Loading and unloading effects are common in all kinds of geotechnical engineering.In order to study the mechanical re-sponse and damage evolution law of rock mass loading and unloading under different stress paths,the damage variable function of the bond was introduced into the traditional bond-based peridynamics constitutive model to reflect the nonlinear stage of strain hardening and then strain softening in the stress-strain curve of rock materials.The mechanics and damage evolution of fine sandstone under dif-ferent loading and unloading paths were studied by using the improved bond-based peridynamics model and the laboratory loading and unloading test.The results show that the improved bond-based peridynamics constitutive model can simulate the mechanical properties of strain hardening and then strain softening of rock materials and the mechanical response and damage development trend under differ-ent stress paths.Under the conventional triaxial path,the compressive strength and confining pressure of rock show a strict positive cor-relation.The defined damage value can intuitively compare the damage development of rock under different loading and unloading paths and conventional triaxial compression.Compared with conventional triaxial compression,the unloading path speeds up the failure of rock materials,and the damage degree of ascending axial pressure＞constant axial pressure＞unloading axial pressure.
rock mechanicsperidynamicsunloading effectstress pathdamage propagate
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