Study On Dynamic Mechanical Properties And Microcosmic Pore Structure Characteristic Of Coals Under The Impact Load

The coal is one of the important energies that affect our economic development at a high speed, however, with the continuously increasing demand for the coal, coal in shallow mines would be gradually reduced and even dried up. Furthermore, with the increase of coal exploited in deep mines, the geological environment appears complicated, in which the stress state is remarkably different from that in the geological environment of shallow mines. With the Drilling and Blasting method used in the hard-rock excavation and gas extraction., it causes rock dynamic disasters and a certain number of casualties and property losses.This paper takes coal samples of a coal mine, named Wang He, as the research object. Under the help of electro-hydraulic servo testing machine to analyze the static mechanics performance of the coal samples in the uniaxial compression test. The study of dynamic mechanical properties of the coal samples with simulating the impact load mainly adopting the Split Hopkinson Pressure Bar(SHPB) and the study of the microscopic characteristics of coal samples with pore structures employing low-temperature nitrogen adsorption method. The main researches are as follows:(1) Taking use of the core drilling machine, the cutting machine and the polishing machine to work the coal samples,which aiming to ensure the demand of tests.Then the compressional wave velocity of coal samples will be measured and the coal samples will be tested under static uniaxial compression employing the electro-hydraulic servo testing machine. Finally, the stress-strain curve and destruction form of coal samples will be also be analyzed.(2) The length-diameter ratio of coal samples in the uniaxial compression impact experiment will be determined, then dynamic stress-strain curve of coal samples will be also analyzed at different speeds of the bullet impacting load. With the increase of the average-strain rate under the different impact load, the failure modes of coal samples,the deformation modulus and the DIF(dynamic strength increase factor)change law of coal samples will be analyzed.(3) The principle and experimental apparatus will be introduced, at the same time,the influence on the low temperature liquid nitrogen adsorption-desorption curvedue to the different coal rock pore structures will be analyzed either. Meanwhile, the low temperature liquid nitrogen adsorption experiments of the coal rock will be conducted under the different impact load, testing the specific surface area, pore volume size and pore size distribution, then analyzing the pore structure change law of coal samples under the different impact load.