| In the vast loess area loess usually be as roadbed filler filling in subgrade,The stability ofloess subgrade largely determines the performance and operational status of the road.CBR asan important parameter for flexible pavement design and strength of roadbed filler indicatorshave important influence to the strength of road.Currently, the values of CBR are usuallyselected using uniform standards, which is significantly differ from the actual.If weatherconditions can be combined in various regions as the reasonable value in selected CBR willhave significant implications for the design and construction of roads.In order to study the variation of CBR value under the influence of different factors,inthe article take the loess of Gansu Kongjiayuan and Shanxi Shijiazhuang loess section as thestudy object,through the CBR laboratory tests to study the factors of CBR value of the twoloess sections.By using the experimental design method of quadratic regression orthogonal tostudy the loess samples of Shijiazhuang sectional.Design CBR values under differentcompactness, moisture content and soaking time three factors and four levels of orthogonaltest to study the different effects of various factors.According to the experimental results ofquadratic regression orthogonal reach conclusion formulas about CBR value in three factors.Through analysis,obtained the variation of loess CBR values in univariate and multivariateeffects.The loess samples of two sections were in certain times of (respectively1,3,5,7,10times) freeze-thaw cycles.Tests all conduct at the heavy compaction standard under optimummoisture conditions.Through experimental study obtained the changes of specimen surfacecondition, reach conclusion about the variation of CBR values and internal moisture beforeand after soaking after freezing-thawing. Through analysis the results of test obtained thevariation of CBR at various factors. It have important significance for the design andconstruction in loess subgrade area. |
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