北方风沙区砾石对堆积体坡面径流及侵蚀特征的影响

发布时间：2018-08-08 19:45

【摘要】：为了研究砾石对工程堆积体降雨侵蚀规律的影响,采用室内人工模拟试验,以土质堆积体(砾石质量分数为0)为对照,研究了10%、20%和30%砾石质量分数堆积体边坡在模拟降雨条件下的径流水力特征、产沙过程及侵蚀动力机制。结果表明:1)产流0~6 min,砾石促进堆积体坡面细沟间径流流动;产流12~30 min后,砾石阻碍堆积体坡面细沟径流流动;2)含砾石堆积体坡面粗糙度增大,水流流态变缓,水流速度降低,且均以层流为主。较土质堆积体而言,30%砾石质量分数堆积体坡面阻力系数增大88.8%~288.4%,弗汝德数降低28.9%~41.8%,水流速度降低0~45.8%;3)径流含沙量随产流历时经历快速降低-平稳过渡-波动上升3个阶段,土质及10%砾石质量分数堆积体高含沙水流现象频发,且随雨强增大,重力坍塌次数增加,重力侵蚀程度增强。20%、30%砾石质量分数堆积体发生高含沙水流的几率约为0。相对土壤流失比与砾石质量分数呈极显著负指数函数关系;4)土壤剥蚀率与各侵蚀动力参数均可用简单线性函数关系描述,单位径流功率是描述风沙区土质和10%砾石质量分数工程堆积体侵蚀产沙的最优因子,径流功率是刻画20%、30%砾石质量分数工程堆积体土壤侵蚀参数更为合理的因子。结果可为全国范围工程堆积体土壤侵蚀模型的建立提供科学依据。
[Abstract]:In order to study the effect of gravel on rainfall erosion of engineering accumulations, laboratory simulation tests were carried out, and the soil mass fraction (gravel mass fraction was 0) was used as control. The runoff hydraulic characteristics, sediment yield process and erosion dynamic mechanism of 10% and 30% gravelly mass fraction accumulative body slope under simulated rainfall were studied. The results show that the gravel promotes the flow of runoff between gullies on the slope of the accumulated body for 6 minutes, and the gravel hinders the flow of runoff on the slope of the accumulated body after 1230 min. (2) the roughness of the gravelly agglomerate slope increases, the flow state of the water becomes slower, and the velocity of the flow decreases. Laminar flow is the main flow. Compared with the soil mass accumulation, the gravelly mass fraction (30%) increases the slope resistance coefficient by 88.8%, the Froude number decreases by 28.9% and 41.8%, the flow velocity decreases by 0% and 45.8%) the runoff sediment content goes through three stages: rapid decrease, steady transition and fluctuation rise with the duration of runoff production. Soil mass and 10% gravelly mass fraction accumulations occur frequently with high sediment content, and with the increase of rain intensity, the number of gravity collapses increases, and the degree of gravity erosion increases. The probability of occurrence of high sediment bearing flow in the accumulations with 30% gravelly mass fraction is about 0. The relative soil erosion ratio has a significant negative exponential function relationship with gravel mass fraction. 4) the denudation rate of soil and the dynamic parameters of erosion can be described by simple linear function. The unit runoff power is the best factor to describe the sediment yield of soil and 10% gravel mass fraction engineering, and the runoff power is the more reasonable factor to describe the soil erosion parameters of the engineering accumulation with 20% or 30% gravel mass fraction. The results can provide scientific basis for the establishment of soil erosion model of national engineering accumulations.
【作者单位】：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;中国科学院水利部水土保持研究所;西北农林科技大学资源环境学院;长江科学院水土保持研究所;榆林学院生命科学学院;山东省水利科学研究院水土保持与生态研究所;南京水利水电科学院;黄河水利委员会西峰水土保持科学试验站;
【基金】：国家自然科学基金项目(40771127) 水利部公益性行业专项(201201048;201201047)
【分类号】：S157.1

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