Strength Problem Of Loess For Different Material Structure And Making Sample Method

There are obvious regional differences in material composition and structure of theloess. The strength of the different regions loess is obviously different. This is still alack of systematic research. It is difficult to grasp the size of loess strength of regionaldifferences. In addition, in the study of compacted loess engineering and indoor test, itoften appear different pressure actually realized the same dry density of soil moisturecontent. It is problem of much intensity differences in Sample preparation under thesame soil water content. Based on this, the paper compares with soil samples inLanzhou and Xi’an soil and research into strength for different material structure andmaking sample of Loess.It is research in composition differences of Lanzhou, Xi’an Soil samples. Lanzhousoil is clayey silt soil with coarse silt and bracket contact. Lanzhou soil is silty clay soilwith fine silt and basal cement. Xi’an clay mineral content of soil samples is highercontent in Lanzhou’s. Its specific gravity, liquid plastic limit are larger.Triaxial shear test, obtained calculated formula in ultimate strength and the moisturecontent and confining pressure of undisturbed loess in Lanzhou. Xi’an undisturbedloess of cohesive force is almost twice the undisturbed loess in Lan-zhou cohesiveforce. Xi’an undisturbed loess of internal friction Angle is smaller than Lan-zhou’s.Under the same condition of water content and dry density, Xi’an loess of the structuralstrength is far greater than the Lan-zhou loess’s.Based on the pressure plate test, it analyzed soil water characteristic curve fordifferent material structureand making sample of Loess. In the same dry density, watercontent of sample preparation conditions, Xi’an loess suction is greater than that ofLan-zhou loess suction. In common sample water content, sample preparation water of Lanzhou is smaller, the greater its suction. Sample preparation water of Xi’an issmaller, the smaller its suction. When soil moisture is small, matrix suction caused bydifferences in sample preparation more than15%.Further considering the differences in sample preparation and the strengthcharacteristics of loess has carried on the conventional triaxial test. Proved differentsample structure of shear strength parameters with sample water content was increasedand then decreased the tendency, with the dry density increases. Under the same drydensity, moisture content when large changes in sample preparation, sampledifferences caused greater shear strength parameters. Xi’an same soil sample structurecohesion is greater than Lanzhou soil cohesion, the internal friction angle is not overLanzhou’s but the difference is not big.Comparison based on true triaxial tests and triaxial test results of the analysis, theeffect of test size and the end effect on the test results. Under the same test conditions,the use of true triaxial tests measured shear strength parameter values were greater thanconventional triaxial tests measured. When the sample water content is small, the twotest methods shear strength parameters resulting difference is small, with sample watercontent increases, the shear strength parameters difference increases. Under truetriaxial test conditions, different sample structure Lanzhou loess, Xi’an loess shearstrength parameters are increasing with the increase in the principal stress ratio. Underthe same b values, with sample water content increases, the amplitude decreases soilcohesion magnitude greater than the reduced internal friction angle.