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分析时间对土的效应,在对现有理论和试验数据总结分析的基础上提出了瞬时正常压缩线的概念;基于蠕变规律,建立老化时间与超固结度的关系;采用UH模型(以统一硬化(United Hardening)参数作为硬化参量建立的三维超固结土弹塑性本构模型)的再加载公式计算瞬时变形,提出超固结土一维弹黏塑性应力应变关系;分析一维弹黏塑性应力应变关系的演化规律,定义特征速率并给出其与超固结参数的关系;在UH模型屈服面方程中引入折算时间,建立三维弹黏塑性本构模型.该模型在UH模型的基础上考虑时间效应,不仅能够描述土的剪切蠕变、松弛、速率效应等黏性规律,而且能够反映土的剪胀、软化等超固结性质;与修正剑桥模型相比,仅增加一个次固结系数来反映土的蠕变规律;该模型在瞬时加载条件下退化为UH模型,从而使弹塑性与弹黏塑性框架得到统一.
The effect of time on soil was analyzed. The concept of instantaneous normal compression line was put forward based on the analysis of existing theories and experimental data. The relationship between aging time and over-consolidation was established based on the creep law. United Hardening parameters as the hardening parameters of the three-dimensional super-consolidated elastoplastic constitutive model of soil constitutive model) to calculate the instantaneous deformation of the proposed super-consolidated soil one-dimensional elastic-plastic visco-elastic strain relationship; analysis of one-dimensional elastic Plasticity, stress-strain relationship, defining the characteristic velocity and giving the relationship with the parameters of overconsolidation. By introducing the conversion time into the yield surface equation of UH model, a three-dimensional elastic visco-plastic constitutive model is established. The model is based on the UH model Considering the time effect, we can not only describe the viscous laws such as shear creep, relaxation and velocity effects of soil, but also reflect the superconsolidation properties such as dilatancy and softening of soil. Compared with the modified Cambridge model, we can only add one more time The coefficient of consolidation reflects the creep law of soil. The model degenerates into UH model under the condition of instantaneous loading, so that the elastic-plastic and elastic-viscoplastic framework are unified.