Economic damages from a worst-case oil spill in the Straits of Mackinac

This paper presents research on the economic damages from a hypothetical worst-case oil spill at the Straits of Mackinac between Lakes Huron and Michigan. This spill could occur because the Enbridge Line 5 oil pipeline traverses the Straits between Michigan's Upper and Lower Peninsula. We quantify potential economic damages to outdoor recreation, commercial fishing, shipping, residential properties, and energy and water supplies. Damages are estimated for two spill scenarios occurring at the onset of the summer tourism season with extensive shoreline oiling. Using evidence from past spills, economic damages would last for between one and two years and would affect locations on the periphery of the spill area, depending on the activity. We project the loss from the worst-case scenario would be at least $1.3 billion.     

地震时海底悬跨管道动力特性试验研究

铺设在地震活跃区域的海底管道可能在地震荷载作用下发生破坏。利用水下振动台研究了海底悬跨管线在地震作用下的动力反应。试验中考虑了地震波输入方向、管道端部支撑情况、悬跨高度、悬跨长度和管内是否有水等因素。完成了这些因素组合的120组试验，得到海底悬跨管道动力响应特性。试验结果表明水中管道与陆地悬空管道的动力反应存在明显差别；悬跨长度是控制管道反应的关键，水平地震输入对管道反应起控制作用，海底悬跨管道在地震作用下的反应与受波和流作用下的反应也存在差别。     

感潮河道溢油扩展、漂移特性实验

溢油污染已逐渐成为内陆突发性水环境污染的主要问题之一。尤其在河口感潮河道，油污染问题日益突出。溢油污染因其对环境、生态、经济等的长期、巨大的破坏性影响，日益受到学术界的关注。然而以往的研究大都集中在海洋溢油方面，河道溢油研究因起步较晚，研究成果较少，考虑潮汐影响的则更少，且研究手段多以数值模拟为主，机理性实验研究较少。该文通过潮汐水槽模拟实验，观察并记录油膜在潮汐水流中、两个半日潮潮周期内的扩展、漂移情况，初步分析溢油油膜在潮汐水流中的扩展、漂移规律。实验结果表明：潮汐水流中，溢油油膜的扩展、输运过程主要受溢油自身理化性质和外界潮汐水流变化的影响。溢油入水后，首先经历重力扩展阶段，此阶段历时很短；然后经历剪切扩展阶段，此阶段历时长，油膜既受内部黏滞力影响，又受水流、风力引起的边界剪切力的影响，同时由于历时长，还受到潮流的输运影响。最后，当油膜很薄时，除受潮流的输运影响；还因受紊动水流及风浪的影响，在漂移过程中破碎或乳化。     

Clear-water scour depth below underwater pipelines

The paper presents (1) a semi-theoretical model for the computation of maximum clear-water scour depth below underwater pipelines in uniform sediments under steady flow and (2) an experimental investigation on the influence of upward seepage on clear-water scour depth below underwater pipelines.Based on the “image method” of the potential flow theory for the flow through the gap between a circular pipeline and the scoured bed, a theoretical model is presented for the computation of maximum scour depth below underwater pipelines in clear-water condition considering the wall correction. Also, a simple theoretical calculation, that involves Chiew's (1991) [Chiew, Y.M., 1991. “Prediction of maximum scour depth at submarine pipelines.” J Hydraul Eng 117(4), 452–466] gap flow curve, is proposed to estimate the maximum scour depth considering the wall correction. The computed results agree satisfactorily with the experimental data. In addition, the potential predictors of the maximum scour depth given by different researchers are compared with the experimental data.The result of an experimental investigation on the scour depth below pipelines under the influence of upward seepage through the bed sediment is presented. In general, the scour depth below pipelines with upward seepage is smaller than that without seepage. There exists a critical value of the ratio of seepage velocity to main flow velocity that corresponds to a minimum scour depth.     

海底悬跨管道在波流和地震联合作用时的模型试验研究

利用波浪-水流-地震联合模拟试验系统,研究了在波浪、水流和谐波地震荷载单独作用或联合作用时海底悬跨管道的动态响应特征。通过试验采集的加速度和动水压力数据分析了管道的悬跨长度、管内状态、外界荷载组合对于管道基频以及动力响应的影响规律。结果表明:随着悬跨长度的增加,管道自振频率减小且管道的动力响应显著增大;水流流速、波浪高度和周期在一定范围的增大会引起管道动力响应增大;三种荷载联合作用于管道时的动力响应大于荷载单独作用,且地震荷载起主要作用,波浪、水流荷载起次要作用。     

万家寨引水工程北干线有压倒虹吸管道充水过程研究

为了充分发挥万家寨引水工程北干线在长距离输水管路的潜在效益,基于北干线有压的1#、2#倒虹吸PCCP管道工程,以1#倒虹吸朔州在线调流阀前管道充水过程为例,分析研究了考虑空气阀作用工况下可能产生的水击压力以及不同的充水流量下1#倒虹吸沿程控制点的充水时间。研究成果为万家寨引水工程北干线充水过程研究提供了理论基础。     

裸露穿河管道在压重块保护下的冲刷特性

水流冲刷引起河床变形的不确定性对水下穿越管道的安全运行造成威胁.为了探究裸露穿河管道在压重块保护措施下的冲刷特性,通过水槽模型试验,研究压重块长度、压重块布置间距、水流流速、河道水深等因素对管道周围河床地形和冲刷深度的影响.试验结果表明:水下穿越管道在压重块保护措施下的冲刷过程可分为冲刷坑形成、压重块迎流侧悬空、管道迎...     

西南成品油管道工程龙江怀远段沉管施工

西南成品油输油管道穿越龙江段工程采取沿河床沉管浅埋敷设方式。穿江处河道水下地形复杂,水下礁石、河底暗河、溶洞发育,现场施工难度大。沉管施工中,采用水下爆破方法开挖沟槽,并选择现场拼装、分段焊接、水上连接、分段充水及整体翻转沉放管道的方案。沉管安装完成后,及时进行压重块安装及沟槽回填。工程完工一年后利用水下摄影和人工水下探摸,管道工程运行情况良好,河床形态未发生大的变化。     

输油管道工程特征及其水土流失防治措施——以平原区和丘陵区为例

为了在输油管道建设过程中采取合理的水土流失防治措施,减少水土流失,对输油管道工程的项目组成、施工组织进行了分析,重点介绍了一般管道敷设和穿越公路、铁路、河流段管道敷设施工工艺。在平原区和丘陵区作为一级分区的基础上,将输油管道工程分为管道作业带区、穿越工程区、站场阀室区、施工便道区和施工生产区5个防治分区。对分段管道的防治目标值加权平均得到工程的水土流失防治目标值,在此基础上分别确立了平原区和丘陵区输油管道工程的水土流失防治措施体系,分析工程措施、植物措施和临时措施的特点,因地制宜地采取合理措施来减少输油管道工程建设过程中的水土流失。研究成果为输油管道工程的水土流失防治措施提供了参考依据。     

长江口溢油事故对东风西沙水库取水的风险预测

东风西沙水库是崇明岛的重要原水工程,为研究长江航行船舶发生溢油事故对水库取水口的影响及相应的保护措施,在二维水动力学模型的基础上,利用MIKE21（SA）模块建立了长江口二维溢油风险分析模型,对东风西沙水库取水口进行风险预测。从预测结果来看,在有风情况下,油膜在风的作用下被吹向岸边,且大部分滞留在岸边;不同风向、不同季节以及发生溢油事故时的潮位特征对油膜漂移轨迹以及覆盖面积有影响;在不同水文、气象条件和不同事故发生地点等12种工况下,油膜24 h内均未到达东风西沙水库取水口附近。事故发生后,如果及时采取调整东风西沙水库运行方式、优化供水系统调度、在水库取水口设置围栏和清油设施等措施,可避免溢油事故对东风西沙水库的正常取水造成影响。     

Risk‐based Approach to Designing and Reviewing Pipeline Stream Crossings to Minimize Impacts to Aquatic Habitats and Species

Extensive new pipeline systems proposed to transport natural gas and oil throughout North America will potentially result in thousands of new stream crossings. The watercourses encountered at these crossings will range from small, ephemeral headwater streams to large, perennial mainstem rivers; from dynamic gravel‐bed streams to stable bedrock channels; and from steep, source reaches to low gradient, response reaches. Based on past experience at pipeline crossings, the potential for both short and long‐term negative impacts on aquatic habitat and species is substantial. In assessing potential hazards to aquatic habitat and species, the diverse physiography and ecology of the stream affected, combined with the number and range of new pipelines proposed, pose significant challenges for project developers charged with collecting, stratifying, evaluating, analysing, interpreting, and presenting stream crossing data in formats that are accessible, usable and useful. It is equally challenging for project reviewers to detect, distill and summarize potential project impacts and then identify reasonable options for their avoidance, minimization, and mitigation. To address these concerns, the US Fish and Wildlife Service, in conjunction with Ruby Pipeline, LLC, developed a pipeline crossing framework and risk analysis approach to stratify potential aquatic impacts, based on both stream characteristics and project types. In this approach, pipeline crossings are ranked in terms of relative short and long‐term risk to aquatic habitat and are then analysed, designed, and monitored in ways appropriate to their risk. This approach allows project developers and reviewers to focus resources and monitoring on the crossings that present the highest risks to aquatic habitat and species, while expediting design and construction, and minimizing the monitoring of low‐risk crossings. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.     

Flow-pipe-soil coupling mechanisms and predictions for submarine pipeline instability

The stability of a submarine pipeline on the seabed concerns the flow-pipe-soil coupling, with influential factors related to the ocean waves and/or currents, the pipeline and the surrounding soils. A flow-pipe-soil coupling system generally has various instability modes, including the vertical and lateral on-bottom instabilities, the tunnel-erosion of the underlying soil and the subsequent vortex-induced vibrations(VIVs) of free-spanning pipelines. This paper reviews the recent advances of the slip-line field solutions to the bearing capacity, the flow-pipe-soil coupling mechanism and the prediction for the lateral instability, the multi-physical coupling analysis of the tunnel-erosion, and the coupling mechanics between the VIVs and the local scour. It is revealed that the mechanism competition always exists among various instability modes, e.g., the competition between the lateral-instability and the tunnel-erosion. Finally, the prospects and scientific challenges for predicting the instability of a long-distance submarine pipeline are discussed in the context of the deep-water oil and gas exploitations.     

海底管道与海床相互作用研究综述

随着海上油气田的快速发展,目前我国已建海底管道超过6 000 km。近年来,管道事故时有发生,管道工程的安全性和管道的稳定性问题得到越来越多研究学者的重视。鉴于海底管道与海床的相互作用是研究管道稳定性问题的关键,阐述了海底管道在波浪作用下与海床间相互作用的试验研究现状,包括机械加载式试验、水槽模型试验、离心模型试验等;以及理论研究现状,包括解析方法和数值方法等。最后对波浪作用下海底管道和海床相互作用尚待研究的问题进行了展望,研究分析认为正确建立管道与海床本构模型等问题是未来研究海底管道稳定性的重要方向。     

油在河流中传输的双层数学模型

本文建立了一个模拟河流中漏油的两层数学模型ＲＯＳＳ２，这个模型考虑漏在河中的油由表层油膜和分布在整个水深中的悬浮油珠两层组成，油的输送过程包括流动、扩散、紊动扩散和掺混、挥发、溶解、乳化、附着在岸边和沉积到河底等过程．该模型可用于瞬时的和连续的漏油且油漏在水面或水中的情况．该模型已用于美国Ｏｈｉｏ－Ｍｏｎｏｎｇａｈｅｌａ－Ａｌｌｅｇｈｅｎｙ（ＯＭＡ）河系及Ｓｔ．Ｌａｗｒｅｎｃｅ河上游．此模型不仅可用于模拟油，也可模拟其它有害物质的泄漏．     

Differentiation between lake whitefish and cisco eggs based on diameter

Cisco (Coregonus artedi) and lake whitefish (Coregonus clupeaformis) are native fish species of management concern in the Laurentian Great Lakes that often overlap in spawning locations and timing. Thus, species-level inference from in situ sampling requires methods to differentiate their eggs. Genetic barcoding and hatching eggs to visually identify larvae are used but can be time and cost intensive. Observations in published literature indicate that lake whitefish eggs may be larger than cisco eggs in the Great Lakes, but this has not yet been substantiated. Samples from shared spawning grounds are unlikely to contain similarly sized or colored eggs from other species. Thus, we assessed whether lake whitefish and cisco eggs could be separated based on size alone. Fertilized, hardened eggs were collected in situ during spawning at Elk Rapids, Lake Michigan and Chaumont Bay, Lake Ontario and preserved in ethanol. Individual eggs were measured and genetically identified. Mean diameter for cisco (2.45 mm, SD = 0.22, n = 444) was smaller than for lake whitefish (3.21 mm, SD = 0.20, n = 99). We used classification trees to identify a species-separating size threshold of 2.88 mm (95% bootstrap CI = [2.877, 2.976]), which classified eggs with an accuracy rate of 96%. Differences between species across other samples from the same locations were mostly consistent with the threshold size, but we suggest validation if applying this method to other populations. Separation of cisco and lake whitefish eggs by diameter can be accurate, efficient, and especially suitable for large sample sizes.     

PCCP管道工作性态的高性能仿真研究

为了快速有效的对PCCP管道结构状态进行了安全分析评估,预防管道发生破坏,消除工程安全隐患,本文基于高性能仿真计算的安全裕度分析方法用来评估PCCP管道的工作性态,以新疆生产建设兵团农二师38团建管局ST灌区的管道工程为例列举了管道结构状态安全评估材料参数及典型工况,研究计算了6种规格的PCCP管道预应力钢丝完好、断丝、管芯混凝土轴向开裂、断丝+管芯混凝土轴向开裂等工况,并对管道进行了安全分级。该方法汲取了AWWA推荐方法的基本思想,更易于理解和操作。     

How does oil and gas behave when released in deepwater?

Deepwater oil and gas releases have come to greater attention of the scientists as well as general public in the recent past, especially after the Deepwater Horizon spill in Gulf of Mexico in 2010. In this short paper we show the general behavior of an oil and gas spill in deepwater. A model, CDOG, developed by Zheng et al. (2003) and had undergone successive improvements is used for the simulations to illustrate the oil behavior. The impact of the oil droplet sizes are demonstrated. Although cases are not specific to a particular spill, through the use of a state-of-the-art model, we show the key parameters that affect the behavior of oil. In this paper we show oil and gas behavior that has not been clearly explained in previous papers and address newly found concerns brought on by the recent awareness. This paper also shows how the oil behavior changes when additives like dispersants are applied. Results of the simulations reveal that the “underwater plumes” with low concentrations of oil can be formed and stay submerged for long periods of time when very small (less than 0.5 mm in diameter) oil droplets are present.     

袖阀管及深孔注浆在地铁站施工建筑物及管线保护中的应用

地铁暗挖施工,对周边建筑物及管线的影响一直受到参建单位的重点关注,暗挖施工对多座建筑物和多条管线都有影响,且管线及建筑物建设时间久远,极大地增加了变形控制难度。采用袖阀管和深孔注浆对建筑物和管线进行保护,取得了良好效果,形成以下结论:地表袖阀管注浆可以有效地将开挖影响范围通过注浆加固体隔开,使开挖后土体变形大部分发生在加固体外侧,有效控制建筑物的变形;小导洞内深孔注浆使得管线下方加固体形成拱形保护壳,减小管线上方土体变形范围,使管线总体变形大大减小,施工期间沉降量最大仅为9.95mm;无论采用袖阀管注浆还是深孔注浆,其注浆参数的选取、施工工艺的控制等都需要结合具体地层参数及时调整,合理控制注浆量和注浆压力。     

Iterative Methods for Looped Network Pipeline Calculation

Since the value of the hydraulic resistance depends on flow rate, problem of flow distribution per pipes in a gas or water distributive looped pipelines has to be solved using iterative procedure. A number of iterative methods for determining of hydraulic solution of pipeline networks, such as, Hardy Cross, Modified Hardy Cross, Node-Loop method, Modified Node method and M.M. Andrijašev method are shown in this paper. Convergence properties are compared and discussed using a simple network with three loops. In a municipal gas pipeline, natural gas can be treated as incompressible fluid. Even under this circumstance, calculation of water pipelines cannot be literary copied and applied for calculation of gas pipelines. Some diferences in calculations of networks for distribution of these two fluids, i.e. water apropos natural gas are also noted.     

地下停车库自动喷水灭火系统的设计与思考

在地下停车库自动喷水灭火系统设计选型上 ,结合环境条件采用预作用自动喷水灭火系统时 ,平时不给管路充有压气体 ,对整个排气充水过程产生的不利灭火的影响并不大。探讨采用降低消防用水冰点达到防冻效果的可能性。在设计过程中喷头布置的根本原则是火灾发生时喷头能够动作 ,并能满足设计喷水强度的要求。此外 ,还应设法调整管道布置 ,保证均匀布水 ,并通过减压措施减小管路中的压力变化 ,防止流量过大 ,使储水能满足火灾延续时间 1h的灭火要求。