Study on Volume Variation and Stability of Riverbed in the Yangtze Estuary

In recent years,regional floods and typhoons have occurred in the Yangtze Estuary.Changing dynamic conditions and dramatic reduction of sediment discharge in the basin are affecting the dynamic equilibrium pattern of the Yangtze Estuary.Based on the field measurement data and theoretical derivation,this paper analyzed the changing process of runoff-sediment discharge into the sea after the operation of the Three Gorges Project(TGP),and the tidal dynamics and sediment variation characteristics of the Yangtze Estuary.The erosion of South Branch mainly occurs in the channel below-10 m contour,and the riverbed volume below contours 0 m and-10 m has a good correlation with the sediment discharge of Datong Station in the previous year.On this basis,the ratio of the horizontal distance from the starting point to the section centroid below the average water level(B_c)and the water depth at the section centroid(H_c)was proposed to describe the change of the section shape.The relationships between the water-diverting ratio,the sediment-diverting ratio and the water-diverting angle,the conditions of runoff and sediment discharge from the upper reach and the characteristics of the riverway section were established,and the theoretical calculation equations of the water-diverting ratio,the sediment-diverting ratio and the diverting angle of each bifurcation were also established.

基于Riverbed的机载电子板卡红外图像分割

在机载电子板卡故障诊断过程中,需要对故障芯片进行准确的定位。针对机载电子板卡芯片布局紧密、工作芯片的热辐射范围广的问题,提出一种新型的人机交互式红外图像分割方法。首先,利用基于图像森林变换的Riverbed算法对故障目标图像进行边界追踪,并将Live Wire的特性与之相结合,优化了对边界模糊的目标的轮廓的提取,显著减少了所需的定位点数;然后,鉴于芯片的外形特征,采用基于梯度幅度直方图和类内方差最小化的自适应方法找到芯片的边界,用得到的芯片边界对目标轮廓进行约束,提高目标区域定位的精度。实验结果表明:该方法有效提高了故障边界提取的速度,与其他经典算法相比较有效提高了芯片的核心发热区域提取的精度,避免了多分割的现象。

Effects of riverbed scour on seismic performance of high-rise pile cap foundation

To explore the seismic performance of a high-rise pile cap foundation with riverbed scour, a finite element model for foundations is introduced in the OpenSees finite element framework. In the model, a fiber element is used to simulate the pile shaft, a nonlinear p-y element is used to simulate the soil-pile interaction, and the p-factor method is used to reflect the group effects. A global and local scour model is proposed, in which two parameters, the scour depth of the same row of piles and the difference in the scour depth of the upstream pile and the downstream pile, are included to study the influence of scour on the foundation. Several elasto-plastic static pushover analyses are performed on this finite element model. The analysis results indicate that the seismic capacity （or supply） of the foundation is in the worst condition when the predicted deepest global scout depth is reached, and the capacity becomes larger when the local scour depth is below the predicted deepest global scout depth. Therefore, to evaluate the seismic capacity of a foundation, only the predicted deepest global scout depth should be considered. The method used in this paper can be also applied to foundations with other soil types.

Modeling the triaxial behavior of riverbed and blasted quarried rockfill materials using hardening soil model

Riverbed modeled rockfill material from Noa Dehing dam project, Arunachal Pradesh, India and blasted quarried modeled rockfill material from Kol dam project, Himachal Pradesh, India were considered for this research. Riverbed rockfill material is rounded to sub-rounded and quarried rockfill material is angular to sub-angular in shape. Prototype rockfill materials were modeled into maximum particle size （dmax） of 4.75 mm, 10 mm, 19 mm, 25 mm, 5O mm and 80 mm for testing in the laboratory. Consolidated drained triaxial tests were conducted on modeled rockfill materials with a specimen size of 381 mm in diameter and 813 mm in height to study the stress-strain-volume change behavior for both rockfill materials. Index properties, i.e. uncompacted void content （UVC） and uniaxial compressive strength （UCS）, were determined for both rockfill materials in association with material parameters. An elasto- plastic hardening soil （HS） constitutive model was used to predict the behavior of modeled rockfill materials. Comparing the predicted and observed stress-strain-volume change behavior, it is found that both observed and predicted behaviors match closely. The procedures were developed to predict the shear strength and elastic parameters of rockfill materials using the index properties, i.e. UCS, UVC and relative density （RD）, and predictions were made satisfactorily. Comparing the predicted and experi- mentally determined shear strengths and elastic parameters, it is observed that both values match closely. Then these procedures were used to predict the elastic and shear strength parameters of large- size prototype rockfill materials. Correlations were also developed between index properties and ma- terial strength parameters （dilatancy angle, ~, and initial void ratio, einit, required for HS model） of modeled rockfill materials and the same correlations were used to predict the strength parameters for the prototype rockfill materials. Using the predicted material parameters, the stress-strain-volume change behavior of prototype rockfill material was predicted using elastoplastic HS constitutive model. The advantage of the proposed methods is that only index properties, i.e. UCS, UVC, RD, modulus of elasticity of intact rock, Eir, and Poisson＇s ratio of intact rock, Vir, are required to determine the angle of shearing resistance, Ф, modulus of elasticity, E50^ref and Poisson＇s ratio, , of rockfill materials, and there is E50＆ref no need of triaxial testing. It is believed that the proposed methods are more realistic, economical, and can be used where large-size triaxial testing facilities are not available.

Mobility Issue on Octagonal Structured ZigBee Network Using Riverbed

Wireless Sensor Network (WSN) is a special type of communication medium through distributed sensor nodes. Popular wireless sensor nodes like ZigBee have splendid interoperability after IEEE 802.15.4 standardization in the domain of wireless personal area network (WPAN). ZigBee has another great feature mobility that makes the ZigBee network more versatile. The mobility feature of ZigBee mobile nodes has a greater impact on network performance than fixed nodes. This impact sometimes turns into more severe because of network structure and mobility model. This study mainly focuses on the performance analysis of the ZigBee mobile node under Random and Octagonal mobility management model with the Tree routing method. The Riverbed academic modeler is used to design, implement and simulate the ZigBee network under certain conditions. This study also presents a competitive performance analysis based on ZigBee mobile nodes transmitter and receiver characteristics under the observation of the mobility model. This indicates that Octagonal mobility model exhibits better performance than the Random mobility model. This study will constitute a new way for further designing and planning a reliable and efficient ZigBee network.

黑龙江(阿穆尔河)河槽演变相关研究成果——俄罗斯科学院远东分院水生态所《Formation of the Riverbed Relief and River Banks》简析

在水文学的探索过程中,对河槽演变的研究是揭示河流流量变化、河流水势变化与研究流域自然地理演变的基础。在中国国内对黑龙江(阿穆尔河)流域的研究中,关于河槽演变的成果和分析不多。《Formation of the Riverbed Relief and River Banks》一书是由俄罗斯科学院远东分院水生态研究所(IWEP FEB RAS,文中简称IWEP)副所长阿雷克谢·尼古拉耶维奇·马奇诺夫教授为第一作者编著的,该书从东亚的地区特征出发,对黑龙江(阿穆尔河)河床地貌的形成与河槽演变过程作了详细的说明。全书共分为五章,共172页,附图片44张(9张是实景彩图),并有英语和俄语两版简介与结论。该书对黑龙江河槽演变的研究具有一定的参考价值。

Application of Short Sequential Extraction Procedure(SSEP) for the Determination of Zn, Cu, and Cd Contents in Riverbed Sludge in Hejiagou, Harbin, China

A short sequential extraction procedure（SSEP） was applied to the determination of more readily available metal fractions of Zn, Cu, and Cd in the riverbed sludge in Hejiagou, Harbin, China. From the results, a potential order of metal availability in seven sludge samples was proposed： Cd 〈 Cu 〈 Zn, and samples S1 , S2, and S4 were used for the determination of total Zn content, and sample S3 used for the determination of total Cu content in the mobile and the mobilizable fractions showed the highest pollution risk. The results with regard to metal mobility in sludge samples were confirmed by the individual and global contamination factors that were calculated from the nonresidual and residual metal contents. The results obtained from metal-release experiments after exposure of sludge to environmental conditions agreed well with those obtained from both SSEP and the individual and global contamination factors, indicating that the maximum metal release could be an additional factor to evaluate the heavy metal availability in contaminated sludge. A substantial time saving was achieved by using the metal-release method in the present study.

A Micro Study to Determine Porosity, Hydraulic Conductivity, Permeability and the Discharge Rate of Groundwater in Ondo State Riverbeds, Southwestern Nigeria

Laboratory study of three riverbed soil samples denoted as A, B and C have been carried out by determining the soils Porosity, Hydraulic conductivity, Permeability and also investigating if there are points of convergence between the discharge rate and angle of tilt for the above mentioned samples. The experimental results for Porosity were approximately within 34% - 37%, Hydraulic conductivity was within 3.02 × 10-5 - 9.70 × 10-5 (m/s) and Permeability was within 2.74 × 10-12 - 8.80 × 10-12 (m2). Pressure generally increases as distance of flow increases for θ = 5° - 25° but there was decrease in pressure as distance of flow increases for all three samples when θ = 0°. The points of convergence for the discharge rate ranged from 0.001 × 10-10 - 4.54 × 10-10 (m3/s), while the angle of tilt convergence points ranged from 0.1° to 3.6°. There was increase in discharge rate as angle of tilt increases for all three samples.

Riverbed发布业界最全面的数字体验管理解决方案

本刊讯Riverbed科技公司日前宣布推出最新版Riverbed SteelCentral，为用户提供市场上最完整、集成的数字体验管理解决方案。现在，Riverbed SteelCentral可以帮助客户评估数字体验的方方面面，

取水工程对松花江悦来河段影响研究

为了研究引水工程的建设对松花江悦来河段水沙变化的影响,构建了松花江干流悦来河段的平面二维水沙数学模型,分析了引水工况对松花江悦来河段的流速、水位、分流比和冲淤分布的影响。研究结果表明:松北引渠引水入松花江致使入江处水位抬升为0.03~0.04 m,由于松南引渠引水,致使取水口附近的主河道水位下降约0.03 m;在天然条件下,松南下口引渠位置分流量为78 m~3/s,分流比为8.8%,在取水方案下,松南上口引渠分流量为104 m~3/s,分流比为8.5%,松南下口引渠分流量为323 m~3/s,分流比为28.9%;在天然条件下,悦来河段主河道呈现冲刷状态,冲刷深度为1.0 m左右,双口引渠导致取水口附近的泥沙淤积较天然条件有所增加,其中松南引渠下口淤积更为显著,引渠口门处淤积厚度可达1.0 m以上。

黑龙江干流黑河市城区段河床演变研究

黑龙江黑河市城区河段河道受自然及人为因素影响,河床演变复杂。采用Mann-Kendall趋势检验法和双累积曲线法分析了水沙变化趋势。基于实测水文和泥沙资料,对河床稳定性及冲淤变化进行了定量研究。研究结果表明,该河段属于少沙河流,结雅河口以上年径流和输沙量随时间呈减小趋势,结雅河口以下年径流没有明显的趋势性变化,年输沙量呈减小趋势。自然状态下,河段岸线和深泓线位置基本稳定,河床冲淤变化不大,以约10年为一个周期,基本可以达到冲淤平衡。在人类活动及支流汇入影响下,黑河水位站至长发岛段纵向不稳定,预测会引起该段未防护岛屿洲滩的岸线变迁。

磁偶极子单自由度定位河床冲刷监测方法研究

为解决传统磁偶极子定位方法依磁力梯度张量反演磁偶极子位置,所需测量矩阵复杂的弊端,从磁偶极子空间分布模式出发,仅以单自由度的磁偶极子在某点处所产生的磁场三分量来定位磁偶极子。依据磁偶极子空间分布模式,推导单自由度磁偶极子的反演方程,实现了磁偶极子单自由度定位。在此基础上,基于推导的反演方程,将磁偶极子单自由度定位方法与重力驱动河床冲刷监测方法相结合,提出了一种具有普适性的河床冲刷监测方法,该方法可以通过单自由度反演公式反映河床冲刷情况。

西北江三角洲河床变化对咸潮上溯影响的数值模拟研究

为研究西北江三角洲河床变化及其与咸潮上溯关系,收集整理以往研究成果资料与水文气象、河道地形数据的基础上,建立一维非恒定流含氯度数学模型,水动力和含氯度验证结果均满足相关规范要求,可以用于计算分析河床变化对咸潮上溯的影响。研究结果表明:①1999—2016年,西北江三角洲网河区河床处于不均匀下切状态,河道容积持续增大,导致河口涨落潮阻力减小,高盐水团沿河口上溯更为简单,咸潮上溯情势日益严峻;②各口门站的涨潮量增加,咸界上移取淡机率降低,思贤滘不同来流条件下,磨刀门水道咸界平均上移3735 m,平岗泵站的取淡机率平均减少5.33%,沙湾水道咸界平均上移2369 m,沙湾第一水厂取淡机率平均减少5.14%,严重影响河口地区的生态系统以及正常取水需求。研究结果可以为西北江三角洲及河口地区的供水安全保障措施研究及工程设计提供基础支撑。

三峡蓄水以来葛洲坝下中华鲟产卵场河床质特征变化规律

为探究葛洲坝下中华鲟(Acipenser sinensis)产卵场的河床质特征变化规律,研究基于水声学和水下视频影像分析三峡蓄水以来现有数据(2004—2020年),研究底质表观特征与水声学特征的相关性,分析产卵场底质特征变化及其原因。结果表明:(1)硬度、粗糙度和分形维数分别与河床质充塞度、粒径和主要组成相关;(2)葛洲坝下中华鲟产卵场河床底质特征参数在2004—2020年发生了明显的变化,硬度、粗糙度和分形维数三种特征均值在2004—2012年均呈现先增加后减少的趋势(P<0.01),在2012—2019年均显著增加(P<0.01),在2019—2020年显著减少(P<0.01);(3)产卵场含沙的底质比例在2004—2008年减少33.08%,在2008—2012年增加12.69%,在2012—2015年减少33.83%,此后其持续减少至2019年,在2019—2020年增加39.37%,期间的底质变化可能与三峡蓄水、泥沙调度、新修水坝的蓄水运行及期间发生的洪水有较大关联,且中华鲟的自然繁殖活动明显受河床质变化影响。研究结果为葛洲坝下中华鲟产卵场河床质的推演和产卵场的恢复与重建提供基础数据。

金沙江堰塞湖溃决后淤积河段疏浚措施实验研究

2018年金沙江上游因强降雨发生大型山体滑坡形成堰塞湖,堰塞湖溃决后大量泥沙随溃坝洪水向下游输移,导致下游河道形态及水流特性突变。某规划电站尾水河段受该事件影响,床面淤积6~10 m。为保障该电站如期正常建设,针对尾水河段上下游3 km河道,开展动床物理模型试验研究,探索尾水河段设计水位恢复方案。河道演变分析表明,堰塞湖溃决后的第1年,工程河段河床单向显著冲刷;至2022年汛前,河道整体表现为上冲下淤,尤其弯道下游石滩显著生长发育。通过模型试验预测了工程河段2027年地形,届时河道床而仍较堰塞湖溃决前高1~6 m,需要采取疏浚措施才能保障规划电站尾水口水位降低至设计水位。为有效减小疏浚范围及疏浚量,详细分析了弯道下游新生石滩段的水沙特性及演变趋势,提出了下游先期局部疏浚,通过自然演变调整床面,再开展整体疏浚的整治方案。试验证明,该方案较直接疏浚方案缩短了疏浚长度,可减少约6.88万m3疏浚量。继续针对新方案开展淤积试验,由于上游电站已陆续建成使用,其拦蓄作用大幅减少了研究河段来沙量,在5个典型年的水沙作用下,研究河段床面整体保持相对稳定,仅尾水出口下游左侧呈现一定程度淤积,建议管理单位定期按需要进行必要的局部疏浚维护,以保障电站安全运行。

基于正交试验的盾构掘进江底变形分析与施工方案优化

盾构隧道的施工易引发开挖面上层土体松动塌陷,造成邻近建筑物沉降破坏。针对盾构隧道施工地层变形的问题,依托南京建宁西路过江通道工程,建立有限元模型模拟盾构隧道开挖过程,探究盾构掘进对河床沉降、深层土体水平及竖向位移等影响。以河床表面最大沉降、沉降影响范围、拱顶竖向位移、隧底隆起为指标,支护应力比、埋径比、盾尾注浆压力、泥浆相对密度等为影响因素安排L16(45)正交试验,分析各个影响因素的显著性及主次顺序,结果表明支护应力比和泥浆相对密度对各项指标影响程度较小,可采取最经济水平。由此得到最优水平组合为A_(4)B_(1)C_(4)D_(3)和A_(4)B_(2)C_(4)D_(3),并设计优化追加试验,追加试验方案1减小了埋径比,增加了盾尾注浆压力,结果表明其对地层变形的控制效果更好,为优选方案。

弗劳德数影响下的沙质河床丁坝群局部冲刷数值模拟

为分析弗劳德数对沙质河床丁坝群局部冲刷的影响,基于MIKE21对三种泥沙粒径沙质河床在不同弗劳德数下的丁坝群局部冲刷进行数值模拟,总结了冲刷范围及特征断面的变化规律。结果表明,局部冲刷除Ⅱ号坝头产生淤积外其余丁坝坝头均产生局部冲刷;同一弗劳德数下,泥沙粒径越小,冲刷范围及断面变化越大,高弗劳德数时更为明显,而同一粒径下,弗劳德数越大,冲刷范围及断面变化会越大,在泥沙粒径较小时更为明显;在泥沙粒径较小、弗劳德数较大时,冲刷范围几乎影响整个丁坝群河道且首坝附近河床整体为先冲后淤。

河道水力几何关系研究进展

河道水力几何关系(河相关系)研究旨在寻求流域因子与河床地貌形态的定量关系。系统回顾了断面水力几何和沿程水力几何关系的研究方法,总结了经验分析法、稳定性理论、极值假说及变分方法的主要成果和存在的不足。结果表明:(1)这4种方法既有各自的优缺点及适用性,又彼此相关。(2)经验分析法是探究普适性水力几何关系式的必经之路;稳定性理论由于设置太多限定条件,难以推广;极值假说在河流地貌调整规律中尚缺少理论支撑;变分方法澄清了最大、最小极值假说的争论,具有广阔的应用前景。(3)断面水力几何和沿程水力几何关系分别在空间和时间维度有所延伸,尤其是多断面水力几何关系在估测河段流量方面具有良好应用前景。

河床地形起伏变化对地表水-地下水-湿地水交互过程的影响研究

地表水动力条件变化及河床沉积物岩性空间差异造成河床地形在空间上起伏变化是水沙界面压力空间分布的主要影响因素,影响地表水-地下水、地下水-傍河湿地水交互过程。为研究河床地形起伏变化对地表水-地下水-湿地水交互过程的影响机理,在黄河下游开封柳园口设置研究断面,统计分析河床地形起伏变化特征数据,建立半理想化地下水流数值模型,分析地表水-地下水-湿地水相互作用过程。结果表明:(1)与平整河床相比,河流横断面河床地形空间起伏变化可增大地表水-地下水转换量及地下水-湿地水转化量;(2)河床地形空间起伏变化使河床下伏含水层发育不同级次的地下水流系统,改变了地下水流路径及其径流时间,与平整河床地形相比,河流横断面河床地形起伏变化使得河流下伏含水层地下水流路径复杂化,近河床界面的浅部含水层不同位置发育有滞留区,且随着河床地形起伏程度越大,湿地侧河床下伏含水层及湿地附近含水层地下水年龄增大。研究结果可为黄河下游悬河段地表水-地下水-湿地协同保护提供理论依据。