Experimental Study On Influence Mechanism Of Microstructure Of Phosphorite On Macro Damage

With the depletion of phosphorus,phosphorus mining is gradually shifting from open to underground mining,which depth is greater than 300 metres.Compared with previous shallow mining,the high stress in deep mining causes more serious rock explosion,how to prediction and prevention of rock explosion is new problem to be solved.Therefore,this paper is based on the engineering background of HouPing Mine belonging to XingFa Group,which is a very deep phosphate mine in northern Yichang,Hubei Province,with a depth of 500 to 700 metres,a few more than 1000 metres.In this paper,the microfracture form of phosphate rock is studied,the law of microfracture is found out,and the mechanism of the influence of microfracture on macrofracture is obtained.On this basis,it provides the basis for safety prediction and prevention in deep underground mining and underground engineering.In order to study the micro structure and failure rule of phosphate block rock and its influence mechanism on macroscopic damage,the following main work is carried out:1.A large number of research achievements on rock microstructure at home and abroad were collected,and the laws of rock microfracture and its effect on macroscopic damage were reviewed;2.Field research to obtain detailed geological data and useful information,observe rockburst phenomenon,and select representative samples;3.The basic physical and mechanical parameters and the stress and strain curves were obtained by the indoor uniaxial and triaxial tests.By means of acoustic emission experiment,the tendency of phosphorus block rock fracture and the integrity of rock samples were evaluated accordingly,also select representative samples of broken debris;4.Using microscanner and element mass dpectrometer to analyze microstructure and element composition of phosphate block rock broken debris in order to find out the reason of rock macroscopic fracture from macroscopic angle.Results of the study: 1.the compressive strength obtained through the uniaxial loading test of rock is transformed into the standard maximum compressive strength of rock.The more the rebound times according to the stress strain curve of rock samples,the more complex the internal structure is,the worse the integrity of the rock is.2.according to the acoustic emission results of the three axis experimental rock samples,there are morepores in the interior,and the cracks will be compacted first when the pressure is pressurized and there are more acoustic emission events.Under the same confining pressure,the number of acoustic emission of the top and bottom rock samples is more than that of the phosphorite.It is indicated that the dolomite and the cemented phosphate rock in the phosphorite have been cemented with most pores and the structure is more compact.3.the influence of grain arrangement pattern on the strength of phosphate rock is greater than that of the constituent material composition to its strength.4.In the process of phosphorus rock failure,the first crack and failure should be the poor cemented crystal interface.When the force reaches a certain value,the cementation surface of dolomite first breaks down,indicating that the grain boundary of dolomite is the weak boundary of grain boundary.The macroscopic fracture and the micro fracture of phosphorite are uniform.