysteresis visco-elastic strain, unrecoverable instantaneousplastic strain and viscoplastic strain.(3) After identifying the basic elements and their combination existing in the creep model of red shale rock, Burgers model was introduced to describe in the instantaneous elastic deformation, decelerated deformation and constant creeping form. The damped least square method was employed to fit creep and relaxation curves in terms of model equations, after which the magnititude of each parameter was obtained. Test curves agreed well with theoretical curves, implying that the model is able to describe creep and relaxation features of red shale rock well in Shabatu Mining area.(4) At last, numerical simulation was conducted to probe the lateral strain creep law of red shale and then the triaxial creep features analysis was carried out numerically.Uniaxial compression creep test results found that the uniaxial compression creep simulation curve and indoor experimental curves were similar in shape, showing the feasiblity of creep simulation. The lateral creep was less than the axial creep. Triaxial compression creep test simulation results show that with the confining pressure increasing, the axial deformation decreased.