Study On Shearing Dfformatiom Of Loess Based On Digital Image Processing Technique

There are some advantages such as non contact and high precision that usingdigital image processing technique to measure the deformation of less samplein the process of triaxial test.Combine digital image processing technique withtriaxial test,experimental study the loess triaxial shear band formation atdifferent densities, confining pressure, moisture content under. By digitalimage processing technique unique to the axial and radial strain and strainvectors, intuitive research shear band formation and its distribution.Can befound:With the gradually increasing moisture content, soil samples showed moreeasily compressed,This is because the moisture content of the soil causes achange in the original structure of the sample.In the optimum moisture content,soil samples axial deformation is relatively concentrated, mainly in the middle1/3of the area, radial deformation distributed throughout the soil surface,the relatively concentration in the middle1/3of the area.At low confiningpressure, undisturbed soil samples stress-strain curve showed softening, thecurve has a distinct peak deformation and the deformation concentrated and largeamount,shear deformation of the specimen has significant shear band formation.Inthe high confining pressure, specimen deformation is uniform, has no localsoftening phenomenon, and therefore, the stress-strain curve is the hardeningor weak hardened， sample shear deformation has no apparent shear bandformation.For remodeling samples at high confining pressure,the axialdeformation is in the middle1/3of the area, the upper and lower distributionhas smaller radial deformation，with the increment of confining pressure, radialdeformation will be decrease,and the distribution is in the sample local position,confining pressure has little effect on remodeling soil sheardeformation.Density for remodeling sample shear band formation studies showed that thegreater the density of the sample showed the stronger ability to resistdeformation.The different parts of the sample shear deformation results thatdue to the take samples and specimens base,causes the upper and lower contacthas a certain frictional resistance with the sample cap,limit its lateraldeformation,therefore,it has a relatively small deformation,deformation rateis also slower.In general,in the middle of sample has a large amount ofdeformation,and the deformation rate is quickly,the upper and lower deformationhas relatively small, the deformation rate is also slower.The middle deformationgreater than the overall average deformation of thespecimen,therefore,deformation of the middle specimen is more true reflectionon the shear deformation characteristics of undisturbed loess,based on digitalimage processing technology can be better reveal the shear deformation of loess.The impact of structural to the shear deformation is the undisturbed loesshas native structural strength,before the structure breaking can withstandwithout a larger load,has a small amount of deformation.But with increasingprincipal stress difference，the structure of undisturbed loess is completelydestroyed，undisturbed loess and loess remodeling deformation tends to be close，the final amount of deformation is very close.