Effect of insufficient tunnel crown thickness on the post-tensioned concrete lining of the Yellow River Crossing Tunnel and its strengthening schemes

The effect of deficiency in tunnel crown thickness on the Yellow River Crossing Tunnel with post-tensioned concrete inner lining was investigated by the elasto-plastic finite element method. Changes in the deformations and circumferential stresses of the post-tensioned concrete inner lining with the gradual decrease of the tunnel crown thickness were compared, and the potential bearing risk of insufficient tunnel crown thickness for the Yellow River Crossing Tunnel was revealed. Based on the finite element calculation results of circumferential stresses under different defective cases, the corresponding reinforcement schemes were proposed. The calculation results show that the inner lining can still maintain a satisfactory stress state when the tunnel crown thickness is equal to or greater than 0. 28 m. When the tunnel crown thickness decreases below 0.28 m, the external surface of the crown and internal surface of the crown＇s adjacent areas may be under tension. The tension stresses will incrementally increase and ultimately exceed the tensile strength of the inner lining concrete as the tunnel crown thickness further decreases gradually. Then, the Yellow River Crossing Tunnel cannot operate normally, and severe cracking, leaking or even failure may occur. When the tunnel crown thickness is equal to or greater than 0.28 m, the reinforcement suggestions are that the void spaces between the inner lining and the outer lining should be back-filled with concrete. When the tunnel crown thickness is less than 0. 28 m, the inner lining should be reinforced by steel plates after concrete back-filling.

Vegetation Formation in Estuarine Tidal Flats: Influences of Basin Scale and River-Crossing Structures of the Eight Rivers of Ise Bay in Mie and Aichi Prefectures, Japan

In this study, we examined the influences of the differences in basin scale and river-crossing structures of 8 rivers of Ise Bay in Mie and Aichi Prefectures, Japan on the vegetation in the estuarine tidal flats of these rivers. The dominant plant communities of the estuarine tidal flats formed from rivers of large-scale river basins (exceeding 300 km2) were determined. In the Miya River, the dominant plant community was the Suaeda maritima and Artemisia fukudo community. In the Kushida River, the dominant plant community was composed of Phacelurus latifolius, Artemisia fukudo, Phragmites australis, and bamboo. In the Kumozu River, the dominant community was composed of the coastal plants Calystegia soldanella, Lathyrus japonicus, and Carex pumila and the exotic plant of Lolium multiflorum. The plant community of Suzuka River was dominated by the exotic plant of Eragrostis curvula. Among the estuarine tidal flats influenced by a small-scale river basin (50 km2 or less), the plant community of Shinbori River (Fukue tidal flat) was dominated by Suaeda maritima, and the plant communities of the Shio and Harai Rivers were dominated by Phragmites australis. The plant community of Tanaka River was dominated by Phragmites australis and coastal plants. Regarding the relationship between the vegetation and the river environment for each study site, we hypothesised that in a large basin area with few structures crossing the river, the river water catchment in the estuary after heavy rains caused large areas of disturbance and formed bare land, providing suitable habitat for an annual salt marsh plant community. In contrast, in cases with many structures crossing the river, a stable channel, an excavated riverbed and the suppression of runoff and the resulting disturbance of the estuary, flooding did not occur during high tide. Moreover, we hypothesised that in a small basin with many structures crossing the river, disturbance to the estuary was not likely, and the perennial salt marsh plant community of Phragmites australis would be widely distributed, except for a river type such as the Shinbori River, in which tide and river flow were managed by a final closure.

Horizontal freezing study for cross passage of river-crossing tunnel

To determine the appropriate soft foundation treatment for a river-crossing tunnel, freezing reinforcement design and technology were introduced based on the channel tunnel design and construction practice. Through finite element analysis and engineering practices, two rows of horizontal perforated freezing pipes were designed and installed on both sides of a passage for tunnel rein- forcement, which produced the thickness and strength of frozen crust that satisfied the design requirements. These information are valuable for guiding the design and construction of river-crossing tunnels in coastal areas.

Discussion on the Construction of Negotiation Mechanism of Cross-bounder Water Pollution Treatment in Changjiang River

In order to construct cooperation platform for the treatment of water pollution in Changjiang River,thoughts and revolution were performed from both central government and regional area two aspects.From the national level,Changjiang region water resources management cooperation counsel committee was constructed as the national cooperation platform;from the regional level,Changjiang region water resources management cooperation counsel committee was constructed as the platform of Changjiang cooperation platform.The two platforms built fine interaction mechanism to deal with the national water management and Changjiang regional water management.

Geometric properties of river cross sections and associated hydrodynamic implications in Wuhan-Jiujiang river reach,the Yangtze River

Based on measured hydrological data by using ship-mounted Acoustic Doppler Current Profiler （ADCP） instrument, we analyzed shapes of river cross sections of the middle Yangtze River basin （mainly focusing on Makou and Tianjiazhen river reach）. Hydrodynamic properties of river channels were also discussed. The research results indicate that nonlinear relationships can be identified between river-width/river-depth ratio （W/D ratio）, sizes of cross section and mean flow velocity. Positive relations are detected between W/D ratio and mean flow velocity when W/D〈1; and negative relations are observed when W/D〉1. Adverse relationships can be obtained between W/D ratio and cross-section area. Geomorphologic and geologic survey indicates different components of river banks in the wider and narrower river reaches respectively. These may be the main driving factors causing unique hydrological properties of river channels in the middle Yangtze River basin. Narrower river cross sections tend to raise water level in the upstream river reach near narrower river channel, giving rise to backwater effects. River knots can cause serious backwater effects, which is harmful for flood mitigation. However river knots will also stabilize river channel and this will be beneficial for river channel management. The results of this paper may be helpful for flood mitigation and river channel management in the middle Yangtze River basin.

Road Lateral Disconnection and Crossing Impacts in River Landscape of Lancang River Valley in Yunnan Province,China

Roads are conspicuous components in a river landscape;however,their impacts on river landscape patterns and ecological processes have not been systematically studied at the watershed scale.In this paper,the Lancang River Valley in Yunnan Province,China was selected as a case to study road lateral disconnection and crossing impacts and identify river-road network interaction.This study was primarily focused on the road impacts on soil erosion intensity and patch density by using GIS analysis at different scales and explored their distribution with terrain factors.The results showed that river density revealed spatial autocorrelation although both of the roads and rivers were distributed unevenly in the valley.The lateral road(road curvature≥1.1)proportion correlated with soil erosion intensity(p 0.01)at the small sub-basin scale.Soil erosion intensity decreased with increasing lateral road buffer width.Light erosion generally accounted for a large proportion of the erosion in the lateral road buffer zones(1.0–4.0 km),while higher class lateral roads imposed greater impacts on soil erosion than lower class roads,which primarily had a moderate erosion level.In addition,the results of road-river intersection density indicated that road crossing impacts were significantly correlated with patch density at the small sub-basin scale.Topography factor(percent of slope>25°in each sub-basin had a close relationship with the ratio of total length of road line with curvature value≥1.1 to the total number of intersections.The correlation(p 0.01)between road impacts and terrain factor revealed that topography affected the road impact distribution in the Lancang River Valley.

基于BPNN-SHAP模型的滑坡危险性评价:以伊犁河流域为例

为进一步提高滑坡危险性预测模型精度、增强模型可解释性,本文以新疆伊犁河流域为研究区,选取8个影响滑坡发生的危险性因子,在反向传播神经网络(BPNN)基础上,借鉴博弈论思想,构建一种可解释BP神经网络模型(BPNNSHAP),解决神经网络滑坡危险性评价的“黑箱”问题。将数据集分为70%训练集和30%测试集,采用5折交叉验证提高模型稳定性,对比深度神经网络(DNN)、随机森林(RF)和逻辑回归(LR)3个模型的评价精度,并探讨BPNNSHAP预测结果的可解释性,完成区域滑坡危险性评价。研究结果表明:相较于其他模型,BPNN-SHAP模型的5个精度评价指标均为最高,分别是:准确率(A)=0.904、精准度(P)=0.911、召回率(R)=0.919、F1分数(F1_(Score))=0.915、曲线下面积(SAUC)=0.901;研究区滑坡极高、高危险区分别占比11.96%、15.53%,其中新源县和巩留县极高、高危险区占比最高,分别为51.1%、45.6%;滑坡主控因子为高程、坡度、降雨量和峰值地面加速度(PGA),定量揭示高程在1500~2000 m、坡度大于14°、年降雨量在260~310 mm、PGA大于0.23 g的区域对滑坡发生起促进作用,表明该区域滑坡可能为高程和坡度主控的降雨型、地震型滑坡。本研究方法可为滑坡危险性评价提供新的技术参考,为伊犁河流域防灾减灾韧性建设提供理论支撑。

水下穿越管道外腐蚀检测评价系统River-ROV的应用性研究

长输油气管道的江河水下穿越管道由于施工和和环境等问题使得管道面临严峻的腐蚀损伤风险,由于缺乏对应的技术手段,绝大多数穿越管段未能开展相关的检测。在全国长输油气管道大力度提升管道安全管理的背景下,迫切地需要先进的检测手段,本文采用江河水下River-ROV检测技术进行应用性研究和试验,选取两处大开挖穿越管段的管道为代表,验证了其技术的适用性和可靠性,实现水下穿越管道的外腐蚀状况检测和评价,为水下穿越管道的维护维修项目提供全面准确有效的数据支持,运营安全管理形成操作性强的技术支持。

Physico-chemical indices of breeding sites of Simulium damnosum in the lower Cross River Basin, Nigeria

To determine the factor influencing the abundance development and distribution of Simulium damnosum(S.I) immature stages in the lower Cross River Basin, Nigeria, the physico-chemical characteristics of water at breeding sites were analysed longitudinally over a 12 month period. Analysis of the water samples showed that water current correlated positively and significantly(p<0.05), with dissolved oxygen(r = 0.95 vs 0.10); conductivity(r = 0.95 vs 0.81); hydrogen ion concentration(r = 0.03 vs 0.46); and biochemical oxygen demand(r = 0.80 vs 0.64); from Agbokim Waterfalls and Afi River respectively. The result indicates that these parameters and low ionic concentration are the most essential requirement for the development of S. damnosum pre-imaginal stages. Amplitudes of annual variability as measured by co-efficient of variation varied between the parameters. From the trends in hydrological variables it was deduced that the integrated impact of precipitation, input of surface runoff and municipal effluents played an overriding role in determining the absolute levels and temporal pattern in the water quality attributes. Of the 3578 pre-imaginal stages of S. damnosum collected, 52.52% and 47.4% were collected from Agbokim Waterfall and Afi River respectively. There was a significant difference(p<0.05) in the number of pre-imaginal stages collected from both sites. The highest number of pre_imaginal stages of S. damnosum collected were at the peak of rain(July—September) indicating that S. damnosum in the River Basin is a wet season breeder. The need for long term laboratory colonization of blackfly immature stages becomes imperative especially how these parameters could be exploited in control programme through the testing of larvicides without adverse ecological damage to the aquatic habitat.

Evaluation of the Anti-Poaching Programme of the Cross River National Park Okwango Division, Nigeria 2002 to 2013

Poaching of wildlife has continued to be the major problem confronting national parks managers in Nigeria in spite of effort being made to curb the ugly trend. This paper examined the anti-poaching programme of the Cross River National Park Okwango Division Nigeria from 2002 to 2013, with a view to making recommendations for the improvement of the programme. Focused group discussions, personal interviews, review of official records and structured questionnaires were used to collect data. Analysis of variance using randomized complete block design and student’s t-test were used to analyse data. Result showed that 1 - 5 arrests of poachers per month per patrol station was significantly (P 0.05) in the number of poachers arrested and fined between 2002 to 2006 and 2007 to 2011. The low performance of the anti-poaching programme was attributed to poorly equipped rangers’ posts as well as well the absence of alternative livelihood options in the enclave and surrounding communities. It was recommended that more rangers should be employed, and the rangers should be adequately kitted, well equipped patrol stations be constructed and the enclave and surrounding communities be involved in the management of the National Park in addition to providing them with alternative livelihood options.

Cross River Watershed Hydrologic Adjustment： Pre- and Post-June 2012 Mega-storm

The Cross River watershed was disturbed by historic logging activity during the past century, but under the management of the USDA （United States Department of Agriculture） Forest Service, the area has mostly recovered from ecological disturbance. Today a new threat is being imposed by climate change; changes affect not only the temperature but also more extreme wind and rain In 2012, a mega-storm event passed through the north shore region of Lake Superior overwhelming many watersheds with excessive rain and runoff. As part of a Cross River study for the Forest Service, pre- and post-event hydrologic adjustment of the Cross River watershed were captured. Samples were collected for δD and δ18O during April, July, and September to estimate HRT （hydraulic residence time） using the stable isotopes of hydrogen and oxygen, The results showed that water collected throughout the watershed shifted toward the signature of the mega-event precipitation signature, then slowly diffused with new precipitation and fractionation processes that resumed into the summer and fall.

On the National Symptoms of Boar Crossing the River:One Hundred Years of Solitude in a Malaysian Chinese Village

After the famous“Rainforest Trilogy”such as Monkey Cup and Elephants,Zhang Guixing,a Malaysian Chinese writer in Taiwan,recently published another Nanyang story Boar Crossing the River,in the background of anti-Japanese War,focusing on the massacres and resistance of the Chinese in Krokop,a Malaysian Chinese village in Borneo from 1941 to 1945 according to a list of“Committee for the Relief of Refugees of the Motherland”.In this novel,Zhang Guixing changes the accustomed narrative mode of individual family history,expands the description to the group images of the Chinese in Krokop,highlights their patriotic sacrifice,and saves the reality of the slaughter of the compatriots by magic means such as the myths and legends of Borneo and masks in children’s imagination.It is also noteworthy that the novel talks about the relationship between individual freedom and national identity in depth,and describes the tragic fate of cross-national love in the period of national opposition.These nation-state discourses in Boar Crossing the River are Zhang Guixing’s biggest transitions when missing in the literary world for 17 years,which indicate a landmark progress in his spiritual history.

Re-examination of Hydrochemistry and Groundwater Potentials of Cross River and Imo-Kwa-Ibo Intersecting Tropical Basins of South-South Nigeria

This review attempted a detailed description of geological and hydrogeological configurations of Cross River and Imo-Akwa Ibo basins.It presented a synthesis of hydrochemistry and a description of the hydrogeological configurations of the two basins.Hydrogeologically,most areas under Cross River and Imo-Kwa-Ibo are poor in terms of groundwater potentials.Based on the hydrochemistry,the basins hold water of excellent quality.Groundwater sources fall in soft to moderately hard classes.The entire sources groundwater has a TDS concentration of less than 500 mg/l.Groundwater classification based on electrical conductivity(EC)showed EC levels were less than 500μS/cm.Most of the examined cations and anions are within WHO reference guidelines for drinking water quality.However,no broad analysis of water quality based on water quality indices.Also,studies modeling pollution or the impact of land use changes on groundwater quality are wanting.Thus,further analysis of the hydrochemistry of groundwater aquifers is recommended.

GPS-RTK联合数字测深仪在凤河河道横断面测量中的应用

以台山市新昌水凤河河道横断面测量为例,由于水下地形复杂,传统的河道横断面测量方法效率低、精度差,已无法满足现代水利建设的需要。为了能够提高河道横断面的测量精度和效率,减少误差,采用GPS RTK技术联合测深仪进行河道横断面测量,可以快速、准确地获取凤河河道横断面的位置坐标、水深、高程等数据。通过两种技术的联合应用,实现对新昌水(凤河)河道横断面的精确测量,为新昌水(凤河)治理工程的设计和建设提供准确的数据支持。

基于“情景-任务-能力”的长三角传染病区域协同处置能力提升

提升传染病区域协同处置能力是深化长三角卫生健康协同发展的重要抓手。卫生应急演练是检验卫生应急体系建设的重要手段。本研究将“情景-任务-能力”的方法引入长三角传染病区域协同处置领域,以构建杭州亚运会测试赛期间发现登革热等输入传染病病例后区域协查和联动处置情景为例,分析应急处置5个阶段的任务、主要责任单位及任务要点,并以“区域联合风险评估和风险管理”为例,从预案方案、组织领导、人员、设备与系统、物资、培训、演练等7个方面着手,详细分析能力评估的内容。同时,采用“任务分类”的思想,针对属于第二类任务的区域联动涉及的协查、评估和培训等任务,以“区域联合风险评估和风险管理”任务为例,提出制定区域联合风险评估和风险管理协议或方案,成立区域卫生应急专家智库,加强区域公共卫生风险评估交流和统一培训等措施建议。

Habitat fragmentation and the population status of rodents in Abayum forest, Ikom, Cross River State, Nigeria

The threat to wildlife population is attributed to various anthropogenic activities. The main objective of this study was to identify the influence of fragment size on the population density of rodents in the study area. Fourteen (14) out of forty (40) fragments existing in the area were randomly sampled. The parameters used for the study were number, size of fragments and the corresponding population distribution of rodents in the study area. Fifty hunters in the area were also interviewed. The fragments were stratified into first, second and third order fragments on the basis of their sizes and randomly selected for the study. Indirect method of wildlife census was carried out through the observation of droppings, trail or tract, burrows, eating habits and noise. Fragment growth rate was 18 to 40 (87.5%) in 7 years. Anthropogenic perturbations in the form of cultivation of permanent cropland, settlement expansion, bush burning, timber exploitation and new settlements in areas previously thinly settled or not accessible to outsiders have resulted in disjointed ecosystems. The population density of rodents correlated with fragment size was highly significant ((P < 0.05) r = 0.9). It was then concluded that fragment size greatly influenced the population and diversity of rodent species. It was recommended that the remaining large fragments in the study area should be protected by law from further fragmentation.

Ecosystems Services of the Tropical Rain Forest Environment: Lessons from the Cross River National Park, Nigeria

This paper essayed to examine ecosystem functions with a case study of the tropical rainforest environment of the Cross River National Park, Nigeria. The paper highlighted the important functions of the ecosystems to include Purification of air and water mitigation of floods and droughts, detoxification and decomposition of wastes, generation and renewal of soil and natural vegetation, pollination of crops and natural vegetation, control of the vast majority of potential agricultural pests, dispersal of seeds and translocation of nutrients, maintenance of biodiversity, protection from the sun’s harmful ultraviolet rays among others. Problems associated with the rainforest ecosystems among which are logging, traditional methods of farming, poaching, excessive noise and encroachment were identified. The paper concluded by highlighting the way forward among others that, awareness creation should be stepped-up in Support Zone Communities;indigenes should be educated periodically on the benefits of the ecosystem services to not just humans but the forest resources and biodiversity themselves.

Species Composition and Gear Characteristics of the Macrobrachium Fishery of the Cross River Estuary,Nigeria

The Cross River Estuary,Nigeria,is an important shrimping area for artisanal fishermen of the coastal communities.The multi-species Macrobrachium fishery is exploited with three main gears,namely beach seine,push net and trap.Studies on species composition of this fishery recorded thirteen shrimp species,one swimming crab (Callinectes amnicola) and two fish species (Eleotris sp.and Pellonula leonensis).The shrimp species identified included Macrobrachium macrobrachion (83.39% and 55.69% by number and weight,respectively),M.vollenhovenii (9.66% and 37.18%),M.equidens (3.8% and 2.87%),juveniles-sub-adults of Penaeus notialis (1.11% and 1.3%),M.dux,M.felicinum,Palaemonetes africanus,Palaemon maculatus,Palaemon elegans,Desmocaris sp.,Leander sp.,Nematopalaemon hastatus and Alpheus pontederiae.While the selectivity index for trap was 0.25,beach seine and push net had a lower index of 0.063.The results present the first comprehensive and representative report for the Estuary shrimp fishery and will assist in the management of the biodiversity of this ecosystem.

Analysis of Medicine Bow-Laramie River Drainage Divide Using Topographic Map Interpretation Techniques, Southeastern Wyoming, USA

Detailed topographic maps provide much of the information needed to understand how drainage divides like the southeast Wyoming Medicine Bow River-Laramie River drainage divide originated. Topographic map evidence for each Medicine Bow-Laramie River drainage divide segment is here described and analyzed first using a commonly published interpretation (accepted paradigm) in which drainage routes developed on a surface of now mostly absent Oligocene and Miocene sediments that previous investigators have hypothesized to have once filled the Laramie Basin and to have also buried (or partially buried) the surrounding Laramie and Medicine Bow Mountains. Second, the same map evidence is analyzed using a recently proposed interpretation (new paradigm) in which massive and prolonged floods flowed across Wyoming as the Laramie and Medicine Bow Mountains began to be uplifted and as the southeast-oriented North Platte River valley eroded headward along the rising Laramie Mountains northeast flank. Low points along the drainage divide (referred to as divide crossings) are interpreted to be places where water once flowed across the drainage divide with the drainage divide being formed when capture events diverted the water in other directions. Valleys leading away from divide crossings are used to determine the nature of observed capture events, many of which are difficult or impossible to explain from the accepted paradigm perspective, but which are consistent with the mountain uplift, headward erosion of deeper valleys, and/or draining of floodwaters trapped in the Laramie Basin as the new paradigm predicts. However, the new paradigm requires a North American continental ice sheet heavy enough to raise entire regions and mountain ranges as massive and prolonged meltwater floods flowed across them, something the accepted paradigm does not recognize.

水下穿越管道检测新技术——水下机器人River-ROV外腐蚀检测

长输油气管道的水下穿越管道由于安全、施工及环境等问题,急需进行腐蚀与防护状况的检测。在这种背景下,为满足管道管理运行单位的需求,融合了多种先进技术的江河水下管道外腐蚀检测系统River-ROV被开发出来,它能够通过实施电信号采集及电磁法探测等手段人对水下穿越管道进行检测,同时获取管道的腐蚀与防护状况。通过实际工程检测,也验证了该技术在国内的水下穿越管道检测中的实用性。