Test Study And Application On Fines Content And Confining Pressure Influence The Mechanical Properties Of Tail Silty Sand

The quantity and size of tailing dams have increased sharply with mining activities.This may bring a series of environmental problems, such as the frequently and severelytailings dam accident, also do serious harm to the local people and surroundingecological environment. Seeing from the composition of tailing dams, tail silty sand isthe main material. The study of physical and mechanical properties of tail silty sand isone of the key parts of the tailing dam stability evaluation and its disease treatment.This paper selected tail silty sand as the research object, based on laboratory test ofparticle content, physical properties test, triaxial compression test and particle flownumerical test to study its physical and mechanical properties under different finescontent and confining pressure, then combined with artificial neural network to set up aprediction model about the strength parameter of tail silty sand. This paper also linkedwith engineering cases to discuss its practical applications. The main research content isas follows:(1) This paper designed six kinds of fine grain content (10%,20%,30%,40%,50%and60%) of tail silty sand sample, through particle size analysis, physical tests toresearch its proportion and void ratio. The results show that, when the fine grain contentis40%, the gradation characteristic is well, and if increasing or decreasing the content,gradation is gradually worse. However, the specific gravity and void ratio didn’t varyclearly with the fine grain content. When fine grain content increased, it increasesslightly.(2) Using laboratory triaxial compression test, four kinds of confining pressurecondition (100kPa,200kPa,300kPa and400kPa) are designed to research mechanicalproperties of those samples. The paper analyzed characteristics and reasons of itsmechanical properties under different fine grain content and confining pressure from theaspects of the specimen failure mode, the stress-strain curve characteristics, yieldstrength, peak strength, residual strength,initial modulus and tangent modulus.(3) Through the PFC3Dparticle flow numerical test technology, six kinds of finegrain content tail silty sand numerical sample described as above are generated, and themesoscopic simulation parameters can be gotten from the method that the numerical testfitting physical test of the stress-strain curve. Then, these parameters are used for nextnumerical test research. Based on the simulation results, the numerical tests reproduce the tympanites failure mode of the physical test, and reveal deformation and failuremesoscopic mechanism of tail silty sand with different fine grain content and confiningpressures.(4) Taking advantage of powerful nonlinear mapping ability of artificial neuralnetwork, the network model was gotten from training with strength parameters samplesof different fine grain content of laboratory triaxial test. This trained network wasapplied to strength parameters estimation in engineering site. The results show that theneural network model can satisfy the related engineering application basically.