坝基防渗墙及墙下灌浆帷幕渗流及渗透稳定性分析

采用三维有限元计算软件SEEPAGE1.0对扎雪水电站坝基进行了稳定渗流计算,分析了悬挂式防渗墙下灌浆帷幕深度对渗流场的影响,探讨了覆盖层中的渗透稳定性问题,确定了经济合理的防渗方案,并分析了防渗墙开裂对渗流场的影响.结果表明,覆盖层中帷幕底部的渗透坡降最大,并以此处为中心,向四周迅速减小.整体渗透稳定性较好,防渗墙底部出现交错裂缝对渗控效果影响不大.     

橡胶坝坝基渗控措施有限元分析

针对小埠东橡胶坝坝基渗漏和稳定问题,在采取加固除险措施基础上采用多孔介质稳定渗流理论建立了坝基典型剖面的二维有限元模型,计算了设置和不设混凝土防渗墙的坝基渗流场的位势分布、渗透坡降和单宽流量,分析了防渗墙对坝基渗流场的影响.结果表明,设置防渗墙后,坝基渗透坡降和渗漏量均显著减小,可满足渗透稳定要求.建议增设厚45 cm的混凝土防渗墙.     

两河口心墙堆石坝渗流特性及其控制方案

建立了两河口工程坝址区的三维渗流有限元模型,并计算分析了坝体及其坝基的三维稳定渗流场特性,获得了坝体和坝基的位势分布、坝体各分区的渗透坡降及渗透流量等.分析了坝基防渗帷幕和左右岸防渗帷幕深度和长度变化及防渗帷幕和坝基岩体渗透参数对渗流场的影响.结果表明,坝体、坝基及左右岸坝肩的防渗措施均可满足要求.建议考虑坝基防渗帷幕仅截断3 Lu线以上岩体的防渗方案,并将左岸防渗帷幕的延伸长度减少50 m.     

调节水位对橡胶坝坝基渗流影响的分析

针对调节水位对橡胶坝坝基渗流的影响,以滹沱河橡胶坝为例,采用有限元法对坝基渗流进行了三维模拟研究,利用等参六面体单元精确模拟了坝区各地层和水平铺盖的空间分布及不同工况下坝基的渗流场分布规律,并分析计算了调节上游水位和降低下游水位的水头分布、单宽渗漏量及渗透坡降对坝基渗流场的影响。结果表明,该坝基满足调节上游水位时的防渗要求。     

阴坪水电站泄洪闸深厚覆盖层地基渗流分析

分析深厚覆盖层条件下大坝的渗流特性,对于保证大坝防渗体系及工程整体安全有重要意义。结合ANSYS大型有限元分析软件,以阴坪水电站为例,研究了在深厚覆盖层及复杂地基情况下,闸基在各典型工况的渗透特性,并对各覆盖层渗透性、防渗墙深度及水平铺盖长度进行了敏感性分析。结果表明,各工况下的渗流参数符合规范要求,对于阴坪水电站深厚覆盖层基础,采用垂直混凝土防渗墙加水平铺盖的防渗措施安全有效,渗流量与渗透坡降均很小,满足渗流稳定性要求。研究成果可供类似工程参考。     

上覆压力对深厚覆盖层地基渗透及渗透稳定性的影响

为了研究不同上覆压力对深厚覆盖层中管涌型土层的渗透及渗透稳定性影响,利用土体渗流—应力耦合装置,在施加不同上覆压力(0、0.3、0.5、0.7 MPa)的条件下,对缺级配砂砾石进行渗透破坏试验。结果表明,随着上覆压力的增大,土体在渗透破坏过程中,局部的渗透特性变化和渗流场分布均存在差异性,反映了细土颗粒被运移和填充孔隙的情况不同,从而影响了水力坡降在局部的分配情况;上覆压力的增大使得土体稳定渗流阶段和渗透破坏阶段的渗透性出现不同程度的减小,临界坡降和破坏坡降的变化与上覆压力之间存在相同形式的非均匀变化关系。     

GMS在心墙堆石坝二维稳定渗流分析中的应用

应用GMS软件中SEEP2D模块对心墙堆石坝进行二维稳定渗流分析.由分析可知,心墙渗透坡降集中于下游面,靠近下游面底部尤为明显,需采取措施确保渗流稳定性.防渗帷幕应穿过弱风化岩层以降低下游水头.反滤排水对下游水头影响不大,对防止下游覆盖层管涌有积极作用.     

金佛山混凝土面板坝二维渗流计算分析

针对渗透水流对土石坝坝体、坝基的渗透破坏危害性极大问题,以金佛山水电站混凝土面板堆石坝为例,根据地质条件和渗流控制特点建立平面二维有限元计算模型,模拟了坝体在不同水位组合条件下的渗流场,研究了渗透破坏的可能性,并分析了防渗帷幕及坝基渗透系数的敏感性。计算结果表明,各种水位组合下混凝土面板及防渗帷幕起主要阻水作用,水力比降大,渗流场分布对防渗帷幕及坝基渗透系数不敏感,渗流流量相对敏感,为坝坡安全性和渗流稳定性评估提供了依据。     

旱涝急转条件下土石坝渗流特性分析与安全控制

为分析旱涝急转条件下土石坝的渗流特性,基于非稳定饱和—非饱和渗流理论及其有限元方法,分析了长江中下游某粘土心墙坝在旱涝急转期间不同库水位上升速度下瞬时浸润线、等势线、渗透坡降等渗流要素的变化特性,建立了渗透坡降与库水位上升历时的经验关系,通过库水位上升速度判断坝体渗透安全性能,并计算了渗流安全控制条件下的临界库水位上升速度。结果表明,旱涝急转期间,随着水库水位抬高、上升速度增大,土石坝渗流场呈现规律性变化;利用库水位上升速度评价坝体渗流安全性能,对于旱涝急转条件下坝址区合理分洪调洪措施制定等具有重要意义。     

深覆盖层上砂砾石坝渗流特性及防渗措施分析

以某水电站枢纽工程为倒,构建三维渗流有限元模型,分析了各材料区渗透稳定性,通过不同防渗布置方案对比研究了厂坝址区渗流特性,并评价了各方案的可行性.结果表明,采用设计值方案,防渗墙和帷幕灌浆渗控作用很好,坝体和坝基各料区的渗透稳定性均符合要求,坝基渗控合理.     

火电厂节能工作浅析

本文探讨了火电厂节能基本程序和工作方法,分析节能工作要从基础工作、技术创新、设备整治、燃烧管理等方面入手的论述.     

Geothermal energy in agriculture in Yugoslavia

SFR Yugoslavia has natural hot water springs practically all over its territory, indicating the presence of geothermal reservoirs underground. There is no final estimate of how much energy can be expected from this new resource, except for figures based on the results of studies and investigations.The first use of geothermal energy in Yugoslavia in numerous spas dates back to the 19th century. Some remarkable examples of central heating are known, but the most widespread use is in agriculture (in greenhouse heating, farm heating and drying of agricultural products).     

浅析磨合期汽车的使用

如何合理使用磨合期的汽车，使其摩擦机件的磨损量能够平稳、均匀地磨合而不至于过度磨损，对汽车实际使用寿命有着重要的意义。从机器磨合期的特点和磨损机理出发，对汽车磨合期如何正确使用进行了有实际意义的探讨。     

Energy conservation measures in an institutional building in sub-tropical climate in Australia

In this study, various energy conservation measures (ECMs) on heating, ventilating and air conditioning (HVAC) and lighting systems for a four-storied institutional building in sub-tropical (hot and humid climate) Queensland, Australia are evaluated using the simulation software called DesignBuilder (DB). Base case scenario of energy consumption profiles of existing systems are analysed and simulated first then, the simulated results are verified by on-site measured data. Three categories of ECMs, namely major investment ECMs (variable air volume (VAV) systems against constant air volume (CAV); and low coefficient of performance (COP) chillers against high COP chillers); minor investment ECMs (photo electric dimming control system against general lighting, and double glazed low emittance windows against single-glazed windows) and zero investment ECMs (reset heating and cooling set point temperatures) are evaluated. It is found that the building considered in this study can save up to 41.87% energy without compromising occupancies thermal comfort by implementing the above mentioned ECMs into the existing system.     

Energy consumption in rural transportation in India

Energy consumption in rural transportation has been computed, taking into account the energy embodied in vehicles or bullocks, as well as the fuels or feeds and food (of operators). Bullock cart transport consumes over four times more energy than vehicles. However, animal transport will continue to be preferred because of its availability.     

Electoral cycles in electricity losses in India

A third of electricity in India is lost each year, where losses refer to power that is supplied but not billed. Utilizing data from the power corporation of Uttar Pradesh, India's most populous state, we study the politics of electricity losses. Examining annual data over four decades, we document that UP's electricity losses tend to increase in periods immediately prior to state assembly elections. Drawing upon geographically disaggregated data for the period 2000–09, we observe higher line losses just prior to the 2002 and 2007 state elections. Our analysis shows that the incumbent party was more likely to retain the assembly seat as line losses in the locality increased. We interpret these results as corroboration that political parties deliberately redirect electricity to flat rate and unbilled users in a context of chronically inadequate supply. Political factors appear to affect line losses in ways that technical and economic factors alone cannot explain.     

Leading-edge Technologies in Hydropower Development in China

After the implementation of the Reform and Opening-up Policy for a period of 40 years, the exploitation of China’s hydropower resources developed significantly. Through vast amounts of scientific and technological research and construction practices, China has accumulated abundant engineering experience with respect to the construction technologies required for 300-meter-high concrete arch dams, 200-meter-high roller-compacted concrete gravity dams, 200-meter-high concrete face rockfill dams, and 250-meter-high earth core rockfill dams, large-flow discharge and energy dissipation, huge underground cavern group constructions, complicated foundation treatments for high earth and rockfill dams and high and steep slope reinforcements. These series of technologies have now reached an international leading level. In the near future, these technical improvements will likely have broader application prospects and make greater contributions toward hydropower development both in China and across the world.     

Uncertainties in decarbonising heat in the UK

Heating is arguably one of the most difficult sectors to decarbonise in the UK's energy system. Meeting the 80% greenhouse gas emission reduction target by 2050 is likely to require that heat related emissions of CO₂ from buildings are near zero by 2050, and there is a 70% reduction in emissions from industry (from 1990 levels). Though it is clear that the use of the natural gas network will reduce over time, recent modelling suggests a limited residual role for gas by 2050 to help meet peaks in heat demand. High levels of uncertainty about the way in which heat will be decarbonised present a number of challenges to policy makers. This paper will explore the risks and uncertainties associated with the transition to a low carbon heat system in the UK as outlined by the 4th carbon budget review. The potential impact of key uncertainties on the levelised costs of heat technologies and the development of energy networks are explored using a sensitivity analysis approach. Policy changes required to decarbonise the heat sector are also examined.