振动沉管挤密碎石桩在闸基处理中的应用

振动沉管挤密碎石桩是近十几年来在挤密砂桩和振冲桩的基础上发展起来的地基处理新技术,具有设备简单、操作方便、成本低、施工快、无污染等特点，被工程界广泛使用，积累了一定的工程经验。其在共产主义闸地基处理中的应用即为一例。     

供水管网中阀门的选择

针对供水企业对供水管网阀门的使用要求，从供水的安全性、技术的先进性、水流的密封性、检验的真实性、质量的可靠性、操作的灵活性、价格的合理性、售后服务的保证性、订供货的一致性以及建立比较完善的检验与复验制度等方面。提出了对供水管网阀门的选择意见。     

加盟奥运特许经营的途径

7月1日．西部第一家北京2008年奥运会特许商品零售店正式在成都亮相。成都是继北京、青岛、上海之后，第4个开设奥运会特许商品零售店的试点城市。     

宁夏汉延渠灌区灌溉水利用系数测算分析与评价

农田灌溉水利用系数表示从水源引水被农作物吸收利用的过程,是反应灌区灌溉用水效率的一项指标。本文以汉延渠灌区为例,综合考虑宁夏的气候环境、土壤类型、灌溉制度及作物种植结构等因素,选取典型渠段和样点灌区,分别采用"连乘法"和"首尾法"计算宁夏汉延渠灌区2018—2019年的灌溉水利用系数,并对其进行对比分析评价,从而确定灌区适宜的计算方法。     

察尔汗盐湖物质来源的讨论

察尔汗盐湖是世界上最大的现代盐类矿床之一。盐湖中有用组份以 K、Mg 为主,伴有 Na、B、Li、Br、I、Rb、Cs、Sr 等元素。关于这些物质成份的来源有多种假说,如昆仑山古湖补给说、深层卤水或油田水补给说以及周边淡水补给说。本文首先根据格尔木河流域距今3万年以来补给察尔汗盐湖主要是山区大气降水这个事实,对昆仑山区古湖泊水是否为察尔汗盐湖提供重要物质来源提出质疑。通过元素比值与水量分析认为深层卤水或油田水可能不是盐湖的主要物质来源。研究认为察尔汗盐湖主要物质来源乃是四周长期风化淋滤及地下水、地表水不断搬运、溶解、析出演化过程的结果。昆仑山区特殊岩性环境及湖区脱硫酸作用可能是察尔汗盐湖缺少大量硫酸盐类沉积的原因。     

Medium-Term Hydro Generation Scheduling (MTHGS) with Chance Constrained Model (CCM) and Dynamic Control Model (DCM)

Medium-Term Hydro Generation Scheduling (MTHGS) plays an important role in the operation of hydropower systems. In the first place, this paper presents a Chance Constrained Model for solving the optimal MTHGS problem. The model recognizes the impact of inflow uncertainty and the constraints involving hydrologic parameters subjected to uncertainty are described as probabilistic statements. It aims at providing a more practical technique compared to the traditional deterministic approaches used for MTHGS. The stochastic inflow is expressed as a simple discrete-time Markov chain and Stochastic Dynamic Programming is adopted to solve the model. Then in order to use the information of long-term inflow forecast to improve dispatching decisions, a Dynamic Control Model is developed. Short-term forecast results of the current period and long-term forecast results of the remaining period are treated as inputs of the model. Finally, the two methods are applied to MTHGS of Xiluodu hydro plant in China. The results are compared to those obtained from Deterministic Dynamic Programming with hindsight and advantages and disadvantages of the two methods are analyzed.     

“鲇鱼”台风期间福建省溪源水库的防洪调度分析

2016年"鲇鱼"台风期间,省溪源水库遭遇建库以来最大洪水,水库通过预泄滕库、避潮错峰等方式成功防御,通过详细介绍"鲇鱼"台风期间水雨情特点以及调度过程,汲取经验,为今后水库洪水调度提供参考。     

干式变压器铁芯接地故障分析

本文通过对20kV及以下系统干式变压器铁芯接地故障进行分析,从定期检查、检修维护、设备管理方面提出了相应的防范措施,可为水电站机组安全运行提供借鉴。     

生产建设项目不同水土保持监测方法的比较分析

生产建设项目的水土保持监测内容由1个目标层、6个控制层、29个要素和96个指标构成。介绍了长江流域水土保持监测中心站开展水土保持工作主要采取的方法,即资料分析法、实地量测监测、定点地面监测、遥感监测、三维激光扫描测量、摄影测量和远程实时监控技术等。比较了各监测方法的原理、适应性及特点。由于各种监测方法均不是独立运用于某一个项目工程,因此,根据项目工程总体布局和工程施工可能造成的水土流失部位的特点,应相互结合各自特点,选择适合的监测方法,对生产建设项目水土流失及水土保持措施进行全过程监测。     

Effect of the Three Gorges Reservoir on vertical distribution of suspended sediment concentration and estimation accuracy of depth-average concentration in downstream reaches

The sediment regime in the middle Yangtze River has been significantly changed from quasi-equilibrium to nonequilibrium since the impoundment of the Three Georges Reservoir (TGR). To understand the effects of the TGR on vertical distribution of suspended sediment concentration (SSC) and estimation accuracy of mean concentration, vertical sediment concentration and flow velocity data at the Shashi and Jianli hydrological stations in the reach before and after the impoundment were collected. Comparisons and analysis of vertical profiles of SSC before and after the TGR impoundment show that after the impoundment of the TGR, due to the coarsening of sediment particle size, the reduction in sediment load, and the significant decrease in sediment saturation, the vertical distribution of SSC in the downstream reaches became more uneven under medium and low water flows, which was reflected in the vertical gradient and the fluctuation degree of SSC significantly increased. In addition, the depth-average sediment concentrations were calculated by the selected-point method and the mean values calculated by the “multi-point method” were regarded as the “true mean” to evaluate the accuracy of the mean value calculated by the “few-point method.” It was found that the relative errors for the selected-point method were mainly positive before impoundment but mainly negative after impoundment. Additionally, the correction factors of one-point, two-point, and three-point methods and the position of the near-bed substituted point for the five-point method were given to reduce the error when the point measurements were used to calculate the depth-average sediment concentration in the downstream reaches.