共查询到15条相似文献,搜索用时 234 毫秒
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采用水平土柱,以质量浓度5%的KCl溶液作为入渗液,并以耕层棕壤为供试材料,测定了不同入渗时间下的水分运移特征.结果表明,累积入渗量与时间呈幂函数关系,随入渗时间的延长,累积入渗量增大但增幅减小;累积入渗量与湿润峰运移距离呈线性关系,随湿润峰运移距离的增大,累积入渗量亦增大;湿润峰运移距离与入渗时间呈幂函数关系,随入渗时间的延长,湿润峰运移距离增大但增幅减小;盐溶液入渗情况下,棕壤的吸湿率约为162.38 cm/h;水分入渗率与时间呈幂函数关系,初始入渗时段入渗率下降速度快,随后入渗率随入渗时间的延长而缓慢下降. 相似文献
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为研究碎石含量与粒径对土壤入渗能力的影响,通过向自然土壤添加不同粒径、不同含量的碎石,在定水头条件下,研究了碎石含量和粒径对其入渗能力的影响,并通过Horton模型、Philip模型、Kostiakov模型及修正的Kostiakov模型对入渗率进行拟合,确定土石混合物入渗过程的适用模型。研究结果表明,相同碎石粒径条件下,累积入渗量与碎石含量呈正相关关系;相同碎石含量条件下,碎石粒径与累积入渗量呈负相关关系;通过Horton模型、Philip模型、Kostiakov模型及修正的Kostiakov模型对入渗率拟合的对比分析,发现修正的Kostiakov模型模拟含碎石土壤入渗率具有较高的精度,适用于试验所选的土石混合物。研究结果可为农业灌溉和水土保持提供参考。 相似文献
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土壤水力参数是表征土壤水力性质的重要参量,是准确预测土壤水分及溶质运移等过程的基础。基于GML非线性参数优化算法,构造了三个不同的目标函数,同时反演van Genuchten-Mualem模型中三个土壤水力参数(进气吸力倒数α、孔隙体积大小分布指数n和饱和导水率Ks),并分析了同一目标函数下不同降雨条件对反演结果的影响。结果表明,选取不同的目标函数对反演结果有显著影响,以累积入渗量作为目标函数能有效反演参数Ks,以压力水头和累积入渗量作为多目标函数则能同时有效反演α、n、Ks三个参数;此外,降雨条件对反演结果也有一定影响,相对于均匀降雨,在非均匀降雨条件下以压力水头作为目标函数对反演结果的精确度和准确度有较大的提升;以累积入渗量作为目标函数对反演结果的精确度略有提升但降低了反演结果的准确度。 相似文献
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对裸地、草坪等城市绿地进行入渗试验,得到土壤含水率、土壤容重、土壤入渗率等入渗试验参数,分析了前期降雨对绿地土壤含水率的影响,获得了试验期间裸地、草坪不同土层土壤含水率与前期影响雨量的线性关系,以及不同容重条件下裸地土壤的入渗率变化规律。试验获得了不同绿地类型初始入渗率、稳定入渗率、平均入渗率、累计入渗量等特征参数,研究了裸地、草坪入渗率与入渗历时的相关关系,分析了影响绿地入渗能力的主要因素。结果表明,土壤下渗过程中形成土壤水的比重相对于形成土壤孔隙重力水的比重小,裸地、草坪的土壤入渗速率主要与土壤容重有关,即与土壤压实度、土壤孔隙等因素有关,与土壤含水率和前期影响雨量的关系不大。 相似文献
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降雨入渗是非饱和土中水分迁移的重要因素。通过VG模型、渗流理论和弹性力学理论,推导出二维非饱土水—力耦合控制方程,利用COMSOL Multiphysics有限元软件对非饱和土渗流变形耦合控制方程组进行计算,研究了不同模型尺寸下土体中压力水头随时间的演化及变化规律,采用数值方法探索半无限非饱和土降雨入渗问题。结果表明,半无限渗流问题在一定条件下可作为有限尺寸的渗流问题;降雨入渗过程中水头水平向变化比竖向大;压力水头在非耦合情况下比耦合情况下入渗更快,但两者的压力水头分布无明显差异;降雨初期顶点位移就发生明显的变化。 相似文献
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渗水桩是一种可以提高地表降雨入渗效率的设施,主要应用于海绵城市建设。渗水桩通过改变地表透气边界,降低土体内孔隙气压力,促使雨水快速入渗,达到"排气减压、促进入渗"的目的。基于水气两相流理论,采用数值模拟方法分析渗水桩的渗水性。结果表明,土体埋设渗水桩可以显著减小孔隙气压力,提高地表入渗率;渗水桩渗水性在中锋型降雨时发挥最优;桩材料的饱和渗透系数越大土壤累积入渗量越大,增长率呈减速增长;保证体积不变渗水桩由窄变宽更利于雨水入渗,超过宽深比阈值后,渗水桩的促渗效果无显著变化。渗水桩有利于提高雨水入渗量,降低地表径流量,研究成果为渗水桩的适宜条件、材料选择及几何形态的设计提供了依据。 相似文献
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土壤水文特征是研究区域水土资源合理配置的基础支撑要素,根据华北土石山区土壤的地貌分异规律,综合考虑地质、植被、土地利用等因素,采用野外调查取样法、环刀法等,研究了易县崇陵流域5种典型植被(油松、侧柏、银杏、刺槐、荆条)条件下的土壤物理性质、土壤水分特征曲线、土壤入渗过程等土壤水文特征。结果表明,同一植被条件下,土壤容重随土壤深度增加逐渐增大,同一深度条件下,荆条覆盖下的土壤容重最小,其他植被覆盖条件下的土壤容重差别不显著;同一植被条件下,随深度增加,饱和含水率逐渐减小,同一植被不同深度条件下的土壤水吸力随土壤含水率的增加逐渐减小;对土壤水分特征曲线进行拟合时,发现Gardner模型适用于油松和银杏,而张景略模型适用于侧柏、刺槐和荆条;土壤入渗过程的渗润阶段发生在土壤入渗开始的前10min内,渗漏阶段持续100~120min;侧柏最佳入渗模型为Kostiakov模型,而油松、银杏、刺槐及荆条最佳入渗模型为蒋定生模型。 相似文献
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非饱和成层土一维降雨入渗水力耦合分析 总被引:1,自引:0,他引:1
为了有效地分析非饱和成层土的水—力耦合问题,基于非饱和土有效应力原理和渗流理论,考虑降雨过程中双层土孔隙特征及渗透性随应力的动态变化特点,建立了非饱和成层土一维降雨入渗水力耦合模型,利用Flex PDE软件编制计算程序,对一典型双层土降雨入渗模型进行了分析。结果表明,在雨水入渗过程中,上粗—下细型土的分界面处会出现较大的孔隙水压力变化,且耦合、非耦合情况差异明显;上细—下粗型土可不考虑入渗过程中水力的耦合效应;对于上粗—下细型土,短历时强降雨在土层接触带会产生较大的孔隙水压力突变。 相似文献
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Based on energy conservation equation and Darcy’s law, a model of beach well infiltration intake system applied in a seawater source heat pump system was established. The model consists of the seawater seepage and the heat transfer process. A porous medium model in a software named FLUENT was applied to simulate the seepage and the heat transfer process. This model was also validated by field experiment conducted on the seashore in Tianjin, China. The maximum relative error between simulation results and experimental results was 2.1% (less than 5%), which was acceptable in engineering application. The porosity and coefficient of thermal conductivity of the aquifer soil were determined to be 0.49 W/(m·K) and 1.46 W/(m·K), respectively in the simulation. In addition, the influencing factors of pumping water of beach well were also analyzed. The pumping water was found to increase when the distance between the beach well and the impervious boundary becomes longer, when the distance between the beach well and the supplying water source shortens, when the diameter of the beach well enlarges, and the drawdown enlarges. 相似文献
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Ofelia Andrea Valdes-Rodriguez Odilón Sánchez-SánchezArturo Pérez-Vázquez Romeo Ruiz-Bello 《Biomass & bioenergy》2011,35(8):3529-3536
There is considerable disagreement on the effects of different soil conditions on the growth of Jatropha curcas L., although different reports agree on some factors, such as a preference for sandy soils over clay soils. This paper presents results on the growth of seedlings of a low-toxic Mexican cultivar in three different soils from the SE of Mexico. The Mexican seeds were sown in soils of different textures: sandy, sandy-loam and clay-loam. The germinated seedlings were monitored during a period of one month. Then, they were uprooted to record below and above ground morphological parameters and dry matter weight. Stem lengths, root collar diameter, length and diameter of the five main roots, number of true leaves and dry matter were analyzed using one-way ANOVA. The soils used were subjected to a chemical analysis to determine soil nutrient contents, which revealed that clay-loam soil had the highest nutrient content, followed by the sandy-loam, while sandy soil presented the lowest values. It was found that seedlings grown in sandy-loam soil were significantly taller than those in clay-loam and sandy substrates (P ≤ 0.05). Root collar diameter, root diameter, number of true leaves and dry matter weight did not present significant differences between plants grown in sandy-loam and clay-loam soils, however they showed significant differences when compared with plants grown in sandy soil. Therefore it can be concluded that development of seedlings in sandy-loam soils was greater, followed by those in clay-loam, while the poorest performance of the seedlings was recorded in sandy soil. 相似文献
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Any refrigerant device consists of several parts, and one of the most significant parts is the expansion device. This expansion device can be classified into several types according to the size of the refrigeration system. The capillary tube is used usually with a small refrigerant system size to reduce the higher pressure in the condenser into the low pressure in the evaporator. In this study, the effect of the capillary tube's diameter and that of the temperature of the condenser and evaporator on the length of such a device has been theoretically studied. Furthermore, a validation between the theoretical analysis and experimental findings from the literature review has been carried out. To achieve the theoretical aspect, MATLAB code has been developed. The results showed that the maximum difference between the theoretical and experimental results regarding temperature and pressure refrigeration is around 5% and 3.4%, respectively. Also, the results depict that the inner diameter and the condenser temperature have an effect on the length of the capillary tube. However, the effect of the inner diameter is higher compared with the condenser temperature. In addition, an equation to predict the length of the capillary tube has been developed with an accuracy of 98%. This equation is created as a function of the capillary tube's diameter and the temperature of the condenser and the evaporator. Moreover, this equation can be used to predict the length of the capillary tube for small refrigeration devices, especially those operating under 10 KW. The findings of this study can help make a mathematical approach used for the design of the capillary tube simpler and easier to apply. 相似文献