三铰拱隧洞预制构件衬砌安装台车组研制与施工

软弱围岩隧洞在设计上采用钢筋混凝土装配式预制构件衬砌的方式近年来越来越多,但在施工上还一直没有形成一套较完善的衬砌安装方法。现介绍一套适用于不同洞径的预制构件衬砌安装台车组,为今后同类隧洞的建设提供一种参考方法。     

滚移式喷灌机关键部件的设计与试验

针对节水灌溉技术中存在自主研发能力弱、技术性能低、设备可靠性差、经济成本过高等问题,设计研制出一种节省材料、降低油耗、工作可靠、喷灌均匀度高的滚移式喷灌机.根据输水支管受力特点,通过Matlab对支管壁厚进行优化设计,优化出3种不同壁厚的输水支管,不仅能够节省材料,降低油耗,还能增加机组爬坡能力.对滚移式喷灌机的自动泄水阀进行了结构设计,计算并确定结构参数,利用ANSYS CFX进行模拟仿真试验.田间性能试验结果表明,该滚移式喷灌机各项指标都满足要求,喷灌机向前移动时支管产生的最大挠度为2.7 m,喷灌均匀度为92.45%,喷灌强度为12.59 mm/h.该研究为滚移式喷灌机的进一步发展提供参考.     

围岩特性和衬砌厚度对衬砌混凝土在设置垫层下温控影响研究

基于有限元分析软件ANSYS,在溪洛渡泄洪洞有压段衬砌混凝土设置垫层的情况下,对不同围岩弹性模量和衬砌厚度进行仿真模拟。通过比较不同衬砌部位,不同点位的最高温度、最大内表温差、早期最大拉应力等,针对围岩弹性模量和衬砌混凝土厚度的变化对衬砌混凝土温度和温度应力的影响进行了分析。研究结果表明,①不同围岩弹性模量下,相同温控措施下衬砌混凝土温度场大致相同。较好围岩会增大早期衬砌混凝土的最大拉应力,减小最小抗裂安全系数,必须采取严格的温控防裂措施,防止早期裂缝。②相同温控措施下,衬砌混凝土越厚,最高温度越高,最大内表温差越大。较薄衬砌混凝土会增大早期衬砌混凝土的最大拉应力,减小最小抗裂安全系数,温控防裂措施要求严格。     

轻型井点降水用泵的选择原则及应用

轻型井点降水是一种简便、有效的降水方法,一般适用于渗透系数在0.5～5 m/d的砂土和沙性土层中降水.对在强风化岩层中使用轻型井点降低地下水位的方案进行了总结,探讨了轻型井点降水用泵的选择及其在强风化岩层中使用.该工艺的实践可为今后类似工程的实施提供借鉴.     

内蒙古临河地区渠道衬砌工程保温防冻胀试验研究

在我国北方的季节性冻土地区,防渗衬砌渠道的冻胀破坏对输水工程的危害最大.针对内蒙古临河地区南边分干渠冻胀破坏问题,提出了在渠道混凝土衬砌下铺设聚氨酯保温板新材料的措施.通过进行现场保温防冻胀试验,分析了各种保温措施下渠道基土的地温、冻深、含水率和冻胀量等影响冻胀变化因素的规律及其特征,总结了不同方案下的保温防冻胀效果,得出了适合该地区混凝土衬砌渠道中聚氨酯保温材料的防冻胀破坏方案:渠道阳坡上部使用3 cm厚的聚氨酯保温板,阳坡下部使用4 cm厚的聚氨酯保温板,阴坡上部使用4 cm厚的聚氨酯保温板,阴坡下部使用5 cm厚的聚氨酯保温板就可以保证混凝土衬砌体不发生冻胀破坏,同时为后续刚性衬砌渠道中采用聚氨酯保温材料防冻胀提供了技术支持.     

Changes in hydraulic performance and comparative costs of lining and desilting of secondary canals in Punjab,Pakistan

Observations on the hydraulic changes of lining of secondary canals in Punjab, Pakistan show that performance improvement objectives are not always achieved. If lining is justified on the basis of water savings through reduced seepage losses, then tail end areas should receive improved water deliveries. Observations in two distributary canals following lining do not demonstrate significant improvements in tail end conditions. Justification of lining on the basis of more stable water conditions is also hard to identify; reduction in the variability of discharges was not observed.Financial analysis of a recent canal lining experience in Punjab indicates that water savings would have to be unrealistically high, and sustained for long periods, if the initial capital cost is to be repaid through improved water conveyance efficiency. Furthermore, the hydraulic improvements achieved through alternative interventions appear to strengthen the argument that lining can be justified only under special conditions, rather than adopted as a wholesale approach to solving water distribution problems. Whatever the intervention, management control must be strengthened; lining is not a substitute for effective canal operational and maintenance inputs.     

中国轻小型喷灌机组现状及发展建议

为了提高中国轻小型喷灌机组的技术水平,全面分析中国轻小型喷灌机组的研究现状和未来的发展趋势.轻小型喷灌机组是中国应用比较广泛的一种喷灌机具,在农田灌溉、排涝抗旱及生态环境建设等方面发挥着较为重要的作用.经过40多年的发展,中国的轻小型喷灌机组已经具有多种机组型式,可满足各种地形条件、投资水平及劳动力状况等不同场合应用.目前国产机组的水力性能较好,部分配套件质量达到或超过国外同类产品水平,但产品的可靠性、使用寿命和外观等与国外产品仍存在较大差距.中国农业生产力水平和经济发展状况决定了在未来较长时间内,轻小型喷灌机组在节水灌溉设备行业仍有较高的市场份额.因此,国家应加大扶持力度,支持开展轻小型喷灌机组配套模式、机械化技术、低能耗技术和使用可靠性的开发研究,进一步提高轻小型喷灌机组的技术水平.     

瀑布沟导流洞围岩稳定与支护结构分析

采用弹塑性有限元分析方法对导流隧洞开挖、支护、运行以及最后封堵的全过程进行了较为全面的仿真计算分析,给出了围岩和混凝土衬砌结构的位移、应力分布等,根据计算结果提出了导流洞结构的设计原则和工程处理措施,基本上解决了高外水条件下隧洞设计的难题.     

江坪河放空洞有压洞口段衬砌混凝土冬季温控方案分析

冬季衬砌混凝土施工面临的寒潮等问题,容易导致混凝土产生裂缝.基于有限元分析软件ANSYS,对江坪河放空洞有压段洞口段衬砌厚度为1.0 m的混凝土的拆模时间、围岩特性以及在遭遇寒潮时保温与否等6种不同的方案的进行了分析,并提出相应的温控方案和温控标准供设计与施工参考.     

Effects of deficit irrigation on the yield and yield components of drip irrigated cotton in a mediterranean environment

A field study on cotton (Gossypium hirsutum L., cv.) was carried out from 2005 to 2008 in the Çukurova Region, Eastern Mediterranean, Turkey. Treatments were designated as I₁₀₀ full irrigation; DI₇₀, DI₅₀ and DI₀₀ which received 70, 50, and 0% of the irrigation water amount applied in the I₁₀₀ treatment. The irrigation water amount to be applied to the plots was calculated using cumulative pan evaporation that occurred during the irrigation intervals. The effect of water deficit or water stress on crop yield and some plant growth parameters such as yield response, water use efficiencies, dry matter yield (DM), leaf area index (LAI) as well as on lint quality components was evaluated. The average seasonal evapotranspiration ranged from 287 ± 15 (DI₀₀) to 584 ± 80 mm (I₁₀₀). Deficit irrigation significantly affected crop yield and all yield components considered in this study. The average seed cotton yield varied from 1369 ± 197 (DI₀₀) to 3397 ± 508 kg ha⁻¹ (I₁₀₀). The average water use efficiency (WUE_ET) ranged from 6.0 ± 1.6 (I₁₀₀) to 4.8 ± 0.9 kg ha⁻¹ mm⁻¹ (DI₀₀), while average irrigation water use efficiency (WUE_I) was between 9.4 ± 3.0 (I₁₀₀) and 14.4 ± 4.8 kg ha⁻¹ mm⁻¹ (DI₅₀). Deficit irrigation increased the harvest index (HI) values from 0.26 ± 0.054 (I₁₀₀) to 0.32 ± 0.052 kg kg⁻¹ (DI₅₀). Yield response factor (Ky) was determined to be 0.98 based on four-year average. Leaf area index (LAI) and dry matter yields (DM) increased with increasing water use. This study demonstrated that the full irrigated treatment (I₁₀₀) should be used for semiarid conditions with no water shortage. However, DI₇₀ treatment needs to be considered as a viable alternative for the development of reduced irrigation strategies in semiarid regions where irrigation water supplies are limited.     

砒砂岩地区人工沙棘群落结构及多样性分析

针对砒砂岩地区困难立地生态恢复与合理利用问题,选取2～10a的沙棘人工林为研究对象,对不同林龄群落结构及植物多样性进行比较研究.结果表明:砒砂岩地区人工种植沙棘后,随着沙棘林龄的增长,植物种类逐步增加.在造林初期,林下草本植物以一年生且旱生的植物地蔷薇为优势种群;造林3a后,以多年生植物赖草、阿尔泰狗娃花为主要优势种;...     

排灌输水隧洞正常水深的简捷算法

为了使标准城门洞形断面正常水深的求解具有简单的显函数计算公式,对标准城门洞形断面正常水深的基本方程进行恒等变形,将水面位于底角圆弧段和顶弧段正常水深的超越方程以及水面位于侧边直线段正常水深的高次方程,变成无量纲化正常水深与已知量综合参数的单变量函数方程.引入准线性函数的概念并将准线性函数作为标准模板,再对正常水深的单变量函数方程应用准线性函数标准模板,在工程常用范围即无量纲化正常水深y∈[0.051,.80]范围内进行优化计算及准线性函数逼近,得到了超越方程和高次方程的替代函数方程,替代函数具有类似于线性函数形式,即正常水深的准线性显函数表达式,并进行误差分析.结果表明,在隧洞底部圆弧段正常水深的最大相对误差小于0.36%,侧边直线段正常水深的最大相对误差小于0.31%,顶弧段正常水深的最大相对误差小于0.39%,说明准线性公式在隧洞有效水深范围内计算的水深准确度较高,可为排灌输水隧洞的断面设计及实现渠道水位控制时确定均匀流水深提供参考.     

改进共原点灰色聚类评价方法在灌区节水改造中的应用

针对灰色聚类评价共原点聚类函数存在的灰类交叉及隶属度等速率变化不合理现象,对原函数的灰类区间以及隶属度走势进行修改,提出了中心化抛物线型函数的改进共原点聚类函数,用此函数对评价体系指标进行模糊化处理,使得评价更具合理性与真实性.采用主客观最优组合权重计算综合聚类系数,解决了权重与阈值信息重叠的矛盾.将改进后的中心化抛物线型函数与共原点灰色聚类函数进行对比分析,分析函数变化趋势以及最终的综合聚类系数,改进的中心化抛物线型函数比共原点灰色聚类更加符合实际情况.最后选取潘庄大型灌区,进行续建配套与节水改造工程建设后评价,评价结果与实际情况较为吻合.     

Measurements and simulations of heat and water balance components in a clay soil cropped with winter wheat under drought stress or daily irrigation and fertilization

Soil water and temperature dynamics were measured in a field experiment with winter wheat on a clay soil. There were four treatments: Control (C), receiving natural precipitation, drought (D), protected from rain by plastic screens during the growing season, daily irrigation (I) and daily irrigation and fertilization (IF). Treatments C, D and I received the nitrogen fertilizer as a single application of solid fertilizer in spring. In IF daily dressings of nutrients were supplied in the irrigation water. All treatments received 20 g Nm^–2. An associated experiment with a newly sown grass ley (L) that was irrigated and fertilized daily (total 5.6 g Nm ^–2) was also performed. Standard meteorological variables (air temperature and humidity, wind speed, precipitation, global radiation, and relative cloudiness) and crop development data (green area index, crop height, relative root distribution in depth) above and below ground were used as driving variables within a physically based dynamic model (SOIL) for simulating water and heat fluxes. Measured soil temperature and water content from one treatment (I) were used to tune the model parameters, tentatively set from literature data. Thereafter, water and heat fluxes in the other treatments were simulated using the same parameter values but with different crop-related measurements as driving variables for each treatment. Measured soil temperature and water content in C, D, IF and L could thus be used for validation of the simulations. The theory formulated in the model could accurately explain measured treatment differences in soil water and temperature dynamics. Since the soil-related parameters were identical in all treatments, the model was shown to be applicable over a wide range of moisture conditions.     

果蔬采摘刚度增强型软体抓手设计与试验

针对目前软体末端执行器在果蔬采摘领域存在刚度低、指尖力小等问题,在多腔体型软体末端执行器的基础上,提出一种通过对发生层的腔体顶部及两侧增加限制性材料以增大夹持力的方法。建立数学模型分析执行器末端位置与输入气压之间的关系;采用Abaqus软件仿真分析执行器弯曲角度、支反力的变化规律;通过对比试验进行抓取验证。有限元仿真与试验结果表明:发生层限制性材料的增加在不影响执行器弯曲性能的前提下,不仅能很好地减小气球效应,而且能够承载更高的工作压强;弯曲角度和压强一定时,增强型执行器的支反力明显大于传统软体执行器,增强型软体抓手最大抓取重量约为414 g,传统型软体抓手最大抓取重量约为108 g,抓取重量约为传统抓手的4倍。     

PLC变频调速节能灌溉系统的设计

在分析了变频调速灌溉系统与阀门开度调节灌溉系统的节能效果之后,得出了一种新型的农业灌溉系统供水方式,即利用PLC结合变频器的方式来实现恒压变流供水。给出了变频调速灌溉系统结构图,并进行了系统软件流程设计。系统能够连续采集水泵流量,与设定的工作压力进行比较,实时改变水泵电机的工作频率调节灌溉流量。从而改变了传统农业依靠控制阀门开度及人工启停水泵电机的操作方法。经过实验证明,采用变频调速的节水灌溉系统,比传统模式节能20%~69%。对设备寿命周期的延长,节约电能和人工成本,提高灌溉可靠性方面均有极积的意义。     

CAD在新型蓄水保墒机具设计中的应用

新型蓄水保墒机具是一种旋转式开沟机,它在坡地、草地、休闲地或不能及时耕种的生荒地上开出一定的沟槽,来蓄积雨水,使雨水渗到地表下的黄土中,被作物自由吸收利用,目前已成为解决西北地区农业干旱问题的新机具。为了使我国农机设计制造技术与其它机械制造业平行发展,使旋转式开沟机的设计与制造质量达到发达国家水平,将计算机辅助设计、优设计技术引用到该机具的设计中。     

Diagnosing irrigation performance and water productivity through satellite remote sensing and secondary data in a large irrigation system of Pakistan

Irrigation policy makers and managers need information on the irrigation performance and productivity of water at various scales to devise appropriate water management strategies, in particular considering dwindling water availability, further threats from climate change, and continually rising population and food demand. In practice it is often difficult to access sufficient water supply and use data to determine crop water consumption and irrigation performance. Energy balance techniques using remote sensing data have been developed by various researchers over the last 20 years, and can be used as a tool to directly estimate actual evapotranspiration, i.e., water consumption. This study demonstrates how remote sensing-based estimates of water consumption and water stress combined with secondary agricultural production data can provide better estimates of irrigation performance, including water productivity, at a variety of scales than alternative options. A principle benefit of the described approach is that it allows identification of areas where agricultural performance is less than potential, thereby providing insights into where and how irrigation systems can be managed to improve overall performance and increase water productivity in a sustainable manner. To demonstrate the advantages, the approach was applied in Rechna Doab irrigation system of Pakistan’s Punjab Province. Remote sensing-based indicators reflecting equity, adequacy, reliability and water productivity were estimated. Inter- and intra-irrigation subdivision level variability in irrigation performance, associated factors and improvement possibilities are discussed.     

可调节水稻筑埂开沟一体机设计与试验

为解决当前江苏农垦各分公司水稻种植过程中筑埂作业质量不高、效率低、水直播田需人工二次筑埂修沟、劳动强度大、成本高等问题,研制一种适应垦区规模化作业条件下的可调节水稻筑埂开沟一体机。对筑埂开沟一体机整体结构进行总体方案设计,确定齿轮箱传动比分别为1.25和1.69。田间试验前,调整角度调节装置使其适用于不同区域水稻田筑埂开沟作业,田间试验结束后检测埂高、埂顶宽、沟深、沟宽、埂体坚实度,根据田间试验结果进行优化改进直至机具定型。结果表明：所设计的机具可在不同区域水稻田一次筑埂成型且同步完成埂边开沟作业,埂高全部合格且平均值达24.5 cm,埂顶宽全部合格且平均值达21.8 cm,沟深平均值达25.1 cm,沟宽平均值达37.6 cm,埂体坚实度平均值达1 992 kPa。该机具通用性和灵活性较好,作业各项指标皆优于相关技术标准,有效提高作业效率和埂体质量,节约作业成本。     

Effect of irrigation and nitrogen application methods on input use efficiency of wheat under limited water supply in a Vertisol of Central India

Field experiments were conducted in a deep Vertisol at the Indian Institute of Soil Science, Bhopal during the years 2001–2005 to assess the effect of five different irrigation strategies through combinations of sprinkler and flood irrigation and two N application methods on yield and water use efficiency of wheat (cv WH 147). The amount of irrigation applied each year differed according to the availability of water in the water harvesting pond to simulate the actual water crisis faced by the farmers in this region during these years due to monsoon failure. Results indicated that when wheat was grown only with 8-cm irrigation at sowing or 14 cm up to the crown root initiation stage, dry sowing of wheat immediately followed by sprinkler and subsequent irrigation through flooding produced the highest yield and water and nitrogen use efficiencies. However, when 20-cm irrigation was supplied up to the flowering stage or 14-cm irrigation was supplied up to tillering stage through sprinkler in 4 and 3 splits, respectively, at critical growth stages, maximized the grain yield and water and nitrogen use efficiencies. Across the years, the crop yield and water and nitrogen use efficiencies increased with increase in water supply.