Abstract:Based on the uniaxial and triaxial compression mechanical tests and the cyclic loading tests in the post-peak period of Benxi limestone,its strength and deformation with different confining pressures,processes of failure and cyclic loading,and failure types in different stress were studied.The results showed that in the post-peak but the strength has not decreased to the residual strength period,the elastic modulus is equal to the elastic modulus in pre-peak,and the new peak stress will be lower than the stress of starting unloading.In the period that the strength decreases to the residual strength,the strength will not decrease with the cyclic loading.It is viable to adopt the method that comparing circumferential elastic strain with circumferential strain of peak to judge the failure type of Benxi limestone.There are two failure types that are tensile failure and shear failure for Benxi limestone in different confining pressures,and the relation between rock damage and failure should be considered in founding the constitutive model.Based on this,circumferential strain and shear strain were selected as the distribution variables in the new statistical constitutive model which describes the brittle stress-drop and relation between stress and strain in the post-peak period very well.