Compaction deformation and acoustic emission characteristics of fractured rock with different lithology in goaf
The compaction characteristics and mechanical properties of different lithologic broken gangues in the goaf significantly impact the movement and failure of the overlying strata.Confining com-pression and acoustic emission tests were conducted to study the deformation,fracture,and acoustic e-mission characteristics of sandstone and sandy mudstone with the same gradation(SSMSG),as well as the combined fractured sandstone and sandy mudstone(CFSSM),under confining compression condi-tions.The results indicated that,during the early loading stage,the strain curve of the broken rock ini-tially exhibited a linear increase.As time progressed,it sharply increased before transitioning to a gentler incline.The stress-strain relationship of the SSMSG and the CFSSM was nonlinear under lateral com-pression.Based on the stress-strain characteristics,the compression deformation of the broken rock could be categorized into three stages:rapid compaction,slow compaction,and stable compaction.As the axial pressure increased,the broken rock samples experienced skeleton destruction of large particles,displacement and sliding of medium particle,and pore filling of small particles.The strain of different li-thology showed a positive correlation with stress,while porosity exhibited a negative correlation with stress.The CFSSM fell between the behaviors of SSMSG.The fractal dimension of broken rock samples was exponentially related to the different proportions of the SSMSG and the CFSSM.Based on the a-coustic emission test results,the compression process could be divided into three stages:sliding flow,fracturing filling,and compaction elastic deformation.The cumulative count and energy curves of broken rock samples at different stages exhibited characteristic periodic changes.With increasing stress,the cu-mulative AE count and energy showed a rapid linear increase in the early stage exhibit,followed by a slower increase before rising again.The acceleration rate decreased gradually in the later stage,resulting in a gentler curve.The cumulative AE count and energy in the CFSSM fell between those of the SSMSG.The research findings provide valuable theoretical guidance for managing the overlying strata,surface movement,and safety in the goaf.
fractured rock in goafcompaction characteristicsfractal dimensionacoustic emission
万方数据
维普
