全级配混凝土轴拉应力-变形全曲线试验研究

Test study on the tensile stress-deformation curve of fully-graded concrete

全级配混凝土拉应力-变形全曲线是大坝非线性反应计算与极限抗震能力分析中的一个重要指标。本文利用先进的全数字化闭环控制大型材料试验机,采用位移控制的加载方式,对最大骨料粒径为150 mm的Ф450 mm×1 300 mm的圆柱体试件进行轴向拉伸试验,研究应变率约为10-7s-1时混凝土试件测距内的受拉变形随拉应力变化的全过程曲线。达到峰值荷载后,在不同的应力水平下对试件进行往复多次加、卸载,研究全级配混凝土软化段加、卸载曲线的特点。拟合全级配混凝土轴拉应力-变形全曲线及加、卸载曲线的计算式,为数值分析中大坝混凝土模型的建立提供可参考的试验依据。

Tensile stress-deformation curve of fully-graded concrete is very important for the nonlinear response calculation and the critical seismic capability analysis of dams.In this paper,the advanced closed-loop servo testing machine is used to perform the axial tension test onФ450mm×1300mm cylindrical specimens(max aggregate size of150mm)under the control of displacement mode,from which the complete curves of tensile stress versus tensile deformation in given range are obtained.After the maximum load,cyclic loads under different stress levels are applied to study the unloading and reloading curves.Sim?ple equations are suggested to fit the complete stress-deformation curves and the unloading/reloading curves of the fully-graded concrete.This paper provides a reference basis for the dam concrete model building in numerical analysis.