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河床漂石-砂卵石介质渗透特性的试验分析.pdf

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太原理工大学硕士研究生学位论文大,随着cu的增大而减小。渗透系数与有效粒径dl o和限制粒径d。。均呈二次函数相关关系,与不均匀系数cu呈对数相关关系。砂卵石介质的渗透系数及水力梯度与漂石的截面面积及体积之间亦具有高度的相关性。2当河道水深不变,淤泥含量较小时,大部分淤泥将通过砂卵石介质孔隙通道被水流带出,淤泥对渗流通量的影响因而不明显。但是,当淤泥层厚度增加到一定程度之后,砂卵石介质部分孔隙将被累积增加的淤泥堵塞,此时,渗流通量将逐渐减小。在等厚度淤积层的覆盖下,河床中砂卵石的渗流通量随着河道水深的增大而增大。但是,在砂卵石表面淤积层厚度较大的情况下,随着试验的进行,河道水深的增大对砂卵石渗流通量的影响逐渐减弱。3在大粒径卵石覆盖层及细颗粒介质与土工布复合覆盖层下对砂卵石的阻泥保渗效果较好,细颗粒介质与土工布复合覆盖层最佳阻泥保渗效果组合结构为土工布细颗粒土工布。在综合考虑砂砾石介质的渗透系数和水质状况的情况下,得出人工渗床最佳砂砾石剖面结构从上到下依次是1 4cm厚1~O.25ram细颗粒土工布20cm厚3~1 mm砂砾石20cm厚6~3mm砂砾石20cm厚lO ~ 6mm砂砾石20cm厚30--一1 Omm砂砾石20cm厚50~30mm砂砾石15cm厚90~50mm砂砾石。本文对不同粒径配比砂砾石介质人工渗床剖面结构的研究,只是根据试验结构进行初步分析,最终得出的最佳剖面结构需要日后的工程实践验证。关键词砂砾石介质;渗透系数;级配曲线;粒径特征;预报模型太原理工大学硕士研究生学位论文Experimental Study on Riverbed Boulder and Sandy GravelMedia Permeability CharacteristicABSTRACTThe serious short of water resources in our country,especially in the northern regions,the groundwater overdraft has become the common problems of the northern regions.Thelimited exploitation of groundwater has also become the main measures for protection ofgroundwater resources.Therefore,in recent years,the water intake project near the river hasgradually increase in the northern china in order to meet the water demand of human daily lifeand social development.The technological problem is the large difference between theoreticalcalculated result and practical engineering water intake quantity in the exploitation riverbedunderground water project construction actually.It Was considered through the detailedreconnaissance in the field analysis that it have a direct relationship with boulder ofaccumulation sand pebble layer in the river trough.The paper researches permeabilitycharacteri stics of the boulder and sandy gravel media the river troughwhich possessesimportant significance for taking underground water project construction near the river andimproving water intake efficiency.Taking the original state natural accumulation sandy pebble and boulders at LiulinCounty Yellow River bottomland as the research object, using the of experimentalstudy,from the aspect of the influence of boulders shape,scale,gradation,profile structure,sediment deposit to osmotic coefficient and osmotic flus of sandy pebble carrying outsystematically study.The following main conclusions were drawn“太原理工大学硕士研究生学位论文1The characteristic diameter index of boulder and sandy gravel media on naturalriverbed contributed significantly to the permeability coefficient.The characteristic diameterinds are different,and the numbers and size of pore space of sandy gravel media,thedischarge area of seepage flow and the percentage filling of fine particle are different too,thatis characteristic diameter inds have influences on the permeability coefficient.There arethe close correlation among permeability coefficient of sandy gravel media and its effectivediameterd10,limit diameterd60and Nonuni coefficientCu.The permeabilitycoefficientKincreases with the increase of the d l o,the same as with the increase of the d60,while the permeability coefficient decreases with the increase of the Cu,there is a logarithmicrelationship between permeability and Nonuni coefficientCu,while a quadraticequation call be fitted to the correlation between permeability coefficient and effectivediameterdlothe same as with NonuniCu.There are the close correlation amongpermeability coefficient of sandy gravel media and the size of boulder and hydraulic gradient.2When the depth of water in the river course is kept constant and the content of sullageOccurs in small amounts,a majority of sullage will be taken away by water through pore wayin the cobblestone medium.Therefore,the effect of sullage on the seepage flux is less visibleBut when the depth of sullage increases to certain extent,a part pore of cobblestone mediumwill be jammed by the increasing sullage.And at the same time,seepage flux decreasesgradually.Covered by the sullage with the same depth,the seepage flux of cobblestone in theriver course increases with the increase of water depth.But in the context of lager depth ofsullage on the surface of cobblestone,alone with the progress of the experiment,the influenceof the increasing depth of water on the seepage flux is weaken liUle by little.3The coating which consists by large size cobble,fine particle and geotextile has thebest mud resist and keep infiltrating function. The best composite structure of fine particle andgeotextile compound coating which to resist mud and keep seepage is geotextilefineparticlegeotextile.After overall consideration to osmotic coefficient and water quality,thetop to bottom best sand gravel profile structure of artificial percolating filter is 1~O.25mmpine particle 1 4cmgeotextile3 l mm sand gravel 20cm6---。3mm sand gravel 20cm1 0太原理工大学硕士研究生学位论文6mm sand gravel 20cm30~10mm sand gravel 20cm50~30mm sand gravel 20cm90~50mm sand gravel 1 5cm.The research on artificial percolating filter profile structure of different particle sizematching sandy gravel media in this paper,which only belongs to preliminary analysisaccording to the test structure,the best profile structure eventually got need the future projectpractice verificationKey WordsSandy gravel mediaOsmotic coefficient,Grading curvePanicle sizecharacteristics;Model forecastV太原理工大学硕士研究生学位论文目 录摘 要..iABSTRACT..目 录.vll第一章引言.11.1问题的提出与研究意义11.1.1问题的提出11.1.2研究意义11.1.2.1科学意义11.1.2.2应用价值21.2饱和多孔介质渗透特性的国内外研究动态21.2.1饱和多孔介质的渗透机理的研究动态21.2.2饱和多孔介质的渗透模型的研究进展41.2.3特殊饱和多孔介质的渗透特性的研究进展71.2.4饱和多孔介质的渗透特性的研究趋势91.3论文的研究内容..101.4研究的技术路线..10第二章试验条件与方案132.1河床漂石一砂卵石介质132.1.1供试河床漂石一砂卵石介质概述132.1.2河床漂石一砂卵石介质质地142.1.3河床漂石一砂卵石介质结构152.2试验方案..162.2.1试验总体设计..16VIl太原理工大学硕士研究生学位论文2.2.2自然河床漂石一砂卵石介质渗透特性试验方案172.2.3无特细颗粒河床漂石一砂卵石介质渗透特性试验方案182.2.4漂石对砂卵石介质渗透特性影响的试验方案一182.2.5黄河淤泥对砂卵石介质渗透特性影响的试验方案一202.2.6砂卵石介质最优渗透系数配比的试验方案一202.2.7人工渗床最佳剖面组合试验方案一212.2.8人工渗床淤积层冲洗技术的试验方案一232.3.试验仪器一262.3.1漂石和砂卵石渗流试验装置一262.3.2其它仪器设备一282.4试验方法一282.4.1试验过程一282.4.2渗透系数测定方法一302.4.3渗流水力梯度测定方法..302.4.4给水度测定方法..302.4.5浊度测定方法..30第三章黄河滩地天然河床漂石一砂卵石介质的的阻渗特性一313.1天然河床漂石一砂卵石的渗流过程..313.1.1天然河床砂卵石渗透系数的量级及其阻渗特性..313.1.2天然河床砂卵石渗透系数随深度的变化特性..343.1.3天然河床砂卵石渗透系数随水力坡降的变化特性一363.2天然河床砂卵石的阻渗机理..383.3天然河床砂卵石渗透系数的主要影响因素..383.4天然河床砂卵石的渗流模型..413.5小结..42第四章河床表层淤泥层对天然砂卵石介质渗流特性的影响一434.1黄河河床地表淤积泥层的特性一434.2淤积层的阻渗特性与机理一44VI|I太原理工大学硕士研究生学位论文4.3淤积层厚度对天然砂卵石介质渗流通量的影响..454.4河道水深等厚度淤积层覆盖下砂卵石介质渗流通量的影响..474.5小结..49第五章便冲於地表覆盖层的阻泥保渗措施的试验研究.515.1无砂混凝土板的阻泥保渗效果作用与机理..515.2大粒径卵石覆盖层阻泥保渗效果作用与机理..525.3细颗粒介质与土工布复合覆盖层阻泥保渗效果作用与机理..535.4小结..56第六章结论与建议596.1研究结论..596.2研究展望一60参考文献.61致j射65硕士期f.-j所获得的成果一67太原理工大学硕士研究生学位论文1.1问题的提出与研究意义1.1.1问题的提出第一章引言水分在多孑L介质中的运动被定义为渗流。早在1856年,法国科学家Darcy开始了室内砂柱的饱和土壤的渗流问题研究,并提出了著名的达西渗流定律,即介质通量或流速与渗流水的能量梯度成正比例。其研究的物理模型具有通体均质、同性、孔隙尺度使水流处于层流状态。其它学者的后续研究表明,达西定律对于具有较大尺度孔隙的介质和极小尺度孔隙的介质使用性受到限制。近几年来,我国学者邵明安等进行了土壤中所含砾石对渗透过程的影响研究。前人的研究提供了不同介质达西渗流条件下的渗透系数,被广大工程技术人员广泛应用于各类工程渗流的计算中。随着社会经济的发展和需求的变化,由于达西渗流物理模型的限制,达西渗流公式的局限性有所显现,如非均质渗流介质条件下渗流、非层流条件下的渗流等。由于我国降水资源的短缺,北方地区傍河取水工程与曰俱增。傍河取水工程的类型多变,但以工业供水和生活用水位用户的供水工程,以开采河床地下水的过程为主,这是由于地下水质较好,不受水体含砂率和水文丰枯季、丰枯年的影响的缘故。但在开采河谷地下水工程建设中遇到的技术问题是河床傍河取水工程的取水量的计算问题,理论计算结果与实际工程弃水量相差过大。如柳林黄河滩地取水工程,根据河床堆积物地层的砂卵石粒径和组成取定的渗透系数为21m/d,但打井后的抽水试验所测定的渗透系数近为1.5m/d,远远小于经验取定值。现场的详细踏勘分析认为,这与堆积砂卵石层中存在的漂石有直接的关系。针对这一具体问题,本项目试图以柳林黄河滩地原状自然堆积砂卵石及其漂石为研究对象,以室内较大尺度物理模型的试验研究为主,辅以适当的现场试验,试图揭示河床漂石一砂砾石介质的渗透特性,并着力探索既有利于取水水量渗透系数增加,又满足取水水质悬浮物要求的漂石一砂卵石介质的最佳级配。为山西省乃至全国的傍河取用地下水提供技术参数支撑。1.1.2研究意义1.1.2.1科学意义本项目所涉及的渗流问题属于恒定饱和渗流范畴。与达西渗流条件相比较,其不同】
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