Granular Mixtures Microscopic Characteristic Analysis

Granular slope is widely distributed in arid mountainous areas of Western China,such as Xinjiang,Tibet and other places.Each slide has little momentum,but is very frequent and there is no long-term effective prevention and control measures Especially the development of the road on both sides of the granular slope,seriously affect the normal operation of highway slope.We have made great progress in the study of Activity patterns and Deformation Failure mechanisms,Grinding degree,uneven,the external factors on the granular slope disaster research self-organized properties and the stability factor gained a lot of knowledge,but the scope is limited to the macroscopic study,Microstructure of granular slope from top to bottom is different,making the deposit morphology and mechanical characteristics of the macroscopic are not identical.From the mechanical of Granular experimental study,reveal the inherent law between the bulk mechanical properties and micro structure change.Reveal the inherent regularity of mechanical properties and microscopic structure changeIn this article,taking Maoxian depression Xiang granular slope as the research object,through the slopes in situ sample acquisition,analysis,test method.From the microscopic view direction,understand the granular strength characteristics and micro structural changes of the granular slope,for providing the basis of analysis of failure mechanism,and provide the reference for the further research of the granular slope.The main contents of this article are as follows:(1)the use of wax sealing method and ethyl cyanoacrylate method to obtain the bulk in situ sampling technology is feasible,can really get bulk in situ kind of natural structure,density,porosity,contact among particles,filling characteristics.(2)the five slope debris sampling,analysis of each sample appearance characteristics,are: 1),from the perspective of the accumulation characteristics of slope,each accumulation slope as the cone,particle size increases from top to bottom in turn,porosity increased gradually;2),grain accumulation average grade is 38.42° slope,the slope of the upper slope was the steepest,average grade is 40.48°,The middle gradient is the smallest,The average gradient was 36.86° degrees.,The average gradient of the lower layer is 37.92°.;3),the grain particles fabric of the relationship between the contact number to gradually reduce from top to bottom,the contact force increases gradually,intergranular pore filler is less and less.(3)in the upper part of the ramp,the particles elongate,ellipsoid,the arrangement of low orientation degree,and more to the surface-surface contact,line-the main surface contact,the pores are filled more small particles or clay,small porosity;in slope,the lower part of the large particle size,mainly elongated strips arranged directional high-contact and more to the line-surface contact point-surface contact-based,inter-particle pores clear,uniform size,fill it less,and many more are not populated based.(4)By mechanical properties and Direct shear test of granular mixtures,Can be obtained: 1),in the absence of positive pressure,the shear force with the change of particle size,gradation difference changes;2),the normal stress condition,gradation and particle size effect on the shear strain huge;normal stress increases,the shear stress increases.(5)the variation of the shear process of fine particles were observed in the positive view,load and different mixing ratio of particle diameter,particle can be divided into the rotation in the shear plane sliding movement,rotation,sliding groove,groove-rotation.(6)the positive pressure is zero,the initial particles arranged in loose,as the shear box mobile,particles can be compressed volume,followed by dilation;if the particles are in positive pressure conditions,particles are arranged closely,the pores will directly into the expansion of the state as the shear.(7)During shearing,Granular particles happen redistributed continuously,Force chain regrouped to form a new framework;the vertical pressure is,the more the number of reconstruction.