The Iron Oxide Colloid Influence On Soil Shear Characteristics Of Collapse

The free iron oxide colloid contained in the soil is one of the factors that affect the shear strength of the soil,which is due to its interaction with the clay minerals to make the soil particles have a certain structural strength.In this paper,the shear strength of each soil layer is studied by triaxial shear test in the soils containing three different layers of iron oxide colloid in soils of three soil layers(red soil layer,sand layer and debris layer)The reason for such a change.The four iron oxide content gradient samples were set to blank samples,remove 1/3 of the iron oxide sample,remove the 2/3 iron oxide sample and completely remove the iron oxide sample,and remove the free Iron oxide colloid before and after the physical and chemical properties of change,microscopic scanning and other aspects of the analysis of soil shear strength caused by factors.After the experimental study,the main results are as follows:(1)After removal of free iron oxide by DCB method,the content of clay particles in the three soil layers increased obviously,while the content of large particles decreased obviously,and the change of red soil layer was the most obvious.This is due to DCB treatment,the large particles of iron oxide and clay minerals interact with the formation of aggregates were destroyed,the original adsorption of coarse particles in the surface of the release of clay particles,as a component of cosmid,the clay content increased.(2)The micro cementing of ferric oxide colloid is one of the guarantees of soil strength.Since the hydrogen bond and the electrostatic attraction force are generated between the goethite and the kaolin,the free iron oxide in the soil is mainly in the form of "bridge" or "coating" and the clay mineral and other particles form a joint state Grain between the particles,so that the formation of aggregates particles.As the agglomerates are embedded in the pores,the sliding friction of the contact surface is increased,and the large pores are filled into small pores,and the porosity is reduced to make the structure more stable.When the iron oxide colloid is removed,the cemented hydrogen bonds are broken,resulting in the fracture of the cemented iron colloid and clay minerals,the gravitational force disappears,the coupling state is destroyed,the aggregate structure is destroyed and the structural strength decreases.(3)From the overall analysis,it can be concluded that the shear strength of the sample decreases with the increase of the water content,and the shear strength of the complete removal of the Fed specimen is increased with the increase of the moisture content.It is shown that the iron oxide colloid can change the shear strength of the soil by affecting the morphological characteristics of the particles and arranging the combined structure and porosity.The iron oxide colloid is mainly by changing the soil cohesion and the size of the internal friction angle to change the soil shear strength.When the water content is constant,the cohesion and internal friction angle of the three soil samples decrease with the increase of the specific gravity of the iron oxide colloid in the sample,but the removal of the sample The clay particles are completely released,the adsorption capacity of the clay particles is enhanced,the capillary cohesion is increased,and the uniformity of the grain structure is small,and the gravitational force between the molecules is easy to be formed,and the cohesion of the partial sample is increased under suitable conditions.(4)The cementation of iron oxide colloid and clay minerals has a significant effect on the structural strength of collapsed soil.The change of the partial stress of the soil by the soil shows that with the decrease of the colloidal content of the iron oxide in the sample,the blank sample is removed,the 1/3 iron oxide sample is removed,the 2/3 iron oxide sample is removed,the iron oxide test is completely removed The overall shear strength values tend to decline.But the downward trend is not all "step"type of decline,but with the free iron oxide colloid play stage,so that it has a stage and the overall impact of the ability.In addition,when the free iron oxide in the three soil layers is completely removed,the partial stress of the specimen increases.