湘南地区红黏土动态回弹模量试验与预估模型研究

湘南地区广泛分布红黏土，它具有天然含水率高、孔隙比大及结构性强等特点，可用于特殊路基填料。为获得红黏土的动态回弹性能，利用动三轴试验研究了偏应力、围压应力和体应力对红黏土动态回弹模量的影响。结果表明：动态回弹模量随围压和压实度的提高而增大，随偏应力的增大而减小；动态回弹模量受含水率影响较大，并在最佳含水率附近达到最大值。基于试验揭示的动态回弹模量与应力的相关性，采用3种应力相关的典型动态回弹模量预估模型对试验数据进行回归分析，进而遴选出最佳预估模型。误差分析表明，对于湘南地区红黏土，考虑偏应力和围压应力的回弹模量预估模型具有更高的决定系数，能更好地拟合红黏土的动态回弹模量。动态回弹模量试验结果和遴选的预估模型将为湘南地区红黏土路基设计提供试验和理论依据。

Research on experiment and prediction model of dynamic resilient modulus of laterite soil in Southern Hunan

The laterite soil is widely distributed in Southern Hunan region. The soil has some special properties, such as a high natural water content, large void ratio and strong structural properties, etc., and can be used as special subgrade filling. To obtain the dynamic resilient performance of the soil, the dynamic triaxial tests are carried out to investigate the influence of deviatoric stress, confining stress and volumetric stress on the dynamic resilient modulus. Results show that the dynamic resilient modulus increases with the increase of confining stress and compaction degree and decreases with the increase of deviatoric stress. The dynamic resilient modulus is greatly affected by the water content and reaches a maximum value near the optimum water content. Based on the stress dependence of dynamic resilient modulus revealed with experiments, three typical prediction models for stress dependent dynamic resilient modulus are adopted to perform a regression analysis for experimental data; and then the best prediction model is selected from them. It is found from an error analysis that the prediction model considering confining stress and deviatoric stress provides a higher determination coefficient. That is to say it is the best prediction model of the dynamic resilient modulus for laterite soil in Southern Hunan. The test results and the selected prediction model can provide a basis of experiment and theory for subgrade design of laterite soil in Southern Hunan.