水位波动下非饱和心墙土坝体的渗流和稳定性     

陈曦  张训维  陈佳林  金锋  于玉贞 《岩土力学》2015,36(Z1):609-613

基于Richards方程,对坝体的饱和-非饱和渗流场进行了模拟,再根据饱和-非饱和渗流场和非饱和土抗剪强度公式,对坝体的稳定性进行了分析。结果表明,水位骤降过程中坝体的安全系数通常呈现先缓慢增加后迅速减小的变化过程,分析坝体失稳时塑性区和位移场发现,水位下降的初期,坝体左侧坡体的安全系数要低于坝体右侧坡体,但水位下降到一定程度,右侧坡体的安全系数迅速减小,并先于左侧坡体失稳;采用有限元强度折减法用于多坡面边坡稳定分析时,只能获得最小安全系数的包络线;心墙具有隔水防渗的作用,对水位变化渗流具有阻尼作用。  相似文献   

汶川大地震中德阳市水库土坝的震害特征     

冒进  ;陈国兴  ;王志华  ;司明婧 《地震学刊》2014,(6):784-791

汶川特大地震给四川省德阳市水库土坝造成了不同程度的震损。依据德阳市境内66座高危以上险情水库土坝震害考察资料和现场震害调查结果,对震损水库土坝进行了分类统计,研究其震害特征及震损原因,结果表明：小型水库均质土坝在此次地震中震损数量最多、险情严重,且震害类型丰富;典型震害包括裂缝、滑坡、沉陷、渗漏以及泄水建筑物与其它附属设施损坏。以德阳市3座典型震损水库土坝为例,分析了水库土坝的基本情况、震前运行状况及震损情况,进而提出了有效的震后抢险措施。  相似文献   

考虑流固耦合效应的辽宁葠窝水库溢流坝段抗震性能分析   总被引：1，自引：0，他引：1  

于程一  唐亮  凌贤长  宋曰良  王敏 《地震学刊》2014,(1):20-27

针对辽宁葠窝水库混凝土重力坝抗震问题,采用耦合的拉格朗日-欧拉有限元分析技术,建立了可考虑库水-坝体-基岩动力耦合效应的典型溢流坝段抗震分析数值模型。模型中,采用等效一致粘弹性边界模拟基岩的人工截断边界;采用混凝土弥散裂缝本构模型模拟混凝土的动力特性。根据烈度与地震动之间的关系,确定了水库坝体抗震设计的输入加速度峰值。据此,分析了在不同季节水位变化条件下坝体地震反应的基本特性。研究表明：完好的辽宁葠窝水库混凝土重力坝溢流坝段能满足8度的抗震设防烈度要求。地震下溢流坝段峰值位移出现在胖坝和瘦坝的坝顶迎水面位置处,胖坝的动位移较瘦坝动位移大。胖坝在闸墩与溢流堰交接处出现了拉应力最大值。有库水条件下,瘦坝峰值拉应力出现在坝趾处,无库水条件下,瘦坝最大拉应力出现在溢流堰与闸墩交接处。  相似文献   

Analysis of seismic disaster failure mechanism and dam-break simulation of high arch dam     

Jingkui Zhang  Liaojun Zhang 《地震工程与工程振动(英文版)》2014,13(2):327-335

Based on a Chinese national high arch dam located in a meizoseismal region, a nonlinear numerical analysis model of the damage and failure process of a dam-foundation system is established by employing a 3-D deformable distinct element code(3DEC) and its re-development functions. The proposed analysis model considers the dam-foundation-reservoir coupling effect, infl uence of nonlinear contact in the opening and closing of the dam seam surface and abutment rock joints during strong earthquakes, and radiation damping of far fi eld energy dissipation according to the actual workability state of an arch dam. A safety assessment method and safety evaluation criteria is developed to better understand the arch dam system disaster process from local damage to ultimate failure. The dynamic characteristics, disaster mechanism, limit bearing capacity and the entire failure process of a high arch dam under a strong earthquake are then analyzed. Further, the seismic safety of the arch dam is evaluated according to the proposed evaluation criteria and safety assessment method. As a result, some useful conclusions are obtained for some aspects of the disaster mechanism and failure process of an arch dam. The analysis method and conclusions may be useful in engineering practice.  相似文献   

新型悬挑式泥石流网格格栅坝及其应用     

刘建兵  ;侯利峰 《中国地质灾害与防治学报》2014,25(3):26-31

悬挑式网格格栅坝是从工程实践中在传统网格格栅坝的基础上演变而来的一种新型的格栅坝体类型,该种坝型继承了网格格栅坝的各种优点,并且通过悬挑格栅的独特设计,更具突出在非排导泥石流时对河流沟谷地的常态水流进行非拦截性排流,使河流沟谷内常态水流更为通畅,不会干扰河流沟谷的正常流通,是传统网格格栅坝的优化坝型,均适用刚性和柔性网格材料筑坝。目前国内还没有该种坝型的研究成果和相关技术资料,文章通过阐述其在以水流为主的稀性泥石流和挟带大量推移质的高含沙洪水的泥石流治理工程中的应用研究,得出该坝型的优缺点和相关技术成果,作为进一步工程实践和研究提供基础技术依据,从而进行悬挑式网格格栅坝在泥石流防治工作中的应用和推广。  相似文献   

鲤鱼潭大坝在集集地震中的变形分析     

刘振平  迟世春 《岩土力学》2014,35(1):248-254

鲤鱼潭黏土心墙堆石坝在台湾“9•21”集集地震中有一定的变形损伤。为了研究大坝的地震破坏机制,分析了大坝的永久位移分布规律,同时采用有限元数据平滑方法,对大坝位移监测数据进行处理,得到了大坝的永久应变场。结果表明,大坝在强震作用下永久变形指向坝内,坝体体积整体收缩;由于反滤料孔隙水压力上升,有效应力降低,在上游坝体在反滤层附近出现拉应变;在两岸坝肩与基岩交界部位存在拉应变,易造成拉伸裂缝。  相似文献   

The impact of beaver dams on the morphology of a river in the eastern United States with implications for river restoration          下载免费PDF全文

Joanna Crowe Curran  Kristen M. Cannatelli 《地球表面变化过程与地形》2014,39(9):1236-1244

Restoration projects in the United States typically have among the stated goals those of increasing channel stability and sediment storage within the reach. Increased interest in ecologically based restoration techniques has led to the consideration of introducing beavers to degraded channels with the hope that the construction of beaver dams will aggrade the channel. Most research on beaver dam modification to channels has focused on the long‐term effects of beavers on the landscape with data primarily from rivers in the western United States. This study illustrated that a role exists for beavers in the restoration of fine‐grained, low gradient channels. A channel on the Atlantic Coastal Plain was analyzed before, during, and after beaver dams were constructed to evaluate the lasting impact of the beaver on channel morphology. The channel was actively evolving in a former reservoir area upstream of a dam break. Colonization by the beaver focused the flow into the channel, allowed for deposition along the channel banks, and reduced the channel width such that when the beaver dams were destroyed in a flood, there was no channel migration and net sediment storage in the reach had increased. However, the majority of the deposition occurred at the channel banks, narrowing the channel width, while the channel incised between sequential beaver dams. The study indicated that where channels are unstable laterally and bank erosion is a concern, the introduction of beavers can be a useful restoration tool. However, because of the likelihood of increased channel bed erosion in a reach with multiple beaver dams, they may not be the best solution where aggradation of an incised channel bed is the desired result. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

延怀盆地现代构造应力场模拟与官厅水库大坝地震安全性初探   总被引：5，自引：0，他引：5       下载免费PDF全文

文彦君  郑文涛 《地震地质》2004,26(1):141-152

官厅水库所在的延怀盆地有多条活动断层分布 ,新构造运动强烈。官厅水库大坝安全与否事关首都安全。为此 ,文中采用有限元方法结合断层位移资料 ,模拟了延怀盆地的现代构造应力场 ;参照模拟的结果 ,结合前人的研究成果 ,对设定地震的烈度进行了拟合 ,讨论了设定地震对大坝的影响。对官厅水库大坝的地震安全性进行了评价。结果表明 :1)延怀盆地最大主压应力方向为N80°～ 85°E ;2 )可能的发震断层为方家冲 -营门矿段断层 ;3)考虑大坝坝址的工程地质条件、发震断层与大坝的空间位置关系、历史大地震对大坝的影响等因素 ,则大坝的地震危险性将有所提高  相似文献   

EPSW电子测绘系统在三峡工程明渠截流中的应用   总被引：1，自引：1，他引：0  

柳长征 《地理空间信息》2004,2(2):36-38

在三峡工程明渠截流进程中,截流戗堤左右头平面位置是一个动态轨迹。采用Trimble激光全站仪配合清华山维EPSW98电子测绘系统实时监测戗堤口门水面宽,方便、快捷、可靠且测量精度高,并解决了采用人工施测可能造成的安全问题。还介绍了采用EPSW电子测绘系统在水下地形测量数据自动成图中的应用,大大提高了出图效率,减少了出错环节。  相似文献   

考虑横缝影响的拱坝动力分析   总被引：6，自引：0，他引：6  

林皋  胡志强  陈健云 《地震工程与工程振动》2004,24(6):45-52,72

本文在求解三维弹性静力摩擦接触问题的有效方法-非光滑方程组方法的基础上,通过能够近似满足动量、动能守恒条件的速度、加速度的修正方法,将该方法推广到动力接触问题的求解中,以考虑地震时拱坝中横缝的开合、错动对坝体动力响应的影响。同时文中采用由多次透射公式表示的人工边界条件来考虑坝-基动力相互作用的影响。数值算例中分析了横缝的数目和布置位置对拱坝动力响应的影响。  相似文献