循环荷载作用下吸水土工布路基湿度及强度控制效果研究

Study on the Moisture and Strength Control Effects of Wicking Geotextile Subgrade under Cyclic Load

摘要: 道路结构的长期服役性能与路基湿化状态密切相关。本文针对循环荷载作用下的细粒土路基湿度控制及强度提升效果，选取我国黄河中下游流域典型路基填料，构建了级配碎石底基层-吸水土工布-粉质黏土路基物理模型，开展了不同循环荷载下路基填料的水分迁移试验研究，探究了最优含水率阶段、饱和阶段和排水稳定阶段下粉质黏土路基湿度、应力、变形以及回弹模量的演化规律。结果表明：循环荷载作用下吸水土工布使土层的基质吸力提高8.3~12 kPa，土工布附近土体水分受重力势和基质势共同驱动向吸水土工布内部迁移并通过微米级孔隙通道向外部进一步导排，排水稳定后土层含水率降低1.39%~3.81%，同时各应力幅值下粉质黏土路基层永久变形均显著降低约55%。在吸水土工布的水力和机械双重加固作用下，粉质黏土路基层动态回弹模量较饱和状态显著提升，各应力幅值下动态回弹模量分别为饱和状态的5.48倍、3.54倍、2.69倍、1.36倍。

Abstract: The long-term performance of road structures is closely related to the moisture conditions of the subgrade. This paper focuses on the effects of moisture control and strength improvement of fine-grained soil subgrade under cyclic loading. A physical model was constructed using typical subgrade fill materials from the middle and lower reaches of the Yellow River in China, which includes a graded gravel base layer, a wicking geotextile, and a silty clay subgrade. Experiments were conducted to study the moisture migration of the subgrade fill materials under different cyclic loads, exploring the evolution of moisture, stress, deformation, and rebound modulus of the silty clay subgrade during the optimal moisture content phase, saturation phase, and drainage stabilization phase. The results show that under cyclic loading, the wicking geotextile increases the matrix suction of the soil layer by 8.3~12 kPa. The moisture in the soil near the geotextile is driven by both gravitational potential and matrix suction toward the interior of the geotextile and is further drained through micron-sized pores. After drainage stabilization, the moisture content of the soil layer decreases by 1.39%~3.81%, and the permanent deformation of the silty clay subgrade under various stress amplitudes is significantly reduced by approximately 55%. Under the dual reinforcement effect of hydraulic and mechanical properties of the wicking geotextile, the dynamic rebound modulus of the silty clay subgrade is significantly improved compared to the saturated state, with dynamic rebound moduli being 5.48 times, 3.54 times, 2.69 times, and 1.36 times that of the saturated state under different stress amplitudes.