Search

Taking the fully mechanized mining face of bulianta 12511 as the research object, the distribution law of dust movement in fully mechanized mining face with 8m large mining height was numerically simulated by using CFD software. Through the simulation results of the original dust field, it is found that the dust produced by the collapsed coal seam diffuses to the rear of the shearer under the action of wind flow, the highest point of movement of high-concentration dust mass can reach 4m, and the dust concentration gradually decreases along the roadway. High concentration dust is mainly concentrated in the 10m range before and after the shearer and on the side of the bottom plate close to the coal retaining plate, with a maximum of 3500mg/m3. In order to effectively reduce the dust in the working face, prevent dust accumulation and pollute the underground working environment, this paper innovatively proposes to install an airborne dust collector in the large mining height working face to control the dust spreading to the pedestrian side at the dust source and purify the dust. By studying the influence of dust collector placement position and treatment air volume on the dust movement and distribution rule and dust removal effect of the working face, the optimal dust removal efficiency of the working face with large mining height is obtained by the dust collector placement position and treatment air volume adaptation combination, and the maximum dust removal efficiency can reach 100%.

In order to solve the problem of dust pollution in mechanized tunneling face, Master the best matching relationship between the long and forced ventilation and the dusting and short dust removal parameters in the working face, reducing the dust concentration of working flour to the maximum degree. This paper takes the high-yield dust comprehensive mining face of Wangjialing coal mine as the research background, by establishing CFD model, the effect of dust control on different axial and radial air out ratio of working face is compared, and the parameters range of effective dust control is obtained, and the actual application of the field is verified and analyzed in order to get the best matching parameters of the control dust removal process. The results show that, after increasing the dust control of the wall winder, a fresh air flow transparent wall along the wall of the tunnel is formed in the tail of the roadheader, the dust can be controlled in the area of the front of the work. When the ratio of the axial and radial air out is 1:3, the dust is controlled in the smaller area near working face, the dust control effect is the best. The total and respirable dust concentration of the driver’s position and the 5m position at the tail of the driving machine can be reduced to less than 26.1 mg/m3 and 12.7 mg/m3. The dust control efficiency is above 80%, the overall dust efficiency is up to 94%, the dust reduction effect is obvious, and reduces the occupational hazards of workers.

Creep strain near crack front zone is one of the main driving forces in nuclear structural materials of stress corrosion crack propagation. To understand the effect of temperature variation on mechanical field near crack tip of nuclear structure material in high temperature water environment, compact tensile specimen was taken as an research object and ABAQUS finite element analysis software was also adopted, the Mise stress, plastic strain and creep strain near SCC crack tip region was studied. Results show that the area of the high-stress region decreases gradually with the increasing of the creep temperature, and its declining rate was faster and faster. The effect of temperature variation on the plastic strain is not very obvious. Temperature only has an obvious effect on a small scale near crack tip. With the increase of the distance from the crack tip, the effect of temperature on creep is gradually reduced.