黄河下游河道疏浚挖槽效果的概化模型试验研究

【作者】 田庆奇；

【导师】 胡春宏；

【作者基本信息】 中国水利水电科学研究院 ， 水力学及河流动力学， 2002， 硕士

【摘要】 1997年《黄河治理开发规划纲要》基于几十年的治黄实践提出了“拦、排、调、放、挖”的综合治理措施，把“挖”作为处理黄河泥沙问题的基本措施之一。本文对“如何挖”最为有利作了初步的试验研究。 通过对黄河疏浚的历史以及现代疏浚工程学的发展进行了回顾和总结，认为已有的疏浚研究大多基于航道疏浚工程，对于防洪疏浚特别是在黄河这种多沙型河流上进行防洪疏浚的研究极为欠缺，本文基于黄河下游河道概化模型试验，对疏浚挖槽后水沙运动机理及效果等进行了研究，得到以下认识。 1．在评述疏浚挖槽效果指标的基础上，提出了挖槽效率减淤指标等概念，为科学的判断挖槽效果奠定了基础。 2．挖槽长度对挖槽效果的影响的试验研究结果表明，河道相对减淤量的增加与挖河长度的增加并不成等比例线性关系，即挖河长度超过一定值后，虽然河道相对减淤量还有缓慢增加，但减淤效率开始减小。据此，挖槽长度的优化值约为10km。 3．基于实测试验资料，就挖槽断面尺寸及挖槽槽底坡降对水流流速、含沙量、河段冲淤量、河段水面线及挖槽效率的影响进行了研究，指出在维持一定疏浚规模的情况下，挖槽断面宜窄深，不宜宽浅，并提出了挖槽断面河相关系B^1／2／H的优化值约为5—8，如果要使全河段获得较好的减淤效果，挖槽坡降的取1／10000为宜。 4．采用合理的挖槽尺寸，有利于提高挖槽效率，在本试验范围内，挖槽效率最高可以达到0.95，即挖1m³泥沙可以减少河道内泥沙0.95m³。相应的挖槽尺寸近似宽200—300m，深2—3m，长10km左右，槽底坡降为1／10000。 5．概括总结出了河段疏浚挖槽后，疏浚挖槽河段及其上下影响河段的河床演变及水面线变化的模式，即挖槽段逐渐回淤，挖槽上游段逐渐冲刷，并且其回淤及冲刷的强度随时间的推移由大变小。通过对各挖槽影响因素的综合分析，得到了式7-1、7-2、7-3等疏浚挖槽尺寸与挖槽效果的关系。更多还原

【Abstract】 According to many years practice in the Yellow-river harnessing, the comprehensive regulation measures such as "holding, drainage, adjustment, discharging and excavation" has been proposed in the book of << the compendium for the Yellow River management exploitation planning>>in 1997. Being one of these strategies, the "excavation" has been recognized as the basis measure to deal with sedimentation of the Yellow River. Based on relevant experiment, the best way of how to excavate will be given in this paper.First the author memorized the Yellow River excavation history and concluded development of modern dredging science, and found that most researches of dredging are related to navigation regulation, little used to flood control especially in the Yellow River with silty.Based on the experiment of generalized physical model of the lower reach of the Yellow River, and the study of the loaden flow mechanism and the dredging efficiency, the author get some new ideas as follows:1. Based on the appraisal of three kinds of means that reflect the effect of dredging, proposed several judging indexes (such as dredging efficiency) to estimate excavating results.2. Through studying the effect of the dredging length, found that it is not a linear relationship between the dredging length and the relatively reduced deposition, for example when dredging exceed a certain length, though the relatively reduced deposition still increase slowly, the depositing volumes begin to decrease. Therefore the optimized dredging length is about 10km.3. According to the experimental datum, studied the dredging dimensions and the dredging slope that give influence on flow velocity, sediment concentration, scouring and depositing volumes, water level and dredging efficiency etc., indicated that in a certain circumstance, the dredging cross-section is narrower-deeper is better. And give the range of B/H for 5-8, the optimized dredging slope is 1/1000.4. Using rational dredging dimensions can improve the excavation efficiency. For this generalized physical model, the excavation efficiency can up to 0.95, the relevant dredging dimensions are 200-300width, 2-3deepth,10km length and 1/1000 slope.5. Based on the physical model, summarized the general mode of river development in excavated segment with its up and lower influence reach after dredging, it means that gradually deposit in dredging segment while wash out in up reach, and the change intensities are weakening as the time goes on. The author also synthetically analyzed each effect factor on dredging, concluded several relationships between dredging dimensions and efficiency as formulae 7-1. 7-2 and 7-3.更多还原