Experimental Research On Magnetic Induction-Stress Of Gestating Process Of Compressional Fracture For Native Magnetic Rock Plate

In this thesis, the relationship between the changes in internal structural and the magnetic induction in the rock plate in the whole process of native magnetically rock plate extrusion is experimentally researched. In the experiment, the country rock of magnetite mining in Gong Changling mine, Liaoyang City, Liaoning Province as the research objects, which s magnetic field strength compliance the test instrument range. Though testing the magnetic field strength around of the native magnetically rock plate, its distribution of the magnetic field is obtained. Loading system and three-channel data acquisition system are used to load axial force and test records of the native magnetically rock plate, achieve the corresponding relationship of four physical:the stress, strain, magnetic induction and lateral displacement and change microscopic changes of pores and microcracks under the force into the measurable magnetic flux density changes. Finally, basic physical quantities of rock mechanical properties and magnetic are linked so that a magnetic teating method of probing rock plate microscopic changes under the extrusion process is formed.Though extrusion destruction test of nine groups rock plate, we can get the curve of strss-strain, stress-magnetic induction desity and stress- magnetic induction desity-strain in the extrusion destruction process of rock plate after data processing and analysis, and summarize the variation of magnetic induction density during the whole process of experiment.The experimental results show:in stress ascent stage, with the increase of stress, magnetic induction intensity decreases, called a symmetric form; and the moment of stress peak, the magnetic flux density bounding decreases; and in stress falling section, the magnetic flux density reduces drastically with unstable failure of rock plate specimens. According to the failure mode of rock plate, the data curve is divided into three categories:rock plate specimen that splitting failure mode and end failure mode haven’t precursory phenomena before the damage. The magnetic induction of rock plate specimen that full failure mode have abnormal, which have the changes from bounding decreases tends to be reduced to the same.