基于广义塑性模型的加筋面板堆石坝数值模拟

为研究地震作用对混凝土面板堆石坝采用的混凝土是否加筋有何影响,基于堆石料的静动力大三轴试验结果,构造了能考虑剪应力水平影响和堆石料颗粒破碎的一个简洁塑性模量表达式,建立了适用于堆石料的广义塑性本构模型。本构模型模拟曲线与三轴静动力试验曲线的对比结果表明:该模型能较好地模拟堆石料在低围压下的剪胀性和高围压下的剪缩性,以及在循环荷载作用下的滞回效应、硬化特性和循环致密性等复杂应力状态。此外,利用该模型的高面板堆石坝动力有限元计算结果表明:加筋前后地震加速度和永久变形的分布规律一致。加筋对大坝的地震反应加速度影响较小,却可有效地减小大坝的地震永久变形;加筋对顺河向地震永久变形的抑制作用大于震陷。加筋间距越小,大坝的地震永久变形越小,但地震永久变形的减小幅度逐渐降低。研究成果可为混凝土面板堆石坝的施工设计提供参考。

Generalized plastic model-based numerical simulation of reinforced concrete face rockfill dam

In order to study what kinds of effects from seismic action on whether the concrete of the concrete face rockfill dam is necessary to reinforced or not，a simple plastic modulus expression which can considers both the influence of shear stress level and the grain crushing of rockfill material is constructed，and then a generalized plastic model suitable for the rockfill material is established. The result from the comparison made between the simulated curve of the constitutive model and the curve o3ained from the triaxial static and dynamic test shows that both the shear-dilatancy under low confining pressure and the shear-contraction under high confining pressure as well as the complicated stress states，i． e. hysteretic effect，hardening characteristics and cyclic compactness，etc. under cyclic loading effect，of the rockfill material can be better simulated by the model. Moreover，the result from the dynamic finite element calculation of high concrete face rockfill dam made by this model indicates that the distribution laws of the seismic acceleration and the permanent deformation before and after reinforcing are consistent. The reinforcing has less effect on the acceleration of seismic response of the dam，but can effectively decrease the permanent deformation of the dam， while the restraint effect of reinforcing on the seismic permanent deformation along the river is greater than that of the seismic subsidence. The smaller the reinforcement spacing is，the less the seismic permanent deformation is to be，but the decreasing amplitude of the deformation is to be gradually decreased. The study result can provide a reference for the construction of concrete face rockfill dam.