【作者】 刘建军；

【导师】 赵明华； 蒋德松；

【作者基本信息】 湖南大学 ， 岩土工程， 2016， 硕士

【摘要】 土石混填体是一种由土体和块石混合形成的非均质散体材料,广泛应用于山区、丘陵地带的公路建设之中,其工程力学特性也备受人们的关注。由于该材料具有物质组成的复杂性,结构分布的不规则性,给其工程力学特性研究和工程应用带来了极大的困难。国内外众多学者对其力学特性、路用性能等进行了一系列的试验与理论研究,也得出了较多的研究成果。但各研究成果之间难以互相对比,且在工程实践中还存在着较多的问题和不足,有待于进一步完善和发展。首先,对土石混填体的路用性能进行研究,主要包括土石混填体的颗粒组成、颗粒级配以及击实特性等。由此了解土石混填体的路用性质,并获得不同颗粒组成条件下的压实最佳含水率与最大干密度,为后续的土石混填体大型直剪试验的试样制作提供依据。其次,基于室内大型直剪试验,在前人研究的基础上,考虑级配参数的影响,通过控制试样质量与体积达到试验所需的压实度水平,分析了各主要参数对土石混填体抗剪强度的影响规律。试验结果表明:在级配良好的情况下,含石量在50%~80%范围内,土石混填体的抗剪强度随着含石量的增加而增加。基于matlab多元线性回归分析,得出了各因素对土石混填体抗剪强度影响程度的主次顺序为:含石量>含水率>压实度>不均匀系数>曲率系数,通过非线性回归分析得到了其抗剪强度关于各因素的拟合公式,且相关指数R2大于0.9。最后,利用直剪试验得出的土石混填体抗剪强度指标,基于强度折减有限元法对土石混填体路基边坡稳定性进行分析,并探讨不同含石量情况对土石混填体路基边坡稳定安全系数和最危险滑动面的影响。得到如下结论:随着土石混填体含石量的增加,边坡进入极限状态时的最大应力值和最大拉应力值在逐渐增大,而其最大塑性应变与最大位移值均逐渐减小。边坡的安全系数也随含石量的增加而逐渐提高,呈现非线性增长趋势,且当土石混填体的含石量从50%增长到60%时,路基边坡安全系数的提高较为明显。更多还原

【Abstract】 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.更多还原