模拟边坡土壤虹吸排水试验研究

根据水力学中的虹吸原理,对模拟边坡土壤中的虹吸管过水量进行探究。通过试验与理论相结合推算出直径4 mm的虹吸管的沿程阻力系数,运用该阻力系数计算虹吸管在土壤中过水流量的关系,并进行试验研究。试验结果表明:土壤中埋设虹吸管的过水量随水位差增高而增大,当水位差大于3 m时将不能增加其过水量;土壤中埋设虹吸管的土层深度与管内过水量呈负相关,土层中土壤的渗透性是影响虹吸管过水量的主要因素。     

罗湾大坝防渗加固沥青混凝土材料试验研究与应用

鉴于罗湾大坝的安全状况,2001年确定进行一期沥青混凝土防渗加固处理。而这个防渗加固方案能否成功,关键就在于能否合理选择沥青混凝土材料。通过室内配合比试验和现场配合比调整试验,选择出了满足设计要求的沥青混凝土。施工完成后,进行了现场测试,测试结果表明,所选沥青混凝土材料合理,施工质量良好。     

二滩水电站机组运行稳定性研究

运行稳定是水轮发电机组长期安全运行的重要保证。以二滩水电站6台机组的稳定性试验数据为例,分析了二滩水电机组的运行稳定性。试验数据分析表明,机组运行工况可划分为小负荷区、涡带工况区、大负荷区,大负荷区机组运行稳定性最佳。建议机组避开不稳定运行区域运行。     

水工结构可靠度设计的简化及条件概率的应用

水工结构可靠度设计采用的两种方法中,以概率极限状态为原则的分项系数法较经验安全系数法更为严谨,但分项系数较多,为此提出二系数设计法对其进行简化。此外,还提出用条件概率法解决可靠度分析中常遇到的一个试验得到两个相关试验值和现场子样容量较小两类问题。对以上问题用实例进行了说明。     

长洲水利枢纽坝址洪水设计

介绍了长洲水利枢纽坝址洪水设计时,对西江中下游历史洪水调查和重现期考证,并对成果合理性、一致性进行分析及频率计算,同时归槽洪水的考虑使长洲水利枢纽设计洪水成果更合理.     

Effects of fluctuating river flow on groundwater/surface water mixing in the hyporheic zone of a regulated,large cobble bed river

Physicochemical relationships in the boundary zone between groundwater and surface water (i.e. the hyporheic zone) are controlled by surface water hydrology and the hydrogeologic properties of the riverbed. We studied how sediment permeability and river discharge altered the vertical hydraulic gradient (VHG) and water quality of the hyporheic zone within the Hanford Reach of the Columbia River. The Columbia River at Hanford is a large, cobble‐bed river where water level fluctuates up to 2 m daily because of hydropower generation. Concomitant with river stage recordings, continuous readings were made of water temperature, specific conductance, dissolved oxygen and water level of the hyporheic zone. The water level data were used to calculate VHG between the river and hyporheic zone. Sediment permeability was estimated using slug tests conducted in piezometers installed into the river bed. The response of water quality measurements and VHG to surface water fluctuations varied widely among study sites, ranging from no apparent response to covariance with river discharge. At some sites, a hysteretic relationship between river discharge and VHG was indicated by a time lag in the response of VHG to changes in river stage. The magnitude, rate of change and hysteresis of the VHG response varied the most at the least permeable location (hydraulic conductivity (K) = 2.9 × 10^?4 cms^?1) and the least at the most permeable location (K = 8.0 × 10^?3 cms^?1). Our study provides empirical evidence that sediment properties and river discharge both control the water quality of the hyporheic zone. Regulated rivers, like the Columbia River at Hanford, that undergo large, frequent discharge fluctuations represent an ideal environment in which to study hydrogeologic processes over relatively short time periods (i.e. days to weeks) that would require much longer periods (i.e. months to years) to evaluate in unregulated systems. Copyright © 2006 John Wiley & Sons Ltd.     

黄土高原沟道坝系模型设计方法

在回顾前人研究成果及分析土壤侵蚀模型试验特点的基础上，提出了黄土高原小流域沟道坝系模型设计的方法。认为在水力侵蚀最活跃的黄土高原地区，降雨强度是影响产流产沙的关键因子，从而需要抓住降雨与侵蚀产沙这对主要矛盾，根据降雨侵蚀空间或时问的集积效果来实现模型流域与原型流域产沙特征的相似。为保证沟道坝系地貌演变相似，除降雨历时遵循重力相似条件外，模型降雨产沙关系还应通过借助天然资料率定产沙量比尺的途径与原型相对应。     

双重介质二维不定常渗流研究

本文采用傅立叶变换方法,求得了弱可压缩液体在双孔介质中二维不定常渗流的拉氏空间解,研究了非稳态变换双重介质裂缝储量比ω和介质间传导系数λ对无限导流垂直裂缝井的压力及压力导数的影响,绘制了影响因素的敏感性曲线,并对早期及晚期的结果进行近似,为试井分析提供了理论基础。     

南水北调东线工程水工混凝土抗拉强度的长期性能研究

通过劈拉强度试验研究了南水北调东线宝应站工程水工混凝土抗拉强度在180d龄期内的增长趋势，初步探讨了粉煤灰掺合料和低掺量合成纤维对水工混凝土抗拉强度的影响。研究结果表明，掺人合成纤维不仅减少了混凝土的早期缺陷，而且有利于混凝土后期抗拉强度的持续增长。粉煤灰与合成纤维复掺对混凝土抗拉强度的提高具有显著的双重复合效应。     

管道双车车间螺旋流周向速度特性研究

考虑到筒装料管道水力输送技术在研究内容方面所存在的欠缺,在管道流量为40 m3/h条件下,运用粒子图像测试技术对管道双车车间水流速度进行了测量,并结合相关理论对管道双车车间水流周向速度特性进行了分析.试验中采用的管道车模型型号相同,均为150 mmx70 mm,所带导流条长度为150mm,安放角为15°,输送管道内径为...