陕北砒砂岩与砂复配路基土动模量与阻尼比研究

Dynamic shear modulus and damping ratio of compound subgrade mixed by arsenic sandstone in northern Shaanxi region and sand

将砒砂岩与福建标准砂混合制成复配土,利用GDS土动三轴仪,研究了不同条件下复配土动剪切模量与阻尼比随动剪应变的发展演化规律,提出了动剪切模量比的对数衰减模型与阻尼比的对数增长模型,通过对试验数据进行归一化处理,讨论了模型参数与复配土质量比、含水率之间的关系,并对比分析了不同质量比、含水率的复配土在达到破坏动应变时的动应力幅值,确定了复配土最大动强度时对应的砒砂岩和标准砂的质量比,为沙漠地区路基采用复配土处理地基提供理论依据。试验结果表明:砒砂岩与砂复配土发生大应变时动本构关系可用双曲线模型进行描述,模型参数与砒砂岩和砂的质量比、含水率相关;当含水率一定,砒砂岩与砂的质量比约为7∶3时,复配土动强度达到最大值;当质量比一定,复配土动剪切模量比衰减模型的参数M,N,其均随着含水率的增大而减小;阻尼比增长模型的参数P随着含水率的增大逐渐增大,参数Q则随着含水率增大而减小,质量比和含水率对其动力特性影响显著。

The evolution laws of dynamic shear modulus and damping ratio of the compound soil mixed by the arsenic sandstone and the Fujian standard sand along with dynamic shear strain are studied by using the GDS dynamic triaxial apparatus for soils.A logarithmic attenuation model for dynamic shear modulus ratio and a logarithmic growth model for damping ratio are proposed.The relationship between the model parameters and the mass ratio and water content of the compound soil is discussed by normalizing the test data.The dynamic stress amplitudes of the composite soil with different mass ratios and water contents reaching the failure dynamic strain are compared,and the mass ratio corresponding to the maximum dynamic strength is determined so as to provide a theoretical basis for the treatment of desert roadbed by the composite soil.The results show that the dynamic constitutive relation for the composite soil of arsenic sandstone and sand can be described by the hyperbolic model,and the model parameters are related to its mass ratio and water content.When the water content is constant,the optimal mass ratio of arsenic sandstone to sand is about 7∶3.When the mass ratio is constant,the model parameters M and N of the attenuation model for the dynamic shear modulus ratio the composite soil decrease with the increase of the water content.The model parameter P of the growth model for the damping ratio increases with the increase of the water content,and the parameter Q decreases with the increase of the water content.The mass ratio and water content of the compound soil have significant influences on its dynamic characteristics.