Engineering Characteristics And Stability Analysis Of Soil-rock Aggregate Mixture Roadbed

Soil-rock aggregate mixture is a kind of non-homogeneous dispersion material mixing by rock and soil formation, which widely used in the highway construction of mountain area and hilly terrain, the engineering mechanical properties are attracted widespread attention. There are great difficulties of the engineering mechanics characteristic research and engineering application about it, Because of the complexity of material composition and the irregularity of structure distribution.Many scholars at home and abroad obtained lots of research results by conducted a series of experiments and theoretical research for its mechanical properties and road performance. But it’s difficult to contrast each other between various research results,and there are still many problems and insufficiency in the engineering practice, which need to be further improved and developed.First of all, the road performance of soil-rock aggregate mixture was studied in this paper, mainly including particle composition, particle gradation and the compaction characteristics, etc. Thus, we acquainted the road performance of the soil-rock aggregate mixture and obtained the optimum moisture content and maximum dry density under different particles in compaction, which provided the basis for sample making of the subsequent Large direct shear test.Secondly, On the basis of previous studies and the lab large-scale direct shear tests, as well as considering the effect of gradation parameters, this paper explored the influence law of the main parameters on the shear strength through attaining the required degree of compaction level by controlling the sample’s quality and volume,.The results showed: Under well-graded case and stone content varying between 50% ~80%, the shear strength increases along with the increase of the amount of stone containing. Based on the Matlab’ multivariate linear regression analysis, the primary and secondary order of the influencing degree of the above various factors to the shear strength was: the rock content > the moisture content> the degree of compaction >nonuniformity coefficient > coefficient of curvature. Through the regression analysis of test results, the fitting formulas of its shear strength were obtained with the correlation index R2 bigger than 0.9.Finally, based on strength reduction finite element method, this paper analysed the Soil-rock aggregate mixture subgrade slope stability by using the soil-rockaggregate mixture shear strength parameters getted by the direct shear test, and explored the influence on subgrade slope stability safety factor and the most dangerous sliding surface of the different stone content. The studies showed: The maximum stress and tensile stress values under limit state gradually increased along with the increasing of the amount of stone containing, while its maximum plastic strain and displacement values gradually reduced. The safety factor of slope also increased with the percentage of rock being improved, which showing a non-linear growth trend. And when the amount of stone containing increased from 50% to 60%,the increase of subgrade slope safety factor was more obvious.