库水位等速上升中均质库岸塌岸现象及浸润线试验研究

为了研究库水位等速上升过程中均质水库岸坡的塌岸现象及岸坡内浸润线的变化特点,以取自三峡库区的含黏粒粉砂为主要试验土料,设计了3个不同结构的均质岸坡模型,对每个模型进行了4种不同速率的水位上升试验。试验结果表明,库水位上升速率越大,均质水库岸坡的塌岸现象越易发生;在库水位上升过程中,库水和地下水与岸坡土体的相互作用同时存在对岸坡稳定有利和不利的因素,其中地下水浸没区的毛细力消失是引起塌岸的关键因素;试验测得浸润线与理论计算结果的比较分析表明,浸润线的理论计算方法可能过高地估计浸润线的位置。     

陆浑水库坝基渗透稳定性研究

本文在厘定坝基渗透模型和边界条件的基础上,运用数值模拟的方法,对坝基渗流场水力坡降和坝基渗透稳定性进行研究。研究表明,目前大坝的运行状况正常;水库在缓慢蓄水过程中,截水槽、坝后逸出带和断层破碎带的水力坡降远小于允许坡降,不会危及坝基的稳定性。这为水库投入正常水位(319 5m、327 5m、331 8m)运行提供了理论依据。     

缅甸某水电站坝址承压水化学特征及对工程影响分析

承压水是在水电开发过程中常见问题,在承压水高渗透压力作用下,坝基可能产生化学溶滤和机械管涌,造成库水渗漏。重点对缅甸某水电站低温、高矿化度的基岩裂隙承压水分布、水文地球化学等特征进行分析,提出坝址承压水对工程建设影响主要是大坝建成后,水库水位抬高,应力增加,最大承压水头高出河水位23 m,在渗透压力不断作用下,导致化学溶滤和机械管涌,造成水库渗漏,发生基地付托,导致坝基不均匀沉降,应采取适当排水方法对承压水进行处理,通过灌浆对承压水进行封堵等处理措施,防止水库大面积渗漏,为水电站顺利建设提供技术支撑。     

浅析坝下游黄土-砂卵砾石二元结构岸坡失稳机理

新疆伊犁河流域水库大坝下游岸坡常具黄土-砂卵砾石二元结构地层组合,成为水库渗漏潜在隐伏结构.随着伊犁河流域水利水电工程建设开发力度的加大,该地层组合中显现出的渗漏和岸坡稳定性等工程地质问题也逐渐增多,有必要对该方面进行研究和总结.本文以斯木塔斯水电站、巴喀勒克水库为例,对其坝下游岸坡稳定性开展运行期的地质调查,并结合研...     

福建安砂水电站大坝左岸边坡稳定性分析

安砂水电站建成以来，大坝左岸边坡仍有掉块现象。文章通过分析原有资料和实地调查，对存在问题的左岸和厂房后边坡，进行地质构造、岩石结构情况研究，综合考虑其构造地貌、坡度、地下水、岩石中缓倾角断层、节理或地层层面相互作用，引入同时考虑地震力E和重力W共同作用下，岩石结构面组合稳定性图解分析等方法，对大坝左岸近坝岸坡进行地震边坡稳定性评价。分析结果认为：大坝左岸岸坡高陡岸坡的上段、中段剖面中的一些结构面及组合面存在下滑及接近下滑的危险。     

周边采煤活动对岳城水库库区大坝和坝基的渗流影响研究

岳城水库属于国家重点水库,同时库区及周边地下是典型的富煤区域,蕴藏着大量优质煤炭资源。为研究周边采煤活动对岳城水库库区大坝和坝基的渗流影响,文中以坝体作为研究对象,在上游建立一条安全限,通过控制大坝和坝基的有效保护边界来控制开采对浅地表造成的影响深度和影响远度。通过数值模拟,结果表明在上游水位159.1 m和下游水位105.0 m的作用下,只要开采影响范围距离岳城水库大坝2 000 m,开采就不会对大坝和坝基的渗透性变化产生影响;同时,也不会对坝肩的渗透性产生影响。     

九甸峡水库区地质构造特征与库岸稳定性关系

九甸峡水库区滑坡、滑塌、卸荷变形现象分布很普遍。它的发生是地形地貌、岩性与地质构造、水文地质条件及水文、气象等综合作用的结果 ,尤其与地质构造之间有着密切的关系。以地质构造为主要表征的岸坡地质结构是库岸稳定与否的决定因素 ,暴雨、洪水、地下水及蓄水后的库水浮托力、河水位的骤然消涨等是库岸失稳的诱发因素 ,查清库区地质构造的发育分布特征 ,对于准确评价库岸稳定 ,合理估价水库效益有重要的实际意义。     

浅谈水库边坡稳定性

随着水库蓄水后水位的变化,其库岸的水文地质环境必然发生改变,水库边坡自然平衡发生破坏,地下水与岩土体之间发生复杂的物理化学作用,从而使库岸边坡有别于其他非水库边坡.从水库边坡的特点出发,对水库边坡的破坏形式、滑坡塌岸的形成机理和预测方法进行了简要的阐述.     

三峡水库塌岸影响因素的物理模拟研究

水库蓄水后库岸边坡失稳破坏是一个复杂的过程,其塌岸模式及塌岸规模往往受多种因素的影响。文章在对三峡库区典型塌岸段地质条件调查研究的基础上,利用物理模拟手段,系统地研究了水库岸坡土体材料、岸坡坡角、库水位、降雨强度对岸坡流失量的影响。研究结果表明,三峡水库存在冲磨蚀型及滑移型两种主要的塌岸模式。岸坡土体流失量与岸坡坡角、岸坡物质组成、降雨强度等成正相关关系,且各因素对流失量的影响程度不同,岸坡物质组成及岸坡坡角是主要影响因素。各因素对岸坡流失量的影响还存在临界值,超过此临界值时,该因素对塌岸的影响将变得非常明显。由于物理模拟经历的时间较短,试验所得规律仅适用于水库蓄水后一定时期内塌岸的研究。     

绕坝渗流地下水位的时空分布模型研究

许多大坝的失事是由于高地下水位引起坝肩失稳所致。绕坝渗流是影响坝肩高地下水位的主要因素。为此通常将大坝基础防渗帷幕延伸到坝肩岸坡内一定距离,以减小绕坝渗流影响。而防渗帷幕运行性态随时间变化,为了评价坝肩防渗帷幕和地下水位的运行性态,首先分析了地下水位观测资料和水位、降水、温度、时效等时空影响因素及其表达式,随后基于岸坡地下水位观测资料,利用最小二乘法建立了大坝岸坡地下水位的时空分布模型。通过比较模型剩余标准差和测点的剩余标准差,可以确定坝肩地下水位的异常测点,分析岸坡防渗薄弱部位,掌握坝肩岸坡渗流场时空分布规律,监控绕坝渗流的性态。     

Event tree analysis for room and pillar mining affecting permeability beneath surface bodies of water

Underground mining and oil and gas drilling have increasingly encroached on public water reservoirs and dams because of the overwhelming demand for energy combined with the growing population. Cases of surface water reservoirs and mine waste impoundments being drained, as well as dam infrastructure being damaged, due to accidents have been documented. The methods used by regulators and industry for determining mining or drilling offset distances are based primarily on three approaches and studies performed in the early 1970s. The former US Bureau of Mines Information Curricular 8741 was the culmination of these studies and continues in use for determining offset distances for underground mining with respect to dams and reservoirs. This study used analytical and empirical methods based on subsidence effects to recommend offset distance extents specifically for miners' safety. A major limitation of the previous studies is that they did not detail the affect mining operations have on changes in groundwater flow due to soil and overburden permeability changes triggered by vertical ground surface subsidence that could lead to increased risk hazards for a reservoir or dam infrastructure. This paper presents a review of international literature related to mining under surface bodies of water (reservoirs) and presents a risk-based event tree analysis quantifying the probability of changes in subsurface permeability due to overburden strain changes. A sensitivity analysis quantifying probabilities of increased subsurface permeability in terms of offset distances from a reservoir is presented and discussed. Empirical results indicate the probability of permeability changes at a 350 ft (107 m) deep mine located at offsets of: 200, 400, and 600 ft (61, 122, and 183 m) were at 41, 0.66, and 0.0067%, respectively.     

地下水资源开发模式和降落漏斗问题

地下水资源不仅有巨大的资源意义而且有巨大的环境意义，理想的水资源开发模式的建立就应当同时兼顾这两个方面。过量开采地下水，不注意含水层的回灌．自然会形成降落漏斗。结合辽宁地区情况，总结出三种理想开发模式。1)首山水源模式：引水(通过河道输送的水库水)或开采地下水一灌溉稻田(第一次利用)一回渗地下补给地下水抽取地下水供工业和城市利用(第二次利用)；2)龙河水源模式：在河谷地段的中上游(山区或丘陵)植树造林建设“绿色水库”．涵养水源；在中游合适地段建设“地表水库”，拦蓄河水；在下游或河口地段通过修建地下帷幕坝建设“地下水库”，拦蓄地下水；使所谓的“三水”甚至“四水”资源得到比较充分的补给和利用。3)铁西水源模式：这种模式的成功之处是孔隙水(杨柳河冲洪积扇)和隐伏岩溶水的联合调度和联合开发，由于两种含水层的迭置且有一定的水力联系，形成了所谓的含水层耦合结构。     

Estimation of environmental impacts on the water quality of the Tahtalıdam watershed in İzmir, Turkey

Water pollution is a widespread problem in different areas of the world. Some of these problems originated from point contamination sources and widespread contaminant outlet sources which are observed in every country. The major elements and chemical loads of surface water have been dominated by constituents derived directly or indirectly from human activities and/or industrial practices that have increased additives in the last several decades. The point sources of contamination may result from the direct wastewater discharges to the dam sites, which are considered to be the most commonly encountered water pollution problems. One of these problems is the eutrophication process which usually occurs in the static water mass of lakes and other surface water reservoirs. This process may be caused by the continuous increase of nitrogen and phosphorus contents and decrease of O₂ level in water causing an anaerobic condition which may stimulate algae-growth flow in these water bodies, consequently reducing the quality of water. Of course, there are many research methods for determining the various kinds of water pollution. In this research, the hydrochemical parameters were evaluated to estimate the types of pollution sources, the level of pollution, and its environmental impacts on the Tahtal dam reservoir.     

新疆某水库大坝变形监测方法研究

结合新疆克拉玛依三座坝线均长达5km左右的平原水库,介绍了由于地质环境影响大坝沉降和位移而建立变形监测控制网、观测方法、数据分析处理以及工作中的一些方法和经验.     

长江流域水沙周期特征及可能影响原因

运用小波变换的方法研究了长江流域干流站(屏山站、宜昌站、大通站与汉口站)以及位于支流嘉陵江流域的北碚站近40年来月均流量与输沙率,研究认为:(1)水利工程(本文主要指水库)对下游河道输沙率的影响远远大于对流量的影响;(2)葛洲坝是低水头径流式发电站,对下游流量变化影响不大,虽然在建库初期对输沙率有一定影响,导致下游河床下切,但远未达到使输沙率固有的1年周期受到影响的程度;(3)三峡大坝的建设已经对下游输沙率产生严重影响,使其固有的1年周期消失,但三峡大坝下游河道输沙率对这种影响的响应与距三峡大坝的距离成反比,即愈往下游,输沙率受三峡大坝的影响愈小;(4)输沙率变化对水利工程影响的敏感程度受流域尺度的影响,流域尺度越大,其反应就愈迟钝,反之亦然。     

基于贝叶斯网络的梯级水库连溃风险

为研究梯级水库漫坝连溃的风险,并探索贝叶斯网络在水库连溃风险分析中的可行性,通过构建洪水作用下双库连溃的贝叶斯网络模型,并选取四川省大渡河上两相邻梯级水库进行分析,以推求水库漫（溃）坝概率及评估连溃风险。分析过程表明贝叶斯网络方法能直观、简便地分析多风险源共同作用下的水库群连溃风险问题。结果表明,两水库天然洪水漫坝条件概率的数量级均为10-6,洪水引发单库漫坝风险较小;正常蓄水位以上,上游水库溃坝洪水致下游水库漫坝条件概率超0.8,即上游水库溃坝导致水库连溃的风险很大。     

Acidification and Trace Metals of Lakes in Taiwan

One hundred and eighty lakes, ponds and reservoirs in Taiwan, and the offshore islands have been investigated since 1985. Effects such as warming/cooling, mixing, photosynthesis and respiration on pH have been identified. These effects were found to be less profound than those resulting from the geology. Since there is little rain or lake water pH data available prior to 1970, it was necessary to use proxy data in order to ascertain the history of lake acidification. In this study, we present data based on diatoms in a sediment core collected from a lake in the remote subalpine region of southern Taiwan. The acidity of this lake water was found to have increased since 1900. We measured the concentrations of 55 chemical species in lake water samples. In addition, concentrations of 26 chemical species were obtained from sediments. Conductivity, alkalinity (HCO₃ ^?), most other major and minor chemical species, as well as the non sea-salt SO₄/Na ratio in lake water clearly decrease with elevation. Distribution of pH is similar, although the trend is less clear. Distribution of trace metals, however, shows a different trend as anthropogenic pollution, diagenetic reduction and lake acidification are at play.     

番禺地区病险水库地质特点及加固对策

广州市番禺区目前尚在发挥效益的水库有15座,其中12座水库存在病害隐患,急需除险加固。基于工程地质勘察与评估工作,查明了辖区病险库的地质特点：坝身质量较差、坝基存在渗漏及渗透破坏问题、软基沉降变形和饱和砂土地震液化问题等,探讨了整险加固的工程措施,如加高加固大坝、防渗处理、抗地震液化加固等。结果为辖区病险水库整治提供技术支持,对国内类似水利工程整险加固有较好的参考价值。     

Quantitative dam break analysis on a reservoir earth dam

Mathematical simulations on dam break or failure using BOSS DAMBRK hydrodynamic flood routing dam break model were carried out to determine the extent of flooding downstream, flood travel times, flood water velocities and impacts on downstream affected residences, properties and environmental sensitive areas due to floodwaters released by failure of the dam structure. Computer simulations for one of the worse case scenarios on dam failure using BOSS DAMBRK software accounted for dam failure, storage effects, floodplains, over bank flow and flood wave attenuation. The simulated results reviewed a maximum flow velocity of 2.40 m/s with a discharge of approximately 242 mз /s occurred at 1.00 km downstream. The maximum discharge increased from 244 m³/s (flow velocity = 1.74 m/s occurred at 8^th. km) to 263 m³/s (flow velocity = 1.37 m/s occurred at 12^th. km); about a 39% drop in flow velocity over a distance of 4.00 km downstream. If the entire dam gives way instantly, some spots stretching from 0.00 km (at dam site) to approximately 3.40 km downstream of the dam may be categorized as “danger zone”, while downstream hazard and economic loss beyond 3.40 km downstream can be classified as “low” or “minimal” zones.     

Pinpointing the key parameters in estimating the bed-load sediment flux in reservoir engineering

When a dam is constructed on a river to store water, sediments transported by the water flow are also stored and reservoir capacity is gradually reduced by sediment accumulation. Prediction of sediment distribution in reservoirs is an important issue for dam designers to determine the reservoir active storage capacity, outlet sill elevation, dam stability, recreational facilities, and backwater conditions. The main objective of this study is to develop the most reliable parameters of sedimentation that are directly or indirectly influencing in the equations and measured dataset. For validation of the proposed parameters, data of 40 reservoir sets gathered from different reliable sources, rather than focusing entirely on bed-load equations. Artificial neural network (ANNs) method was used to validate this study. Several graphs and statistical analysis were presented to emphasize the influencing effect of those parameters that were detected by ANNs and are directly controlling the error in the bed-load sediment flux using measured particles datasets.