粗粒硫酸盐渍土动态回弹模量试验及预估模型

Laboratory Test and Prediction Model of Dynamic Resilient Modulus of Coarse-grained Sulfate Saline Soil

针对中国西北地区路基土存在水盐迁移引起的次生盐渍化现象,为明确粗粒硫酸盐渍土路基受荷载、湿度及盐分影响下的动回弹特性,通过室内动三轴试验,研究了15种应力路径、3个含水率和4种含盐量状态下粗粒硫酸盐渍土动态回弹模量的演变规律.试验结果表明:相同湿度的粗粒硫酸盐渍土动态回弹模量随围压及体应力的增大而提高,而随偏应力的增大则表现出低含盐量的先提高后降低和高含盐量的不断提高的发展趋势,同时盐含量越高,偏应力与体应力对其动态回弹模量影响越明显;同一应力水平下,含水率与含盐量的增加引起粗粒硫酸盐渍土动态回弹模量逐渐提高,且盐分较水分的影响更显著.基于试验揭示的动态回弹模量对应力的依赖性,从与应力相关的典型三参数复合模型中甄选出2种适用性较广泛的理论模型对测试数据进行回归分析,继而对比出最佳的预估模型;误差分析表明,获取的Ni模型具有较高的合理性和可靠性,并建立了精度较高的该模型参数预估公式.通过预估值与试验实测值的进一步对比分析,验证了该模型参数预估公式的准确性,适合于预估粗粒硫酸盐渍土动态回弹模量.研究成果可为盐渍土地区路基路面结构设计提供动力参数.

The phenomenon of secondary salinization caused by water and salt migration of subgrade soil has been observed to take place in Northwest China.To clarify the dynamic rebound characteristics of the coarse-grained sulfate saline soil(CGSSS)subgrade under the influence of load,humidity,and salinity,indoor dynamic triaxial tests were conducted to study the evolution law of dynamic resilient modulus of CGSSS under fifteen stress paths,three wa⁃ter contents and four salt contents.The test results show that the dynamic resilient modulus of CGSSS with the same humidity increases with the increase of confining pressure and bulk stress,but with the increase of the deviator stress,the dynamic resilient modulus shows a lower development trend.The salt content first increases and then de⁃creases,and the high salt content increases.At the same time,the higher salt content results in the more obvious the influence of deviator stress and bulk stress on the dynamic resilient modulus;under the same stress level,the dy⁃namic resilient modulus of CGSSS increases gradually with the increase of water content and salt content,and the ef⁃fect of salt tends to be more significant than that of water.Based on the stress dependence of dynamic resilient modu⁃lus revealed by the test,two widely applicable theoretical models are selected from typical three-parameter compos⁃ite models related to stress,and then the best prediction model is compared.The error analysis shows that the ob⁃tained Ni model has higher rationality and reliability,and a parameter prediction formula of the model with higher precision is established.Through the further comparative analysis of the predicted value and the experimental value,the accuracy of the parameter prediction formula of the model is verified,which is suitable for predicting the dynamic resilient modulus of CGSSS.The research results can provide dynamic parameters for the structural design of sub⁃grade and pavement in saline soil areas.