纤维增强橡胶砂复合土动力学特性室内试验研究

Dynamic characteristics of fiber reinforced rubber sand composite soil

针对橡胶颗粒与土混合而成的散粒体作为地基回填材料时承载力可能下降和变形较大的缺点,本文提出在该混合料中加入聚丙烯纤维进行改良,通过共振柱试验研究了橡胶含量、纤维含量和有效围压对混合复合土动剪切模量和阻尼比的影响。结果表明:随着橡胶含量R_(C)、纤维含量F_(C)和固结围压σ_(3)的增大,复合土动剪切模量的衰减及阻尼比的增长均有所减缓。复合土的最大动剪切模量G_(max)受R C和σ3的影响较大,受F C的影响较小,提出了G_(max)与R_(C)、F_(C)、σ_(3)的经验拟合公式。同时,本文给出了复合土G/G_(max)~γ曲线在Davidenkov模型中参数A和B的建议值,及参数γ_(0)与F_(C)的线性增长公式。并对复合土的阻尼比增长曲线进行拟合,给出了不同工况下λ_(min)、λ_(0)、β与F_(C)线性拟合公式。

In view of the shortcomings that the bearing capacity may decrease and the deformation is large when the granular mixture of rubber particles and soil is used as the foundation backfill material,this paper proposes to add polypropylene fiber to the composite soil for improvement.The effects of rubber content,fiber content and effective confining pressure on the dynamic shear modulus and damping ratio of the mixture were studied by resonance column test.The results show that with the increase of rubber content R_(C),fiber content F_(C)and consolidation confining pressureσ_(3),the attenuation of dynamic shear modulus and the increase of damping ratio of composite soil are slowed down.The maximum dynamic shear modulus G_(max)of composite soil is greatly affected by R C andσ3,and less affected by F C.And the empirical fitting formula of G_(max)with R_(C),F_(C)andσ_(3)are proposed.At the same time,this paper gives the recommended values of parameters A and B in the Davidenkov model of the G/G_(max)~γcurve of the composite soil,and the linear growth formula of parameterγ_(0)and F_(C).The empirical formula proposed by Chen et al.is used to fit the damping ratio growth curve of composite soil,and the linear fitting formulas ofλ_(min)、λ_(0)、βand F_(C)under different test conditions are given.