北京地下水人工回灌悬浮物堵塞试验研究

针对北京地下水人工回灌过程中严重影响到回灌效率的入渗场地介质堵塞问题,采用北京市地下水回灌场地实际地层的土体,开展室内土柱模拟试验,以永定河河道内砾砂和西郊西黄村砂石坑的圆砾作为入渗介质,注水中悬浮物浓度分别为5、1、0.5g/L。试验结果表明:悬浮物堵塞会引起土柱渗透系数大幅衰减;悬浮物堵塞主要发生在回灌场地表层,在试验柱内可分为两层,表层为严重堵塞区,最深达12cm,下层为堵塞影响区,深度可达65cm;渗透介质颗粒越粗、悬浮物浓度越大,严重堵塞和堵塞影响的深度越大,而渗透介质颗粒越细、悬浮物浓度越大,土柱越快发生堵塞。     

砂粒运移对砾石充填层损害试验与数值模拟

为了研究储层砂粒运移、堵塞对砾石充填层损害造成的砾石充填防砂水平井产能的影响,采用室内驱替试验,应用实际油井出砂和充填砾石模拟了不同砾石与地层砂粒径比情况下,砂粒的运移对砾石充填层渗透率的损害规律及砾石充填层堵塞机理.结果表明:砂粒运移、侵入及堵塞导致砾石层渗透率发生明显变化,地层砂与砾石层接触面附近损害最为严重.根据砾石与地层砂粒径比及砂粒入侵程度不同,砾石层挡砂机理主要为地层砂未侵入、浅层桥接、深层桥接、孔隙充填和地层砂完全通过5种类型;根据试验结果,采用线性回归法建立了单位体积砾石层内地层砂堵塞量动态模型并数值仿真模拟软件,对砂粒在砾石充填层中的运移过程进行数值仿真模拟,模拟结果与试验结果基本一致.对定量评价地层砂颗粒运移对砾石层损害及油井产能预测有重要意义.     

压力回灌中回灌量衰减因素探讨

回灌量衰减是地下水回灌中常见的问题,导致回灌量衰减的原因有很多种.根据沈阳市某压力回灌试验的实测数据,查明引起回灌量衰减的因素有自然衰减作用和堵塞衰减作用.通过对比可知,堵塞作用发生的时间远远滞后于自然衰减作用.同时,堵塞作用也是造成回灌量减少的主要原因.最后针对研究区回灌量衰减特征,给出其衰减计算公式.     

建筑物斜坡反滤层的施工

水工建筑物下游反滤层的设置,有两种型式:一种是水平铺设,如涵闸下游护坦底部的反滤层。另一种是倾斜铺设,如扬水站压力池下部护坡底部的反滤层。水平铺设的反滤层,施工比较容易。但设置在斜坡上的反滤层,施工中如果控制不好,往往会出现各层反滤料互相掺杂的现象,会影响反滤效果。所以必须采取有效的施工措施,防止这一弊病的产生。我县王信扬水站压力池前部1:1的斜坡上,设置三层反滤料(图1)。在反滤层     

天然与人工滤层对渗管出水的影响

为了探究天然河床砂厚度对渗管取水工程出水量的影响,以及天然河床砂和人工反滤层的交互作用,通过物理模型试验,设置3种天然河床砂厚度、3种来流流量和不同水深,观测不同工况下渗管出水量的情况.根据试验结果进行回归分析.回归方程计算的出水量与试验值误差基本都在±5%以内,平均误差的绝对值仅为0.19%,较以往参考值算法更加精确;出水量的改变与天然河床砂渗透系数和人工反滤层渗透系数的大小有关,当天然河床砂的渗透系数小于人工反滤层最小渗透系数时,渗管出水量随着天然河床砂厚度的增加而减小;反之,则随着天然河床砂厚度的增加而增加.反滤层渗透系数对渗管出水量的影响要大于水头高度对出水量的影响.回归方程的方法提高了渗管出水量计算的精度,可用于实际工程的指导,在渗管取水工程的设计中需考虑天然河床砂与人工反滤层之间的交互作用,根据天然河床砂的渗透系数与厚度合理选择人工反滤层.     

网式过滤器滤网堵塞成因分析与压降计算

为分析网式过滤器滤网堵塞的过程和成因,并获得滤网堵塞后压降计算的相关参数,对网式过滤器进行堵塞试验。试验结果表明:滤网堵塞经历了介质堵塞和滤饼堵塞2个过程,形成的滤饼内层泥沙颗粒粒径较大,外层颗粒粒径分布较均匀;滤网孔径和含沙量是影响堵塞的重要因素,滤网孔径越小,滤网堵塞所用时间越短;相同孔径下,含沙量越大,堵塞所用时间越短,滤网越容易堵塞。根据试验结果建立了滤网内外压降与滤网孔径、滤网厚度、孔隙率、形成滤饼层厚度、滤饼孔隙率等的定量关系式,并分别计算了孔径为430、280、200μm滤网的内外压降,并与实测压降进行了对比分析。结果表明,计算得到的滤网内外压降与实测值基本一致,可以反映滤网堵塞的规律;滤网内外压降随水流流量、滤网厚度、形成滤饼层厚度增大而增大,滤网孔径越小,滤饼孔隙率越小,滤网两侧压降越大。     

渗渠取水工程反滤结构的试验研究

反滤层是渗渠取水工程中最重要的组成部分,渗渠反滤层是防止河床土体渗透破坏的有效措施,是渗渠出水水质的重要保障,反滤层的结构组成以及渗透性能直接影响渗渠"滤土"和"排水"效能。结合工程实际,通过水工模型试验,探讨反滤结构组成对渗渠渗滤作用的影响。试验研究和理论分析表明:反滤层结构变化对渗渠的集水流量和净滤作用都有较大影响,若以集水流量为主要指标,则单一均质滤层多层均质滤层级配滤层;若以净滤作用为主要指标,则多层均质滤层与级配滤层的去浊能力远高于单一均质滤层,且随着表层积沙厚度的增加,级配反滤层有更加明显的去浊效果,而且随着过流时间的增长,三种类型滤层结构的渗渠取水效能会越来越低。本研究成果对于渗渠结构在工程实际中的设计、施工、运行提供了一定的实践和理论依据。     

砾石覆盖对抑制旱作农田土壤风蚀效果的风洞模拟

针对中国阴山北麓旱作农田风蚀比较严重的现实，将旱作农田地表铺设不同覆盖度和粒径的砾石后进行风洞试验，旨在探索砾石覆盖度和粒径在抑制旱作农田土壤风蚀效果方面的作用，为采取合理的防风蚀措施提供技术依据。利用野外风洞原位测试方法，完成了6种风速下对应净风和挟沙风时的不同砾石粒径和覆盖度下的旱作农田土壤风蚀测试。结果表明：无论净风还是挟沙风，增加砾石覆盖度，旱作农田抗风蚀效率均提高，但当砾石覆盖度超过28%后，其对提升抗风蚀效率作用不大；在相同覆盖度下，随砾石粒径的增加，输沙量、抗风蚀效率略有变化，但不明显；将耕     

生态净化工程预处理单元对泥沙沉积的时空规律研究

生态湿地预处理单元是沉降原水的大颗粒泥沙,初步净化水质,减轻后续生态处理负荷的主要场所,掌握预处理单元对原水悬浮物的去除效果,及泥沙沉积的时空规律,可为清淤工作的安排提供科学的依据,从而维持其处理效果。以盐龙湖工程预处理区为例,按季度开展了为期1年的泥沙沉积时空规律研究。研究结果表明:该区沉积物厚度、干重以及含固率顺水流方向呈现前高后低、依次降低的趋势;泥沙沉积厚度与原水悬浮物浓度成正相关关系;根据原水悬浮物浓度与沉积物厚度的关系,可确定单位时间内预处理区泥沙沉积的厚度。     

微灌砂过滤器石英砂滤料颗粒粗糙度参数测算与分析

微灌砂过滤器砂滤料颗粒的表面粗糙度直接影响到砂滤层水头损失和对水中杂质的滞纳能力,从而影响到滤层过滤效果。为了对砂滤料颗粒表面粗糙度进行定量分析,以粒径范围为1.0~1.18、1.18~1.4和1.4~1.7 mm的3种滤料的砂滤料颗粒为研究对象,每种滤料选取15粒石英砂作为样本,以砂滤料颗粒表面形貌的均方根偏差、表面高度分布的偏斜度和表面高度分布的峭度表征颗粒表面粗糙度,采用三维表面形貌仪对粗糙度参数进行测量,采用统计分析方法对粗糙度参数进行分析。结果表明,3种滤料砂滤料颗粒表面波峰波谷的波动幅度分别占滤料当量粒径的15.6%、14.6%和13.1%,说明微灌砂过滤器砂滤料颗粒表面粗糙度比较大;石英砂滤料颗粒表面高度分布的峭度比较大,说明砂滤料颗粒表面形貌高度分布比较集中;石英砂滤料颗粒表面高度分布的偏斜度都为负,说明砂滤料颗粒表面凹陷部分所占比例偏大,影响过滤效果。通过研究认为,要使过滤器石英砂滤料获得更好的过滤效果,应选取相对较大颗粒的石英砂滤料,并对砂滤料的生产工艺进行改进,使砂滤料粗糙度适当增大。     

Emitter and filter tests for wastewater reuse by drip irrigation

Agriculture is the main user of water in Italy, as in most regions of the world. Particularly in Mediterranean regions, where it is more difficult to meet the agricultural water demand with conventional resources, wastewater reuse represents a viable option. Drip irrigation is particularly suitable for wastewater reuse because it minimises the health risks to farmers and product consumers due to contact with the wastewater. The performance of drip irrigation systems using wastewater is mainly limited by emitter clogging, and this discourages farmers from introducing it. The paper gives the results of experimental trials on the behaviour of six kinds of filters (gravel media, disk and screen) and four types of drip emitters (vortex and labyrinth) using five kinds of municipal wastewater that have not undergone previous advanced treatment. The performance of the emitters and filters tested depends on the quality of the wastewater: total suspended solids and organic matter content influence the percentage of totally clogged emitters, the mean discharge emitted, the emission uniformity coefficient, and the operating time of the filter between cleaning operations. Vortex emitters were more sensitive to clogging than labyrinth emitters. The gravel media filter guaranteed the best performance, but the disk filter, which is cheaper and simpler to manage, assured performance similar to that of the gavel media filter. The test showed the importance of the technology used in manufacturing disk filters. Screen filters were shown to be unsuitable for use with wastewater, with the exception of diluted and settled wastewater. The theoretical discharge of filters, suggested by the manufacturers for clean water, is not adequate for wastewater of the kind used in the trials (suspended solids greater than 78 mg/l and BOD₅ more than 25 mg/l of O₂). The operating times of the filters between cleaning operations, less than 1 h in most trials, suggest the use of automatic cleaning systems. The existing clogging risk classifications proposed for clean water can only be considered reliable for wastewater when labyrinth emitters and gravel or good quality disk filters (such as Arkal) are used; they are not adequate for vortex emitters or screen filters.     

Effect of filter, emitter and location on clogging when using effluents

The effect on emitter clogging of four filtration systems (sand, screen, disc and a combination of screen and disc filters) and six emitter types placed in laterals 87 m long, using two different effluents with low suspended solid levels from a wastewater treatment plant, was studied for 1000 h. Four of the emitters were molded and welded into dripline wall, two of them being pressure-compensated and the other two non-pressure-compensated. The other two emitters, both pressure-compensated, were inserted into thick wall. Emitter clogging was affected mainly by emitter type, location along the lateral and the interaction between these two factors. Differences among emitters with larger clogging were only observed at the end of dripline. Two molded and welded emitters showed the worst performance: one non-pressure-compensated with the lowest passage section, and the other pressure-compensated that, after 800 h working at higher dripline flow and particle load, experienced an important decrease in flow rate. Only with the effluent that had a higher number of particles, did the filter and the interaction of filter and emitter location have a significant effect. Emitters placed after screen and sand filters showed the largest flow rates at the lateral ending, even though only sand filtration significantly reduced turbidity and suspended solids. Emitters protected by a disc filter experienced the largest flow rate reductions.     

地下滴灌抗根系入侵堵塞的研究进展

作物根系入侵滴头造成堵塞是影响地下滴灌系统运行的一个重要原因,目前国内外解决根系入侵堵塞的主要方法有：生产专用滴头和过滤器,滴头包括从结构上改进以防止根系入侵以及从滴头材料中添加缓释的除草荆氟乐灵来避免根系向滴头附近生长两种方式;专用过滤器是在过滤器内部安装放置除草剂氟乐灵的密封装置,过滤时氟乐灵随水进入滴头,起到防止根系入侵滴头的作用;向地下滴灌系统注入化学物质来杀死滴灌周围的根系;合理控制系统运行状况,避免出现水分胁迫等。     

浑水泥沙粒径与含沙量对迷宫流道堵塞的影响

为客观评价浑水中泥沙特性对滴头流道堵塞的影响以及合理选择滴灌水质处理方法,采用L9（34）的正交试验设计方法,进行了浑水间歇灌水测试,并提出了以滴头平均相对流量和灌水均匀度系数作为基本参数的滴头堵塞程度综合评价方法,比较分析了压力、含沙量以及泥沙粒径等变化对滴头堵塞比例和堵塞程度的影响规律.研究结果表明：对于粒径小于0.1 mm的泥沙颗粒,工作压力对流道堵塞的影响非常显著,其次为泥沙粒径;滴头堵塞程度的大小是由粒径、含沙量、工作压力三者相互耦合作用引起的,且相互之间不存在单调相关关系.在实际灌水过程中,当灌溉水中含有较多小于0.1 mm的泥沙颗粒时,应尽量滤除粒径小于0.048 mm的颗粒,并可加入分散剂,阻止细小黏粒的团聚絮凝作用,以提高滴头抗堵塞能力.     

细小泥沙对半透膜微润管堵塞的影响

为探明半透膜微润管对细小泥沙抗堵塞性能的影响,采用有压连续灌水方式对微润管3种粒径组成小于0.100 mm的泥沙颗粒进行了不同质量分数浑水灌溉堵塞试验.分析了泥沙粒径、含沙量以及压力水头对灌水器堵塞的影响,同时探讨了灌水器发生堵塞时的敏感粒径范围和含沙量质量分数值.试验结果表明:随着浑水含沙量的增大堵塞越严重,呈正相关关系;粒径在0.061 0 mm~0.100 0 mm对微润管的堵塞影响最大;相同水质条件下,随着压力水头的增大微润管堵塞程度会降低.研究结果为进一步利用半透膜微润灌溉技术提供了相关的理论基础.     

改进暗管排水技术淤堵防护措施试验研究

基于室内土柱试验,依据太沙基准则,考虑2种反滤体铺设方式、2种土工布类型以及3种土工布铺设位置,模拟改进暗管排水条件下反滤体或土工布的单一防护措施以及反滤体与土工布结合的组合防护措施下排水流量的衰减过程,得到不同方案的土工布淤堵量及土壤流失量,提出改进暗管排水条件下反滤体及土工布的合理布局。研究结果表明,依据太沙基准则选择改进暗管排水的砂砾石规格是合理可行的;仅在暗管周围铺设土工布的分层和混合反滤体方案对防护土工布淤堵和土壤流失均有较好效果;综合考虑流量衰减过程、土工布淤堵量和土壤流失量,确保改进暗管排水的长期稳定运行,应优先考虑分层反滤体结合暗管周围铺设合理土工布的方案。     

大田滴灌用网式过滤器滤网堵塞成因分析

过滤器是滴灌系统中最核心的设备,其中网式过滤器以其良好的过滤性能保障了滴灌系统的正常运行,在我国新疆等西北地区农业滴灌系统中应用最广泛。但其应用过程中也存在滤网清洗不彻底以及堵塞的问题,为此,在对网式过滤器滤网堵塞成因及机理进行全面论述基础上,分别从水源水质、不同滤网类型、反清洗设计问题以及水肥一体化对滤网的化学影响等方面对滤网堵塞成因进行了详细的分析,并提出相应对策;这为今后深入研究滤网堵塞机理、解决滤网堵塞问题提供一种思路,为进一步研制更适用西北地区的农业滴灌过滤设备提供理论依据。     

温度对施肥滴灌系统滴头堵塞的影响

为探究不同灌水温度下水肥一体化滴灌滴头堵塞成因与过程,采用固定周期间歇滴灌的多因素完全随机试验设计方法,分别在冬、夏两个季节研究了3种不同泥沙级配浑水与3个不同施肥质量浓度组合对滴头堵塞的影响和堵塞变化过程。结果表明,灌水温度是影响滴头堵塞的重要因素,与水质交互耦合效应显著,夏季施肥和未施肥2种情况下灌溉滴头的抗堵塞性能均高于冬季,夏季有效灌水次数是冬季的1.26~1.43倍;施肥加速滴头堵塞的作用受泥沙级配和灌水温度的影响,冬季灌溉水中0.034~0.1 mm粒径粗颗粒含量越多,施肥质量浓度对堵塞的影响越敏感,夏季灌溉水中0~0.034 mm细颗粒越多,施肥质量浓度对堵塞的影响越敏感。建议灌水温度较低时,水肥一体化滴灌应控制在较低的施肥质量浓度下灌溉,适当增大次灌水时间,减少灌溉次数。     

Surface topographic characteristics of suspended particulates in reclaimed wastewater and effects on clogging in labyrinth drip irrigation emitters

Drip irrigation is the most effective and reliable method for reclaimed wastewater irrigation. Emitter clogging is the major problem for extending the drip irrigation technology. The existence of suspended particulates in irrigation water is the main reason for the emitter clogging. However, the reclaimed wastewater quality is extremely complex, and there is a series of physical, chemical, and biological reactions between suspended particulates and other materials contained such as microorganisms, which make the characteristics of suspended particulates in reclaimed wastewater complicated. In this paper, two types of widely used wastewaters treated with fluidized-bed reactor (FBR) and biological aerated filter (BAF) processes respectively were selected. The scanning electron microscope (SEM) technology and fractal theory were used to quantitatively describe the characteristics of the surface topography of suspended particulates. The results showed that the suspended particulates in two reclaimed wastewater were flocculent and porous. The pore system mainly consisted of solid suspended particulates, and most areas between the particulates were filled with microbes and extracellular polymers (EPS). The complex structure of biofilms was formed. That the biofilms grew and detached in irrigation system and deposited continuously at the inlet and outlet of labyrinth path was the major reason for the emitter clogging. The surface topography of suspended particulates in both reclaimed wastewaters showed fractal and multifractal characteristics, and the fractal dimension could not characterize the local and microsingularity of particulates but multifractal dimension could. The uniformity of the distribution of sediment pores increased with the size. Comparatively, the uniformity of suspended particulates in reclaimed wastewater treated by FBR was lower. With operation of reclaimed wastewater irrigation system, the average discharge of emitters decreased continuously with obvious fluctuations. The clogging degree of emitters was low during the first 256 h, and the clogging degree of the two types of reclaimed water was similar. But then, the degree of clogging increased greatly, and the FBR treatment on the emitters discharge were more obvious than BAF. It was closely related to the growth, detachments and sediment of biofilms in the irrigation system. Hence, using the reclaimed wastewater treated by BAF for drip irrigation is more suitable.     

含沙水磁化处理减缓滴头堵塞机理研究

为探究含沙水磁化处理对悬浮泥沙在滴灌管网中沉降的影响,揭示含沙水磁化处理对滴头堵塞的减缓机理,以内镶贴片式迷宫流道滴头为研究对象,设置4种磁化强度(0、0.2、0.4、0.6 T)和4种粒径级配(0～0.100 mm、0.075～0.100 mm、0.038～0.075 mm、0～0.038 mm)的泥沙,泥沙质量浓度...