交通荷载-超静孔压耦合下土工格栅加筋海绵城市道路的变形机理研究

The inclusion of geogrid reinforcement in permeable roadways in “sponge city” can not only improve roadway bearing capacity but also has the potential to mitigate distresses caused by excess pore water pressure and reduce the permanent deformation of aggregate bases and subgrade. However, the mechanism of the potential under the coupling effect of traffic loading and excess pore water pressure is still not well understood. In this study, the additional stresses in aggregate bases and subgrade induced by geogrids will be derived based on the layered elastic theory by applying the confinement effect and tensioned membrane effect at the interface as external forces. The resilient behavior, permanent deformations, and loading/unloading moduli of the aggregate base and subgrade materials will then be investigated through repeated triaxial tests with the additional stresses applied on samples by a specifically designed high-stiffness cylindrical membrane. The influence of the additional stresses on the resilient behavior at the unloading stage will be interpreted according to the test results. The hypoplastic model will be modified to simulate the resilient behavior and rutting accumulation of aggregate bases and subgrade. At last, the elastic solutions of stresses induced by geogrids and the modified hypoplastic model will be simplified and utilized to establish a method for calculating the permanent deformations of bases and subgrade of geogrid reinforced permeable flexible pavements in “sponge city”. The research achievements of this project will provide mechanistic and technical supports for the design and construction of geogrid reinforced permeable flexible pavements in “sponge city” in China.

采用土工格栅加筋处理海绵城市道路不仅能够提高道路的承载力，还有削弱持水基层内部超静孔隙水压力所引起损害和降低基层与路基塑性变形累积速率的潜力。但目前，这些潜力在交通荷载-超静孔压耦合作用下的发生机理尚未明确。本项目将基于层状弹性理论导出格栅对加筋海绵城市道路基层和路基的附加应力弹性解；在动三轴试验中通过特制圆筒型弹力套对透水基层和路基试样定量施加附加应力，研究附加应力在交通荷载-超静孔压耦合作用下对回弹变形、塑性变形、加载模量和卸载模量等的影响机制；基于动三轴试验结果，通过改进亚塑性模型对附加应力下加筋土的回弹增大特性与塑性变形累积特性进行模拟；并基于简化后的附加应力弹性解和改进亚塑性模型，建立海绵城市道路的加筋透水基层和路基的塑性变形简便计算方法。本研究将为我国土工格栅加筋海绵城市道路的设计与建设提供理论与技术支撑。

采用土工合成材料加筋处理海绵城市道路不仅能够提高道路的承载力，还有削弱持水基层内部超静孔隙水压力所引起的损害和降低基层与路基塑性变形累积速率的潜力。但目前，这些潜力在交通荷载-超静孔压耦合作用下的发生机理尚未明确。本项目针对这些问题，（1）导出了在土体塑性变形驱动下土工格栅对海绵城市柔性道路的空间附加应力弹性解；（2）基于亚塑性理论，阐明了交通荷载-超静孔压耦合作用下土工格栅加筋海绵城市柔性道路回弹增大特性及其对塑性变形的影响机理；（3）建立了交通荷载-超静孔压耦合作用下海绵城市加筋柔性道路的变形分析，定量评估了格栅在降低塑性变形和抑制超静孔压损害方面的作用；（4）建立了多层（十层）弹性体系的解析解，并应用于吸水土工合成材料加筋道路的性能分析方法；（5）建立了土工合成材料加筋板铺装道路的应力分析方法。本研究将为我国土工格栅加筋海绵城市道路的设计与建设提供理论与技术支撑。