锦屏二级水电工程动态支付管理及风险分析

由于锦屏二级水电工程规模大、施工周期长、工程条件复杂,前期工程采用“进度计量付款+进度提前奖励”的合同模式很难达到业主要求的进度控制目标。主体工程开工后,合同中采用“工程进度动态支付”管理,即根据一个滚动周期内实际完成工程量的平均值与计划量的平均值进行对比,确定合同单价调整系数,并由此计算每期进度付款。以锦屏二级水电工程厂房枢纽施工合同为例,通过总结锦屏二级水电工程前期项目施工情况,分析该动态支付管理办法在厂房枢纽工程中的投资控制风险,明确了在锦屏二级水电工程中采用进度动态支付管理的可行性,为业主工程管理提供新的思路。     

严格工程结算审查 强化建设资金管理

1 引言 金河电站工程是西藏自治区“十五“计划重点工程项目,也是西藏自治区电力公司首次作为业主方承建的大型水电工程建设项目.强化电站工程建设资金管理,是摆在我们面前的重要任务. 建设单位的资金管理,其核心内容是严格工程结算的审查.工程结算是依据国家有关的基本建设法     

一期工程中合同的单价支付与总价支付

三峡工程是规模宏大的跨世纪工程，工程采用的“业主责任制，招标投标制，建设监理制”在我国水电工程建设中是一项重大实践。长江委承监三峡一期工程施工承建合同８９个，合同总金额３０余亿元。结合三峡一期工程监理合同支付管理实践，对单价合同和总价合同的适用范围及合同工程单价分解，支付计量方法和支付审核方法进行了探索，可供从事合同商务管理的人士参考。     

三峡枢纽工程投资控制和管理

三峡工程的枢纽工程静态投资５００．９亿元，由三峡总公司按照“合理预测、静态控制、动态管理，总量控制、合理调整”的原则进行投资的控制和管理。这种管理方式的主要特点是：合理预测工程静态投资；对投资实行静态控制、动态管理；编制业主执行概算，对静态投资实行总量控制、合理调整；规范价差结算制度，以公式法取代文件证明法，以业主执行概算单价和当年完成的实物工作量计算投资完成额作为向国家结算价差的依据，严格区分两个层次的价差结算制度。在三峡枢纽工程投资控制和管理过程中，充分发挥专家的智慧和中介机构的作用。     

"达标投产"--乐滩水电站工程的建设目标

为了全面提高水电工程的建设管理水平，推动水电工程建设的技术进步，在乐滩水电站工程建设中，业主公司把“达标投产”确立为工程建设目标。针对工程的实际情况，采取下列主要措施：推行项目的均衡生产、及时发现和处理不良地质问题、抓好设计优化工作、厂房采取不装修措施、加强总进度控制和重大技术措施的研究、开展危险点动态预防系统管理、建立工程信息管理系统，确保“达标投产”的实现。     

水利工程单价合同的结算控制

单价合同大多用于工期长、技术复杂以及业主为了缩短工程建设周期,初步设计完成就进行施工招标的工程项目,在水利工程施工承包合同中多被采用。本文叙述了单价合同结算的特点和依据,对单价合同结算中的工程计量与计价的意义、工程计量审核原则、工程计量方法、工程计量审核原则、工程计量方法、工程变更、工程索赔等进行了详细的介绍。     

论如何建立大型水电工程业主统一供应主材保障体系

本文介绍了大型水电工程主要材料供应的特点、目标,从计划、招标采购、供应厂商管理、仓储、、调拨、质量管理和材料核销等方面对建立业主统一供应主要材料保障体系的提出了设想,对今后大型水电工程业主参与工程主要材料的供应管理进行了初步的探索。     

大型水电工程规范化分包管理

通过10+a来在大型水电工程现场业主分包管理的具体实践,对工程分包的定义、分类、条件以及有关法律法规进行研究;对目前水电工程建设领域工程分包存在的主要问题进行了梳理和总结,对目前所在建的TB大型水电工程建设现场业主分包管理主要做法、经验和取得的成效进行了简要介绍;对工程建设领域长期存在或将继续存在并难以在短时期内彻底解决的问题提出了解决措施。     

锦屏水电工程项目进度计划管理

锦屏水电工程岸坡地势陡峭,地质条件复杂,施工场地布置困难,施工中的不可预见因素多,进度控制协调工作量大且十分复杂,需要采取科学的施工组织设计和强有力的进度管理措施.结合锦屏水电工程特点,详细论述了锦屏水电工程进度计划管理的特点、管理形式、管理措施及进度控制手段,同时阐述了大型水电工程高效进度管理条件下的保障措施,以期为我国大型水电工程项目进度计划管理提供一定的参考.     

阿鸠田水电站工程建设与管理

总结了阿鸠田水电站工程的建设与管理经验,内容包括:工程管理理念;工程计划的编排;业主团队的组建;质量控制;进度控制;投资控制;安全生产等。可供地方中小水电工程建设参考和借鉴。     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.