干密度对路基性能的影响研究

通过滤纸法试验，测得3种干密度下的土-水特征曲线，拟合得到3种干密度下的Van Genuchten模型参数，分析干密度对土-水特征曲线及Van Genuchten模型参数的影响。通过室内回弹模量试验，分析压实度和含水率对回弹模量的影响，并建立回弹模量与压实度和含水率之间的关系式。基于水力耦合机制，结合试验结果建立地下水位变化作用下的路基湿度及变形的动态响应模型，计算地下水位从-6 m上升到-3 m后，路基的含水率和回弹模量分布以及路基的变形。计算结果表明，干密度对土-水特征曲线Van Genuchten模型参数产生显著影响，饱和体积含水率随着干密度的增大线性减小，残余体积含水率随着干密度的增大线性增大，参数a与进气值的倒数线性相关，参数n随干密度的增大线性增大；回弹模量随着含水率的增大而减小，随着干密度的增大而增大；地下水位上升导致路基土的含水率显著增加，回弹模量明显下降，引起不可忽视的路基变形；不同填筑压实度下，地下水位变化引起的路基变形差异很明显，控制路基土的压实度是提高路基土性能的有效途径。

Research on influence of dry density on subgrade performance

The soil-water characteristic curves in three dry densities are obtained with filter paper method; the parameters of Van Genuchten model are received by fitting test data; and the influence of dry density on soil-water characteristic curve and parameters of Van Genuchten model is analyzed. The effects of compactness and water content on resilient modulus are analyzed with laboratory test of resilient modulus; and the relationship between them is established. At last, based on hydromechanical coupling mechanism and combined with the test results, the dynamic response model of subgrade moisture and deformation under the variation of groundwater level is built; the distribution of water content and resilient modulus and the deformation of subgrade are calculated when the groundwater level rising from -6 m to -3 m. The results show that: dry density has great influence on parameters of Van Genuchten model of soil-water characteristic curve, the saturated water content linearly decreases, the residual water content and parameter n linearly increase with the increase of dry density; and the parameter has a linear correlation with the reciprocal of air entry value; the resilient modulus decreases with the increase of water content and increases with the increase of compactness. The water content increases and resilient modulus decreases significantly caused by the rise of groundwater level; then it results in unnegligible deformation of subgrade. Under different filling compactness, the difference of deformation of subgrade caused by variation of groundwater level is obvious. Therefore, controlling compactness is an effective method to improve the performance of subgrade.