| In the process of geotechnical engineering construction and operation and maintenance,disasters caused by rock deformation and failure often occur,which seriously threaten the safe production of the project.Carrying out research work from an experimental point of view,exploring the evolution characteristics of acoustic emission in the process of rock deformation and failure,and analyzing the correspondence between rock deformation and acoustic emission information are the basis of geotechnical engineering disaster prediction.In this paper,the digital speckle correlation method and acoustic emission were used as experimental monitoring methods.Pre-cracks of type I three-point-bending,offset pre-cracks three-point-bending and uniaxial compression test methods were used to study on the evolution characteristics of acoustic emission during the evolution process of rock deformation and failure under tensile,tensile and compressive shear and analyze the information and characteristics of rock deformation and failure precursors.In the aspect of research on the evolution characteristics of acoustic emission of rock deformation and failure under tensile action,pre-cracks of type I three-point-bending experiment was carried out with specimens with different prefabricated cracks,and the evolution characteristics of rock displacement field were obtained by digital speckle correlation method;based on the analysis of acoustic emission parameters,the evolution characteristics of acoustic emission amplitude,energy,cumulative energy,event rate and b value in the process of rock deformation and failure were obtained,the acoustic emission precursor information of rock failure was obtained,and the change rule of acoustic emission parameters with the change of prefabricated crack height was revealed;based on the joint analysis of acoustic emission parameters and deformation indexes,the crack opening rate and ring count were obtained correspondence.In the aspect of research on the evolution characteristics of acoustic emission of rock deformation and failure under the action of tension and shear,the three-point-bending experiment of rock offset crack was carried out by using prefabricated crack specimens with different offset distances.Through the evolution analysis of rock displacement field,acoustic emission amplitude,ring count,b value and relative displacement rate of crack,the evolution characteristics of displacement field and acoustic emission parameters in the process of rock deformation and failure were obtained The relationship between the relative displacement rate of the crack and the ring count was given.In the aspect of research on the evolution characteristics of acoustic emission of rock deformation and failure under compression and shear,the rock uniaxial compression experiment was carried out,the evolution characteristics of rock maximum shear strain field were obtained by digital speckle correlation method,the acoustic emission was located by rock double difference position method,and the position results were compared with the strain field to obtain good corresponding effect;the evolution analysis of acoustic emission amplitude,ring count,energy,cumulative energy,event rate and b value was used to obtain the evolution characteristics of acoustic emission parameters of rock failure.The joint analysis of relative displacement rate and energy of crack revealed the corresponding relationship between them. |
PDF Full Text Request