Experimental Research Of Magnetic Induction Abnormality Of Compression Failure Process For Ferromagnetic Rock

Lithosphere is the place of human beings. With the economy developing, humans begin development of underground space. Because of the underground rock instability, rock blasting tunnel collapse and other underground cavern engineering problems occurred, which directly affect the safety of human life and property. Therefore, understanding the change process and rules of rock fissures to ensure the safety of the project under stress is significant. During of the whole process the ferromagnetic rock specimen extrusion destroy, this thesis is to study relationship between stress, strain and magnetic induction. By analyzing the stress-strain-magnetic induction intensity curves the precursor of ferromagnetic squeezing rock specimen destruction is obtained.In the experiment, the magnetic rock is collected from the Gongchangling mine, Liaoyang City, Liaoning Province, which magnetic field strength meets the test range. The rock is manufactured into standard cylindrical specimens. This rock comes from a small part of the huge lithosphere. The rock is lack of the small fissures. According to the thermal expansion anisotropy, the ferromagnetic rock specimens were heated to increase the small fissures. By loading system and dual-channel data acquisition system, the heated specimen is subjected to uniaxial compression test and the real-time monitoring to obtain the relationship between stress, strain and magnetic induction. The physical parameters of rock mechanics and magnetism physical parameters are linked so that a magnetic test method of rock extrusion failure process microscopic changes is formed.Though extrusion destruction test of the rock specimen, we can get the stress, strain and magnetic induction curve in the extrusion destruction process of rock specimen after data processing and analysis, summarize the variation of magnetic induction density during the whole process of experiment and obtain magnetic induction changes anomalies when the specimen is damaged.The experimental results show:in the stress rising stage, with the strain increasing, the stress increases, the magnetic induction intensity decreases. In the plastic flow stage, stress remains almost unchanged, magnetometer occurs three mutations, the first is dropped into a rose, second magnetic induction intensity leveled off, and the third is the magnetic induction sudden rapid decline; After the destruction of the specimen, with the stain increasing, the stress decreases, the magnetic induction occurs rise or flatten. The ferromagnetic rock specimens were heated for three times, which one temperature is 300℃,600℃ and 500℃ respectively, the other is 700℃,600℃ and 700℃ respectively. After extrusion destruction test of the rock specimen, rock specimen has been fully cracking.