基于大型动三轴试验的筑坝砂砾石料动模量和阻尼比研究

为获得筑坝砂砾石料的动模量、阻尼比参数及其影响因素和影响规律,采用大型动三轴试验仪,对某沥青混凝土心墙砂砾石坝的筑坝砂砾石料进行了动模量、阻尼比试验,研究了筑坝砂砾石料的动应力-动应变特性,分析了围压对最大动模量、动剪切模量比和阻尼比的影响,并以修正等效线性模型为基础,确定坝壳料和过渡料的动模量和阻尼比等特性参数。试验结果表明:随着围压增大,筑坝砂砾石料的动剪切模量增大,阻尼比减小;随着动应变的增大,动剪切模量比逐渐减小,阻尼比变大;修正等效线性模型引入归一化动应变,能较好地消除围压对动模量衰减规律和阻尼比的影响,能较准确地反映筑坝砂砾石料的动力变形特性。研究成果可为类似工程提供借鉴和参数 。

Dynamic Modulus and Damping Ratio of Sandy Gravel Material Based on Large-scale Dynamic Triaxial Test

The dynamic modulus and damping ratio of sandy gravel material of a sandy gravel dam with asphalt concrete core wall are tested by large dynamic triaxial tester. The dynamic stress-strain characteristics of sandy gravel dam material are studied. The influence of confining pressure on the maximum dynamic modulus, dynamic shear modulus ratio and damping ratio is analyzed. The characteristic parameters such as the dynamic modulus and damping ratio of the dam shell material and transition material are determined using the modified equivalent linear viscoelastic model. Test results show that with the climbing of confining pressure, the dynamic shear modulus of sandy gravel dam material increases while damping ratio decreases. With the growth of dynamic strain, the dynamic shear modulus declines while damping ratio increases. By incorporating normalized dynamic strain into the modified equivalent linear model, the influence of confining pressure on dynamic modulus attenuation and damping ratio are better eliminated, and moreover the dynamic deformation characteristics of sandy gravel dam material are more accurately reflected.