渠道混凝土防渗体下土体特性变化试验研究

渠道衬砌结构的冻胀破坏在寒冷地区普遍存在,对其使用效果和寿命造成了很大影响,为了解季节性冻土区渠道防渗体冻胀发生的原因,以梯形渠道弧形混凝土防渗体为例,从渠道衬砌结构的防渗体下土体温度变化及防渗体冻胀位移量变化特点入手,通过在灌区选取典型渠道进行原型原位观测试验,监测不同时间点不同影响因素下渠道不同位置土壤深度处地温及冻胀位移量变化,分析土体各特性的变化机理。结果表明,不同土层深度处土壤含水率的大小为未冻层>临界层>冻土层;不同土壤深度处的温度变化基本相同;10cm厚的保温板的保温效果优于20cm厚保温板的保温效果。研究成果为解决灌区渠道衬砌的冻害及渗漏问题以及未来大中型灌区渠道施工过程中采取有效的防冻胀措施提供了参考依据。     

寒旱区湿陷性土地基渠道衬砌结构改造的数值模拟研究

寒旱区输水渠道防渗衬砌结构极易发生冻胀破坏而影响灌区供水安全和稳定运行。为提高湿陷性黄土地基渠道的抗冻胀性能,以宁夏固海扬水灌区衬砌渠道为例,通过分析原型渠道冻胀破坏特征,基于提高防渗体抗冻胀变形能力的思路,提出了三种不同边坡系数、断面结构形式和边坡筑构材料的防渗结构优化方案,并应用ABAQUS软件,分别计算分析了不同方案的衬砌结构受热力耦合作用下的冻胀变形特征与受力状态。结果表明,在湿陷性黄土地区,弧底梯形渠道的抗冻胀性能普遍优于梯形断面渠道;在渠道防渗衬砌体基土之间加设一定厚度的水泥砂浆垫层,能有效减弱衬砌结构在冻胀作用下的应力集中现象;适当减小渠道边坡系数能有效减少渠道内的冻胀应力峰值;在三种衬砌改造结构中,其峰值应力减幅分别为70.49%、63.36%、27.68%,最大冻胀量降低率分别为7.70%、5.05%、-2.82%,选取边坡系数为1∶1.75的弧底梯形断面型式,并在混凝土防渗面板与基土间设置水泥砂浆垫层时,其抗冻胀效果最佳,可在同类地区推广应用。该研究结果为跨越湿陷性黄土地基的灌区渠道结构改造提供参考,也可为同类地区渠道的防冻胀设计提供依据。     

交口抽渭灌区东干四支渠衬砌工程防冻胀设计

通过对交口抽渭灌区东干四支渠衬砌工程的防冻胀设计验算,阐述了在湿陷性黄土地区渠道衬砌采用防冻胀设计的理论依据及方法,为今后类似工程提供借鉴     

弧形坡脚梯形渠道砼衬砌冻胀破坏断裂力学模型及应用

为给实际弧形渠道冻胀设计提供一种简单有效的计算方法,应用材料力学方法对渠道砼衬砌冻胀问题进行合理简化,建立了弧形坡脚梯形渠道砼衬砌冻胀力学模型,并在该模型基础上引入断裂力学,将砼衬砌板断裂视为(Ⅰ+Ⅱ)复合型(张拉型+剪切型)裂缝扩展问题,并利用已有的断裂准则,建立弧形坡脚梯形渠坡、渠底两个部位的冻胀断裂力学模型。实例应用结果表明,所建模型计算的砼衬砌板厚度满足抗冻胀要求,且与实际情况相吻合。     

考虑太阳热辐射的梯形渠道温度场动态数值模拟和衬砌冻胀分析

针对因缺乏渠道表面实测温度而难以准确模拟渠道温度场的问题,考虑太阳热辐射对渠道阴坡、阳坡和底板温度的影响,建立渠道表面增温计算模型,采用有限元软件ABAQUS,对经历三次降温情况下渠道的温度场变化过程进行数值模拟并分析渠道衬砌冻胀情况。结果表明,在太阳热辐射影响下渠道阴坡冻深显著大于阳坡和底板冻深,计算冻深和衬砌破坏规律也与实际情况吻合较好,在降温过程中阴坡的混凝土衬砌相较于阳坡和底板更容易发生冻胀破坏,按照多年最大冻深利用规范计算时也有相同规律,研究成果可为渠道混凝土衬砌温控防裂设计提供新思路。     

浅谈灌区配套渠道U型混凝土现浇衬砌施工应注意的问题

灌区配套U型渠道混凝土现浇衬砌渠道,由于其断面较小衬砌厚度较薄,又在野地作业,要从渠槽开挖,现浇模板制作,原材料质量,混凝土拌和,运输,支模浇捣,拆模养护等各工序加强管理和控制。     

宁夏引黄灌区骨干渠道糙率原型观测分析

为给衬砌渠道的设计及运行管理单位提供有利的条件,同时积累衬砌渠道糙率的原型观测经验与成果,选取宁夏引黄灌区具有代表性的11条不同流量级别的骨干渠道,开展衬砌渠道原型糙率观测试验;并结合宁夏引黄灌区衬砌渠道实际情况,提出不同衬砌材料的糙率建议取值。结果显示,无论是使用单一材料的衬砌渠道还是使用多种材料的复合衬砌渠道,实测数据率定的糙率值普遍较设计值偏大,偏大原因有断面几何尺寸不标准、渠底比降与设计偏差较大、不同灌季的渠水含沙量等;现浇混凝土、预制混凝土板、格宾石笼填充卵石、格宾石笼填充块石、卵砾石糙率建议值分别为0.013 5~0.014 0、0.014 5~0.015 0、0.028~0.030、0.027~0.029、0.026~0.029。     

灌区渠道标准断面流量拟合参数影响因素分析

渠道标准断面量水是灌区量水的主要方法之一。通过对浙江省5个灌区共16个渠道标准断面进行率定,建立水位流量关系曲线,拟合形成渠道流量幂函数公式,确定流量拟合系数K和指数u,并分析渠道宽度、坡降和衬砌型式对流量拟合系数K和指数u的影响。结果表明,渠道标准断面流量拟合系数K和指数u与渠道宽度和坡降总体呈正相关关系,并随渠道衬砌型式的不同发生相应变化。     

土工膜在瓜里科灌区渠道修复工程中的应用

考虑委内瑞拉瓜里科灌区运行特点、原材料、人力及建筑业水平等因素,采用在渠道原衬砌板上铺土工膜对灌区渠道修复,选取渠道试验段修复设计,提出了土工膜加固方案设计和施工要点.结果表明,该方案修复渠道行之有效,渠道水量损失减少,防渗效果显著.     

渠道防渗工程结构和防治冻害措施的设计

本文对宝鸡峡灌区近年来大量渠道衬砌设计进行了总结,较为详细地探讨了渠道断面形式、防渗层结构及防治冻害措施。     

黑龙江地区渠基土工程性质试验研究

为了探究黑龙江地区引发渠道工程结构变形的原因,了解渠道所在地区渠基土的工程性质,以引嫩扩建骨干一期工程内的乌南干渠和红旗干渠基土为例,通过多种室内试验研究黑龙江地区渠道土的工程性质,并从含盐、物质组成分析了土体分散性产生的内在因素,同时针对工程实际情况提出了相应的整治措施。结果表明,工程两个灌区的渠基土均为具有分散性、膨胀性且含盐已达到盐渍土标准的特殊土;钠离子含量是土样产生分散性的主要原因,蒙脱石含量不是判断土样分散性的必要条件;土样的无荷膨胀率为4.2%~7.1%,50kPa下有荷膨胀率为2.5%~4.0%;土样的粘聚力为16.68~34.92kPa,内摩擦角为11.5°~21.1°;避免冬季施工、加强基础稳定、加固渠底固脚等整治措施可为分布有该类特殊渠基土的渠道工程建设提供参考。     

Life cycle energy analysis of a residential building with different envelopes and climates in Indian context

In this paper life cycle energy (LCE) demand of a residential building of usable floor area about 85.5 m² located at Hyderabad (Andhra Pradesh), India is evaluated under different envelopes and climates in Indian context. The house is studied with conventional (fired clay) and alternative wall materials (hollow concrete, soil cement, fly ash and aerated concrete) under varying thickness of wall, and insulation (expanded polystyrene) on wall and roof. The house is modelled for five different climatic zones of India, i.e. hot and dry, warm and humid, composite, cold and moderate. Study suggests that alternative wall materials alone (without insulation) reduce LCE demand of the building by 1.5-5%. Aerated concrete (AC), as wall material, has better energy performance over other materials. LCE savings are significant when insulation is added to external wall and roof. It varies from 10% to 30% depending on the climatic conditions. Maximum LCE savings with insulation are observed for warm and humid climate and least for moderate climate. For same thickness of insulation, LCE savings are much more with roof insulation than wall insulation. But wall insulation is found to be preferable to a thicker wall. It is also observed that there is a limit for thickness of insulation that can be applied on external walls and roof from life cycle point of view. This limit is found to be about 10 cm for composite, hot and dry, warm and humid, and cold climates and 5 cm for moderate climate.     

转底炉的炉衬材料及炉门机构

介绍转底炉炉衬采用新型节能保温材料－无石棉耐高温硅酸钙板，可减少炉衬散热损失１４．１％，同时还减少炉衬厚度２５ＭＭ，炉门设计新颖，动作快、密封性好、压紧力可调。     

Insulated solar storage tanks

This paper presents the theoretical and experimental investigation of an insulated parallelepiped, outdoor solar, water-filled storage tank of size 1 m × 0.5 m × 0.3 m, that is made from galvanized iron. The absorption coefficient of the insulating material has been determined. The effects of plastic covers and insulation thickness on the water temperature and the energy gained or lost by water are investigated. Moreover, the effects of insulation thickness on the temperature profiles of the insulating material are discussed. The results show that the absorption coefficient decreases as the insulation thickness increases. Also, it is found that the glass wool insulation of 2.5 cm thickness has the best results compared with the other thicknesses (5 cm, 7.5 cm, and 10 cm) as far as the water temperature and the energy gained by water are concerned.     

Numerical study of a ventilated facade panel

An energy-saving facade panel for non-residential buildings has been numerically investigated. Structured like a composite Trombe-Michel wall, the panel consists of a glazing, an absorber plate and insulation and contains a dead air space between glazing and absorber, as well as a convection channel between absorber and insulation. The influence of convection channel spacing on both recovery of solar energy during sunshine periods and on heat losses during night hours has been assessed. Two different options have been considered. First, the total panel thickness was maintained, which involves an increase of channel spacing having to be compensated by a corresponding decrease of the insulation thickness. Then, this constraint was removed so that an increase in channel spacing was allowed to entail an equivalent increase of the total panel thickness. The results indicate that large spacing favors energy recovery during sunshine periods for both options and reduces, although only slightly, heat losses during night hours for the second option. In the case of the first option, however, these losses tend to grow when channel spacing increases.     

Cost benefits analysis and emission reductions of optimum thickness and air gaps for selected insulation materials for building walls in Maldives

The demand for electricity in the Maldives continues to increase by more than 11% in recent years. This is mainly due to the growing number of high-rise air-conditioned buildings and the increasing use of electrical appliances in the residential and commercial sector. This paper investigates potential cost savings and emission reductions achieved by installing different insulation materials of optimum thickness in building's walls. The paper also investigates the effect when air gaps are introduced in the wall. The optimum insulation thickness is based on the cost benefits of each insulation material over its lifetime. This study found that by introducing optimal thickness of different insulation materials and by having air gaps of 2 cm, 4 cm and 6 cm, energy consumption and emissions can be reduced by 65–77%, in comparison to a wall without insulation or air gaps. And, hence have considerable cost savings.     

河北平原区土壤水分空间变异特征研究

以河北平原区望都灌溉试验站为例,选取210m×210m的正方形田块进行试验,在该范围内布置64个测点,分别测量0~30、30~50、50~80cm三个深度的土壤含水率信息。利用经典统计和地统计方法分析了田间土壤含水率的空间变异结构,并采用协同克里格插值技术得到了该区域土壤含水率的空间分布状况。结果表明,0~30cm土层及50~80cm土层的土壤含水率具有中等空间相关性,其相关距离分别为66.4、75.7m,而30~50cm土层表现出了强烈的空间相关性,相关距离为88.2m,研究结果可为实现灌区精准灌溉和土壤墒情预测提供科学的理论指导。     

关中平原灌区SWAT模型基础数据库的构建

分布式水文模型为变化环境下灌区水循环演变的研究提供了有效手段,为了将SWAT模型运用于关中平原灌区水循环研究,以泾惠渠灌区为例,利用HWSD土壤数据、SPAW软件及统计分析法,构建了灌区土壤数据库;基于遥感数据获得了灌区2014年的土地利用情况,构建了土地利用数据库;充分考虑灌区水系、渠系分布(无排水沟)、人工侧支循环的逆汇流特性及输配水管理特点,利用ArcGIS自定义了SWAT的河网水系及子区,并通过pre-defined操作导入模型,将灌区划分为52个子区,分别设置了合理的土壤类型及土地利用类型的面积阈值,将研究区划分为279个HRUs,构建了灌区空间离散数据库。SWAT模型基础数据库的构建为灌区SWAT模型的构建及水循环演变规律的研究奠定了基础。