筑坝粗粒料力学性质及本构模型参数试验研究

Experimental study on mechanical properties and constitutive model parameters of coarse-grained materials for dam construction

对某高坝筑坝粗粒料进行了大型三轴试验,分析了不同围压、级配下2种粗粒料的强度特性、变形规律。结果表明:2种粗粒料的应力—应变曲线具有明显的非线性,体变曲线整体变化规律为低胀高缩、先缩后胀,随着围压的增加,内摩擦角逐渐减小。低围压下,堆石料应力—应变曲线表现为硬化、体变变化为先缩后胀,砂砾料表现为软化、先缩后胀,峰值摩擦角随着围压的升高快速减小;高围压下,砂砾料由软化过渡为硬化,但堆石料在3000 kPa下出现软化、其他条件下均为硬化,体变均由剪胀过渡到剪缩,随着围压的升高,峰值摩擦角的减小速率逐渐变小。研究得到,邓肯—张E-B模型参数随着围压、密度、级配的变化呈规律性变化。

A large-scale triaxial test was carried out on the coarse-grained materials for a high dam to analyze the strength characteristics and deformation laws of the two kinds of coarse-grained materials under different confining pressures and gradations.The results showed that the stress-strain curves of the two kinds of coarse-grained materials have obvious nonlinearity.The overall change law of the volume deformation curve is low expansion and high shrinkage,first contraction and then expansion.With the increase of confining pressure,the internal friction angle gradually decreases.Under low confining pressure,the stress-strain curve of rockfill material is hardened,and the volume change is first contraction and then expansion.Sand gravel material is softening,first contraction and then expansion,and the peak friction angle decreases rapidly with the increase of confining pressure;under low confining pressure,the stress-strain curve of rockfill material shows hardening,volume change is shrinkage first and then expansion,sand gravel material is softening,shrinkage first and then expanding,and the peak friction angle decreases rapidly with the increase of confining pressure;under high confining pressure,gravel material changes from softening to hardening,but rockfill softens at 3000 kPa and hardens under other conditions,and the volume strain transits from dilatancy to shear shrinkage.With the increase of confining pressure,the decreasing rate of peak friction angle decreases gradually.The parameters of Duncan Chang E-B model change regularly with the change of confining pressure,density and gradation.