Study On Damage And Damage Mechanism Of Cementite Filling Based On Acoustic Emission

The parameter of acoustic emission(AE)also belong to material's constitutive parameters as well as the parameter of stress and strain.When the stability of cement filling body with ballast with historically mechanical behaviors was valued,it is hard to value by the constitutive relations of stress-strain.Because mechanical behaviors historically was unknown.But AE make up the deficiency,because of the irreversibility of AE parameter.Because micro-crack propagation rate can be quantified by the probability density of material's acoustic emission events in the course of loading.So this paper adopt AE events probability distribution density function between stress level ? %and AE events accumulation N deduced by Dai and Labuz when they studied the AE characteristic of concrete,rock and so on.In the uniaxial loading of cement filling body with ballast mixed with different aggregate rate.,AE events probability density was calculated by the AE events accumulation of loading process at different time.The relation between mechanical parameter(corresponding stress level)and AE parameter(AE events probability distribution density)can be quantified by analyzing the curve of AE events probability distribution density-stress level.Analyzing above research,the paper sum up some conclusion as below:(1)Analyzing the whole stress-strain curve of cement filling body with ballast with different quantity of ballast,the deformation process of filling body specimen can be classified into 5 stage that is consolidation stage,elastic deformation stage,yield deformation stage,failure stage and residual bearing capacity stage.The increase of ballast reduce initial micro-crack and porosities,and improve inner structure of cement filling body with ballast.(2)Along with the increase of ballast,accumulated AE events increasing rapidly occur when consolidation stage turn to plastic deformation stage.Because of the relation between accumulated AE events and damage,so main stage of the damage of cement filling body with ballast trend to come later in the whole loading process.When the amount of ballast is fewer in cemented tailing filling,damage value and variation of whole loading process is similar to cemented tailing filling's.As the amount of ballast creasing,reaching to 45%,the damage value of cement filling body with ballast is remaining a lower level and varies not obviously.It demonstrate that the creasing of ballast restrain the previous damage of cement filling body with ballast's bearing capacity.(3)The crack model of cement filling body with ballast can be classified into splitting failure model,stripping failure model and bursting failure model by analyzing much of cement filling body with ballast's AE testing.The amount of ballast determine the model.Connecting the amount of ballast and AE parameter,if AE rate parameter a trend to become smaller,the failure is splitting failure model;if a trend to steady,the failure is stripping failure model;if a rise rapidly,the failure is bursting failure model.