Research On The Three-Dimensional Model Design Of Gas Migration In The Gob Coal Face

Gob gas emission accounts for a large proportion of the total amount of gas emission. Therefore, only to understand and master the flow state of airflow, the law of gas occurrence, migration and emission in the gob, and find out gas accumulation points, can we adjust the stope ventilation system targeted, determine the reasonable parameters of the stope, and prevent gas accumulation. However, due to site conditions, it is hard to observe the physical process of gob gas flow. Therefore, from the experimental point of view, this paper used Shaqu Mine 14205 fully mechanized coal face as a prototype, based on the similarity theory and similarity criteria, then we built test system for the simulation study of gas migration in the gob coal face in the laboratory, for the study of the flow state of wind and the law of gas migration.This paper analyzed the gas emission law and emission forecasting in the mechanized coal face in detail, and gob gas concentration distribution qualitatively. At the same time, using the theory of gob with "horizontal three-zone" and "vertical three-zone", combined with the specific circumstances in Shaqu Mine 14205 face, we identified the height of the caving zone and the division of gob "horizontal three-zone", which laid the foundation for the construction of gob three-dimensional model.In order to guarantee the similar relationship established between the model and the prototype, and to achieve the purpose of simulating the real underground environment scientifically, based on the similarity theory and the similarity criterion, we proposed the similarity criterion, which the three-dimensional model of gas migration in the gob coal face should follow, and determined the geometry of the model and other relevant parameters, with which it achieved the geometric similarity motion similarity and dynamic similarity between model and prototype. In this paper,we designed and constructed the three dimensional, the main contents include:the main part of the designed model including ventilation system, test bench for simulation stope, ventilating fan and ancillary equipment, collection and detection system; ball valve used in the model as a throttle to achieve the conversion of a model with various ventilation ways, and described the use of methods; analyzed the characteristics of gob, and completed gob filling based on the analysis; calculated the local resistance and friction, and selected fan according to the maximum air resistance; according to the law of gob gas source and emission, designed gas release system; selected the detection elements according to the parameters test needed to be measured; followed the requirements of geometric similarity strictly, used reasonable experimental materials, and erected the three-dimension model of the tunnel, face and gob in the laboratory.Finally, by using the model, we made qualitative and quantitative researches of gob gas migration law in "U+L" ventilation way, which is with two intakes and one return. By comparing the experimental results, the feasibility of model test was analyzed.