行车荷载与湿度变化作用下路基结构动回弹模量计算方法及演变机理

Because of the influence of climates, soils and other complex conditions, the resilient modulus of the subgrade decreases significantly in hot-humid region, and the working performance of subgrade decreases gradually, which will affect the durable stability of road structure. However, the calculation method and evolution mechanism of dynamic resilient modulus of subgrade structure under non-uniform spatial distribution of moisture and stress are still not systematically studied well in hot-humid region.The subgrade structure under the hot-humid environment will be taken as the research object. Firstly, experiments and prediction models of soil-water characteristic curve related to stress-compactness of subgrade soils will be carried out based on the compaction degree of subgrade and overlying load, and the calculation method of moisture content distribution in subgrade will be put forward. Secondly, experiments on dynamic resilient modulus and damping ratio of subgrade soils will be carried out to establish the prediction models of resilient modulus and damping ratio of subgrade soils, which can comprehensively reflect the moisture and stress state of subgrade. Finally, on the basis of above research results, the mass matrix, damping matrix and stiffness matrix of each point of soils in subgrade are established. Then the dynamic response of subgrade structure under non-uniform distribution of moisture and stress will be calculated. The calculation method of dynamic resilient modulus of subgrade structure will be proposed based on the principle of deflection in elastic half-space, and its evolution mechanism with moisture content will be revealed, which will be verified by model tests. The research findings of the project will realize the leap of dynamic reslient modulus of subgrade from material modulus to structural modulus, and it will be an important theoretical foundation for improving the design method of subgrade and pavement in China.

由于受湿热环境、行车荷载等复杂条件影响，湿热环境中的路基回弹模量显著降低，路基工作性能逐渐劣化，影响道路结构持久稳定。而国内外对湿度与应力空间非均匀分布下的路基结构动回弹模量计算方法及演变机理尚未开展系统研究。本项目拟以南方湿热环境路基结构为研究对象，首先基于路基层位上覆荷载和压实度状况，开展土水特征曲线试验与预估模型研究，并建立路基湿度场计算方法；其次，开展路基土动态回弹模量与阻尼比试验，得到路基土的材料模量与材料阻尼比，并建立能够综合反映路基湿度和应力状态的路基土回弹模量预估模型和阻尼比预估模型；最后，在上述研究基础上，构建路基内部土体各点的质量矩阵、阻尼矩阵和刚度矩阵，进而建立湿度与应力空间非均匀分布特性下的路基结构动回弹模量计算方法，揭示其随湿度变化的演变机理，并通过模型试验进行验证。研究成果将实现路基动回弹模量从材料模量到结构模量的跨越，为完善我国路基路面设计方法奠定理论基础。

由于受湿热环境、行车荷载等复杂条件影响，湿热环境中的路基回弹模量显著降低，路基工作性能逐渐劣化，影响道路结构持久稳定。而国内外对湿度与应力空间非均匀分布下的路基结构动回弹模量计算方法及演变机理尚未开展系统研究。.本项目拟以南方湿热环境路基结构为研究对象，首先基于路基层位上覆荷载和压实度状况，开展土水特征曲线试验与预估模型研究，并建立路基湿度场计算方法；以花岗岩残积土（低液限含砂黏土）为研究对象并制备试样，将饱和后的试样进行应力相关土水特征曲线试验。通过制备不同的初始干密度来进行土体初始干密度的控制，并通过在不同干密度试件上施加不同的竖向应力序列来实现应力与干密度相关土水特征曲线试验的研究。利用轴平移技术，采用了压力板仪来进行不同应力和干密度条件下的土水特征曲线试验研究。其次，开展了路基土的动三轴试验，根据路基内部土体的湿度状态和应力状态，制定了试验方案并开展了路基土的动三轴试验。得到了路基土的材料模量与材料阻尼比，并建立了能够综合反映路基湿度和应力状态的路基土回弹模量预估模型和阻尼比预估模型；最后，在上述研究基础上，构建了路基内部土体各点的质量矩阵和刚度矩阵，实现了路基内部非均匀湿度场和模量场的计算；进而建立了湿度与应力空间非均匀分布特性下的路基结构动回弹模量计算方法，揭示了其随湿度变化的演变机理，并通过模型试验进行验证。