黄土区工程堆积体石砾对流速及产沙影响试验研究  

Experimental study of runoff velocity and sediment yield affected by gravels of engineering deposits in loess area

作　　者：李建明[1] 王文龙[1,2] 李宏伟 黄鹏飞 郭明明[1] 董玉锟 李艳富[6] 

机构地区：[1]西北农林科技大学水土保持研究所/黄土高原土壤侵蚀与旱地农业国家重点实验室,陕西杨凌712100 [2]中国科学院水利部水土保持研究所,陕西杨凌712100 [3]浙江省水利水电勘测设计院,杭州310014 [4]江西省水土保持科学研究院土壤侵蚀与防治重点实验室,南昌330029 [5]西北农林科技大学资源环境学院,陕西杨凌712100 [6]南京水利科学研究院,南京210000

出　　处：《水力发电学报》2015年第9期64-74,共11页Journal of Hydroelectric Engineering

基　　金：水利部公益性行业专项(201201048;201201047);中国科学院西部行动计划项目(KZCX2-XB3-13);中国科学院知识创新工程重大项目(KZZD-EW-04-03)

摘　　要：由于堆积松散、颗粒粗、组成物质复杂、坡度大等特点，生产建设项目工程堆积体侵蚀过程与农地、撂荒地相比有较大区别，是典型的人为加速侵蚀。在各类生产建设项目工程堆积体野外调查基础上，室内概化堆积体代表性下垫面，通过人工模拟降雨试验研究堆积体中石砾对流速及产沙影响。结果表明：（1）不同石砾含量下垫面流速在产流3min内迅速递增，随后趋于相对稳定。坡度小于25。时，含石砾坡面流速小于纯土体，此时石砾存在增加径流弯曲度，阻碍径流流动，平均稳定流速与雨强及石砾含量呈幂函数关系；而坡度大于25。时流速与雨强及石砾含量呈二元线性关系。（2）产沙率在产流前12min呈波动性递减，随后趋于相对稳定，初期产沙率是稳定期的1．7-3．1倍。雨强1．5mm／min较1．0ram／min的平均产沙率增加82．7％-117．3％。坡度对堆积体产沙影响存在一个阈值，在25。左右时产沙率最大，可达其他坡度下的1.3～1．7倍。在初期及稳定期的产沙率均表现为纯土体大于含石砾坡面，可增加0．6％～28．7％，各场次降雨下产沙峰值主要集中在产流开始后的前3min内。（3）在侵蚀初期、稳定期及整个侵蚀过程的平均产沙率均与流速呈显著相关。随雨强增大1．5倍，次降雨侵蚀量可增加74．0％～95．9％，且总体表现为纯土体侵蚀量大于含石砾坡面，产流前12min侵蚀量可占次降雨侵蚀量的38．3％～50．7％，因此，在进行堆积体水土流失防治中，尤其要注重初期的措施配置，以减免堆积体严重侵蚀。Erosion processes on engineering deposits of construction projects are different from those in farmland and fallow land due to their loose accumulation, coarse texture, complex composition, and steep slope. For this reason, such erosion is often considered typical of artificially-accelerated types. We have developed physical models for the deposited bodies with different slopes and different gravel contents based on field surveys on a large number of engineering deposits, focusing on the impacts of gravel content on runoff velocity and sediment yield in the condition of simulated rainfall. Results show that 1） flow velocity increases rapidly in the initial 3 min rainfall and then tends to be relatively stable. At slopes less than 25°, flow velocity on the slope of a deposited body that contains gravels is lower than that on a pure soil slope because gravels enhance the curvature of flow path and hence reduce flow velocity. A power function can fit well the relation of average stable velocity versus rainfall intensity and gravel content, while a binary linear relation fits better for slopes greater than 25°. 2） Sediment-yielding rate shows a decreasing volatility in the initial 12 min runoff and then tends to be stabilized, with its initial value 1.7 - 3.1 times greater than the stable stage. In each rainfall test, a peak of sediment yield was observed after 3 min runoff. An increase in rainfall intensity from 1.0 to 1.5 mm/min leads to an increase of 82.7% - 117.3% in the average yielding rate. There exists a threshold slope of about 25° that maximizes the yielding rate up to a peak 1.3 - 1.7 times those at other slopes. At the initial and stable stages, the yielding rate on pure soil slope was 0.6% - 28.7% greater than gravels-containing slope. 3） Average sediment yielding rate shows significant correlation with flow velocity in the entire erosion process including the initial and stable stages. The amount of erosion increases by 74.0% - 95.9% as rainfall intensity increases by 50%, and the erosion on p

关 键 词：工程堆积体 石砾含量 模拟降雨 流速 产沙 

分 类 号：S157.1[农业科学—土壤学]