饱和土结构性参数演化规律及其简化模型研究

A simplified stress-strain relationship of saturated soil based on structure's evolution

引入两类超固结比的概念,对不同围压下,具有两类不同超固结比的饱和原状、重塑黄土试样进行三轴固结不排水剪切试验。结合应力分担率的定义对试验所得的应力-应变曲线进行整理,获得了应力分担率随应变水平呈两阶段变化的特征曲线。定义结构性发挥系数对应力分担率曲线进行归一化处理。结果表明:两类超固结比下,相同围压、具有不同超固结比的试样的结构性发挥系数演化规律具有很好的归一性;不同固结围压时,两类超固结比下,该系数也同样具有很好的归一性。由此提出了描述结构性演化规律的计算模式和相应的理论计算公式。结构性发挥系数的理论公式为一个3段式函数,形式简单、参数少,且具有较好的稳定性。对比分析表明:计算和试验结果具有很好的一致性。

Two types of over-consolidated ratioes are defined.Undisturbed and remolded saturated loess are tested by undrained shearing test under different confining pressures and over-consolidated ratios.On the base of the definition of stress sharing ratios,the relationship between stress sharing ratio and strain level is obtained from test results,which behaves as two phases.Structure releasing coefficient is defined and it is used to analyze the stress sharing ratio curve.The results show that,under two types over-consolidated ratios,the structure releasing coefficient＇s regulation of samples with the same pressure but different over-consolidated ratios is unanimous;under different pressures and two types over-consolidated ratios,the coefficient has the same characteristic.On the base of that,a model and the corresponding formulation are put forward to describe the structure＇s regulation.The formulation is a three phases fuction which has a simple form with only two parameters.The comparative analysis indicates that the calculation results have a good consistency with the tests.