Abstract: A large number of experiments have proved that fluid flow and stress characteristics are different from each other under loading and unloading effect state. In recent years, research on hydro-mechanical coupling of fractured rock mass under loading conditions has advanced greatly, but corresponding research on hydro-mechanical coupling considering unloading effect has still been in an early stage. And then, constitutive relationship including seepage parameters between unloading stress and strain is constructed based on existing fracture deformation curve, meanwhile, fluid flow and stress characteristic of an example under different operation modes is analyzed according to coupling theory mentioned above. The calculation results illuminated as follows: stress field changing make fluid flow coefficient close to slope surface increasing and saturated line falling so as to augment slope stability when taking consideration of unloading effect; and displacement and stress field vary greatly after considering seepage effect, but discrepancy of both characteristic distribution between considering coupling and discarding coupling was knee-high to a duck; and the final conclusion is that stress field changing influencing fluid flow field is larger than that fluid flow changing influencing displacement and stress field.

Key words: unloading, fractured rock mass, hydro-mechanical coupling, fluid characteristic, slope