Development And Stress Measurement Method Of Brittle Similar Material

The rock mass in Metal mines with high strength,hardrigidity,and great brittleness is easy to break.The phenomenon of Surrounding Rock Movement and Mining Subsidence,induced by the exploitation,is different from sedimentary rocksof coal measure strata and more complex.In order to research the activity law of Metal mines ground pressure by Similar Model Test,the first technical problem should be solved isthe development ofbrittlesimilar materialand stress measuring method of the scale model.Therefore,this research focuses on the two key issues:(1)We adopt self-developed experimental equipment to conduct the direct uniaxial compressive test on material specimen with specific size,it is to research the tension and compression ratio among different plaster dry bulk density of pure specimens as well as the effect on it when different content,particle size plaster specimens of mica gypsum powder specimen was incorporated.Experiments revealed that the content of non adhesive powder and the ratio of tension and compression on the particle size to the material are of significance.With the increase of non adhesive powder,all of the specimens’ compressive strength and tensile strength show a law of obvious magnification.In a small range,with the increase of non adhesive powder,the compressive strength and tensile strength show a law of obvious increase.While the further increase of non adhesive powder,it shows a law of decline.Compared 400 mesh non adhesive powder and 800 mesh non adhesive powder,the latter one increase tension and compression ratio higher than the former.The material ratio developed can simulate a variety of rock with different degrees of brittleness of low intensity and moderate intensity.(2)The best ideal stress measuring method is to directly put the stress sensor into the model,because the failure reason of the stress boxmeasuring methodis not only the invalid of the stress sensor,but also the structure’s irrationality.In this paper,the design principles of stress measurement sensorareto meet the matching deformation.The stress sensor will be test by 6 cycles of loading for calibration,if the element still maintains good flexibility characteristics;it is indicating that the developedstress sensor element has high reliability.The element can be used to measure the internal stress of the model in all directions,which overcomes the disadvantage of earth pressure cellthat measures only vertical stress.When the strain gauge is embedded on the surface of the element and inside the element,respectively,we find that different readings strain and the former better reflect the true condition.