冻土动力学参数研究的成果综述与展望

Study of the dynamic parameters of frozen soil: achievements and prospects

通过对前人的试验成果进行整理,得到冻土动力学参数随温度、频率、应变幅、含水量和围压等因素的整体变化规律.整体上看,冻土的动弹性模量和动剪切模量随温度的降低而增大、随荷载振动频率的增加而增大、随动应变幅的增加而减小、随含水量的增加先增大后减小、随围压的增加而增大;冻土的泊松比随温度的降低而增大;冻土的阻尼比随温度的降低而减小,随频率、应变幅、含水量、围压的变化规律性不强.通过对试验条件和数值模拟时的实际工况对比分析,给出如下建议:动弹性模量和动剪切模量的预估适合用两段式线性模型,-5℃可以作为两段式的分界点;列车荷载作用下冻土的动力响应属于小应变幅的振动,冻土动力学参数应选择波速法的试验结果.

The variation of dynamic parameters of frozen soils based on the previous test results were summa-rized.From the summary one can see that all the dynamic parameters in frozen soils are depended on tempera-ture,frequency,strain amplitude,water content and confining pressure.The dynamic young′s modulus and shear modulus of frozen soils increase with decreasing temperature,increase with frequency,decrease with in-creasing dynamic strain amplitude,increase first and then decrease with water content and increase with confining pressure;the Poisson′s ratio of frozen soils increases with decreasing temperature;The damping ratio of frozen soils decreases with temperature drop,but not varies clearly with frequency and strain amplitude and water con-tent and confining pressure.By comparative analysis of the conditions of experiments and actual working condi-tions in numerical simulation,the following suggests are put forward：predicted values of dynamic young′s mod-ulus and shear modulus suit to be descripted with two-section linear models,demarcated at -5 ℃;Dynamic re-sponse of frozen soil to train loads belongs to the response of small strain amplitudes,thus,the dynamic parame-ters of the frozen soil should choose that from wave velocity method.