人工冻土复合幂-指数非线性强度模型

Composite power-exponential nonlinear strength model of artificial frozen soil

人工冻土应力-应变曲线形态通常呈现软化型,传统的指数模型、双曲线模型不能描述软化型曲线,而复合幂-指数非线性模型(CPE模型)可以更好地反映人工冻土的单轴抗压强度的软化力学特性。以山东某矿区黏土为例,在-10℃、-15℃、-20℃3种温度下进行冻结黏土单轴压缩试验,得到其软化型应力-应变曲线,通过分析温度对曲线软化规律的影响,建立人工冻土CPE模型,并通过拟合的方法求得参数最优解,发现各模型参数与温度呈线性关系,根据温度对模型各个参数的影响规律,得到了考虑温度影响的应变软化型应力-应变曲线CPE模型。将建立的人工冻土CPE模型的计算结果与试验结果进行比较,结果表明:计算结果与试验结果吻合度较高,能准确地预测单轴压缩软化型应力-应变曲线的变化趋势。建立的人工冻土CPE模型参数较少,参数容易求解且具有明确物理意义,便于工程应用。

The stress-strain curve shape of artificial frozen soil usually shows a softening type.The traditional exponential model and hyperbola model cannot describe the softening curve,but the compound power-exponential nonlinear model(CPE model)can better reflect the softened mechanical properties of uniaxial compressive strength of artificial frozen soil.Taking clay from a mining area in Shandong province as an example,the uniaxial compression test of frozen clay was carried out at three temperatures-10°C,-15°C,and-20°C,and its softening stress-strain curve was obtained.Through analyzing the influence of temperature on the softening law of the curve,an artificial frozen soil CPE model was established,and the optimal solution of parameters was obtained through fitting method.It was found that each model parameter has a linear relationship with temperature.According to the influence of temperature on each parameter of the model,a strain softening stress-strain curve CPE model considering the influence of temperature was obtained.The calculation results of the established artificially frozen CPE model were compared with the test results.The results showed that the calculation results were in good agreement with the test results and could accurately predict the changing trend of the uniaxial compression softening stress-strain curve.The established artificial frozen soil CPE model has few parameters,the parameters are easy to solve and have clear physical meaning,which is convenient for engineering applications.