Experimental Study on Elastovisco-Plastic Rheological Properties of Saturated Limestone Under Multi-level Load and Unload Cycles

A set of triaxial rheological experiments were performed to obtain elastovisco-plastic properties of saturated Maokou limestone specimens by multi-level load and unload cycles method to explore time-dependent geological disaster in mining engineering. Take saturated Maokou limestone of Meitanba Coal Mining Area in China for example; the elastovisco-plastic deformation properties of this kind of rock were studied. The experimental result are given as follows: (1) instantaneous elastic response is nearly linear, Instantaneous plastic modulus increases with increasing stress; (2) The relation between visco-elastic strain and deviatoric stress is nonlinear, and nonlinear relationship between visco-plastic strain and deviatoric stress is also shown. With the increase of the deviatoric stress level, visco-plastic strain grows rapidly; (3) the steady creep rate increases at an exponential function with deviatoric stress increase. The visco-plastic strain properties of radial creep are similar to that of axial creep. But radial creep strain only is 25%–30% of axial creep strain, radial creep rate is about 35% of axial creep rate. The acquisition of elastovisco-plastic parameters of saturated Maokou limestones provides useful information for study on the time-dependent stability of Maokou limestone tunnel of Meitanba Coal Mining Area in China.