Regularities of Methane and Coal Dust Ignition Caused by Electric Sources in Mine Workings

Fires and explosions pose the greatest threat in underground mines that use high-voltage electrical grids. The paper presents data on explosions of combustible methane and coal dust mixtures in Russian mines. It is shown that there always exists a high risk of fire resulting from a malfunction in the electrical grid. The research aims at determining the type and parameters of an electric arc, spark or open flame generated at the breaking points of electric conductors which initiate the ignition of a combustible medium. It was found that the commonly known ionic and thermal theories of ignition do not match the present state of knowledge. The methodology consisted in investigating patterns of electric charge generation and transfer up to the point of the mains failure. Regularities of energy processes in the atomic and molecular structure of the conductor material are presented. For the first time ever the concept of transformation of the electromagnetic energy generated in the alternator into photon packets of high-frequency energy is justified. An electron of the conductor atom absorbs a quantum of the generated energy, converts the generated frequency into a high-frequency photon packet and radiates it into the electric grid. It has been found that an electric arc or a spark, acting as a source of ignition for a combustible medium, is an electromagnetic emission of energy in the visible range.

Experiment Study on the Durability of Geotechnical Prestressed Anchorage Structure under Cyclic Loading

Based on the analysis of the pretension force influence factors for geotechnical prestressed anchorage cables that are used in a practical engineering, the cyclic loading characteristics of prestressed force long-term variation is revealed, and the conception of large and small cycles of prestressed force variety are also put forward. Based on these analysis, a device for the fatigue failure test and the corresponding test methods are manufactured and developed to analyze the durability problem of the inner bond section of prestressed anchorage structure under repetitive loading and cyclic loading. In the experiment, the means of indoor similar model test is adopted, in which the different loading scheme and loading amplitude were taken into account. According to the test results, the fatigue failure regularities of inner bond section for geotechnical prestressed anchorage structure are revealed.