7 research outputs found

    Experimental Study on Soil Erosion and Sediment Yield of

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     通过对生产建设项目弃土堆置体的野外调查及抽象概化,将抽象概化出的4类弃土堆置体作为研究对象,在室内模拟降雨条件下对不同弃土堆置类型的侵蚀产沙过程进行试验研究。结果表明:各类型弃土堆置体的入渗率、径流含沙量随降雨时间变化呈波动式减小,径流率随降雨时间变化呈波动式增大,侵蚀速率随降雨时间变化呈平缓型、多峰型2种变化趋势;产流时间与降雨强度呈负幂函数关系,平均入渗率、平均径流率、平均侵蚀速率与降雨强度呈线性关系,平均径流含沙量与降雨强度呈指数函数关系,总产沙量与总径流量呈线性关系。坡顶平台有车辆碾压的倾倒堆置在全部设计降雨强度条件下产流时间最短、平均入渗率均最低;当降雨强度从1.5mm/min提高到2.0mm/min时,总产沙量增大2.58倍,在降雨强度为2.0,2.5mm/min情况下,平均径流含沙量、平均侵蚀速率均明显大于其他堆置类型,且差异达到显著水平(P<0.05)。Abstract:Based on the field investigation and generalization of the development construction project ofspoilbanks,according to generalized results,four different types of spoilbanks were selected as researchobjects.The soil erosion and sediment yield process of four types were simulated in indoor rainfall experimentalcondition.The results were given in the following,the infiltration rate and sediment concentration of allspoilbanks decreased in a fluctuating tendency with the rainfalls time,while the runoff rate increased in afluctuating tendency with the rainfalls time.The variation of erosion sediment and transport rate appeared intwo types with the rainfalls time,which were smooth and multimodal distribution.Runoff generation timehad a negative exponent relation to rainfall intensity.Rainfall intensity had a linear function with averagerunoff rate,average erosion sediment and transport rate,respectively.Average sediment concentration hadexponential function relation to rainfall intensity,while total sediment yield and runoff volume accorded withlinear correlation.The type of rolling compaction by construction machinery at the top of slope had theshortest runoff generation time and lowest average infiltration rate in all design conditions of rainfall intensity.The total sediment yield increased 2.58times with rainfall intensities increasing from 1.5mm/min to 2.0mm/min.Under the rainfall intensity with 2.0mm/min and 2.5mm/min,the average sediment ratio ofrunoff and average erosion sediment rate were higher than that of other spoilbanks and their difference wassignificant(P<0.05)

    Types and characteristics of spoilbank in development construction project

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    采取路线调查与典型调查方式,依据中国主要水蚀类型区,并结合生产建设项目分布的情况,以平原、丘陵、土石山区3大地貌类型为基础的地貌分类框架,以黄土、黑土、褐土、棕黄壤、红壤等为基础的土壤类型分类框架,对分布于不同类型区的各类点式工程、线式工程产生的人为弃土堆置体进行现场调查,依据弃土的堆置方法和堆置形态可将弃土堆置体抽象概化为散乱锥状堆置、依坡倾倒堆置、分层碾压坡顶散乱堆置、线型垅岗式堆置、坡顶平台有车辆碾压的倾倒堆置5类人为堆置微地貌。研究结果可为生产建设项目弃土堆置体下垫面室内仿真模拟研究提供理论依据和技术支撑</span

    Temporal and spatial variability of grain production in Shaanxi based on GIS

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    &nbsp;综合应用变异系数、重心迁移模型、比较优势模型以及统计学和GIS分析方法,探讨了1980-2009年陕西省粮食生产时空格局演进过程。结果表明:陕西省粮食生产总体变化显著,粮食产量呈波动增长趋势,但粮食种植面积不断减少将危及区域粮食安全;根据粮食产量高低和生产稳定性特征,将陕西省分为高产低变型(宝鸡、咸阳、渭南、汉中)、低产低变型(安康、商洛)、高产高变型(西安)、低产高变型(榆林、延安、铜川)四个粮食类型区;各地区人均粮食产量差异较大,铜川、西安和商洛粮食紧缺,宝鸡、咸阳、渭南和榆林粮有盈余,延安、汉中和安康粮食基本自给;粮食生产总体分布不均衡,南北差异较大,重心移动的阶段性明显,总体呈&quot;北上东进&quot;的移动趋势;各类粮食作物具有比较优势的区域分布具有一定规律,小麦、玉米和大豆、稻谷生产具有优势的地区分别在关中、陕北、陕南。研究结果以期为粮食安全背景下的区域粮食生产宏观布局与优化以及农业的结构调整提供较为科学的决策依据。</span

    Standardization Parameter for Spoilbank Underlying Surface

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    室内模拟降雨实验是进行生产建设项目人为弃土水土流失特征研究的重要方法。为了使实验下垫面设计更加科学合理,实验结果应用范围更加广泛,通过对陕西关中平原区和秦巴山区各类生产建设项目弃土堆置体的实地调查,结合室内实验,运用经典统计学有关原理对堆置体的坡度、坡长、坡面物质组成进行统计分析。结果表明:秦巴山区生产建设项目弃土堆置体在不同坡面位置上,块石和土壤结构体的含量均明显大于关中平原区;两研究区内细粒土含量极少且均未超过2%;块石和土壤结构体重力分选作用明显,D&lt;10mm的坡面物质在不同坡位的含量数据变化较小且无明显规律;因此在室内进行下垫面仿真设计时,对D&lt;10mm的坡面组成物质可不考虑坡面位置的差异性。两研究区内弃土堆置体坡度多集中在26&deg;~35&deg;之间,贡献率分别为90.2%和88.8%;弃土堆置体坡长多集中在2~8m之间,贡献率分别为100.0%和79.4%。因此,在室内进行下垫面仿真设计时应重点对上述坡度、坡长范围进行实验测试。Laboratory rainfall simulation is an important method for studying erosion characteristics of spoilbanks in development construction projects.In order to provide a scientific foundation for the design of thespoilbank underlying surface in laboratory rainfall simulation,authors firstly investigate development construction project spoilbank in Guanzhong plain and Qinba mountain area,Shaanxi province.The theory ofstatistics was applied to analyze gradient,length of slope,composition of slope surface.The results showedas follows:The percentages of stones and soil aggregates at different position of spoilbank slopes in Qinbamountain area were higher than spoilbank in Guanzhong plain;the percentages of fine-grained soil both intwo studied areas were less than 2%;stones and soil aggregates&rsquo;gravity separation effects were obvious;thepercentages of material(particle diameter<10mm)at different position of spoilbank slopes didn&rsquo;t obviouslychange.Therefore,percentages of material(particle diameter<10mm)at different position of spoilbankslopes can&rsquo;t be considered during the design of the spoil underlying surface for laboratory rainfall simulation.The gradient of spoilbank were between 26&deg;and 35&deg;in two studied areas with contribution rate 90.2%and88.8%respectively;slope length of spoilbank were between 2mand 8mwith contribution rate 100.0%and79.4%respectively.Therefore,ranges of gradient and length were mainly considered during design experiment of the spoilbank underlying surface in laboratory rainfall simulation

    工程堆积体坡面砾石分布及含量概化

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    &nbsp; &nbsp; &nbsp; &nbsp; 为室内试验中更好地模拟工程堆积体,利用图像分析法和经典统计学方法对六大典型水蚀区的368座工程堆积体中粒径D>1 cm的坡面砾石的分布和含量进行概化分析,得到工程堆积体下垫面上中下坡位砾石含量的概化区间。结果表明:工程堆积体坡面各粒径砾石含量大多服从正态分布,且山区和平原丘陵区之间的砾石总含量有显著性差异。工程堆积体坡面砾石重力分选作用明显,且随着砾石粒径的增加,分选程度增大。在室内进行工程堆积体下垫面设计时,山区堆积体的砾石总含量宜设置在50%~60%之间,其中,细粒砾石含量宜设置在20%~30%之间,中粒砾石含量宜设置在10%~15%之间,粗粒砾石和巨粒砾石含量宜设置为10%,堆积体上中下坡位坡面砾石含量配比宜设置为1∶1.3∶1.5;平原丘陵区的砾石总含量宜设置在15%~20%之间,其中细粒砾石、中粒砾石、粗粒砾石、巨粒砾石含量分别宜设置在5%~10%、3%~7%、2%~5%、2%~3%之间,堆积体上中下坡位坡面砾石含量配比宜设置为1∶1.5∶2.5。</p

    工程堆积体标准小区界定与可蚀性因子改进

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    将USLE模型应用于工程堆积体侵蚀预报时结果偏差较大,这是因为其标准小区与土壤可蚀性因 子不适合直接应用于工程堆积体侵蚀预报。针对这一问题,结合对我国6大水蚀类型区工程堆积体参数 的调查、统计、分析,界定工程堆积体标准小区的坡度、坡长;结合国内外已有研究成果,分析论证堆积体可 蚀性因子的改进办法,并引用相关数据验证其可行性。结果表明,6大区域工程堆积体坡度、坡长及坡面物 质组成均与USLE中规定的标准小区相差较大;为了尽量消除误差,建议工程堆积体标准小区坡度采取众 数35&deg;,坡长采取平均值5m;堆积体可蚀性因子更名为土石质因子Tr,并将单位体积土石混合体中石砾总 表面积Cs,作为石砾因素指标纳入堆积体土石质因子Tr中,与堆积体物质中土壤可蚀性因子K 共同构建 工程堆积体土石质因子函数。验证结果表明,堆积体可蚀性因子改进办法是可行的。工程堆积体坡度、坡 长的界定及可蚀性因子的改进,对提高基于USLE模型的堆积体侵蚀预报精度有重要意义。</p

    Runoff and Sediment Yield Modeling on Spoilbank with Soil-stone Mixture

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    以前期概化的4类弃土堆置体为研究对象,采用室内人工模拟降雨试验,研究不同弃土堆置类型在4种不同降雨强度下的产流产沙特征。结果表明:各堆置类型弃土堆置体的径流率随降雨时间呈波动式增大,径流含沙量随降雨时间呈波动式减小,侵蚀速率随降雨时间呈稳定、波动2种变化趋势;平均径流率、平均侵蚀速率与降雨强度呈线性关系,平均径流含沙量与降雨强度呈指数函数关系,总产沙量与总径流量呈线性关系。坡顶平台有车辆碾压的倾倒堆置在降雨强度为2.0,2.5mm/min情况下,总产沙量和总径流量明显大于其它堆置类型Abstract:Four different types of spoilbanks were selected as research object based on previous research generalization,the runoff and sediment characteristics of different types under four different rainfall intensitieswas studied by indoor artificial rainfall simulation experiments.The results showed that the runoff rate of allspoilbanks increased in a fluctuating tendency with the rainfalls time,the sediment concentration of runoffdecreased in a fluctuating tendency with the rainfalls time,while the erosion rate appeared in two types withthe rainfalls time,which were stability and fluctuation.Rainfall intensity had a linear function relation withaverage runoff rate and average erosion rate.Average sediment concentration of runoff had an exponentialfunction relation with rainfall intensity,while total sediment yield and runoff volume accorded with linearcorrelation.Under the rainfall intensity with 2.0mm/min and 2.5mm/min,the total sediment and runoff ofthe type of rolling compaction by construction machinery at the top of slop were significantly higher than other spoilbanks
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