基于超大型三轴仪的堆石料动力特性缩尺效应研究

堆石料的缩尺效应是导致高土石坝变形预测不准的重要因素之一，目前针对堆石料静力缩尺效应的影响已有部分研究，但针对堆石料动力变形特性的缩尺效应研究仍十分鲜见。本文对两河口板岩及古水玄武岩开展了超大型(试样直径800 mm，最大粒径为160 mm)和常规大型三轴(试样直径300 mm，最大粒径为60 mm)动剪切模量和阻尼比试验，研究了平行相似级配条件下最大粒径对最大动剪切模量、动剪切模量比、阻尼比以及沈珠江等效线性模型参数的影响。试验结果表明：①超大型三轴试验的最大动剪切模量大于常规大型三轴试验，随着动剪应变的增大，超大型和常规大型三轴试验的最大动剪切模量差别逐渐减小;②超大型三轴试验的动剪切模量比G_d/G_dmax小于常规大型三轴试验，即超大型三轴试验的动剪模量比衰减得更快;③超大型三轴试验的阻尼比大于常规大型三轴试验，随着动剪应变的增加，二者的差距逐渐增大;④超大型三轴试验得到的沈珠江等效线性模型参数k₂、k₁以及λ_max分别是常规大型三轴试验的1.14~1.32倍、1.26~1.31倍以及1.31~1.44倍，超大型和常规大型三轴试验得到的模量指数n差别不大。本文研究成果可为同类工程动力响应分析提供更加合理的试验与数值计算依据。

Experimental study on scale effect of dynamic characteristics on rockfill materials using super large-scale triaxial apparatus

The scale effect of rockfill materials is one of the significant factors leading to inaccuracies in the deformation prediction of high rockfill dams.Currently，there have been partial studies on the static scale effect of rockfill materials，but research on the scale effect of dynamic deformation characteristics of such materials remains relatively scarce.This paper conducts dynamic experiments on Lianghekou shale and Gushui basalt with sample diameters of 800 mm(maximum particle size of 160 mm) for super large-scale test and sample diameters of 300 mm(maximum particle size of 60 mm) for conventional large-scale test.The study investigates the influence of maximum particle size on the maximum dynamic shear modulus，dynamic shear modulus ratio，damping ratio，and the Shenzhujiang equivalent linear model parameters under parallel grading conditions.The experimental results show that the maximum dynamic shear modulus in super large-scale tests is greater than that in the conventional large-scale tests.As the dynamic shear strain increases，the difference in dynamic shear modulus between super large-scale and the conventional large-scale triaxial tests gradually diminishes.The dynamic shear modulus ratio G_d/G_dmax in super large-scale triaxial tests is smaller than that in conventional large-scale triaxial tests，indicating that the dynamic shear modulus in super large-scale triaxial tests decays more rapidly.The damping ratio in super large-scale triaxial tests is greater than that in conventional large-scale triaxial tests.As the dynamic shear strain increases，the difference between the two gradually enlarges.The Shenzhujiang equivalent linear model parameters k₂，k₁，and λ_max in super large-scale triaxial tests are 1.14-1.32 times，1.26-1.31 times，and 1.31-1.44 times those in the conventional large-scale triaxial tests，respectively，while the modulus exponent n in super-large scale and the conventional large-scale triaxial tests remains nearly consistent.The research findings presented in this paper provide essential and more reasonable experimental and numerical basis for dynamic response analysis in similar engineering applications.