高寒区超高水头闸门山型充气水封研究

发布时间：2018-05-07 20:01

本文选题：高寒区超高水头 + 山型充气水封　；参考：《西北农林科技大学》2014年硕士论文

【摘要】：随着我国水利水电开发的发展，2020年以前我国还将建设一批200m及以上超高坝工程，以促进水能和水资源的综合开发利用。这些高坝建成后，水库面临着高水头大流量泄流问题，尤其是设有底孔闸门的大坝都面临高水头闸门的问题，当水封失效后，局部漏水形成高速水流，诱发闸门支臂振动，容易产生失稳破坏，因而闸门中的水封显得尤为重要。高水头闸门水封为了保证密封又减小摩阻，通常都采用充压伸缩式水封，其充压介质主要为水，其优点是可以利用水库水压作背压，其缺点是由于高寒地区低温环境的特殊性，在水封内腔的水介质会因冰冻而失效，甚至会导致水封装置破坏，使其应用受到限制；同时当库水位变幅较大且水库泥沙和污物较多时，难以利用水库水位作背压；另外其加压卸压很快，背压不好控制。因此考虑采用压缩空气作为充压介质，其压缩性与回缩性好，减缓加压卸压速度，方便控制，有利于保持背压恒定，更重要的是不会冰冻；但由于空气分子小于水分子，采用空气容易泄露，为此通常在背压腔中增设充气袋。但是此类工程目前只在较低水头闸门中应用，而超高水头闸门中还比较少见，应用超高水头时的性能需要研究。本文在前人对高水头闸门中应用的水封橡胶材料进行力学实验，单轴拉伸、双轴拉伸、纯剪切三种实验基础上，针对闸门水封橡胶的超弹性能，根据水封橡胶单双轴拉伸和纯剪切实验，得到了其名义应力应变曲线；对通用的橡胶本构模型进行了系统的对比与分析，给出了水封橡胶数值仿真最优超弹性本构模型；其次采用不同的橡胶粘弹性本构模型，通过对某超高坝底孔闸门水封有限元计算，得出水封应力松弛失效时间，通过与闸门实际运行监测资料对比，，验证Burgers本构模型是最合理的；克服了以往设计阶段均采用标准线性固体模型来预测水封性能及失效时间的缺陷。针对高寒区超高坝底孔闸门常规山型水封存在的问题，采用材料分区布置，提出了一种新型充气山型水封结构；并考虑橡胶材料的超弹性、不可压缩性、大变形等特点，对水封在最不利工况下，进行了三重非线性有限元数值仿真；在橡胶材料应力不超过其容许值前提下，对充气袋断面形式进行了优化，得出最佳断面形式。最后采用流固耦合理论，对水封过程进行了流体动力学分析，对其水封盖板与闸门面板间的水流流态，水流压力，以及水封关键部位—封头上的应力状态进行了初步分析。研究表明，该水封能解决高寒区闸门水封失效问题。
[Abstract]:With the development of water conservancy and hydropower development in China, a number of super-high dam projects of 200 m and above will be built before 2020, in order to promote the comprehensive development and utilization of water energy and water resources. After the completion of these high dams, the reservoir is faced with the problem of high head and large discharge, especially the dam with bottom gate is faced with the problem of high head gate. When the water seal fails, the local leakage forms high speed flow, which induces the vibration of the branch arm of the gate. It is easy to cause instability and damage, so the water seal in the gate is particularly important. In order to ensure the seal and reduce the friction resistance, the high head gate water seal usually adopts the pressurized and telescopic water seal, the main pressure medium is water, its advantage is that the reservoir water pressure can be used as back pressure, and its shortcoming is due to the particularity of the low temperature environment in the high and cold area. The water medium in the inner cavity of the water seal will fail because of freezing, and even lead to the destruction of the water seal device, so its application will be restricted, at the same time, it is difficult to use the water level of the reservoir as the back pressure when the water level of the reservoir is large and the sediment and dirt of the reservoir are much more. In addition, its pressure relief pressure quickly, the back pressure is not easy to control. Therefore, considering the use of compressed air as a charging medium, its compressibility and retraction are good, the speed of pressure relief is slowed down, the control is convenient, and it is helpful to keep the back pressure constant and, more importantly, it is not frozen; but because the air molecule is smaller than the water molecule, Air leakage is easy to use, usually in the back pressure chamber to add an inflatable bag. However, this kind of engineering is only used in the low head gate, but it is rare in the super high head gate. The performance of the super high head gate needs to be studied. In this paper, on the basis of mechanical experiments, uniaxial tension, biaxial tension and pure shearing of water seal rubber used in high head gate, the hyperelastic properties of water seal rubber were studied. The nominal stress-strain curves are obtained by uniaxial tensile and pure shear tests, and the general constitutive model of rubber is compared and analyzed systematically, and the optimal hyperelastic constitutive model of water-sealed rubber is presented. Secondly, by using different rubber viscoelastic constitutive models, the stress relaxation failure time of the water seal is obtained by finite element calculation of the water seal of the bottom gate of a certain super high dam, and the monitoring data are compared with the actual operation data of the gate. The Burgers constitutive model is proved to be the most reasonable one, which overcomes the defect that standard linear solid model is used to predict the water seal performance and failure time in the previous design stage. In order to solve the problem of conventional mountain water seal for the gate of super high dam bottom in high cold region, a new type of aerated mountain water seal structure is proposed by using material zoning arrangement, and the characteristics of rubber material such as super elasticity, incompressibility and large deformation are taken into account. Three-fold nonlinear finite element numerical simulation was carried out for the water seal under the most unfavorable working conditions, and the optimum section form was obtained under the premise that the stress of rubber material did not exceed its allowable value. Finally, the hydrodynamic analysis of the water seal process is carried out by using the fluid-solid coupling theory, and the flow state, the flow pressure and the stress state on the seal head between the water seal cover plate and the gate panel are preliminarily analyzed. The study shows that the water seal can solve the failure problem of gate water seal in high cold area.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV663

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