三峡库区兴山县灵老爷崩滑体治理工程施工技术

崩滑体在体积大小、稳定状态、危害程度方面都是千差万别的,要针对不同情况分类处理,对大多数可能产生形态失稳的崩滑体进行监测和预报,对可能产生危害的崩滑体应采取工程治理措施。笔者根据三峡库区兴山县灵老爷崩滑体的具体情况,结合环境要求,提出防治工程的治理方案,并取得良好的效果,对三峡库区其他类似地质问题具有借鉴意义。     

美姑河牛牛坝水电站库区泥石流基本特征

金沙江支流美姑河牛牛坝水电站库区泥石流沟分布面积广、发生频率高。调查结果表明库区现有不同类型泥石流沟31条,其中属于高度危险的泥石流沟4条,中度危险的泥石流沟15条。本文对流域面积较大、活动性较强的12条泥石流的容重、设计流速、流量、冲出量等重要工程参数进行了计算,并对水库蓄水后的泥石流沟状况与发展趋势作了进一步分析,研究表明在水库施工期泥石流灾害对工程建设有较严重的影响,特别是靠近库首的泥石流对工程的安全构成威胁。水库蓄水后,库区泥石流活动程度有所降低,不会明显影响水电站正常运行。     

Effects of drawdown scenario on retrogressive lateral erosion in a reservoir

The drawdown of reservoirs behind dams is an important management strategy (e.g., for removal of aging infrastructure, flushing of sediment), and an opportunity to study erosional processes. A numerical model was developed to examine retrogressive bank erosion across reservoir drawdown scenarios and to evaluate factors controlling the rate, volume, and mechanisms of lateral erosion. Modeled processes included dynamic drawdown of groundwater, sequential slope failures via limit equilibrium analysis, and retrogression considering stress interaction between failing blocks. Field measurements were coupled with Staged, Slow, and Rapid drawdown scenarios. Results highlight the importance of including retrogression as an avenue for lateral erosion, as sequential block failures were found to occur in all scenarios except Slow drawdown. This result indicates that bank stability models without some means of characterizing the evolution of slope failure during drawdown are likely underestimating bank failure rates and volumes. In contrast, dynamic groundwater was not found to be a dominant control for any drawdown scenario. Model results also demonstrate that the drawdown increment is a first-order control on slope instability via the development of drained or undrained conditions. A majority of failures occurred under undrained conditions. To maximize slope stability, using slow drawdown to activate internal friction under drained conditions is essential. The design of the drawdown rate created a tradeoff between the amount of impact created and when the impact is produced. The study also articulated the need for coupling models and field observations for rapidly changing systems.     

Comparison of Machine Learning Models Performance on Simulating Reservoir Outflow: A Case Study of Two Reservoirs in Illinois,U.S.A.

Reservoir outflow is an important variable for understanding hydrological processes and water resource management. Natural streamflow variation, in addition to the streamflow regulation provided by dams and reservoirs, can make streamflow difficult to understand and predict. This makes them a challenge to accurately simulate hydrologic processes at a daily scale. In this study, three Machine Learning (ML) algorithms, Random Forest (RF), Support Vector Machine (SVM), and Artificial Neural Network (ANN), were examined and compared to model reservoir outflow. Past, current, and future hydrologic and meteorological data were used as model inputs, and the outflow of next day was used as prediction. Simulation results demonstrated that all three models can reasonably simulate reservoir outflow. For Carlyle Lake, the coefficient of determination and Nash–Sutcliffe efficiency were each close to one for the three models. The coefficient of determination, relative mean bias, and root mean square error indicated that the SVM performed better than the RF and ANN, but the SVM output displayed a larger relative mean bias than that from RF and ANN. For Lake Shelbyville, the ANN model performed better than RF and SVM when considering the coefficient of determination, Nash–Sutcliffe efficiency, relative mean bias, and root mean square error. The study results demonstrate that the three ML algorithms (RF, SVM, and ANN) are all promising tools for simulating reservoir outflow. Both the accuracy and efficacy of the three ML algorithms are considered to support practitioners in planning reservoir management.     

尾矿库地震液化机理及抗震评估指标体系研究

2008年"5.12"汶川大地震中,四川、陕西和甘肃三省尾矿库均受到不同程度的破坏和影响。本文针对四川汶川地震造成灾区尾矿库排洪系统失效,坝基沉降,坝体滑坡、垮塌、开裂等现状,对尾矿库地震溃坝机理进行了分析,研究了地震作用机理和地震液化的影响因素;在此基础上,建立起用于评估尾矿库抗震能力和地震溃坝可能性的指标体系,指标体系考虑了地震强度、防洪、抗滑、抗渗透和安全管理五个方面,能够较为全面的分析和评估尾矿库在抗震方面的基本特性,并通过研究给出了各个指标的分级方法。该体系的建立为尾矿库抗震能力评估、避免特殊工况下尾矿库溃坝事故的发生具有一定应用价值,可为尾矿库运行期的安全管理提供依据。     

水库淹没区耕地生态服务功能价值估算研究——以黄金坪水电站为例

以黄金坪水电站为例,采用碳税法、造林成本法以及工业氧价格替代法计算气体调节功能价值,并采用其它多种方法计算水土保持价值,以估算水库淹没区耕地生态服务功能价值。通过研究,使水库淹没区耕地总价值构成及量化趋于合理,为进一步完善淹没区耕地补偿构成和补偿标准提供参考。     

汶川地震震损水库土坝动力反应与几何坝形的经验关系

在5·12汶川地震后的四川省水库土坝震害调查成果的基础上,选取汶川地震中受损的有完整资料的96座水库土坝为研究对象,应用等效线性模型对土坝进行了二维动力反应分析。选择3条有代表性的汶川地震实测记录,以三水准峰值加速度输入,得到土坝的动力反应(放大系数、最大动剪应力)与土坝几何形状(宽高比、上游坡比、坝高)间的经验关系。结果表明,土坝放大系数和最大动剪应力随着宽高比和上游坡比的增大而减小,随着坝高的增大而增大;输入波的频谱和峰值强度均对土坝动力反应与其几何形状的经验关系有重要影响。     

乌拉泊水库水质分析及保护对策

根据乌鲁木齐市环境监测中心站多年的监测数据,运用单因子指数法、综合污染指数法和综合营养状态指数法分析了乌拉泊水库水质状况及变化趋势,并提出了保护和改善乌拉泊水库水质的对策建议,以期为乌拉泊水库环境保护管理提供依据。     

基于大坝安全鉴定和专家经验的病险程度评价技术

针对目前我国大坝安全鉴定办法在病险水库严重程度评价中的不足,提出一种大坝病险严重程度的评价方法。以现行大坝安全鉴定技术和专家经验为基础,将水库大坝病险分为五级;提出病险严重性分级以及定性定量转换原则;建立防洪能力、渗流、稳定、变形裂缝、抗震能力、金属结构、工程质量、运行管理、现场检查9个评价大坝病险程度因素的指标体系以及分级和定性-定量转换方法;采用线性加权和法进行病险严重程度综合评价;研究并提出病险程度综合评价影响系数模型以及两种权重确定方法;建立了一套较为完整的病险程度综合评价体系。通过举例分析,提供了使用该方法的途径和过程,表明该方法的可操作性,可行性和实用性。     

基于SWAT模型的圩区农业非点源污染模拟

以荻泽联圩为研究对象,应用SWAT模型模拟太湖流域典型圩区农业非点源产污规律,建立了研究区域的非点源污染基础信息库,实现了流域的空间参数化过程;将参数化过程中提取的模型参数纳入到数据库中统一管理,按照模型要求建立了数据库字段和参数内容的对应表,解决了模型运行时众多离散单元的自动赋值问题;采用虚拟水库控制技术,解决了SWAT模型在控制出流的圩区中的应用弊端。