黄河三角洲粉质土的动模量和阻尼比试验研究

结合室内共振柱和动三轴实验,对黄河三角洲饱和原状粉质土体(粉土、粉砂、粉质粘土)动模量和阻尼比的影响因素和发展规律进行了详细的研究。研究表明,在粉粒和粘粒含量对动模量的共同影响中,粉粒含量起着举足起重的作用;侧限压力对归一化剪模比和阻尼比的影响均较显著,相比粘粒含量的影响不大。通过与Seed建议的砂土及饱和粘土的G/Gmax~γ曲线和λ~γ曲线进行对比,结果显示研究区的粉质土相比一般的砂土和饱和粘土而言,其动力变形特性更接近于砂土,但是与砂土也存在着非常明显的差异;其发展规律与其他地区沉积粉质土也较为不同,具有明显的区域性。采用修正了的Hard in-D rnevich模型和对数模型分别对G/Gmax~γ曲线和λ~γ曲线进行拟合,给出了三类粉质土的归一化动力变形G/Gmax~γ/γr关系曲线,对模型中有关参数的影响因素做了初步的探讨。

EXPERIMENTAL STUDY ON SHEAR MODULUS AND DAMPING RATIO CHARACTERISTICS OF SILTY SOIL IN THE DELTA OF YELLOW RIVER

Based on resonance column method and dynamic triaxial tests, shear modulus and damping ratio characteristics of saturated silty soil (silt, silty sand or silty clay) in the delta of Yellow River were studied in detail. The results show that the silt content has a great influence on dynamic shear modulus. Normalized shear modulus and damping ratios vs. shear strain curves are both affected by confining pressure, and the effect of clay content is not significant. By comparing test results with the modulus reduction and damping ratio curves for sand and saturated clay suggested by Seed, once can conclude that the dynamic characteristics of deformation of the silty soil is very similar to those of sand, but there is a distinct difference. The trend of the modulus reduction and damping ratio curves from our test is also different with silty soils in other area. Modified Hardin-Drnevich models and logistic models are used to describe the trend of the normalized modulus reduction curves and damping ratios vs. shear strain curves in the paper.