The Deformation And Strength Characteristics In Saturated-unsaturated Remodeled Loess

Loess is a special soil. Since loess is a common geotextile material in Western China, it can notonly be used as building materials but also as environment of some projects. Lots of scholars hadcarried research or practice on the distribution, formation, behavior and strength deformationcharacters on loess, and they all made remarkable achievements. However, for thesaturated-unsaturated loess with different initial moisture contents, its stress-strain, volume strainas well as strength characteristics are of rare published.Based on the existing study results, this article takes Q2loess in Yan’an Shaanxi Province as theresearch subject. After the improvement of unsaturated soil triaxial apparatus, a series ofconsolidation drained shearing tests within saturated-unsaturated remodeled loess samples(ρd=1.6g/cm3) by controlling their moisture contents under conventional triaxial compression(CTC) stress path are carried. First of all, aiming at the strain test results, the qualitative analysisof stress-strain and deformation characters with different moisture contents as well cell pressure isconducted. Then, combined with the stress results, the quantitative analysis about the strengthcharacters is carried on. The conclusions are as follows:(1) The stress-strain curves of remodeled loess are changing from strain soften type to stable andstrain harden type as the moisture contents change. Thus, liner, hyperbola and power functionswill have better fitting over them separately. Cell pressure has little impact on the stress-strainforms of remodeled loess.(2) When suffering from stress, the ability of remodeled loess samples to resist deformationwill decrease as the moisture content increases, and their amounts of volume change are closelyrelated to moisture content as well. Loess sample with lower moisture content will deliver a“dilatancy” phenomenon when it sheared, while the one with higher moisture content will deliverthe “shrinkage” phenomenon. The soil volume change trend from expansion to shrinkage can alsobe controlled by increasing cell pressure.(3) The remodeled loess samples’ cohesion and internal friction factor are nonlinear decreasewith the increase of soil moisture content. There are some special moisture points controlling thevariation trend of cohesion and internal friction factor, so these points can be used to express thenonlinear relationship as the power function form. In this paper, taking moisture content as a state variable, the shearing strength and ultimate load ofunsaturated loess can be estimated. Since the estimation formula has an advantage of simpleexpression, less parameters, specific physical meaning, and safety estimation results, it will be aconvenient way to calculate the strength of soil with any given moisture content in engineeringpractice.