Elastoplastic pipe-soil interaction analyses of partially-supported jointed water mains

Water distribution networks are essential components of water supply systems. The combination of pipe structural deterioration and mechanics leads to the failure of pipelines. A physical model for estimating the pipe failure must include both the pipe deterioration model and mechanics model. Winkler pipe-soil interaction (WPSI), an analytical mechanics model developed by Rajani and Tesfamariam (2004), takes external and internal loads, temperature changes, loss of bedding support, and the elastoplastic effect of soil into consideration. Based on the WPSI model, a method to evaluate the elastic and plastic areas was proposed in the present study. An FEM model based on pipe-soil interaction (PSI) element was used to verify the analytical model. Sensitivity analyses indicate that the soft soil, long pipe and high temperature induced the axial plastic deformation more likely, which, however, may not occur in normal scenarios. The soft soil, pipes in small diameters, long unsupported bedding are prone to form flexural plastic area. The results show that the pipes subjected to the same loads have smaller stresses in the elastoplastic analysis than elastic analysis. The difference, however, is slight.

The Disinfection of Drinking Water in Trunk Water Mains

This study aimed to explore the disinfection of drinking water in trunk water mains, based on published conditions denoted within the Irish Republic. The variables within the study were consumer draw-off rates, trunk main length, pipe diameter, and water temperature. All these factors are known to impact the free chlorine residual in operational supply networks. Based on published conditions obtained within the literature review, 60 hypothetical trunk mains were generated for this study. Of primary concern were the variables that affect the chlorine decay rate;total amount of chlorine decay;available amount of chlorine in the periphery of the trunk main;and the costs associated with effective chlorine disinfection of trunk mains. Based on the analysis performed, the following were the salient observations: 1) Low consumer draw-off rates and increased trunk main length and diameter increased the risk of the free chlorine residual in the periphery of the trunk mains not complying with the Environmental Protection Agency’s (EPA) minimum recommended residual value of 0.1 mg/l (EPA Drinking Water Audit Report, 2014). 2) Increasing the diameter of the trunk main from 125 mm to 180 mm had a negligible effect on the chlorine decay rate. However, increasing the trunk main diameter from 125 mm to 180 mm was shown to have a major impact on the total amount of chlorine decay and free chlorine residual available in the periphery of the main. The key parameters that affected disinfection costs associated with trunk mains include length, diameter and the need for chlorine boosting.

Water System Condition and Asset Replacement Prioritization

The goal of asset management is to identify and track the maintenance and replacement of assets that have reached their useful life. For that reason, gathering data and collecting information is a critical step when developing an asset management plan. Such data gathering includes physical and operational properties of the assets as well as collecting and tracking important events during the lifespan of the asset (i.e., pipe breaks, replacement year, maintenance performed, etc.). Critical factors in the asset management plan may be overlooked when there is no data or poor quality data. However, many utilities lack the resources for examining buried infrastructure and lack good quality work order data, so other methods of data collection are needed. The concept for this paper was to develop a means to acquire data on the assets for a condition assessment to identify pipes that were most likely to break and those with the highest consequences for same. Three utilities were used as examples. It was found that for buried infrastructure, much more information was known than anticipated but the actual predictions relied on only a few factors related to pipe type. However, there is a need to track the consequences, in this case breaks, which would indicate a failure. The latter would be useful for predicting future maintenance needs and the most at-risk assets, but is often missing in utility systems as many utilities do not adequately track breaks sufficiently. In this case two utilities were analyzed and predication on a third was developed.

Relationship between water inrush from coal seam floors and main roof weighting

A water-resistant key strata model of a goaf floor prior to main roof weighting was developed to explore the relationship between water inrush from the floor and main roof weighting. The stress distribution,broken characteristics, and the risk area for water inrush of the water-resistant key strata were analysed using elastic thin plate theory. The formula of the maximum water pressure tolerated by the waterresistant key strata was deduced. The effects of the caved load of the goaf, the goaf size prior to main roof weighting, the advancing distance of the workface or weighting step, and the thickness of the waterresistant key strata on the breaking and instability of the water-resistant key strata were analysed.The results indicate that the water inrush from the floor can be predicted and prevented by controlling the initial or periodic weighting step with measures such as artificial forced caving, thus achieving safe mining conditions above confined aquifers. The findings provide an important theoretical basis for determining water inrush from the floor when mining above confined aquifers.

Influential factors and control of water inrush in a coal seam as the main aquifer

In this paper, a combination of field measurement, theoretical analysis and numerical simulation were used to study the main control factors of coal mine water inrush in a main aquifer coal seam and its control scheme. On the basis of revealing and analyzing the coal seam as the main aquifer in western coal mine of Xiao Jihan coal mine, the simulation software of PHASE-2D was applied to analyze the water inflow under different influencing factors. The results showed that water inflow increases logarithmically with the coal seam thickness, increases as a power function with the permeability coefficient of the coal seam, and increases linearly with the coal seam burial depth and the head pressure; The evaluation model for the factors of coal seam water inrush was gained by using nonlinear regression analysis with SPSS. The mine water inrush risk evaluation partition within the scope of the mining field was obtained,through the engineering application in Xiao Jihan coal mine. To ensure the safe and efficient production of the mine, we studied the coal mine water disaster prevention and control measures of a main aquifer coal seam in aspects of roadway driving and coal seam mining.

MECHANICAL BEHAVIOUR OF MAIN FLOOR FOR WATER INRUSH IN LONGWALL MINING

In this paper a new mechanica1 medel indicating the mechanical behaviour of main floor in longwall mining is proposed. In the medel the unfractured rnain floor is considered as an elasto plastic plate, and the combination of fractured blocks as a voussoir beam. Using the plastic hmit theory of plates, th limit load acting on rnain floor and the position of its largest deformation are gotten. The stability conditions for the key blocks of the voussoir beam are analysed by "S-R" stability theory. The results of the theoretical analysis are important for the study on the water inrush from seam floor.

Estimation of water volume transports through the main straits of the East China Sea

The structure of current speed and the variability of volume transports of the Kuroshio in the Tokara-kaikyo and Osumi-kaikyo are discussed on the basis of data of KER in the period from 1977 to 1984. The average geostrophic transport through these two straits is estimated to be 24. 5×106 m3/s and only 1/12 of the transport is through the Osumi-kaiky5. Countercurrents on both sides of the Kuroshio trunk are observed in the Tokara-kaikyo. Calculation indicates that the average geostrophic current speed is less than the GEK current speed, systematically. On the basis of the current measurements, the northward transports through the Taiwan Strait in winter and summer are estimated to be 1. 05×106and 3. 16×106m3/s, respectively. From Chu's data (1976) the average transport of the Kuroshio flowing into the East China Sea passing through the passage east of Taiwan is about 29. 3×106m3/s. From Miita and Ogawa's data (1984) the average transport through the Tsushima-kaikyo is 3. 6×106m3/s. Thus the volume transports through the above four straits are roughly in balance, the total outflowing transport is slightly larger than the total inflowing transport. The possible reasons resulting in the difference of transports are also discussed.

Evaluation of Total Hydrocarbons Levels and Traces Metals in Water and Sediment from Main Outfall Drain in Al-Nassiriya City/Southern Iraq

This study was conducted during Dec2011-Nov2012 on three stations located in the south sector of Main Outfall Drain (MOD) River. Station 1 was near Al-Holandee Bridge which was the general carriage way in the center of Al-Nassiriya city, station 2 was 20 km far from the first station, while station 3 was in the beginning of the new branch. This study reveals the Seasonal Variation of Total petroleum hydrocarbons (TPHs) in both surface waters, sediment and it is related with trace metals nickel and vanadium in water (dissolved, particulate) and sediment (residual and exchangeable) phases. Also, the study shows the relationships between the concentration of Ni and V with Total Organic Carbon (TOC%) in the sediment.

Water Consumption and Use Efficiency of Main Crops on Semi-drought Area of Western Liaoning Province

The laws of water consumption in corn,peanuts and millet on the semi-drought area of western Liaoning Province were studied through the FAO-Penman Monteith method and the water balance method.Among three corps,the amount of the day water demand,the whole growth period water demand and the soil water deficit of corn were all the largest.At the same time,its degree of agreement between the water demand and the level of precipitation was the worst,and its average in crop coefficient was larger.The amount of th...

The Main Task of Water Transportation in 2004

The coastal port deep-water berths from existing 135 berths increase to 164 berths, and the throughput capacity will rising from current 231 million tons to 340 million tons which include build container berths from current 54 berths increase to 69 berths, the throughput capacity will from current 12 million TEUs increase to 19.4 million TEUs. In the final stage of Tenth Five-year plan, the quantity of national coastal port deep-water berths will from current 800 berths increase to

压水堆主泵及液态金属泵转子动力学研究进展

核主泵是核电站的关键设备之一,也是反应堆冷却系统的唯一旋转机械设备,其稳定运转对整个反应堆的正常工作至关重要,因此,针对核反应堆主泵开展转子动力学研究,探究主泵转子部件的模态振型、固有频率和支撑系统的刚度阻尼、液膜厚度十分必要。以国内外有关压水堆主泵及液态金属泵的转子动力学研究为重点,围绕压水堆主泵、钠冷快堆主泵、熔盐堆主泵、铅冷快堆主泵4种核主泵类型,从核主泵及其转子部件的结构特点出发,对现阶段主泵导轴承润滑性能和主泵转子结构固有频率、模态分析、临界转速等转子动力学特性的研究进展进行综述和展望,以期对有关核主泵转子动力学特性的计算分析起到一定的借鉴和指导作用。

基于BP神经网络的低渗透底水油藏油井见水模式预测模型

注水开发使得低渗透底水油藏油井见水模式更加复杂,需要进一步明确及预测油井见水模式来针对性地指导水淹治理措施。神经网络模型具备处理多元回归问题和计算速度快等优势,可被用于分析地质工程多因素参数与油井见水模式的内在关系,构建见水模式预测模型。在油井见水模式划分的基础上,通过灰色关联理论和神经网络算法对BCL低渗透底水油藏油井见水模式的主控因素和预测模型进行了研究。发现水层厚度、隔夹层数、隔夹层长度和避水高度是该类油藏注水开发下影响油井见水模式的主控因素。基于主控因素结合神经网络算法建立了油井见水模式预测模型。通过对18组测试数据进行验证,平均预测误差1.4%,获得了较好的预测精度。通过易于获取的主控因素快速预测注水开发低渗透底水油藏油井的见水模式,为该类油藏的高含水针对性治理提供基础依据。

基于主要驱动因子筛选法和深度学习算法的浙江省动态需水量预测

收集了浙江省2000—2020年各用水行业需水量数据,采用基于Spearman秩相关分析的主要驱动因子筛选法筛选了影响各行业需水量的主要驱动因子,进而构造了改进的长短时记忆(LSTM)神经网络需水量预测模型,对各行业需水量进行动态滚动预测,并将改进LSTM模型的预测结果与传统单变量LSTM预测模型、卷积神经网络模型、支持向量回归模型的预测结果进行了对比。结果表明,基于主要驱动因子筛选法改进的LSTM模型能实时动态滚动预测各行业每年需水量,且预测结果精度高于其他3种模型。

滇中地区主要森林凋落物有效截留量及其影响因素

[目的]研究滇中地区主要森林类型凋落物有效截留量差异及其影响因素,为该地未来植被恢复和森林管理提供科学支撑。[方法]利用样方调查法、烘干法和浸泡法分析了昆明市双河—磨南德水源林自然保护区内的地带性次生常绿阔叶林(SF)、针阔混交林(TF)、旱冬瓜林(ACF)、华山松林(PA)、成熟云南松林(OPY)、幼龄云南松林(YPY)、银荆林(AD)7种主要森林类型凋落物未分解层(OL)和半分解层(OF)的有效截留量及其影响因素。[结果](1) 7种森林类型凋落物厚度为2.06~7.57 cm,其中OL层1.10~4.30 cm, OF层0.83~3.93 cm,凋落物层厚度排序为TF>ACF>PA>OPY>SF>AD>YPY,凋落物蓄积量为4.75~17.45 t/hm^(2),其中OL层占比为32.02%~62.48%,OF层占比为37.52%~67.98%,凋落物层蓄积量排序为TF>PA>SF>OPY>ACF>AD>YPY。(2)凋落物最大持水率为115.3%~170.7%,初始吸水速率为3.65~5.62 g/(g·h),凋落物持水率和浸水时间的关系可用对数函数y=aln(x)+b表示,吸水速率与浸水时间可用幂函数y=kt~n表示。(3)凋落物最大持水量为7.05~32.19 t/hm^(2),排序为PA>TF>SF>OPY>ACF>AD>YPY,有效截留量为5.45~25.34 t/hm^(2),以TF最高(25.34t/hm^(2)),PA(24.99 t/hm^(2))和SF(24.62 t/hm^(2))次之,YPY最低(5.45t/hm^(2)),影响有效截留量的场地特征主要为蓄积量、自然含水率、分解强度以及厚度,影响有效截留量的水动力过程主要是最大失水量、前6.0 h平均吸水速率和前2.0 h平均吸水速率。[结论]滇中地区未来植树造林应以针阔混交林为主,注重对地带性次生常绿阔叶林的保育,采取辅助自然更新的措施促进人工纯林向混交林演化,同时减少踩踏、收集凋落物等人类活动的干扰,从而增加森林生态系统凋落物的水源涵养能力。

准噶尔盆地东道海子凹陷下侏罗统浅水三角洲沉积演化及主控因素

准噶尔盆地东道海子凹陷下侏罗统发育浅水三角洲,但其沉积演化与控制因素仍不明确。基于东道海子凹陷及其周缘测录井、岩心、地球化学测试等资料,对该地区下侏罗统沉积相、古地貌、古气候进行分析。结果表明:东道海子凹陷下侏罗统浅水三角洲可识别出三角洲平原、内前缘、外前缘3种亚相,其中平原亚相以分流河道为主,可形成上百米厚的砂砾岩,内前缘水下分流河道发育含泥质夹层的中—细砂岩,外前缘主要为席状砂沉积,形成泥岩与泥质粉砂岩薄互层;古地貌东高西低,根据相对位置与坡度可分为古高地、古斜坡、古洼地3类地貌单元;地球化学指标与沉积特征显示早侏罗世古气候干湿交替,湖平面发生3次湖退—湖进,三角洲平原进退幅度达数十千米。推测古地貌与古气候共同控制了浅水三角洲的沉积展布与演化,其中整体平缓的古地貌为浅水三角洲的形成奠定基础,局部地貌的高低与演化决定沉积体系的展布与变迁,而干湿变化的古气候影响湖平面的升降旋回,进而控制三角洲的进积与退积。综合上述分析,建立了进积型及退积型2种浅水三角洲沉积模式。该认识有利于深化气候和地貌对浅水三角洲控制作用的认识,为准噶尔盆地东道海子凹陷下一步勘探提供借鉴。

生产集聚对粮食生产用水绿色效率的影响研究--以我国粮食主产区为例

基于2002-2021年我国13个粮食主产区的省级面板数据,运用区位基尼系数和Super-SBM模型对粮食主产区粮食生产集聚度和粮食生产用水绿色效率分别进行测度,在此基础上通过面板模型探究粮食生产集聚对粮食生产用水绿色效率的影响,并利用中介效应模型对路径机制进行检验。结果表明:研究期内我国粮食主产区粮食生产集聚度整体呈上升趋势,粮食生产用水绿色效率呈现“北高南低”的空间分布状态且整体无明显改善。粮食生产集聚度与粮食生产用水绿色效率呈“倒U形”关系,规模化经营和种植结构调整在“倒U形”关系中发挥中介效应且规模化经营的中介效应更大,科技创新的中介效应不显著。因此政府应因地制宜制定合理的粮食生产集聚政策,引导农户、组织及企业适度规模经营,提高种植结构的合理性,建立粮食生产集聚与技术创新的高效联动机制,促进粮食生产用水绿色效率的提升。

大口径引输水管道漏损监测技术研究进展

大口径引输水管道作为城市公用建设基础设施,承担着向各个用水节点供水的重任,具有距离长、口径大、输水量大、运行压力高等特点。引输水管道系统在运行过程中,因老化、第三方施工、内外荷载、自然或人为因素等造成的输配水管道泄漏、破裂、爆裂等管道损坏事件逐年增加。一方面造成供水资源的浪费,另一方面增加运行成本和影响服务质量。通过采取先进的漏损监测技术和管理手段,及时发现和定位泄漏位置,合理控制和降低管道漏损,可有效提高供水能力,保障供水安全。文章通过全面分析管道系统漏损原因,梳理漏损监测方法,分析不同监测方法的适用性,提出管道漏损监测技术的建议和方法。对于大口径引输水管道漏损监测技术的研究与应用具有一定的指导意义。

A Value Engineering Analysis of Head Loss in Pumping Mains

With net zero carbon emissions targets approaching over the next 20 to 30 years, the water industry must act now to develop energy efficient techniques and designs to reduce emissions and reduce the carbon footprint of water utility providers. There is also the potential for significant energy and therefore financial savings to be realised from the adoption of more energy efficient designs approaches. Water utility providers account for a significant proportion of national electricity consumption. The purpose of this research is to determine if, over the long term, opting for a larger diameter pipe at design stage can lead to significant financial and emissions savings for water utility providers when considering pumping mains. Pumping mains are widely used throughout the water and wastewater industry where a gravity solution is not possible. 72 hypothetical water main design scenarios were analysed and the long term financial and environmental impact of each hypothetical water main was assessed. It was found across all design scenarios that larger diameter water mains were capable of delivering the same rate of flow of smaller diameter pipes at a much reduced velocity and requiring reduced pumping power. It was concluded that pumped mains of larger diameters can ultimately be more energy efficient and cost effective over the long term when selected in favour of smaller diameter pumped mains in otherwise identical design scenarios.

基于自然要素的大尺度河流水环境承载力评价与预测

水环境承载力是保护水环境的重要指标,用于水资源的合理规划与管理,确保水环境的可持续利用。为探讨适用于大型河流的更为系统全面的水环境承载力评价指标体系,在现有水环境承载力研究的基础上,选取长江干流为研究对象,以“自然要素、水资源、生态环境、社会经济”4个方面作为指标层,共选取25个具体指标,运用改良的主成分分析法对长江干流水环境承载力的时空尺度变化趋势进行了评价,通过ARIMA模型预测了长江干流未来3年水环境承载力的发展情况。结果表明,综合指标分值在时间尺度上的变化整体呈上升趋势,综合得分由-1.66逐渐上升为1.26,从Ⅳ级(差)上升为Ⅰ级(优),未来3年将继续保持小幅度上升趋势。