The geotechnical geologic disaster is an important research subject for the current field of geotechnical engineering problem

and the microscopic bond strength of rock-soil is an important factor affecting macroeconomic stability.Based on the discrete element method

this article derives the constitutive model of particles connection damage

and conducts the numerical simulation test of the rock-soil′s uniaxial compression

tension and shear in the whole process.The results show that the bond failure of the soil particles meso unit mainly depends on the adhesive force between particles

uniaxial compression test forms shear zone closed to 60 degrees

and the coefficient of friction between the particles is a sensitive parameter affecting the macroscopic strength.The middle of the uniaxial tension test model forms through-crack vertical to the load

normal bond strength is an important parameter affecting the macroscopic strength

and numerical simulation results are consistent with theorelical ones.The paper studies the three-point bending failure test under different material parameter conditions

it is found that bond shear strength is also an important factor affecting the macroscopic shear

and macro crack failure occurs in midspan and tortuously expands to the load point.This topic reveals the effect of different microscopic parameters of geotechnical materials on macroscopic strength and the formation mechanism of failure process under different loading methods

which lays the theoretical and technical foundation for a more in-depth study on the progressive failure process of the geotechnical mechanical properties and the formation and development of sliding fracture.