The development of new river channel projects and its design is important to solve difficult control of the Yellow River regime and high emergency costs problem.Analyze the defects of traditional engineering and elaborate the structural form of the new steel pile dam project combining with data from 2021 and 2022,showing that the combined pile dam demonstration project in the downstream river can achieve the river control goal and solve the problem of large shortage of funds for rock throwing and rescue.In the engineering design of Shaojiaqiao and Hongyazi prototype test, the steel structure shaped dam’s sheet pile length of 12m and the lower steel pipe pile length of 19m were determined according to the overturning stability calculation; The design of steel permeable pile dam in the form of double-row and overall interconnection in the lower extension of the control guide can increase the shape of the support area, which can effectively strengthen the overall stability while improving the effect of slow flow and siltation and restricting flow and sending guide.

以2021年7月河南抗洪抢险工作实践为基础,对我国抗洪和救灾工作中普遍存在的问题进行剖析,按照发现问题、指出问题、分析问题、解决问题的思路开展研究,提出解决相关问题的建议.结合已有研究成果,针对性地提出诸如降低水库汛限水位、完善防洪减灾工程、给洪水多留顺畅通道等解决问题的途径.列举的技术方案包括:(1)推广使用清华大学"一种钢筋混凝土预制板桩组合坝"专利技术,在原有堤防的迎水面插入钢筋混凝土预制板桩,提升加固中小河流堤防,以便在今后的防洪减灾中变被动为主动;(2)利用铁船变流促淤技术,实现"高水变流促淤、低水挑流护岸"功能;(3)用长臂打桩机将钢结构异型板桩构件从口门两端堤头迎水面打入,抢筑裹头后再沿堵口坝基线陆续交错打入异型板桩并加以焊连,同时顺板桩背面填渣推进,在上述铁船变流技术配合下,即可封堵成功;(4)以"避水苑"工程形式改变水灾时紧急转移群众的单一模式,即采用上述专利技术,沿村边修建工程稳定性强的板桩组合坝,作为防护坝墙,路口设置应急挡门作为应急门户,并在村角修建"避水阁",在泵站动力强排下,解决防洪避水自保问题;(5)预制板桩组合坝的施工可采用变宽深开沟机与沉桩造基槽协同配合的新施工方法,尤其采用插拔自如的液压式打桩机将冲槽桩锤打入的沉桩造槽施工方法,对邻近建筑物影响小,不惧地下水位高难题,且板桩端可进入土体密实层,此挡水板桩坝墙施工,具有工序简单、适应性强、基础较深、密闭性好、施工高效、成本低、外观规则及便于同绿植方案结合等优点.

The variety and impact factors of the dissolved oxygen(DO)concentration and saturation at the two sections,up-stream or downstream,of the Three Gorges Project dam after the impoundment are analyzed based on the field data. The results reveal that,since a great deal of oxygen dissolves into water due to the air entrainment when water sluices through the orifices, the phenomenon of DO super-saturation is observed in the downstream of the dam. However,DO concentration(saturation)in the downstream hardly varies if water sluices through the electricity power stations. When water sluices through the electricity power stations and orifices synchronously,DO concentration(saturation)of the downstream is mainly affected by the ratio of the two discharges. Additionally,the downstream water level also has an impact on the downstream DO concentration. When the total discharge is more than 35 000 m3/s and the downstream water level is higher than 68m,or when most of the discharge sluices through the orifices,great attention must be paid to the effect of DO super-saturation on the aquatic.

A simple and easy prediction method for dissolved gas saturation in the water downstream of hydro-project is proposed in this paper. The saturation in the water downstream of sluice structure is calculated by assuming that the gas transfer between water and air is rapid enough to saturate the water in bubble swarm area, as is reasonable when sluicing water from sluice structure is intensively re-aerated. Then the saturation is further averaged by mixing flows from sluice structure and power house. Several cases including four different hydro-projects along Columbia River and Three Gorges Project are predicted for validation, and the calculated dissolved oxygen saturation is close to the original monitoring data. The results demonstrate that the presented method is easy to be applied and suitable for different projects. The method is also used to predict the dissolved oxygen saturation in the water downstream of Three Gorges Dam at different typical reservoir water levels, which shows that the dissolved oxygen saturation at the Huanglingmiao section is as much as 140% under the condition of 100-year flood. In order to mitigate and avoid the effect on aquatic of super-saturation, eco-operation is required beside the flood control when the flood exceeds 100-year point.

Based on the original monitoring data of water quality at four representative sections near the dam of Three Gorges Reservoir during 1998-2004,probabilistic neural networks of water quality evaluation model is applied for water quality evaluation near the dam before and after the storage.The oxygen-balance parameters,the poison parameters,and the nutrient salt parameters are chosen as the evaluation parameters.The evaluation results after the storage of reservoir are compared with which before the storage.The results show that,in the early days of the storage,the evaluation results of the oxygen-balance parameters vary a little in the front of the dam,and get a little better behind the dam;the evaluation results of the poison parameters and the nutrient salt parameters become better both in the front and behind the dam.The analysis shows that the nutrient salt parameters make the greatest effect to the water quality among the all.However,after the storage,the DO extra-saturation phenomenon behind the dam,the secondary pollution problem and the eutrophication problem in the reservoir should be paid great attention to them.

Numerical simulation is an important method to study the pollution problem due to the wastewater discharge. The features of water flow and wastewater distribution and related difficulties in numerical simulation are discussed in the present paper. Both advantages and disadvantages of the depth-averaged model and varied multi-layer models are analyzed when they are applied to investigate the wastewater discharging into Three Gorges Reservoir (TGR). The present study may be helpful to the further development of wastewater effluent model for TGR as well.