堆石料剪胀特性大型三轴试验研究

基于不同初始孔隙比e0和不同固结压力σc情况下筑坝堆石料大型三轴固结排水剪切试验,分析了堆石料应力应变关系与体积应变关系以及剪胀率ζ与塑性剪应变εsp关系的变化规律。研究表明:对于颗粒级配确定的堆石料,剪胀剪缩转化关系由临界初始孔隙比(e0)crit与临界固结压力(σc)crit共同决定;堆石料破坏时的剪胀率ζf可以成为材料剪胀性的判断标准。通过试验数据非线性拟合分析,提出了堆石料应力应变关系与塑性体积应变关系的统一表达式以及初始物理力学状态依赖的应力-剪胀方程和破坏时剪胀率ζf表达式,并由此获得了堆石料剪胀剪缩转化的判断准则。

Study on shear dilatancy behaviors of rockfills in large-scale triaxial tests

On the basis of the results of large-scale triaxial tests on typical rockfills for the construction of dams,their shear behaviors under different void ratios or confining pressures including the relationship of(σ1/σ3)-εa and εv-εa,and relationship of dilatancy ratioζ and plastic shear strain εsp were analyzed.It was shown that ① For the rockfills with determined particle grading,the conversion between shear dilatancy and shrinkage of the samples depended upon a critical initial void ratio(e0)crit and critical consolidation pressure(σc)crit;② The shear dilatancy ratioζf at the failure of the samples could be a criterion by which whether shear dilantancy appeared or not could be judged.By means of the nonlinear fitting of the results of triaxial tests,the relationship of(σ1/σ3)-ε a and the relationship of εvp-εsp were described by a uniform formulation,and then the equation of stress-dilatancy and the formulation of dilatancy ratioζf at the failure,which depended upon the initial state of the samples,were proposed respectively.So a criterion was established on the formulation of shear dilatancy ratio ζf which depended upon the initial void ratio e0 and confining pressure σc of the samples.