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首先分析了温度对饱和粘土力学特性的影响规律,基于真强度概念并结合潜在强度的确定方法推导出不同温度下饱和粘土临界状态应力比的理论计算公式;随之将温度作为变量引入到姚仰平等人提出的UH模型(采用统一硬化(Unified Hardening)参数建立的三维超固结土弹塑性本构模型)中,建立了能够考虑温度影响的UH模型;并根据姚仰平等人提出的变换应力方法,将模型简单地三维化.该模型继承并发展了UH模型,不仅能够描述某一恒温下超固结土的硬化、软化、剪胀等应力应变特性,而且能够反映由于升温引起的体积变化特性.与修正剑桥模型相比,所提出的模型仅增加了一个参数来反映粘土的前期固结压力随温度升高而降低的特性.在常温时此模型就退化成原始的UH模型,而在常温且无超固结时就退化为修正剑桥模型.模型的温度适用范围为介于孔隙水熔点与沸点之间的温度(例如本文所采用试验所涉及的介于适用范围内的温度20℃~95℃).通过与已有的试验结果对比分析表明,模型能够较为合理地描述超固结土的基本力学特性.
Firstly, the influence of temperature on the mechanical properties of saturated clays was analyzed. Based on the concept of true strength and the determination of potential strength, the theoretical formula for calculating the critical stress ratio of saturated clays at different temperatures was deduced. Subsequently, the temperature was introduced into Yao Yang In this paper, a UH model that can consider the influence of temperature is established in the UH model (unified three-dimensional elasto-plastic constitutive model based on Unified Hardening parameters) proposed by Pearson et al. According to the transformation stress proposed by Yao Yang et al The model inherits and develops the UH model, which can not only describe the stress-strain characteristics of hardening, softening and dilatancy of overconsolidated soil at a constant temperature, but also reflect the change of volume due to temperature rise Characteristics.Compared with the modified Cambridge model, the proposed model only adds a parameter to reflect the decrease of the pre-consolidation pressure of clay as the temperature increases.The model degenerates into the original UH model at room temperature, At room temperature and without overconsolidation, it degenerates into a modified Cambridge model.The temperature range of the model is between the melting point and boiling point of pore water Degrees (e.g. a temperature in the range between applicable tests employed herein relates to the 20 ℃ ~ 95 ℃). By comparison with the existing experimental results showed that the model can be described with reasonable mechanical properties over substantially consolidated soil.