Construction Processes Paradigm and Reinforcement Alternatives for Tailings Dam Soil

In the last decade, Brazil was the scene of two of the world’s biggest disasters related to mining tailings dams. The collapse of the Mariana and Brumadinho dams was catastrophic event that brought to light major environmental and humanitarian crises. Facts like this incite debate on the safety of dam construction methods and highlight the need for a broad discussion of dam safety legislation in the country. From the above, this paper promotes a review of various forms of construction of tailings dams and their associated problems, as well as discusses the techniques for soil reinforcement and their construction methods. The work also brings an overview of the Brazilian dams from April to July 2019, tracing the context of the Brazilian tailings dams months after the tragedy of Brumadinho. The methodology includes a robust literature review and discourse analysis. In Brazil, the number of ruptured dams is alarming, especially in the state of Minas Gerais, in which more than 7 have broken in the last two decades. Among the damages, the deaths impact society abruptly and were cataloged 455 deaths, of which 216 correspond to the rupture of the dam of the Córrego do Feijão mine in Brumadinho. To evaluate and diagnose a dam, one should consider ordinance N ° 70,389, 2017 revoked by Resolution ANM n ° 95, of February 7, 2022. In this context, in March 2019, we experienced several disturbing situations regarding dam instability in the state of Minas Gerais, being categorized as risky structures. To exemplify, one can cite dams classified as level 2 risk that became level 3. Due to the above facts, several studies are being conducted to improve soil aspects. For example, we highlight the increase in soil resistance that can be done using commercial and alternative materials available in the environment.

Deformation warning index for reinforced concrete dam based on structural health monitoring data and numerical simulation

The material mechanical parameters of the dam body and foundation will change when a dam is reinforced during the aging process.This causes significant changes in the structural state of the project and makes it difficult to ensure its structural safety.In this study,a new deformation warning index for reinforced concrete dams was developed according to the prototype monitoring data,statistical models,three-dimensional finite element model(FEM)numerical simulation,and the critical conditions of the dam structure.A statistical model was established to separate the water pressure component.Then,a three-dimensional FEM of the reinforced concrete dam was constructed to simulate the water pressure component.Furthermore,the deformation components that affected the mechanical parameters of the dam under the same amount of reservoir water level change were separated and quantified accurately.In addition,the method for inversion of comprehensive mechanical parameters after dam reinforcement was used.The influence mechanisms of the deformation behavior of concrete dams under the reservoir water level and temperature changes were investigated.A new deformation warning index was developed by combining the forward-simulated critical water pressure component and temperature component in the period of extreme temperature decrease with the aging component separated by the statistical model.The new deformation warning index considers the structural state of the dam before and after reinforcement and links the structural strength criterion and the deformation evolution mechanisms.It provides a theoretical foundation and decision support for long-term service and operation management of reinforced dams.

Shaking table test and numerical simulation on the effect of reinforcement on the seismic safety of dam slopes

The seismic safety of the reinforcement dam slope is studied through shaking table test and numerical simulation.The dynamic characteristics of dam slopes,failure mechanism,seismic stability,as well as the effect of reinforcement during earthquakes are discussed.An elasto-plastic analysis method (FLAC) is used to simulate the dynamic failure process of the reinforcement dam slope.The change law of permanent displacement of dam slope is studied.The effect of the length and the space of reinforcement on the depth of slip surface and the slope stability are investigated.Good agreement is obtained between the numerical results and those from shaking table tests.The results show that the dynamic failure is a gradual process not at a particular time.With the increase of the reinforcement length or the decreasing reinforcement spacing,the slip surface becomes deeper and thus the slope stability is improved.The reinforcement can obviously enhance the overall stability of slope dam.It can also effectively control the shallow sliding of slope.These researches provide basic data for reinforcement measures design of earth-rockfill dam.

Stability and reinforcement analyses of high arch dams by considering deformation effects

The strict definition and logical description of the concept of structure stability and failure are presented. The criterion of structure stability is developed based on plastic complementary energy and its variation. It is presented that the principle of minimum plastic complementary energy is the combination of structure equilibrium, coordination condition of deformation and constitutive relationship. Based on the above arguments, the deformation reinforcement theory is developed. The structure global stability can be described by the relationship between the global degree of safety of structure and the plastic complementary energy. Correspondingly, the new idea is used in the evaluations of global stability, anchorage force of dam-toe, fracture of dam-heel and treatment of faults of high arch dams in China. The results show that the deformation reinforcement theory provides a uniform and practical theoretical framework and a valuable solution for the analysis of global stability, dam-heel cracking, dam-toe anchorage and reinforcement of faults of high arch dams and their foundations.

Seismic response of concrete gravity dam reinforced with FRP sheets on dam surface

This paper aims at exploring the effects of anti-seismic reinforcement with the fiber-reinforced polymer （FRP） material bonded to the dam surface in dam engineering. Time-history analysis was performed to simulate the seismic failure process of a gravity dam that was assumed to be reinforced at the locations of slope discontinuity at the downstream surface, part of the upstream face, and the dam heel. A damage model considering the influence of concrete heterogeneity was used to model the nonlinearity of concrete. A bond-slip model was applied to the interface between FRP and concrete, and the reinforcement mechanism was analyzed through the bond stress and the stress in FRP. The results of the crack pattern, displacement, and acceleration of the reinforced dam were compared with those of the original one. It is shown that FRP, as a reinforcement material, postpones the occurrence of cracks and slows the crack propagation, and that cracks emanating from the upstream surface and downstream surface are not connected, meaning that the reinforced dam can retain water-impounding function when subjected to the earthquake. Anti-seismic reinforcement with FRP is therefore beneficial to improving the seismic resistant capability of concrete dams.

Geotechnical and Structural Benefits of Utilizing Reinforced Soil in Earth Dams

Approximately, 75% of constructed dams in the world are earth dams. The use of an earth dam is restricted by its geometrical area, weir restriction, and the availability of sufficient amount of earth material. These restrictions can be alleviated by the use of reinforced soil. In this research study the use of geotextile to stabilize and increase the shear strength of clay soils has been investigated. The results show an increase of about 25% in shear strength and cause an enhancement of stability in sandy soil in earth dams.

边坡工程与堤坝工程研究进展

边坡稳定性问题是土力学的三大经典问题之一,由于其受地质、环境等复杂因素影响始终无法完全解决。近年来,随着我国交通强国、一带一路及西部大开发等国家战略的相继实施和推进,土木、交通、水利等领域中的边坡工程与堤坝工程又面临许多新的难题和挑战。该文简要评述边坡工程与堤坝工程的国内外研究现状,主要包括三个方面:边坡稳定性理论与方法、堤坝灾害机理与分析方法以及边坡和堤坝工程加固技术,重点探讨土坡与堤坝的破坏机理、灾变数值模拟方法、稳定性分析理论与安全评价等研究的最新进展,并展望未来研究方向。随着地质学、地震学、土壤学、生物学、计算力学、人工智能等学科发展,交叉学科的互融共通将有力促进土坡工程与堤坝工程的科技进步。

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。

基于深度蒙特卡洛树搜索的拱坝仓面排序研究

合理的仓面排序方案对于加快工程进度和优化资源配置有着重要影响。然而,现有仓面排序方法将这一序贯决策问题简化,多数采用多属性决策方法,存在仅对大坝实时施工状态进行分析以及未考虑未来仓面浇筑方案对当前排序策略影响的问题;部分采用多目标优化方法进行仓面排序多目标优化问题分析,但主要是采用静态权重,存在忽略了仓面排序策略随环境动态变化的不足。针对以上问题,本文提出基于深度蒙特卡洛树搜索的拱坝仓面排序方法。首先,分析仓面排序问题的约束条件和目标函数,建立仓面排序强化学习模型;其次,针对仓面排序强化学习模型具有复杂且庞大的离散状态空间,为提高搜索效率,提出融合深度学习的蒙特卡洛树搜索方法,分别利用深度神经网络进行先验动作概率分布预测和策略函数评估;最后,以乌东德拱坝工程为例进行研究,结果表明本文方法可以有效地分析拱坝仓面排序问题,且相比于粒子群方法、证据理论方法,本文方法分析的施工工期可分别提前6天、14天,平均机械利用率分别提高1.19%、1.35%。本研究为拱坝仓面排序分析与优化提供了新思路。

东庄拱坝基础加固措施效果分析

拱坝基础加固是保证坝肩稳定和拱坝安全的重要工程措施,以东庄拱坝坝基加固措施为研究对象,系统模拟坝肩岩体中断层、夹泥裂隙、宽大裂隙和相应的加固措施,采用弹塑性本构对其坝基加固效果进行了有限元分析。计算结果表明:基础加固措施对坝体位移和应力的最大值影响很小,但在一定程度上使坝体以及建基面的屈服区减小,改善了坝体受力;基础加固措施对拱坝坝体的塑性区影响不大,但是基础加固后建基面屈服区明显减小,基础加固措施明显改善了坝基的受力状态,基础加固措施对于断层f5和夹泥裂隙Rnj3的屈服区体积影响相对较小,对于宽大裂隙L22的屈服区体积影响较为显著。东庄拱坝基础加固措施改善了坝体和坝基受力、提高了坝基的稳定性。

小型土石坝水库除险加固及渗流安全稳定评价

水利除险加固对于早期建设的许多病险水库安全运行至关重要。沙表北水库建成年代早,影响水库安全稳定的工程地质条件复杂,同时坝体存在安全稳定隐患,有渗流安全隐患。以沙表北水库为研究背景,从坝顶加固、防渗加固和坝坡加固提出系统加固方案,针对大坝渗流和安全稳定进行复核分析,提出合理的监测补充措施。

水库坝坡稳定性及防渗加固方案分析

针对石水坑水库的坝坡稳定性和防渗加固问题展开研究,通过对水库大坝的迎水坡与背水坡现状、坝体可能存在渗漏和压实性较差等分析,揭示了存在的安全隐患和加固需求。此次设计了灌浆加固、护面修复等加固方案,并采用《水工结构有限元分析系统(AutoBANK)》的程序进行计算,对不同工况下的稳定性进行分析,选定了计算断面和工况,对加固方案的可行性与效果进行了分析。研究结果表明,加固方案在提升水库坝坡稳定性和防渗效果方面具有显著成效,为水库的安全运行提供了科学依据。

复杂地质条件下东庄特高拱坝坝趾加固措施研究

特高拱坝的起裂、屈服和失稳破坏等主要来源于拱坝坝踵和坝趾等应力集中区域,尤其是坝趾处可能发生压剪损伤,该部位岩体稳定和基础加固决定着拱坝的安全度。基于东庄水利枢纽工程特高拱坝,结合基于变形加固理论的三维弹塑性有限元整体变形分析成果与地质力学模型试验成果,提出了东庄水利枢纽工程特高拱坝坝趾加固设计方案。

水利工程项目堤坝复合混凝土防渗与加固施工技术

为了提高水利工程项目堤坝防渗与加固施工水平,确保水利工程长期稳定运行,提出了堤坝复合混凝土防渗与加固施工技术研究。首先,设计复合混凝土防渗墙,在堤坝地基中形成一道稳固性较高的防渗墙体;其次,采用双排布孔的布置形式,在堤坝两岸坡段上布设灌浆孔;在此基础上,利用劈裂灌浆加固技术,对水利工程项目堤坝复合混凝土进行加固施工。实验结果表明,该施工技术应用后,堤坝段落的渗透系数始终小于1×10^(-6)cm/s,满足水利工程项目堤坝防渗要求,能够提高防水性能与加固效果。

陆水大坝闸墩无损切割拆除施工

除险加固工程中,混凝土结构存在部分拆除的情况,此时必须在保证剩余部分结构不受损坏的基础上完成拆除。针对陆水大坝闸墩的实际情况,采取“绳锯切割、打孔吊装拆除素混凝土+人工破碎钢筋混凝土+气体切割拆除钢结构”的组合施工方案完成闸墩部分拆除,闸墩顶部附属结构全部拆除的任务。该方案在安全文明施工的前提下,圆满地完成了拆除任务,为大坝闸墩恢复施工奠定了基础,保障了枢纽除险加固工程的顺利完成。

大坝工程防渗灌浆技术及其防渗加固处理措施研究

针对现阶段较为广泛应用的防渗灌浆技术进行了总结与分类,分析了各个防渗灌浆技术的优缺点及适用场景,总结了大坝防渗加固所应考虑的地理环境、工程工艺、大坝材质等条件。以甘肃省张掖市黑河二龙山水电站工程为例,结合水库原始设计资料,针对坝基、坝肩、坝底的防渗加固给出了施工设计方案。

某L河固床坝坝后消能设施加固设计研究

文章以某L河固床坝坝后消能设施加固设计研究保障城市平稳供水为背景,在分析工程地质、施工导流等因素的基础上,通过水力学计算分析,提出了最佳设计方案,最终取得良好的效果,不仅对同类型固床坝坝后消能设施加固设计可以起到参考借鉴,也对于工程管理部门日常技术管理工作提供参考。

综合物探在水库大坝渗漏隐患检测中的应用

水库大坝渗漏隐患检测是水利工程安全运行及除险加固工作的重要环节,对保障大坝安全运行及下游人民生命财产安全具有重要意义。笔者根据水库大坝物性特征的分析,充分利用直流电法对渗漏通道视电阻率响应特征灵敏的优点,合理选取了充电法及高密度电法对水库大坝进行综合探测,首先利用充电法追索坝体渗漏通道,然后结合高密度电法对每条测线二维纵向剖面进行解析,通过两种方法的相互验证,有效圈定渗漏隐患发育位置及规模,取得了可靠的成果,从而达到由点及线、由线及面的综合探测效果,为水库大坝渗漏通道排查及除险加固提供精确可靠的依据。

BIM在淤地坝除险加固工程设计中的应用

BIM(Building Information Modeling)系统是近些年大型交通工程、建筑工程领域逐渐推广的重要发展理念,Civil 3D、Revit等通用软件的应用引起了工程设计领域的重大变革。本文重点介绍了Civil 3D技术在水土保持淤地坝除险加固工程设计中的具体应用,利用BIM系统的强大建模及管理功能,可以实现设计方案比选更加直观、技术论证更加合理、工程量分析计算更加精准、设计效率更加高效快捷的目的。

水库病险坝防渗加固施工中高压喷射灌浆的设计及施工技术

本文以某水库病险坝的防渗加固处理为例,探究了高压喷射灌浆的设计方案和施工技术。以P.O42.5水泥和水按照水灰比1:1.5配制后,掺入泥浆质量2%~3%的外加剂,提高灌浆材料的速凝和抗渗性能。计算灌浆量和孔距等参数后,选择“三管法”进行高压喷射灌浆施工。在施工结束30天后,从灌浆区域内钻芯取样并检测芯样的性能指标,抗压强度在1.85~2.50 MPa之间,芯样密度在1.72~1.91 g/cm3之间,符合水库病险坝的除险加固和防渗要求。