| Complete stress-strain process of rock mechanical properties and stress field study on permeability of rock is the subject of research directions in the field of rock mechanics.Rock there are several discontinuous surface,which contains pores,joints,cracks and other defects,which provides space for the storage and flow of fracture fluid.Is mostly dominated by water-filled caves in the southern coalfield of maokou limestone Karst mineral deposit and study on fracture strength characteristic of maokou limestone,fluid mechanics characteristics and study on the damage characteristics of seepage field for the South coal mine water prevention and control,tunnel excavation provided a theoretical basis.The main results of this paper are as follows:(1)The results showed that the mechanical characteristics of fractured limestone samples are sensitive to seepage pressure,which will reduces rock strength and deformation modulus,activating the lateral deformation of fractured limestone.the strength characteristics of fractured limestone can be characterized by the Mohr-Coulomb yield criterion under the hydro-mechanical coupling;(2)The permeability values display four stages of decrease-gradual increase-rapid increase-small drop in complete stress-strain process,which roughly correspond to volumetric compression stage,elastic deformation stage,failure stage near peak strength point and residual strength,respectively.At low seepage pressure,the correspondence above is perfect.However,at high seepage pressure,there is a deviation from the correspondence above,i.e.permeability reduction stage is shorter than the stage of volumetric;(3)For the relationship between the permeability of the volume compression phase and its volumetric strain at volume compression phase,we can use the negative exponential function to fit at the lower osmotic pressure due to its different anastomosis and we use three polynomials to fit at the higher osmotic pressureve. |
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