百色水利枢纽主坝工程地质特点和勘测研究

针对百色水利枢纽主坝和消力池复杂的地质条件,历经完整的勘察阶段,在勘察过程中采用综合的勘察手段和先进的勘察技术,查明了主坝区的工程地质条件,通过深入地分析和研究,对存在的工程地质问题进行了准确评价,为设计提供了合理的地质参数和切实可行的建议。     

百色水利枢纽工程任务和目标的调整

已建的广西百色水利枢纽是治理和开发郁江的关键性水利工程,原设计工程任务是以防洪为主,兼顾发电、灌溉、航运、供水等综合利用。随着西部大开发深入,广西经济社会的发展对百色水利枢纽提出了更高要求。分析了区域经济社会发展对百色水利枢纽工程防洪、水资源配置任务和目标调整的要求,并提出开展满足调整后工程任务、目标要求的防洪、兴利调度方式研究的建议。     

丹江口左岸土石坝混凝土防渗墙施工监理质量控制

丹江口大坝加高工程施工过程中,左岸土石坝左联段防渗体加固采用混凝土防渗墙方案。本文通过监理实践,总结了左岸土石坝左联段加固混凝土防渗墙监理质量控制的过程与方法,详细列出了施工过程中的质量控制点,对加固混凝土防渗墙原材料检测、拌和物检测、预埋管检测、第三方质量检测及质量检查孔情况进行了详细介绍。质量检测结果表明,质量控制效果明显。     

Exploration and evaluation of AR,MPCA and KL anomaly detection techniques to embankment dam piezometer data

In the U.S., the current practice of analyzing the structural integrity of embankment dams relies primarily on manual a posteriori analysis of instrument data by engineers, leaving much room for improvement through the application of advanced data analysis techniques. In this research, different types of anomaly detection techniques are examined in an effort to propose which data analytics are appropriate for various anomaly scenarios as well as piezometer locations. Moreover, both the parametric (Auto Regressive [AR] and Moving Principal Component Analysis [MPCA]) and nonparametric (Kullback–Leibler Divergence [KL]) techniques are applied in order to test if the widely-held assumptions about piezometer data, i.e., linearity between piezometer data and pool levels, as well as normally distributed piezometer data, are necessary in the anomaly detection task. In general, KL performs better than MPCA and AR, and delivers more consistent results throughout the different piezometers and anomaly scenarios. Given that KL is a nonparametric technique, the authors conclude that the prior assumptions about piezometer data do not always provide the best performance for anomaly prediction.     

胶凝砂砾石坝坝坡比分析研究

胶凝砂砾石坝属于新型筑坝技术,坝坡比是胶凝砂砾石坝断面设计的重要参数,直接影响工程的安全性和经济性,应通过坝体抗滑稳定性和应力分析来确定最优坝坡比和坝体断面。通过和面板堆石坝、碾压混凝土重力坝坝坡比的对比,结合胶凝砂砾石坝坝体受力特征分析,对胶凝砂砾石坝在基本荷载组合条件下的坝坡比进行了理论分析和研究。胶凝砂砾石坝设计初期,类似Ⅳ类硬质岩的坝基地质条件,且材料设计抗压强度6.0 MPa、坝高小于70 m时,胶凝砂砾石坝综合坝坡比可在1.2~1.3之间初选;上游坝坡比宜大于1∶0.3、小于1∶1.0;下游坝坡比宜大于1∶0.5、小于1∶1.0。在综合坡比一定时,将坝体设计为对称梯形断面对坝体抗滑稳定有利;将坝体设计为上游坝坡比小、下游坝坡比大的非对称梯形坝对降低坝体主应力水平有利。     

破碎岩体上混凝土重力拱坝的设计要点分析

由于巴基斯坦高摩赞大坝坝址地质条件复杂,岩体破碎,天然条件下不满足修建混凝土坝的地基条件。以现场勘查和试验为基础,采用大范围大深度的固结灌浆处理方案。结合生产性灌浆试验,采用声波测试结合承压板载荷试验,验证固结灌浆对提高坝基变形模量的效果,并采用固结灌浆处理后的岩体物理力学参数对大坝进行了有限元分析。在多方论证的基础上,经过对大坝体型和结构的精心设计,在十分破碎的岩体条件下,成功建成了133 m高的混凝土重力拱坝。研究成果为国外混凝土重力拱坝的设计提供参考。     

土石坝心墙的三维渗流

土石坝心墙的三维渗流Ｋ．Ｈ．阿纳哈耶夫渗流的二维特性对土坝渗透参数的影响很大,于山区狭窄坝址处尤为明显。之所以需要研究这种现象,是由于需要合理选用坝的断面和尺寸、坝的防渗构件以及选择过渡区滤层和排水设施等缘故,Ｅ．Ａ．查马林、阿斯库拉瓦、波克罗夫斯基...     

Phosphorus retention and transformation in a dammed reservoir of the Thames River,Ontario: Impacts on phosphorus load and speciation

Extensive efforts are underway to reduce phosphorus (P) export from the Lake Erie watershed. On the Canadian side, the Thames River is the largest tributary source of P to Lake Erie’s western basin. However, the role of dams in retaining and modifying riverine P loading to the lake has not been comprehensively evaluated. We assessed whether Fanshawe Reservoir, the largest dam reservoir on the Thames River, acts as a source or sink of P, using year-round discharge and water chemistry data collected in 2018 and 2019. We also determined how in-reservoir processes alter P speciation by comparing the dissolved reactive P to total P ratio (DRP:TP) in upstream and downstream loads. Annually, Fanshawe Reservoir was a net sink for P, retaining 25% (36 tonnes) and 47% (91 tonnes) of TP in 2018 and 2019, respectively. Seasonally, the reservoir oscillated between a source and sink of P. Net P release occurred during the spring of 2018 and the summers of 2018 and 2019, driven by internal P loading and hypolimnetic discharge from the dam. The reservoir did not exert a strong influence on DRP:TP annually, but ratio increases occurred during both summers, concurrent with water column stratification. Our analysis demonstrates that Fanshawe Reservoir is not only an important P sink on the Thames River, but also modulates the timing and speciation of P loads. We therefore propose that the potential of using existing dam reservoirs to attenuate downstream P loads should be more thoroughly explored alongside source based P mitigation strategies.     

Dam-Break Wave-Front Celerity

This work is concerned with the role that friction and inertia effects can play on the magnitude of dam-break wave-front celerity. Classic analytical solutions are presented. A large collection of experimental data is used, covering a wide range of different initial conditions: fixed bed or mobile bed (five types of bed material), dry or wet bed downstream, and with or without bed step. To overcome the limitations of analytical solutions, a numerical model is used. The model is based on the shallow-water approach with contact-load dominated sediment transport, and it makes use of developments recently made in the study of sheet flows. The analytical and numerical results are compared with experimental data. It was found that the celerity is mainly dictated by the friction coefficient, by the sediment inertia, by the initial downstream water depth, and by the initial bed step height. For good data fitting, the friction coefficient must be influenced by the type of bed, fixed or mobile. In the latter, the coefficient must vary with the bed material characteristics. The dissimilarities between the experimental, analytical, and numerical results are interpreted.     

Lessons Learned: Failure of a Hydroelectric Power Project Dam

The case of a hydroelectric power project is presented to show how lack of understanding and poor filter design, along with insufficient control of construction quality, caused the failure of a dam. This paper summarizes the forensic investigations and attempts to explain the conditions that led to the formation of sinkholes on the embankment slope and the subsequent initiation of progressive failure of the embankment. The steps necessary to restart the power project, including the final remedial design, are then detailed. This paper also discusses how the functions of various engineering design components are integrated in the context of failure of the embankment. This case serves as a lesson for practicing engineers concerning the difficult technical, professional, and procedural issues that may arise during the design and construction of critical infrastructures.