面板堆石坝的施工探讨

目前,浙江省乃至全国采用面板堆石坝的坝型较为广泛,今介绍面板堆石坝的施工过程,及施工中应注意的几个关键施工环节,以确保大坝的施工质量及进度.     

混凝土防裂技术在堆石坝面板中的应用

在面板混凝土施工配合比设计时,对混凝土的膨胀性进行补偿,加强混凝土施工过程控制,解决了堆石坝混凝土面板由于受几何尺寸和外部环境作用而产生横向收缩裂缝的问题.介绍了天台黄龙水库混凝土面板堆石坝的面板混凝土配合比设计和施工过程控制相结合的混凝土防裂技术的应用,在避免和减少施工后收缩裂缝方面收到很好的效果.     

面板堆石坝混凝土面板设计

根据已建混凝土面板堆石坝的观测资料及计算成果说明面板的受力机理,据此分析面板厚度、分缝和止水、面板混凝土和配筋设计,以及面板的分析计算方法发展面板坝适合江西省省情,应加强对面板坝的研究、推广和应用     

水布垭混凝土面板堆石坝施工方案分析

水布垭工程为目前世界上最高的混凝土面板堆石坝，坝高233m，分六期施工，有7个填料区，坝体分区复杂，料物种类繁多，施工强度高，运输高程大，施工工艺复杂。坝料的挖装、含水量控制、运输卸料、碾压以及结合部处理等施工方案和施工方法的确定，是确保大坝按期完工、安全度汛以及坝体质量的关键。     

堆石坝面板混凝土施工期温度和应力全坝段仿真分析

针对堆石坝面板混凝土易开裂问题及其结构特点,开展了面板混凝土施工期温度和应力变化规律的仿真研究.依托某混凝土面板堆石坝工程,建立了三维仿真计算网格;采用三维不稳定温度场和应力场的有限元仿真计算程序,对堆石坝面板全坝段施工过程的温度和应力进行了动态仿真计算和分析.结果表明,堆石坝面板施工期内部拉应力较大,且最大拉应力出现在最大温降龄期;此外,面板短间歇面施工期拉应力较小,长间歇面在上层混凝土浇筑后拉应力较大.     

三板溪水电站主坝趾板和面板施工质量控制

三板溪水电站主坝为混凝土面板堆石坝,趾板、面板是其关键防渗体,加强质量管理,控制混凝土裂缝是其施工的关键。结合三板溪水电站趾板、面板混凝土的特点,从施工方面讨论解决混凝土防裂的措施,为类似工程的施工提供借鉴。     

双沟水电站砼面板堆石坝坝体填筑技术

双沟水电站面板堆石坝,坝高110m,于2007年9月填筑完成,经过2年监测的各项检测指标稳定、正常.在施工过程中采用了翻模砂浆固坡等新工艺、新方法,缩短了施工工期,降低了工程造价.本文总结双沟面板堆石坝施工的方法、工艺,特别是寒冷地区冬季填筑施工经验,供同行在施工中参考借鉴.     

小粒径风化石料填筑堆石坝地震反应分析

国家规范对混凝土面板堆石坝筑坝材料有较为严格的要求,为了验证库区滑坡体开挖区颗粒级配不良的小粒径微风化石料能否作为大水沟水库混凝土面板堆石坝坝体主堆石区填料,对该种石料进行了现场压实试验.对应于现场试验所能达到的最大密实度,通过室内试验,取得了此类石料在该种状态下的变性模量Es、泊松比v、渗透系数K及三轴快剪力学参数c,ψ.并依据室内外试验参数,采用一维剪切层法,对该坝进行了在7级地震烈度情况下的动力反应分析,求得了该坝的最大动剪应变和剪应力反应分布,坝体内绝对最大动剪应变为4.41×10-3,绝对最大动剪应力为40kPa,远小于坝体本身的强度,验证了该种石料可以作为面板堆石坝的填料,拓宽了混凝土面板堆石坝填筑材料的选择范围.     

象山县隔溪张水库砼面板堆石坝设计

砼面板堆石坝目前在我国发展较快，已取得了一定的设计经验，通过对象山隔溪张水库面板堆石坝坝体设计，基础处理，趾板设计，面板设计，分缝与止水设计，观测设计等方面的叙述，进一步为设计这一坝型提供参考和积极经验。     

响水涧抽水蓄能电站上水库主坝应力变形分析

面板堆石坝的应力变形,尤其是面板的应力变形及周边缝、垂直缝的变形是工程设计施工人员最为关注的部位．以响水涧抽水蓄能电站上水库主坝为例,建立三维有限元模型,计算分析各工况下坝体、面板的的应力应变以及周边缝、垂直缝的变形,为面板坝设计施工提供参考性意见．     

施工度汛的分割多目标风险模型及应用

施工度汛风险量化分析普遍采用风险期望值模型,这将导致高损失低概率与低损失高概率的计算结果可能相同.分割多目标风险法(PMRM)给定分割概率,计算给定概率范围内的条件概率,得到多种风险函数,最后将这些风险函数加入到风险决策模型的目标函数中进行风险决策.在湖北鄂坪面板堆石坝施工度汛中,应用分割多目标风险方法,计算不同措施组合的风险,结果合理,能克服传统风险期望值模型的缺点,能为决策者提供科学依据.     

A generalized plasticity model for the stress-strain and creep behavior of rockfill materials

The generalized plasticity constitutive equations that simulate, in a unified manner, the stress-strain response and the creep behavior of rockfill materials are derived using the concept of elastoplasticity. A single yield surface is assumed to capture the onset of plastic strains with, however, two separate potential functions for the stress-induced plastic strains and the creep strains,respectively. The involved tensors and scalars are then specified directly, following the generalized plasticity method, to substantiate the constitutive equations. The model thus obtained is verified using triaxial compression experiments, true triaxial experiments and triaxial creep experiments. The effectiveness of the model is also demonstrated by a successful application in studying the behavior of a high concrete face rockfill dam(CFRD). It is found that for a high CFRD with a long construction period, neglecting the creep of rockfill materials during construction results in an underestimation of the deformation of the dam.The deformation and stress of the concrete slabs may also be considerably underestimated.     

贴坡型混凝土面板堆石坝应力变形及坝坡稳定分析

利用堆石坝对地形条件适应性强的优势,某混凝土面板堆石坝设计建于条形山脊上,依天然坡面分别贴岩坡填筑堆石料,使原山体成为坝体一部分,形成国内比较罕见的贴坡型混凝土面板堆石坝.假设堆石料服从Duncan-Chang本构模型,采用平面非线性有限元法,预测了坝体在竣工期和蓄水期应力变形;并根据极限平衡理论和考虑堆石料的非线性强度计算了坝体稳定安全系数.全部计算结果表明:贴坡型混凝土面板堆石坝的坝体变形规律与常规混凝土面板堆石坝有较大的不同,坝体沉降和水平位移较小,受地形和岩坡开挖形态影响较大,下游岩坡开挖成阶梯形态对降低和控制坝体沉降具有较明显的效果,可减小下游坝体滑动的趋势,对维持和提高坝体竣工和蓄水后的稳定性有利.     

Numerical simulation of the separation between concrete face slabs and cushion layer of Zipingpu dam during the Wenchuan earthquake

The Zipingpu concrete-faced rockfill dam(CFRD)experienced strong ground motion from the 2008 Wenchuan earthquake.Separation between concrete face slabs and the cushion layer was observed after the earthquake.The separation voids under the stage III slabs make up 55%of the total area of the stage III slabs.The observed maximum height of the separation voids was nearly 23 cm at the top of the stage III slabs.Separation voids were also observed locally below the top of stage II slabs near the left abutment,with a maximum height of 7 cm.In this study,a static and dynamic elasto-plastic finite element analysis on Zipingpu CFRD was conducted to capture the separation during the Wenchuan earthquake.The rockfill materials were described using a state-dependent elasto-plastic model that considered particle breakage.The model parameters of rockfill materials were obtained from feedback analysis.The numerical results were largely consistent with the field measurements during construction and after the Wenchuan earthquake.A three-dimensional state-dependent elasto-plastic model that can trace the separation and re-contact of a soil-structure interface was employed to investigate the interaction between concrete face slabs and a cushion layer.The analysis showed the distribution of separation voids observed in the Zipingpu CFRD has a close relationship to the water level and slab dislocations at the time of the earthquake.The phenomenon of the separation from the Wenchuan earthquake was successfully captured by the proposed numerical procedure.     

CFRD应力应变分析方法评述

根据混凝土面板堆石坝的应力应变分析资料,对ＣＦＲＤ的应力应变分析方法进行了评述,并提出今后这方面的研究方向。     

水布垭面板堆石坝安全监测分析

水布垭混凝土面板堆石坝最大坝高233 m,坝体原型安全仪器监测数据是反映工程实体质量在施工期及运行期的工作状态的最直接的参数.根据目前已有的监测资料成果分析,相应的监测设施布置合理,监测数据真实可靠,为分析判断工程运行工况和实体质量提供了客观依据.     

输入地震动对面板堆石坝坝体加速度放大系数的影响

采用等效粘弹性模型对某面板堆石坝进行了三维动力有限元分析,分别计算了坝体在不同地震设计烈度(峰值加速度为0.1g~0.4g)下面板堆石坝的地震动力反应。结果表明:坝体的峰值加速度随着输入地震动的增大而近似线性增大;但是峰值加速度的放大倍数随着输入地震动的增大而非线性减小。地震峰值加速度变化规律对面板堆石坝的抗震设防具有一定的借鉴意义。     

Seismic performance assessment of high CFRDs based on fragility analysis

Due to a large number of high concrete face rockfill dams(CFRDs) being constructed, the seismic safety is crucially important and seismic performance assessment must be performed for such dams. Fragility analysis is a method of great vitality for seismic performance assessment; it can intuitively forecast the structural effects of different ground motion intensities and provide an effective path for structure safety assessment. However, this method is rarely applied in the field of high earth dam risk analysis.This paper introduces fragility analysis into the field of high CFRD safety assessment and establishes seismic performance assessment methods. PGA, Sa(T1, 5%), PGV and PGD are exploited as the earthquake intensity measure(IMs). Relative settlement ratio of dam crest, cumulative sliding displacement of dam slope stability and a new face-slab destroying index(based on DCR and COD) are regarded as the dam damage measures(DMs). The dividing standards of failure grades of high CFRDs are suggested based on each DM. Fragility function is estimated according to incremental dynamic analysis(IDA) and multiple stripes analysis(MSA) methods respectively from a large number of finite element calculations of a certain CFRD, and seismic fragility curves are determined for each DM. Finally, this study analyzes the failure probabilities of the dam under different earthquake intensities and can provide references and bases for the seismic performance design and safety risk assessment of high CFRDs.