堆石料流变的黏弹塑性本构模型研究

堆石坝流变变形主要是堆石料在环境因素作用下的劣化和高接触应力下的颗粒破碎重排引起的。在等向压缩方程中引入反映堆石料颗粒强度的固相硬度参数,选用双曲线型式的固相硬度衰减模型,以反映堆石料颗粒强度随时间劣化的特性;在分析堆石料流变试验结果的基础上,建立了流变变形的双曲线型流动准则;推导了流变变形的计算公式,并构建了流变模量表达式,从而建立了一个可统一考虑加载与流变过程的堆石料黏弹塑性本构模型。通过模拟两种典型堆石料的流变试验资料验证了模型的有效性。

Viscoelastic-plastic constitutive model for creep deformation of rockfill materials

The underlying mechanism of creep deformation of rockfill dams is the particle deterioration due to environmental changes and the particle breakage under high contact stresses. A solid hardness parameter reflecting particle strength is introduced into the isotropic compress equation. In order to describe the deterioration process of rockfill particles with time, the solid hardness parameter is assumed to vary with time, following a mathematical representation of hyperbola distribution. By analyzing the data of triaxial creep tests on rockfill materials, a hyperbolic creep flow rule is established. The creep formulae for deformation are derived, and the expressions for creep modulus are proposed. Then a visco elastic-plastic constitutive model for rockfill materials is proposed considering the influence of both loading and creep deformation. Finally, the validity of the proposed model is confirmed by comparing the simulated results with the measured data of two kinds of rockfill materials.