红壤土质路堑边坡壤中流发育特征及侵蚀响应

The interactive impacts of subsurface flow and surface flow change the erosion drive force and cause serious soil erosion on the road cutslope. Most of the sediments lost from the road system stemmed from the cutslope. The cutslopes which weathered from the granite are selected as the objects in this research in red soil hill region, south of Jiangxi province. Field investigations, in-situ long-term monitor are employed to figure out the generation characteristics of subsurface flow and the main impact factors. The soil moisture distribution of the road cutslope under the impacts of subsurface flow is analyzed by the Time Domain Reflectometer (TDR). In order to clarify the interaction of surface flow and subsurface flow on the soil erosion processes, rainfall simulation and scouring tests are conducted on the road cutslope. According to the data collected from the in-situ monitor and simulation tests, an erosion model in consider of the interaction of subsurface flow and surface flow is set up. The results of this research provide practical value in unpaved road design, management and erosion control, a deeper understanding of the road “erosion-hydrology” processes, and a great improving for the “hillslope-watershed” erosion research.

路堑边坡在地表径流和壤中流交互影响下，侵蚀动力增加导致严重的水土流失，是道路泥沙的重要来源。本项目拟以赣南红壤丘陵区花岗岩发育的土质路堑边坡为研究对象，通过野外调查、典型坡面定位监测，研究路堑边坡壤中流发育特征及主要影响因子，结合水分长期定位监测结果分析壤中流作用下路堑边坡水分分布规律；借助原位壤中流模拟试验和冲刷试验，分析地表径流和壤中流交互影响下，路堑边坡产流产沙规律，探讨路堑边坡侵蚀临界坡度，揭示不同侵蚀驱动力作用下，路堑边坡侵蚀作用机制；在此基础上，以饱和入渗理论为基础，构建地表径流和壤中流耦合侵蚀模型。研究结果对提升道路的设计、规划和侵蚀治理有重要的实用价值，对深化认识道路“侵蚀-水文”过程，完善“坡面-区域”侵蚀研究有重要的理论意义。

土质道路边坡广泛分布于南方红壤低山丘陵区，在地表径流和壤中流共同作用下，常常诱发严重土壤侵蚀，是小流域重要的侵蚀策源地。本项目以南方红壤低山丘陵区土质道路边坡为研究对象，通过野外定位观测试验，分析了不同雨型条件、不同植被防护措施条件下，土质路堑边坡地表产流和产沙过程，阐述雨型对路堑边坡降雨-径流关系的影响，结合室内模拟降雨试验，研究了雨强、坡度等因子对边坡地表径流、壤中流及底层渗透过程的影响，结合模拟供水试验，阐明了地表径流和壤中流耦合作用对路堑边坡侵蚀过程的影响及泥沙颗粒特征。野外监测结果表明，雨型对路堑边坡侵蚀有显著影响，短历时暴雨型降雨下边坡土壤侵蚀模数最大，而梅雨型降雨径流系数最高，植被能够有效缓解雨型对边坡侵蚀的影响，尤其是降低坡面产沙。室内模拟试验结果表明，小雨强下降雨产流主要以壤中流和底层渗透的形式输出，大雨强条件下降雨产流为地表径流输出为主；模拟供水条件对边坡产流和产沙过程有显著影响，随着供水流量增大地表径流和土壤侵蚀速率显著增大，壤中流促进地表产流并提高地表径流侵蚀动能，加速侵蚀过程，尤其是对边坡底部的渗透降低了路堑边坡水力侵蚀的临界坡度，诱发重力侵蚀能力增强。研究结果对当前土质路堑边坡的防护及坡面侵蚀机理研究有重要理论和实践意义。