Abstract: Water and joints have a significant effect on the mechanical properties and failure modes of slope rock mass.
In order to further reveal the influence of joint inclination angle (β) on the deterioration effect and sensitivity of rock mass under
fluid-solid coupling,uniaxial compression tests of rock mass with different joint inclination angles were carried out based on
RFPA2D-Flow numerical software. The results show that joints significantly reduce the peak strength of rock mass,but the evolution
of deformation stages of different β rock samples is consistent. The evolution process of acoustic emission (AE) (quiet
period,stable development period,sharp rise period,attenuation period) can effectively characterize the damage evolution. The
peak strength and peak strain have a quadratic function relationship with β,and the elastic modulus and AE parameters are
positively correlated with β. The quantitative model of β and macro-micro mechanical parameters is established. The degradation
sensitivity of rock mass parameters is significantly different with the boundary of β≈30°:when β<30°,the deformation capacity
(peak strain) degradation of rock mass is the most sensitive. When β>30°,its ability to resist deformation (elastic modulus) is
the most sensitive deterioration index. This law provides a clear basis for slope stability control,and deformation control should
be given priority to gently inclined jointed slopes (β<30°). Steeply inclined jointed slopes (β>30) need to focus on preventing
stiffness degradation and instability. This study not only clarifies the inherent law of rock mass degradation under the fluid-solid
coupling of joint dip angle,but also provides a refined sensitivity criterion for slope engineering stability evaluation.

Key words: fluid-solid coupling,joint inclination angle,deterioration effect,acoustic emission,sensitivity evaluation