Study On Loading-electrical-magnetically Coupling Law Of Gangue-based Functionally Cemented Body

The cemented materials using coal mine solid waste including coal gangue have been widely used as green mine technologies including gob filling,shotcrete support of coal mine tunnel,gob-side entry support body,et al.The structural health condition of bearing structures（man-made structure system）built by gangue-based cemented body play a key role in surrounding rock control.Traditional methods to monitoring damage of structures such as embedded sensor cannot be used in coal mine since restricted conditions including small operating space and complex environment.Therefore,realizing self-sensing of gangue-based cemented body is important to surrounding rock control.By adding conductive addtives,the gangue-based functional cemented body（GFCB）with self-sensing abiligy can be made,and non-destructive testing for gangue-based cemented structures is realized.Based on this,this dissertation takes GFCB as research object,and proposes an eddy current non-destructive testing method for it.To this end,the mechanical-electircal-magnetic coupling mechanism of GFCB is the key scientific problem to be investigated.The research contents include the gangue-based functional cemented material and its sensing ability,eddy-current sensing mechanism,electrical-magnetic and damage parameters calibration of GFCB,mechanical-electrical evolution and correlation between mechanical and electrical parameters,and the research methods like theoretical analysis,experimental verification and numerical simulation were used.The following main research results are obtained:（1）An eddy-current NDT for sensing deformation and damage of gangue-based functional cemented structures was proposed.The gangue-based functional cemented mateirals（GFCM）was developed,and the sensing ability of CFCM was evaluated by key index like fractional change in resistance,gague factor and linear error.The effect of steel fiber,carbon fiber,and carbon black on sensing ability of GFCM was studies,and steel fiber was proved to be best functional filler.An eddy current testing system based on STM32 microcontroller was built,wthich was used to optimize steel fiber content.An advanced functional material is proposed,which gauge factor reach 33.86.（2）The complex permittivity of steel fibers-reinforced GFCM was studied.By mixing steel fiber,the loss coefficient of GFCM was improved obviously,which means the absorbing ability to electromagnetic field was increased.The impedance spectrum of GFCM with different damaged index and steel fibers content were measured,and the equivalent circuit of steel fibers-reinforced GFCM was built.The effect of damage and fiber content on the values of R_m2 was obtained.（3）The strength properties and its influence factor of GFCM was revealed.The mechanism of after-peak loading ability echancement was studied further by acoustic emission method.The mechanical-electrical coupling relationship of GFCM was analyzed using machine learning based on support vector machine and KFold cross validation algorithm.The results show that the predictions of compressive strength through equivalent circuit parameters are relatively accurate.（4）A meso-structure-guided numerical approach to evaluate strain and damaging sensing of GFCM was proposed.A GFCM model with radom distribution of steel fiber was built.The electrical parameters change mechanism of GFCM during loading was analyzed using meso-parameters including electric current density and electrical potential gradient.There are 112 figures,25 tables and 214 references in this dissertation.