花岗岩残积土的动剪切模量和阻尼比试验研究

以广东台山花岗岩残积土为研究所对象,采用共振柱试验方法对不同应力状态下花岗岩残积土的动剪切模量G和阻尼比D进行测试,并进行模型适用性分析.结果表明,动剪切模量G与应变γ的关系整体呈典型双曲线形态分布,围压σ_0~'对G-γ曲线的影响随γ增大逐渐减小;围压对D-γ关系的测试结果影响不明显;双对数模型能够反映最大剪切模量G_(max)随围压的非线性递增趋势,工程中可以采取该模型对G_(max)参数进行预测;小应变下,土体G-σ_0~'关系曲线较为接近,当γ>10~(-5)时,各围压下G值衰减较快,工程参数选取时,应注意小应变范围内剪切模量随应力状态(深度)的变化差异.根据Martin-Davidenkov模型及选用的阻尼比经验公式对动力参数G/G_(max)和D进行拟合分析,并给出了小应变下动力参数的推荐值,可为同类工程提供技术参考.

Experimental Study on the Dynamic Shear Modulus and Damping Ratio of Granite Residual Soil

Taishan granite residual soil was taken as the research object,the dynamic shear modulus G and damping ratio D of granite residual soil under different stress states were studied and predicted by resonance column test.The model prediction analysis was carried out. The research shows that the test points of G-γ present typical hyperbolic distribution,and the influence of confining pressure decreases with theγ increased. The influence of confining pressure on the relationship between D and γ is not obvious. The double logarithmic model may reflect the relationship between G_(max) and γ,the model can be used to predict the parameters of G_(max). Under the small strain,the curves of the relationship between G and γ of the soil under different stress states are close to each other,when the γ >10~(-5),the G value decreases rapidly under various confining pressures. In the selection of engineering parameters,attention should be paid to the variation of shear modulus with stress state( depth) in small strain range. Martin-Davidenkov model and the empirical relationship between D and γ has been used to built the variation law of G/G_(max) and D with γ,and the dynamic shear modulus and damping ratio of small strain range are used as recommended values. This study may provide technical reference for similar projects.