The Static And Dynamic Mechanical Behavior Of Coal Powder In Silo And The Structural Response

The coal bunker is typical kind in silo applications filed,its storage and throughput is one of the most important aspects of coal production in mining areas,directly decide the productive capacity of coal.The calculation of lateral pressure in silo wall during discharging is a key problem in the structural design,in most countries,the codes for coal bunker structural design are based on the modified Janssen formula.Due to lack of fully considering the influence of the stored material flow,the formula can not be used to calculate stored material pressure during discharging.The phenomenon of overpressure on the wall in dynamic is always the key to conduct research of silo failure mechaniam.In view of the silo discharge accidents occurred frequently over the years,it is urgent to plan further research of the static and dynamic pressure of wall and its structural deformation.Considering the change of the flowing state of coal powder and mechanical behavior of its influence on silo,this paper is based on the theory of discrete element method,in the establishment of coal powder model,conducting the software of EDEM and PFC3D respectively to stimulate the loading process of coal powder in silo and last this paper analyzed and compared the change of wall pressure and the law of overpressure,which find that The peak value of lateral pressure in static and dynamic are both located in the funnel side of transition section of the straight and the funnel,the lateral pressure ratio reached the peak in the upper of silo.Combined with the pressure results of silo from EDEM discrete element simulation,coupling with finite element method and the discrete element method,this paper has also utilized the finite element software Patran/Nastran to analyse the structure of the model of cylindrical bin and silo respectively,which find that dangerous position appears in the upper silo and conical transition during discharging.According to the change of the flow of coal powder in hopper,in view of theoretical calculation and numerical simulation,this paper has also analyzed the flow characteristics of coal powder in the conical funnel,pyramid funnel and hyperbolic funnel,and has draw a conclusion that hyperbolic funnel is most suited to discharge under the same conditions.Compare to conical funnel,the hyperbolic funnel could reach timesaving of a third nearly,the friction between stored material and wall is smaller.By using the design of pyramid warehouse bulk flow test device,which is used to make the test of coal powder flow and the pressure of wall,this paper has stimulated the best angle for discharging in the changing variables of particles size of coal powder and angle of hopper.On the basis of DH5923 dynamic signal test and analysis system,this paper test the lateral pressure by the way of indirect measure method and has concluded that the test of lateral pressure are basically consistent with theoretical distribution and the peak of pressure appeared at the lower straight silo.