文县燕儿沟拦挡坝受损原因与加固措施研究

拦挡坝受损是泥石流治理工程常见的问题,因地制宜提出加固措施可保障工程自身安全,且使已有防治体系继续发挥防灾减灾效能。在查明拦挡坝破坏模式及受损原因的基础上,根据受损部位、破坏程度和损坏原因的不同,采取相宜的加固措施,尤其对坝体存在多种破坏类型的情况则采取多种措施的综合加固方案。本文以燕儿沟泥石流为例,在掌握灾害发育特征的基础上,查明流域内拦挡坝破坏类型,并分析受损原因,研究提出安全合理、行之有效的加固措施,为此类加固工程提供借鉴思路,为往后防治工程结构设计提供参考。     

长江某水电站坝基剪切带发育规律与抗滑稳定研究

坝基剪切带是水利水电工程建设中经常遇到的重大工程地质问题,常对坝基岩体稳定性有着直接影响;研究剪切带的工程地质特征特别是空间发育与分布特征,对红层地区水利水电工程建设具有重要意义。本文以长江某水电站为例,从坝基红层沉积环境与沉积相分析入手,通过对坝基岩性组合、矿物组成、结构和粒度标志、沉积构造等的综合分析,恢复坝基古沉积环境,进一步确定原生软弱夹层的沉积微相;结合区域地质构造背景,分析剪切带发育规律与空间分布特征,进而开展坝基抗滑稳定研究。研究结果表明:层间剪切带的发育及空间分布特征主要受红层沉积环境与沉积相控制;坝基层间剪切带大多发育在半韵律层的顶部,即发育在软硬岩层接触面及厚层软岩内;由于岩相变化快,所以同一剪切带的空间分布常不连续,在不同空间位置的类型也不尽相同;剪切带是具多种黏土矿物成分且含量不同的高分散体系,其具有不同的工程地质特征及强度参数;剪切带空间分布特征与性状的不连续性,对坝基岩体稳定性有着重要影响,常直接关系到工程的建设工期与造价。因此,以沉积环境和沉积相分析为切入点,能够清晰的认识剪切带的空间发育分布规律,可用于指导红层地区工程地质条件评价与坝基岩体稳定性分析。     

主震和余震联合作用下复杂地基上重力坝的稳定性分析

大地震主震发生之后通常伴随强余震,多次余震下大坝的结构损伤破坏累积效应明显。为了解复杂地基上重力坝在主、余地震联合作用下的变形和稳定性,以紧邻汶川地震震中的某大型水利工程重力坝典型坝段A#坝段为研究对象进行研究分析。首先,仅考虑主震作用的影响,采用拟静力法模拟地震主震荷载,运用地质力学模型试验方法,研究主震作用下A#坝段坝与地基的变形特征和模型最终破坏形态;再考虑主、余地震联合作用的影响,采用动力法（即时程分析法）基于ANSYS有限元软件进行计算。研究结果表明,主震作用下模型试验与有限元计算结果基本一致,坝与地基均发生了大变形,且通过模型试验得到了A#坝段最终破坏形态;在主、余地震联合作用下,A#坝段坝与地基的变形的累积增加效应明显,变位特征值比主震作用下明显增大,其坝体最大变形处（坝顶）变位值增幅约为37%,对坝与地基稳定性影响较大。因此,对位于地震高发带复杂地基上的重力坝,应考虑主、余地震联合作用的影响,这样更利于工程的安全。     

Seismic liquefaction analysis of a reservoir dam foundation in the South–North Water Diversion Project in China. Part II: seismic response simulation

As shown in Part I of this study, the saturated surface silt of the dam foundations in Tianjin is vulnerable to liquefaction with a seismic intensity of VII. According to the Chinese codes for the seismic design of buildings (Hydropower Research Institute of China), specifications for seismic design of hydraulic structures (DL 5073–2000), China Water Power Press, Beijing (in Chinese) 2000, Ministry of Construction of China, code for seismic design of buildings (GB 50011–2001) and China Building Industry Press, Beijing 2001), specific procedures were selected for anti-liquefaction treatments in this project. Numerical simulation analyses, which have become an indispensable step in engineering practice, especially for large projects such as this, have been applied to dam foundations before and after anti-liquefaction treatments to see how they will behave in an earthquake. Simulated results of the dam foundations during an earthquake were obtained for excess pore water pressure, acceleration, displacement, and properties that are considered useful for earthquake geotechnical design. The simulation is in good agreement with empirical methods for the performance of the dam foundation during the earthquake. Results also show that the anti-liquefaction treatments that made use of a cutoff wall and a platform beyond the dam improved the integral stability of the dam. The cutoff wall can prevent lateral spreading (of the left side foundation soil in the case presented here), and the platform prevents an increase in pore water pressure.     

水库岩溶渗漏及防渗研究综述

岩溶地区水库渗漏是可溶岩地区兴建水利枢纽的主要工程地质问题之一,尤其是在可溶岩广布、岩溶发育强烈、地形复杂地区,岩溶渗漏成为了该类地区水利水电工程的一个普遍问题.库区的岩溶渗漏不仅影响建坝后的正常蓄水,还将危及坝体的安全与稳定.因此,有必要对库区渗漏,特别是岩溶地区的库区渗漏进行渗漏机理、渗漏特征、渗漏条件等进行详细分...     

Detection of seepage paths in earth dams using self-potential and electrical resistivity methods

Earth and rockfill dams are designed to operate under steady state seepage. Anomalous seepage may be a threat to the integrity of the structure. In spite of advances made in the fields of geotechnical engineering, it is not possible to have 100% leak-proof structure. Any excessive and unplanned seepage may lead to the failure of the dam, especially in unconsolidated or fractured terrains. Geophysical methods play an important role in mapping seepage paths and monitoring the changes of the seepage with time, enabling to plan technically and economically worthwhile remedial measures. In the present paper, utilisation of electrical methods for delineation of seepage zones at two of the four Saddle dams of the Som-Kamla-Amba project, Rajasthan State, India; which is founded on heterogeneous rock mass, is discussed. Electrical resistivity method was used to delineate zones favourable for seepage, whereas, self-potential (SP) method was used to delineate the seepage paths. SP measurements have shown negative anomaly of the order of 10–20 mV in amplitude, indicating low seepage, coinciding with the seepage measurements made by the project authorities.     

Evaluation of excavation‐induced relaxation and its application to an arch dam foundation

Based on the damage mechanism of rock during excavation, the maximum tensile strain criterion for pinpointing relaxation region or excavation‐disturbed (damage) zone (EDZ) is introduced. To simulate the deformation and stress redistribution caused by the deterioration of the deformation and strength parameters in the EDZ, the ‘restraint‐relaxation’ finite element algorithm is formulated using the deformation and strength parameters of pre‐and post‐relaxation. The Xiaowan arch dam project (292 m high) is studied by the proposed method, in which the permissible tensile strain and fluidity parameter are evaluated using back analysis. The computation results have good agreement with the field monitoring. An important inference from the study is the necessity of considering the relaxation effects on the dam/foundation system during the construction and operation period. Copyright © 2011 John Wiley & Sons, Ltd.     

泥岩层状破碎带特大涌水处理方法探索与实践

泥岩地质条件一般较差,在这种基础上修建大型水利工程,基础处理难度较大。哈达山水利枢纽工程坝基为近水平发育的泥岩,坝基深处发育层状破碎带,严重影响坝基的稳定安全。通过分析这种地层中的涌水的渗透通道,采取了一系列注浆处理措施。这种处理方法既节约成本,又保证施工质量。结合本工程发电厂房集水井特大突水及整个P7破碎带处理方法,总结针对泥岩地层中特大涌水处理的思路和方法。     

Dam-break risk analysis of the Attabad landslide dam in Pakistan and emergency countermeasures

The Attabad landslide dam caused significant property losses and many human casualties in Pakistan, and also greatly affected the operation of the China-Pakistan Karakoram Highway (KKH). This paper discusses the risk of dam breach and hazards to the KKH project construction site following a dam breach. The paper examines the following three topics. (1) The geomorphologic dimensionless blockage index (DBI) and the analogy method were used to analyze the stability of the Attabad landslide dam. The long-term behaviors of landslide dams downstream of the Attabad landslide dam indicate that the risk of a dam breach exists, but the probability of a total dam failure is low. (2) The peak discharge of a potential breach of the Attabad landslide dam was calculated for scenarios in which 1/4, 1/3, 1/2, and total failure of the dam was breached. The potential breach discharge decreases with the downstream distance. (3) The potential impacts of the landslide dam breach on the KKH project construction site were analyzed. Based on the composition of the landslide dam, the probability of a 1/3 dam breach is high. To ensure the safety of downstream areas, disaster preparedness plans that correspond to the 1/2 dam breach scenario should be developed. Based on experience in addressing the landslide dam that was caused by the Wenchuan Earthquake, artificial controlled drainage measures are suggested and provide a technical reference for addressing the Attabad landslide dam and achieving recovery and normal operation of KKH.     

护底条件下淹没丁坝坝头局部冲刷试验

淹没丁坝是一种典型的航道工程整治建筑物,工程实施中坝头附近局部冲刷防护问题尤为重要。为研究护底条件下的淹没丁坝坝头局部冲刷特性问题,采用正态模型试验方法,重点研究了护底条件下淹没丁坝坝头局部冲刷坑形态、最大深度与护底宽度的变化响应规律,结果表明,护底条件下坝头局部冲刷坑位于护底边缘附近,当护底宽度小于20 m左右时,最大冲刷深度变化较小,但冲刷坑位置有所远离坝体,最大冲刷深度随着护底宽度的变化规律可用指数关系表达。基于量纲分析原理,建立了粉细沙河床护底条件下淹没丁坝局部冲刷最大深度计算公式。     

金沙江乌东德水电站区热水塘断层活动性研究

乌东德水电站预可行性研究阶段,陆车林、尖山包、河门口、白滩、三台子、乌东德六个比选坝址中,热水塘断层穿过其中河门口和白滩两个坝址。为了查明该断层规模、性状、活动性,作者在航片解译的基础上,经过野外验证和地质追踪调查,分析了沿断层带的地形地貌、地层岩性、岩溶发育特征,确定了该断层的性质。通过取岩样测年及显微构造等多种方法对断层的活动性进行了深入研究,认为该断层在中更新世前有一定的活动性,但后期活动性明显减弱,晚更新世后没有活动。综合地震资料分析,该断层不是工程活动断层,为坝址比选提供了重要依据。     

工程水文地质学及其在水电工程中的应用概述

工程水文地质问题产生于人类工程活动与地质环境中岩土体和地下水之间的相互制约和相互作用过程中,由于问题本身的复杂性,目前对这类问题的研究尚处于相对分散的单一研究状态,缺乏系统的从地质机制分析到地质模型抽象,进而由模拟再现到发展趋势预测以及治理措施论证的全过程研究。本文在系统分析、总结水电工程中水 -岩和水 -工程建筑的作用类型及特征基础上,认为可能出现的工程水文地质问题主要是;水库诱发地震、岩溶渗漏、库岸及高边坡的稳定、坝基、坝肩抗滑稳定、枢纽区深层承压水问题等。     

三峡工程地质勘察研究的理论与实践

举世瞩目的三峡工程目前已进入关键的建没阶段。本文从区域稳定与地震危险性、水库区工程地质与环境地质、水库诱发地震、坝址及建筑物工程地质以及天然建筑材料等五个方面论述三峡工程长期以来所进行的工程地质勘察研究工作,并着重对三峡工程区的地质地震问题作了较为详细的探讨。最后对这一巨型工程的地质勘察工作进行了经验总结。     

Risk variation of reservoir regulation during flood season based on bivariate statistical approach under climate change: a case study in the Chengbihe reservoir,China

The risk analysis of reservoir regulation in the flood season is crucial and provides the valuable information for reservoir flood control, safety operation, and decision making, especially under climate change. The purpose of this study is to propose a framework for reasonably estimating the variation of reservoir regulation risk including the dam extreme risk and the overtopping risk during the flood season under climate change. The framework consists of an integrated diagnostic system for detecting the climate abrupt change time, a copula function-based bivariate statistical approach for modeling the dependence between the flood peak and flood volume, a Monte Carlo simulation for generating numerous random flood peak–volume pairs, and a risk calculation model for routing the design flood hydrographs to obtain the frequency curve of the maximum water level reached in front of dam and evaluating the reservoir regulation risk. The methodology was implemented in the Chengbihe reservoir in south China by using the 55-year (1963–2017) hydrometeorological data, including temperature, evaporation, precipitation, and streamflow, in the flood season. Results show that the hydrometeorological series during the flood season changed abruptly in 1992 and the entire data can be divided into two periods (1963–1992 and 1993–2017). The dam extreme risk and overtopping risk during the two periods are assessed, respectively, and a comparison analysis is made based on different flood limit water-level schemes (185.00–188.50 m). It demonstrates that both the dam extreme risk and the dam overtopping risk increase under the influence of climate change. The dam extreme risk increases by 22.91–95.03%, while the climate change-induced increase in the dam overtopping risk is between 38.62 and 123.59%, which indicates that the dam overtopping risk is more sensitive to climate change than the dam extreme risk. The risk evaluations in the study are of great significance in the safety operation and risk management of reservoirs under future climate change.

     

Role of construction of large dams on river morphology (case study: the Karkheh dam in Iran)

Unfortunately in developing countries, human activities without attention to the environmental aspects damage to nature. For example, construction of large dams dries wetlands in southwest of Iran. Also, construction of dams is a very important factor for morphological changes. The case study of this research is downstream of the Karkheh dam. This dam is the largest Earth dam in Iran and locates in southwest of Iran. It was constructed in 1999. Small sinuosity coefficient of zone near to dam has been illustrated by satellite images in 2002 and 2014. This subject shows instability of this part of reach; also, the results of Shulits equation illustrate that this part is instable. But, increasing of morphological characteristics (sinuosity coefficient, central angle, and relative radius) show that stability of this reach is increasing. Surveying confirm this matter and shows that severe erosion in upstream and sedimentation in downstream of reach is finishing. Also, it is observed that flow discharge reduced (?56 %) after construction of dam and average width of river reduced (?21 %) from 2002 to 2014. In the early years after the construction of the dam, sediment discharge reduced considerably (?14 %) from Pay-e-Pol to Abdol Khan hydrometric stations. Increasing of morphological characteristics (especially at zones near to dam) and decreasing changes of bed level (sedimentation and erosion) prove that effects of dam are overcoming on effects of other factors, and these effects are permanent in long term.     

糯扎渡电站溢洪道边坡稳定分析及系统锚固方法

糯扎渡水电站位于云南省思茅市境内,是澜沧江流域开发中具有十分重要意义的工程。设计土石坝方案的溢洪道开挖边坡的稳定性关系到该方案的合理选择。通过对溢洪道附近的平硐与露头的野外调查,获得了1 400余条结构面的详细信息,在岩体结构面统计基础上,运用随机网络模拟的方法得到了溢洪道开挖边坡的裂隙网络图像,分析了岩体结构面的连通率,采用Hoek和Brown提出的GSI体系,对岩体质量进行综合定量评价,在此基础上,提出各高边坡岩体力学参数的综合指标。应用模拟退火算法,搜索出边坡潜在的最危险滑裂面的位置,并运用Sarma法分析了开挖边坡的稳定性,提出各个边坡稳定性的分析评价成果以及建议的边坡系统锚固措施。     

狮尾河流域地质灾害治理防护堤工程施工设计问题讨论

云南省云龙县狮尾河流域地质灾害治理防护堤工程的施工设计存在不少问题,特别是河道地形变化和防护堤越过已建固床坝这2个问题,严重制约着施工进度,影响着施工质量和工程安全。在分析原施工设计存在的问题的基础上,提出了切实可行的解决办法,并取得了良好的治理效果。     

某高坝工程坝肩侧裂结构面基本特征及量化模型研究

某高拱坝工程, 坝肩抗滑稳定的侧裂边界主要受与河流呈小角度斜交的随机结构面 (基体结构面 )控制。查明这类结构面的工程地质性状, 提出其量化评价指标, 对该高拱坝工程坝肩稳定性评价和相应设计参数的取值具有重要的工程实际意义。本文基于大量的现场调查工作, 获取了侧裂结构面数万个现场实测数据。基于这些数据, 作者对侧裂结构面的发育状况和工程地质特征作了全面的分析和定量评价。在此基础上, 提出了坝肩抗力体部位侧裂结构面的工程分区。该分区采用结构面的发育密度作为指标, 能简明直观地描述抗力体部位结构面的发育状况和宏观连通特性。最后, 作者根据本文的研究成果, 从抗滑稳定的边界条件特性出发, 对该高拱坝工程坝肩抗滑稳定性条件作出了评价。