多雨地区路基湿度变化对路面力学响应影响研究

Study on Effect of Subgrade Moisture Variation on Pavement Mechanical Response in Rainy Regions

摘要:

为了分析多雨地区环境作用下路基湿度变化对路面结构力学响应的影响，通过建立考虑应力水平和基质吸力的动态回弹模量 MR预估模型，采用 COMSOL 软件建立路基路面结构数值模型，运用系数型偏微分方程将 MR嵌入数值模型的本构关系中，结合实测数据与规范法计算结果对比，验证了模型的适用性，并对不同降雨和地下水位条件下路面弯沉和疲劳寿命的历时变化规律进行分析。结果表明：回弹模量随含水率增加而减小，弯沉值随含水率增加而增大；当路基土的饱和度由 79% 增至 90% 时，路面最大弯沉值增加了 126 μm。当地下水位由-5 m 升至 0 m 时，路表最大弯沉值增加 62%。采用我国和美国路面设计规范中的疲劳寿命计算方法得到的沥青路面层疲劳寿命结果均有较高的准确度，最大误差只有 2%。随着地下水位的升高，面层底最大拉应力呈线性增大而疲劳寿命减小；当地下水位升高 5 m，面层底拉应变提升 28.35%，沥青路面层疲劳寿命降低 62.8%。研究结果为多雨地区道路结构设计和长期性能保障提供理论依据。

Abstract:

To analyze the effect of subgrade moisture variations on the mechanical response of pavement structures under environmental conditions in rainy regions, a prediction model for the dynamic resilient modulus (MR) considering stress levels and matric suction was established. A numerical model of the subgrade and pavement structure was developed using COMSOL software. The MR was then embedded into the constitutive relationship of the numerical model through the application of a coefficient-type partial differential equation. The applicability of the model was verified by comparing measured data with results calculated using specification methods. The temporal variation patterns of pavement deflection and fatigue life under different conditions of rainfall and groundwater tables were further analyzed. The results showed that the resilient modulus decreased with increasing moisture content, while the deflection value increased. When the saturation of subgrade soil increased from 79% to 90%, the maximum pavement deflection increased by 126 μm. Additionally, when the groundwater table rose from -5 m to 0 m, the maximum surface deflection increased by 62%. Both the fatigue life calculation methods specified in Chinese and American pavement design specifications yielded highly accurate results for asphalt pavement surface layers, with a maximum error of only 2%. As the groundwater table increased, the maximum tensile stress at the bottom of the surface layer increased linearly, while the fatigue life decreased. When the groundwater table rose by 5 meters, the tensile strain at the bottom of the surface layer increased by 28.35%, and the fatigue life of the asphalt pavement layer declined by 62.8%. These findings provide a theoretical basis for road structure design and long-term performance assurance in rainy regions.