三种土壤质地工程堆积体坡面流速及产沙特征

生产建设项目工程堆积体由于土壤质地、砾石质量分数差异较大,导致侵蚀过程流速及产沙特性发生变化。通过人工模拟降雨试验,研究砂土、壤土及黏土3种土壤质地堆积体的流速与产沙特性。结果表明:①堆积体坡面流速在产流开始3 min内递增,随后趋于稳定;②小雨强时砂土堆积体侵蚀主要发生在产流的中后期,壤土堆积体发生在产流前期和中期,而黏土堆积体的侵蚀发生在整个降雨过程,21 min后的累计产沙量占次降雨总产沙量砂土、壤土和黏土堆积体分别为52.3%~95.6%、29.6%~44.9%和42.1%~50.0%;③产流历时、雨强与径流率、入渗率、流速、产沙率均呈显著相关性;④雨强增加1.5~2.0倍,3种土质堆积体侵蚀量增大1.2~39.8倍。相同雨强下砂土堆积体侵蚀量是壤土的6.0~6.3倍,是黏土的3.2~3.5倍;相同砾石质量分数下砂土堆积体侵蚀量分别是壤土和黏土的5.0~9.8倍和2.7~3.8倍。研究成果对于明确含砾石堆积体侵蚀过程机理具有重要意义,并为建立堆积体侵蚀预报模型奠定基础。

Characteristic of Flow Velocity and Sediment Yielding on Engineering Accumulations Slope with Three Soil Textures

The process of velocity and sediment yielding on engineering accumulations slope are different from traditional due to differences in soil textures and mass fraction of gravel in production and construction projects. In this paper we examined the characteristic of flow velocity and sediment yielding on engineering accumulations with three soil textures (sandy soil, loam, and clay) via artificial simulation experiments. Results showed that: (1) Flow velocity increased at first within 3 minutes after the beginning of the runoff and then stabilized. (2) For sandy soil accumulations,erosion mainly occurred in the middle and late stages of runoff at small rainfall intensity; for loam, in the early and middle stages; and for clay accumulations, throughout the whole runoff process. The accumulative sediment yielding 21 minutes after runoff beginning accounted for 52.3%-95.6%,29.6%-44.9%, and 42.1%-50.0% of the total erosion amount of sand, loam and clay accumulations. (3) Significant correlations were found with runoff rate, infiltration rate, velocity, and sediment yielding rate against runoff time and rainfall intensity. Erosion amount increased by 1.2-39.8 times as rainfall intensity increased 1.5-2.0 times. Erosion amount for sandy accumulations was 6.0-6.3 times that of loam accumulations, 3.2-3.5 times that of clay accumulations under the same rainfall intensity, and 5.0-9.8 times and 2.7-3.8 times those of loam and clay accumulations with the same mass fraction of gravel. The research findings are of great significance for clarifying the mechanism of erosion process of engineering accumulations, and lay a foundation for establishing the erosion prediction model for engineering accumulations.