ZM系列渠道防渗减压阀的研究和应用

挖方或傍山衬砌的渠道,往往因地下水的挤压使渠底板开裂、鼓泡掉块、翻倒等。为保证渠道稳定,湖南省水科所研制出 ZM 系列渠道防渗减压阀.其基本构造为:在聚氯乙烯硬塑管模内,装入单向排水的逆止阀,管的两端用土工织物封盖。其性能良好,适用范围广,能有效地排除地下水压力对防渗层的破坏,而渠内过水时水流不外渗。     

滴灌设施的冬季维护与管理

<正>目前滴灌已在团场大面积应用,滴灌设备投资大,年使用时间短,停置时间较长。为了延长其寿命,发挥其应有效用,加强滴灌设施的冬季保养与维护具有重大意义。 (1)设备排水,防止冻裂。排净水泵、过滤器、地下管道、逆指阀中的水。对于没有排水螺钉的逆止阀,要打开盖板,然后,将各阀门置于     

泵站水锤的防护措施及其简易计算(下)

(一) 装设缓闭式逆止阀缓闭式逆止阀是一种靠缓冲机构使逆止阀缓慢关闭的一种泄流防护水锤设备,主要有主阀本身缓慢关闭和旁通辅助阀缓慢关闭两类. 主阀本身缓闭的逆止闪,在阀轴或阀板上装有缓冲器     

逆止阀与旁通管联合运用控制泵站水锤的研究

在普通逆止阀进出口之间设置一根跨越逆止阀的旁通管,停机时允许一定流量自由倒流,从而既避免了逆止阀快速关闭引起阀后过高的水锤压力,又控制了水泵机组的飞逸倒转,在可能产生水柱分离的管道系统中,可有效地限制水柱分离再弥合时产生的最大水锤升压。这种组合形式结构简单,运行可靠,维护方便,节省投资,具有极大实用价值     

ZM系列渠道防渗减压阀研制成功

<正> 傍山和深挖方的渠段,由于渠外侧地下水压力的影响,往往使渠内防渗层边坡下部及底板遭到破坏,如混凝土开裂,柔毡或塑料薄膜鼓泡掉块,严重的甚至引起滑坡。为了防止这种现象发生,以往做法是在渠内埋设排水竹管或预留排水孔,这样虽能导排出地下水,但给渠内水流形成了向外渗漏的人为通道,难以达到节约用水的目的;同时,由于集中渗漏,易于形成塌洞,使衬砌体架空,给管理和维修工作带来后患。 针对这种情况,湖南省水科所研制的“ZM系列渠道防渗减压阀”(下称减压阀),能有效地排除地下水压力对防渗层的破坏,而渠内过水时不外渗。 它的基本构造是:在聚氯乙烯硬塑管模内,装有单向排水的逆止阀,管的两端用土工织物封盖,如附图所示。 该装置对已经或正待衬砌的各种材料的渠道防渗层都适用;且可用于保护塘坝或涵     

逆止阀的使用与安装浅谈

1.逆止阀的安装位置逆止阀的安装位置目前尚无具体规定,因此,目前各泵站出口处逆止阀与闸阀的安装位置也不相同,在某些泵站中,水泵出口逆止阀与闸阀的安装顺序为:水泵出口→闸阀→逆止阀,如图1所示。     

倒装逆止阀用于停泵水锤防护的尝试

泵站出口同时装设闸阀和逆止阀时,以往大多数是泵出口先装闸阀,然后再装逆止阀。本文将讨论先装逆止阀后装闸阀的优点及其对水锤防护的作用。     

高地下水位渠道衬砌排水试验

近年来,山东省渠道衬砌的发展比较迅速,许多新建和扩建的大中型骨干输水工程都采用了混凝土板等衬砌措施,较好地解决了土基渠道渗漏损失大、边坡易坍塌和引黄灌区泥沙淤积等问题。本文结合胜利油田七干渠渠首段衬砌工程的排水试验和应用实践,就高地下水位条件下渠道衬砌的施工排水和防扬压力排水问题进行了总结和分析,以期供类似工程设计时参考。     

一种潜水电泵逆止阀的试探

一、问题的提出潜水电泵以其结构简单,体积小,重量轻,安装、折卸、维修方便,占地面积小,无需建造专用泵房,受到广大用户欢迎,因而广泛地使用于农田排灌、矿山排水及城镇和工厂给水。但潜水电泵也存在其不足的一面。效率偏低,耗电较多,究其原因,除其所配潜水电机本身效率偏低、输水管径偏小之外,所配逆止阀局部阻力过大亦是导致其     

农用水泵节能法

１取消底阀底阀阻力系数较大，一般可降低扬程１５米左右。取消底阀以后水泵的效率会显著提高。若在出水管口装上一拍门，再用黄油封住填料盒，这样，停泵后再次启动时就不必充水。２取消闸门和逆止阀闸阀和逆止阀的阻力系数比较大。闸阀的作用是为了调节水量，但农...     

Conjunctive use of saline and non-saline irrigation waters in semi-arid regions

In arid and semi-arid regions, effluent from sub-surface drainage systems is often saline and during the dry season its disposal poses an environmental problem. A field experiment was conducted from 1989 to 1992 using saline drainage water (EC=10.5–15.0 dS/m) together with fresh canal water (EC=0.4 dS/m) for irrigation during the dry winter season. The aim was to find if crop production would still be feasible and soil salinity would not be increased unacceptably by this practice. The experimental crops were a winter crop, wheat, and pearl-millet and sorghum, the rainy season crops, grown on a sandy loam soil. All crops were given a pre-plant irrigation with fresh canal water. Subsequently, the wheat crop was irrigated four times with different sequences of saline drainage water and canal water. The rainy season crops received no further irrigation as they were rainfed. Taking the wheat yield obtained with fresh canal water as the potential value (100%), the mean relative yield of wheat irrigated with only saline drainage water was 74%. Substitution of canal water at first post-plant irrigation and applying thereafter only saline drainage water, increased the yield to 84%. Cyclic irrigations with canal and drainage water in different treatments resulted in yields of 88% to 94% of the potential. Pearl-millet and sorghum yields decreased significantly where 3 or 4 post-plant irrigations were applied with saline drainage water to previous wheat crop, but cyclic irrigations did not cause yield reduction. The high salinity and sodicity of the drainage water increased the soil salinity and sodicity in the soil profile during the winter season, but these hazards were eliminated by the sub-surface drainage system during the ensuing monsoon periods. The results obtained provide a promising option for the use of poor quality drainage water in conjunction with fresh canal water without undue yield reduction and soil degradation. This will save the scarce canal water, reduce the drainage water disposal needs and associated environmental problems.     

Chinese experience on plastic membrane-concrete thin slab lining for canals

Of the many types of canal linings in the world, concrete, compacted earth and buried plastic membrane linings are most commonly used. Another type of canal lining — plastic membrane-concrete thin slab lining — has been used in China since 1975. It has the advantages of both plastic and concrete linings, including good seepage control, smooth lining surface, steeper side slopes, effective film valve to eliminate external water pressure, reliability, durability, and lower construction cost. This type of canal lining is a viable alternative to other types of linings, especially in developing countries where the cost of labor is low or farmland is limited.     

Identifying sources of recharge to shallow aquifers using a groundwater model

The poor water quality of sub-surface drainage, hereafter drainage, water generated in the western San Joaquin Valley in California creates management challenges for farmers and water managers. Elevated concentrations of salt and trace elements in agricultural drainage limit the disposal options. In this constrained environment, determining the original source of drainage water is a crucial step in developing appropriate drainage management policies. Numerical modeling results of near-surface water-table fluctuations indicate that the substantial groundwater rise observed in the vicinity of the region's major water supply canal could not be attributed solely to seepage from overlying irrigated fields. An inverse solution approach is used herein to test the theory that seepage from the canal itself and/or that from surface water retention ponds (designed to protect the structure from flash floods) is responsible for an accentuated groundwater mound. The results suggest that canal seepage is the more likely source of non-agricultural aquifer recharge.     

渠道边坡稳定的盐敏感性特征研究

工程中灌排渠道在运行多年后,随着土中含盐量的增加,会造成渠道边坡不同程度的滑塌、变形及结构的破坏。通过对盐化土的剪切试验和界限含水率试验,得到不同含盐量下土的抗剪强度指标和稠度界限,运用单因素试验分析含盐量对土的抗剪强度和稠度界限的影响规律。随着含盐量的增加,土体的团聚体稳定性降低,增加了粘粒的分散性,土的抗剪强度有所下降;同时土的稠度界限也会降低,增大了土的流动性,明确地说明含盐量增加也是影响灌排渠道边坡稳定性重要因素。     

Automatic regulation of canal offtakes

A mechanical scheme has been developed for the accurate control of flow rates from one canal or reservoir to another canal that is particularly applicable for operations at canal headings or bifurcations. The system is hydraulically actuated using water from any pressure source, or the change in water pressure accross the structure. It does not depend on electricity or motors which are vulnerable to electric outages and lightning strike damage. The system is a modification of the Danaidean controlled-leak system that uses a large float in a float chamber to mechanically control a canal gate (or valve). The new system is called the Dual-Acting Controlled Leak (DACL) system because valves control leakage both into and out of the float chamber to control canal levels to within ±3 mm. This paper focuses on comparisons between control methods and possible configurations for the DACL system.     

淮河入海水道渠北地区排涝现状分析与启用北泓漫水闸应急排涝研究

在分析淮河入海水道渠北地区排涝现状的基础上,针对由于滨海枢纽隔水墙设计允许水位差的限制,当渠北遭遇较大降雨时,依然出现涝灾的实际,提出了启用北泓漫水闸进行排涝的方案。该方案可有效分泄上游地区涝水,也有利于下游地区排涝,特别有利于突击排除洼地涝水,还可减少甚至避免污水排入总渠,有利于保护环境。     

Effects of water quality and frequency of irrigation on growth and yield of barley (Hordeum vulgare L.)

A field trial on a loamy sand soil was carried out to study the effect of three irrigation waters with different qualities on growth and yield of ‘Gesto’, a barley (Hordeum vulgare L.) cultivar. Three irrigation water quality treatments (canal irrigation water, drainage water, and mixed canal and drainage waters at 1:1 ratio) were imposed with two irrigation frequencies (I and 2 week intervals). In addition, nitrogen and phosphorus fertilizers were applied at different rates. Barley grain and straw yields were significantly decreased under the use of drainage water (EC 10.7–16.7 dS m⁻¹), attributed mainly to reduction in the number of spikes per plant and grain weight. The mixed irrigation water (EC 6.8–9.9 dS m⁻¹) produced high seedling emergence and good vegetative growth, which was followed by high grain and straw yields. These yields were not significantly different from those under fresh canal irrigation water (EC 2.8–3.9 dS m⁻¹). Thus, mixed water could be another alternative for irrigation under similar experimental conditions especially with high rates of nitrogen (250–350 kg ha⁻¹) and phosphorus (90 kg ha⁻¹) fertilization at weekly irrigation intervals, which could eventually save more fresh irrigation canal water for other cultivated crops.     

A model for the design of drainage in flat agricultural lands

A model is presented that can be used to determine drainage measures and their costs. It has been elaborated for a wet tropical climate, for situations with open field drains, shallow groundwater table and a homogenous soil underlain by an impervious layer. The land is flat and the proposed agricultural use requires control of the groundwater table.A basic element of the model is a scheme to compute the water balance per day for a drainage parcel. Discharge, evapotranspiration, groundwater level and soil moisture storage are estimated as functions of rainfall, potential evapotranspiration, vegetation and soil characteristics and of an assumed drainage intensity. The water balance computation is performed for periods of 5–40 years of daily rainfall data, for a series of drainage intensities. The results can be subjected to a drainage criterion, from which a design drainage intensity and a corresponding drain spacing can be derived.Finally the layout of canals for a block of 4 × 1 km² is determined and excavation and a series of canal characteristics are computed.A summary of some applications is included.     

Estimation of water levels in a main drainage canal in a flat low-lying agricultural area using artificial neural network models

The Chiyoda basin is located in the Saga Prefecture of the Kyushu Island, Japan, and lies next to the tidal compartment of the Chikugo River, into which excess water in the basin is drained away. This basin has a total area of approximately 1100 ha and is a typical flat and low-lying agricultural area. The estimation of the water levels at the gates and along the main drainage canal is a crucial issue that has recently been the subject of much research. At these locations farmers and managers need to control the operation of the irrigation and drainage systems during periods of cultivation. An attempt has been made to apply a feed-forward artificial neural network (FFANN) to model and estimate the water levels in the main drainage canal. The study indicated that the artificial neural network (ANN) could successfully model the complex relationship between rainfall and water levels in this flat and low-lying agricultural area. Input variables and the model structure were selected and optimized by trial and error, and the accuracy of the model was then evaluated by comparing the simulated water levels with the observed ones during an irrigation period in July 2007. The water levels at two locations, located upstream and downstream of a main drainage canal, were investigated by using a time series at intervals of 20, 30, and 60 min. At these intervals, rainfall and tide water levels in the Chikugo River were measured, and the backward time-step numbers of the input variables of rainfall and tide water level were searched. For the upstream location, the optimal combination yielding good agreement between the observed and estimated water levels was obtained when the interval of the time series was 60 min. The number of backward time-steps of the input variables of rainfall and tide water level were 5 and 4, respectively. In contrast to the downstream location, the optimal combination was obtained for the interval time series of 20 min with 4 backward time-steps for both the input variables of rainfall and tide water level. The present study could provide farmers and managers with a useful tool for controlling water distribution in the drainage basin, and reduce the cost of installing water level observation points at many locations in the main drainage canal.