土石混填体抗剪强度特性及影响因素的试验研究

Experimental studies of shear strength characteristics and influencing factors of soil-rock aggregate mixture

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,其抗剪强度特性主要受含水率、含石量、颗粒级配及压实度等因素的影响。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,随不均匀系数的增大,土石混填体抗剪强度先增加后减小,不均匀系数在22.99左右时取得峰值,而曲率系数对其影响较小;土石混填体的抗剪强度分别随着含石量、压实度的增加而不断增加,但当压实度超过92.5%后增加趋势变缓。随着含水率的增长,其抗剪强度先增加后减少,在最优含水率附近时达到峰值。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R^2大于0.9。

Soil-rock aggregate mixture is one type of non-homogeneous dispersion material mixed by rock and soil. Its shear strength is mainly affected by the moisture content, rock content, particle gradation and the degree of compaction, etc. On the basis of previous studies and the lab large-scale direct shear tests, this study considers the effect of gradation parameters, attains the required degree of compaction level by controlling the quality and volume of samples, and analyzes the influence of the main parameters on the Shear strength. The results show that, in well-graded case, as nontmiformity coefficient increases, the shear strength increases first and then decreases, and achieved peak when the coefficient is around 22.99, while little impact by the coefficient of curvature. The shear strength of soil-rock aggregate mixture increases with the increasing rock content and compaction degree respectively, but the increases less when the degree of compaction is more than 92.5%. The shear strength decreases after the first increase with the increasing moisture content, and peaks at near optimum moisture content. Based on the Matlab＇ multivariate linear regression analysis, the order of primary and secondary influencing factors on the shear strength is rock content 〉 moisture content〉 degree of compaction 〉 nonuniformity coefficient 〉 coefficient of curvature. Through the regression analysis of test results, fitting formulas of it＇s shear strength are obtained with correlation index R2 bigger than 0.9.