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为研究循环荷载作用下风积土累积塑性变形特性,以哈大高铁苏家屯试验段风积土为研究对象,通过一系列固结不排水动三轴试验,研究不同含水率、振动频率、压实系数的土样在不同动应力水平下的累积塑性变形规律。试验结果表明循环荷载作用下,风积土的εp-lg N曲线呈稳定型、破坏型和临界型3种类型。极差分析结果表明动应力幅值σdmax是影响风积土累积塑性应变εP的最重要因素,其次为含水率ω和压实系数kc,振动频率f对εP几乎无影响。基于动三轴试验结果和已往模型研究,提出了改进的Monismith数学模型,建立了模型参数a和b与上述4个因素之间的多元线性回归公式。利用所建模型计算了不同工况时风积土的εp-lg N曲线,其值与试验结果吻合较好,验证了模型的有效性。
In order to study the cumulative plastic deformation characteristics of aeolian soil under cyclic loading, taking the aeolian soil in Sujiatun test section of Harbin-Dalian High Speed Railway as the research object, a series of three-axis tests with consolidation and undrained drainage were conducted to study the effects of different moisture content, vibration frequency, Cumulative Plastic Deformation Law of Soil Samples with Real Coefficients at Different Dynamic Stress Levels. The experimental results show that the εp-1gN curves of aeolian soil are stable, destructive and critical under cyclic loading. The range analysis results show that the dynamic stress amplitude σdmax is the most important factor affecting the cumulative plastic strain εP of aeolian soil, followed by the moisture content ω and the compaction coefficient kc, and the vibration frequency f has almost no effect on εP. Based on the moving triaxial test results and previous model studies, an improved Monismith mathematical model is proposed, and the multiple linear regression formula between model parameters a and b and the above four factors is established. The εp-lg N curve of aeolian soil under different working conditions was calculated by using the proposed model. The results agree well with the experimental results, and the validity of the model is verified.