Major Technologies for Safe Construction of High Earth-Rockfill Dams

The earth-rockfill dam is one of the primary dam types in the selection of high dams to be constructed in Western China, since it is characterized by favorable adaptability of the dam foundation; full utilization of local earth, rock, and building-excavated materials; low construction cost; and low cement consumption. Many major technical issues regarding earth-rockfill dams with a height of over 250 m were studied and solved successfully in the construction of the 261.5 m Nuozhadu earth core rockfill dam. This paper describes research achievements and basic conclusions; systematically summarizes the accumulated experiences from the construction of the Nuozhadu Dam and other high earth-rockfill dams; and discusses major technical issues, such as deformation control, seepage control, dam slope stability, safety and control of flood discharging, safety and quality control of dam construction, safety assessments, early warning, and other key technical difficulties. This study also provides a reference and technological support for the future construction of 300 m high earth-rockfill dams.

STUDY ON COUPLING MODEL OF (SEEPAGE-FIELD) AND STRESS-FIELD FOR ROLLED CONTROL CONCRETE DAM

Based on the construction interfaces in rolled control concrete dam(RCCD), the methods were proposed to calculate the influence thickness of construction interfaces and the corresponding physical mechanics parameters. The principle on establishing the coupling model of seepage_field and stress_field for RCCD was presented. A 3_D Finite Element Method(FEM) program was developed. Study shows that such parameters as the thickness of construction interfaces,the elastic ratio and the (Poisson's) ratio obtained by tests and theoretical analysis are more reasonable, the coupling model of seepage_field and stress_field for RCCD may indicate the coupling effect between the two fields scientifically, and the developed 3_D FEM program can reflect the effect of the construction interfaces more adequately. According to the study, many scientific opinions are given both to analyze the influence of the construction interfaces to the (dam's) characteristic, and to reveal the interaction between the stress_field and the seepage_field.

ANALYSIS MODEL ON GRADUAL CHANGE PRINCIPLE OF EFFECT ZONES OF LAYER FACE FOR ROLLED CONTROL CONCRETE DAM

The effect zones of layer face for RCC （rolled control concrete） dam have gradual change characteristics. Based on the analysis thought of complex material, a model was built to analyze above principle of RCC dam by use of series-wound and shunt-wound connection. Some methods were proposed to determine the instantaneous Young＇s modulus, delayed Young＇s modulus and viscosity coefficient of effect zones of layer face. Above models and methods were used to mine the principle of gradual change of key calculation parameters which can response the characteristics of effect zones. The principle of gradual change was described. A model was established to analyze the threedimensional viscoelastic problem of RCC dam. Above programs were developed. The examples show that the proposed models and methods to determine the key calculation parameters of effect zones can reflect the status of RCC dam accurately.

Auto Identification of Rolling Layers in Roller-Compacted Concrete Dam

A scheme for identifying rolling layers in roller-compacted concrete (RCC) dam automatically was presented. First, a conceptual model was developed. Second, by using a computational geometry method, the auto identification of rolling layers and auto matching between rolling compaction machines and rolling layers were realized based on spatial control points. An application to the construction of Guandi RCC dam showed that the auto identification of rolling layers played an important role in ensuring the engineering quality.

Electromagnetic Dam in Twin-Roll Strip Caster

The electromagnetic dam （EMD） in twin-roll strip caster was simulated with FEM. The results show that the direction and magnitude of Lorentz force distributing in the EMD changed in a period. The negative part is about 30% of the positive part, and the acting time of the negative force is about 40% of a period. In order to prevent the liquid steel from leaking efficiently, the distance between two poles should be the same from the top to the bottom of the EMD, otherwise the magnetic induction will be very small at the top and large at the bottom.

Wear analysis of a side dam in twin-roll strip casting

Reducing wear on a side dam can prolong the casting operation life of a twin-roll strip casting process,thus reducing production cost and improving casting stability.To lengthen the service life of the side dam,it is necessary to understand the wear performance of the side dam material.To investigate the wear behavior mechanism of the side dam,in this study,the UMT-2 friction and wear tester was used to determine the relationship between the wear rate of the side-dam material and various parameters.Based on the roughness of the contact area between the side dam and the end of the casting rolls as well as on the amount of deformation of the side dam,which was derived using a thermal-deformation simulation model,the reasons for the uneven wear of the side dam were obtained.

基于CA-RL的堆石坝填筑仓面碾压作业动态路径规划

碾压作业是堆石坝填筑仓面施工的关键工序,科学合理规划碾压路径能够在保障碾压质量的前提下提高碾压效率。在当前路径规划研究基础上进一步考虑碾压机数量变化、压实质量感知等动态要素可以提高路径规划模型面对复杂动态的仓面施工环境的适应性。本文通过建立基于元胞自动机的填筑仓面信息模型、提出条带整体压实质量评价方法,解决压实质量等仓面信息的储存更新的问题;通过建立基于强化学习的碾压作业路径规划模型、构建碾压机状态集和动作集、设计奖励函数和探索利用策略,解决碾压机数量变化的路径分配的问题;耦合上述两种模型,实现堆石坝填筑仓面碾压作业动态路径规划。结合国内某堆石坝工程开展了工程应用,结果表明:本方法可动态考虑碾压机数量变化、压实质量感知等要素,路径规划结果在保障碾压质量的前提下路径长度相较现场施工实际路径平均缩短22.3%,能够有效提升碾压效率。

面板堆石坝含特细砂砂砾石填筑料碾压特性研究

阿尔塔什水利枢纽工程大坝主堆石区填筑料以砂砾石料为主,该地区河滩砂砾石料颗粒级配中的砂为特细砂,其在砂的级配中缺少中粗砂、级配不连续、保水性较差等特殊性级配料的特点导致其在施工过程中势必会影响到碾压的压实效果,给施工过程的质量控制带来很大难度。阐述了施工中通过对含特细砂砂砾石填筑料进行的不同加水量、不同厚度、不同碾压遍数及碾压机械等不同的碾压工艺参数进行试验检测、综合统计分析研究,探索出适合该工程的相关碾压施工参数标准,优化了施工碾压参数,提升了施工现场试验检测控制的时效性,为大坝填筑建设提供了稳定、可靠的施工参数,增强了坝体整体填筑的可靠性,为减小坝体沉降变形、提高大坝抗震安全储备和控制大坝施工质量等提供了有利条件。

数字化大坝智能碾压监控系统在抽水蓄能电站的应用

抽水蓄能电站具有调峰、填谷、调频、调相、储能、事故备用等多种功能,在我国“双碳”目标下,加快发展抽水蓄能电站,是建设现代智能电网新型电力系统的重要支撑。面板堆石坝作为抽水蓄能电站的主要坝型,施工管理难度较大。浙江缙云抽水蓄能电站通过数字化大坝智能碾压监控系统的建设,实现对碾压轨迹、遍数、高程、速度、激振力等参数进行实时监控和分析预警;有效提高现场施工质量管理信息化管理能力。

面板堆石坝填筑材料碾压试验对填筑标准及参数的研究

面板堆石坝具有技术成熟、性能优越、造价低等优点,加上贵州地区出露地层主要以石灰岩为主,且其分布广泛,岩性均一,易于开采,是很好的面板堆石坝的填筑材料,因此面板堆石坝在贵州地区广泛应用。通过对大坝填筑前的碾压试验,探讨总结坝体填筑的质量控制要点及填筑标准参数。

复合土工膜防渗斜墙在碾压土石坝工程中的应用与质量控制

碾压土石坝因其技术简单、取材方便等特点,常作为矿山开采水利工程设施的流行坝型,为避免因有色金属渗漏而导致水源污染和生态破坏的潜在风险,采取有效的防渗措施对水坝的设计与施工至关重要。旨在探讨复合土工膜防渗斜墙解决方案,通过多层次结构的组合,包括长丝无纺土工布、双糙面HDPE膜、钠基膨润土毯等,形成可靠的防渗屏障,锚固于坝脚30 m外的截渗齿槽中,通过与土体的紧密结合,成功构建有效的防渗系统,以期为类似矿山建设水利工程设施的设计与施工提供有益的经验借鉴。

软岩筑坝技术在黄石沟水库的应用

黄石沟水库大坝设计为黏土心墙堆石坝,上下游堆石区均为饱和抗压强度小于30 MPa的软岩筑坝。现场碾压试验确定堆石料碾压参数为虚铺108 cm,26 t振动平碾静碾2遍+振碾10遍。碾压试验实测干密度达到2.07 g/cm^(3)左右,孔隙率达到18%左右,渗透系数达到8.9×10^(-2)cm/s左右,各项指标均达到设计要求。截至目前上游堆石料累计检测15次,平均孔隙率18.36%;下游堆石料累计检测10次,平均孔隙率18.28%。软岩筑坝要做好上坝材料质量检验,及时调整爆破参数,确保上坝材料级配、强度合格。

基于填筑技术的黏土斜心墙坝水库建设研究

基于填筑技术的黏土斜心墙坝水库建设,探讨不同铺土厚度和碾压次数对干密度和压实度的影响,以及黏土斜心墙坝渗透系数试验分析。通过试验发现,铺土厚度30cm、碾压8遍的组合在干密度和压实度方面均表现出色,满足水库工程设计要求,因此研究将该组合作为黏土心墙料填筑的最佳方案;单环法在红色黏土土料的渗透系数最高为7.0×10^(-6),因此采用单环法进行渗透系数控制,可以更好地反映实际施工条件下的心墙渗透性能。

花岗岩堆石料32 t振动碾碾压试验研究

堆石料碾压质量直接影响面板坝的变形,32 t振动碾在花岗岩地区筑坝的应用鲜有报道。以五岳抽水蓄能电站主堆石料碾压施工为例,开展了主堆石料为花岗岩的32 t振动碾碾压试验研究,分析了碾压遍数和洒水率对主堆料干密度、孔隙率和渗透系数的影响。结果表明:堆石料的干密度随碾压遍数的增加而增大,孔隙率和渗透系数随着碾压遍数的增加而减小,增大洒水率有利于堆石料的碾压和干密度的提高。综合抽水蓄能电站运行特点、设计参数和经济性能,推荐五岳抽水蓄能电站32 t振动碾碾压参数为:铺料厚度90 cm、洒水率10%、碾压8遍。

Nonlinear finite element analysis of effect of seismic waves on dynamic response of Shiziping dam

Many high earth-rockfill dams are constructed in the west of China. The seismic intensity at the dam site is usually very high, thus it is of great importance to ensure the safety of the dam in meizoseismal area. A 3D FEM model is established to analyze the seismic responses of Shiziping earth-rockfill dam. The nonlinear elastic Duncan-Chang constitutive model and the equivalent viscoelastic constitutive model are used to simulate the static and dynamic stress strain relationships of the dam materials, respectively. Four groups of seismic waves are inputted from the top of the bedrock to analyze the dynamic responses of the dam. The numerical results show that the calculated dynamic magnification factors display a good consistency with the specification values. The site spectrum results in larger acceleration response than the specification spectrum. The analysis of relative dynamic displacement indicates that the displacement at the downstream side of the dam is larger than that at the upstream side. The displacement response reduces from the center of river valley to two banks. The displacement responses corresponding to the specification spectrum are a little smaller than those corresponding to the site spectrum. The analysis of shear stress indicates that a large shear stress area appears in the upstream overburden layer, where the shear stress caused by site waves is larger than that caused by specification waves. The analysis of dynamic principal stress indicates that the minimum dynamic stresses in corridor caused by specification and site waves have little difference. The maximum and minimum dynamic stresses are relatively large at two sides. The largest tensile stress occurs at two sides of the floor of grouting corridor, which may result in the crack near the corridor side. The numerical results present good consistency with the observation data of the grouting corridor in Wenchuan earthquake.

冲击碾压法加固堰塞坝料的室内模型试验研究

为丰富堰塞坝开发利用理论,探究适宜堰塞坝料的密实方法和设计参数,研究了冲击碾压方法对堰塞坝料的密实效果和密实机理。基于相似定律设计了不同冲击轮质量及牵引速度的天然堰塞坝料室内冲击碾压模型试验,综合采用宏-细观方法测试了冲击碾压后的动应力发展传播规律、变形特性、颗粒运动和加固效果等。试验结果表明:(1)冲击轮引起的冲击荷载为三角形脉冲荷载,产生的接触应力随着牵引速度和冲击轮质量的增大而增大,引起的地基动土应力随着碾压遍数的增加而增加;(2)冲击碾压对堰塞坝料地基表层的加固效果良好,地基内部动土应力和位移皆随深度迅速减小,深度3.6m范围内的堰塞坝料强度提升明显;(3)提高冲击轮的速度对加固效果的影响更大,可以有效提高冲击动应力,进而使得冲碾加固效果向深层传递;(4)满足易贡堰塞坝料的冲击碾压参数为:冲击轮质量13.5t,牵引速度3.46m/s,碾压遍数12。

数字化大坝施工技术在清原蓄电站面板堆石坝的应用

传统的面板堆石坝填筑施工质量控制过程是依靠现场施工人员对碾压施工过程中的填料、碾压轨迹、碾压速度、碾压遍数、碾压状态(动/静碾、激振力)等关键指标进行记录管控。该管控方式管理粗放、效率低,且人为因素不确定性大,不利于面板堆石坝填筑施工质量的高标准控制,易造成质量控制偏差,形成工程质量缺陷和安全隐患,同时也不能为电站施工、运行及工程建设管理等提供有效信息服务和决策支持。辽宁清原抽水蓄水电站下水库混凝土面板堆石坝碾压施工过程引入“大坝填筑施工过程智能化监控系统”,实现了大坝填筑从填料-压实-结果确认的全程可视化、标准化管理,减少人为干预,提高碾压施工效率,保证坝体填筑施工质量,提升工程建设管理水平。

冲击碾压加固松散堰塞坝料的细观机制研究

为系统研究冲击碾压过程中松散堰塞坝料的细观密实机制,基于自行设计的可视化冲击碾压模型装置及粒子图像测速技术,研究了不同冲击碾压参数对堰塞坝料地基的表面变形、内部变形及颗粒位移规律的影响。试验结果表明,冲击碾压加固过程是冲击和碾压两者共同作用,由于水平冲击作用,冲击点下方地基的变形具有非对称性。“高速轻轮”的施工参数会强化冲击效果,弱化碾压效果,造成地基表面平整性差。堰塞坝料冲击轮加固过程中的最大位移发生在三边形冲击轮圆弧面较平滑处与土体接触时,随后由于模型冲击轮重心上升,地基出现部分弹性回弹。提高冲击轮的牵引速度能够促进冲击能量向深层传递,但水平影响宽度有限;提高冲击轮的质量则能促进能量向两侧水平方向传递,但影响深度有限。对于模型试验的易贡堰塞坝料地基,冲击碾压最佳牵引速度约为0.75 m/s。结果可为堰塞坝料地基的冲击碾压浅层加固提供理论依据。

大石峡特高混凝土面板砂砾石坝填筑控制指标研究

随着重型碾压机具不断发展,通过重型碾压机具和采用较高的施工控制指标来提高筑坝料的干密度和变形模量,是高混凝土面板堆石坝坝体变形控制一种主要手段。依托大石峡特高混凝土面板砂砾石坝,开展了砂砾石料现场最大、最小干密度试验,开展不同碾压机具作用下现场碾压试验,确定填筑控制指标和施工碾压参数。研究表明:天然砂砾石料在一定规模的重型碾压作用下可得到较高的相对密度和干密度;而块石料需采用大型的重型设备碾压、增加碾压遍数等措施,孔隙率才能达到设计填筑标准。现场大坝填筑施工质量检测表明,选用的重型碾压机具和碾压施工参数合理可控,可满足大坝填筑控制指标要求。

基于案例分析的翻滚流水域救援方法研究

翻滚流是水域救援中常见的危险性极高的水流形态之一,已造成大量人员伤亡和救援人员牺牲。为全面剖析翻滚流水域的危险性,本文在大量调研和案例分析的基础上,发现低水坝下的翻滚流本质是一种“淹没水跃”,具有难发现易低估、有创伤风险、水温低缩短人员存活时间、气泡量大造成浮力降低、自救和救援难度大等特点。结合实践经验和理论分析,提出翻滚流水域保持冷静调整呼吸、从岸边脱困、从底部或水面顺流游出脱困等自救方法,探讨岸上救援、舟艇救援、阻水救援等救援方法,并给出注意事项和示意图,研究成果对救援人员认识低水坝和翻滚流、掌握翻滚流安全自救和救援方法具有借鉴意义。