【作者】 胡鹏飞；

【导师】 杨胜发；

【作者基本信息】 重庆交通大学 ， 港口、海岸及近海工程， 2011， 硕士

【摘要】 由于水动力条件和卵石运动机理较为复杂,在进行航道整治时往往对一些复杂卵石浅滩滩性和河床演变规律认识不足,从而导致采用的整治方法未能从根本上解决碍航问题,需反复整治。为此作者在对卵石浅滩特性进行深入研究的基础上,针对顺直过渡段卵石浅滩,采用概化模型试验和二维水流数值模拟手段对其航道整治方法和整治水位确定两方面问题进行了分析和研究。单纯采用挖槽整治方法并不能从根本上改变挖槽处水流结构,水流受周围河床形态影响较大,相应的挖槽处床沙的输移路径也没有发生根本变化,挖槽区域仍处于卵石输沙带内,洪水期上游来沙时挖槽内仍会有泥沙落淤,存在复淤趋势。采用丁坝整治方法使得丁坝附近水流结构发生明显改变,呈强三维性。在坝头附近产生的旋涡作用体系是造成丁坝局部冲刷的主要原因。在底部螺旋流的作用下,冲刷河床形成局部冲刷坑。床沙沿冲刷坑边缘附近绕过坝头向下游输移,卵石输移路径发生明显变化,卵石输沙带向丁坝对岸一侧发生偏移,有利于维持丁坝的整治效果。运用二维数学模型模拟燕子碛滩整治工程挖槽和筑坝两种整治方法整治前后流场变化,并结合实测资料对两种整治方法的整治效果进行分析。挖槽整治方法模拟结果验证了概化模型试验结果。尽管挖槽内的流速大于床沙的起动流速,但由于水流结构没有发生根本变化,挖槽区仍处于卵石输沙带内,挖槽仍然有复淤的趋势;筑坝整治方法整治前后流场分析和地形变化结果也与概化模型试验结果相一致,筑坝方法更有利于维持整治效果。在丁坝等整治建筑物位置基本确定的情况下,采用枯水期对浅滩河床冲刷作用最大的流量,即造床流量作为整治流量,其相对应的水位作为整治水位的整治水位确定方法,并结合燕子碛浅滩整治工程给出了该方法的应用实例。更多还原

【Abstract】 The hydrodynamic conditions and gravel movement mechanism are both relatively complex, and some complex gravel shoals characteristics and riverbed evolution aren’t understanded sufficiently in the course of waterway regulation, so the adoptive regulation method maybe failed to solve navigation obstruction fundamentally, they often need regulated repeatedly. Therefore, based on the in-depth study of the characteristics of gravel shoals, this paper researched the regulation method of straight transition section gravel shoals and regulation water level by means of generalized model tests and two-dimensional mathematical model.Single dredging regulation method can’t fundamentally change the flow structure in dredging zone. The flow structure is influenced by the surrounding riverbed morphology. Dredging zone is still in the belt of bed-load transport. During flood period, the upstream bed-load begin to transport to downstream, and there will still be sediment falling in dredging zone. There will be deposition in the dredging zone possibly.Damming regulation method can obviously change the flow structure near the spur dyke, and the flow structure strongly shows the 3D characteristics. The local scour near the head of spur dyke is mainly caused by the generated eddy system. The scour pit is gradually forming under the action of bottom spiral flow. Bed-load transport over the head along the edge of scour pit, bed-load transport path begin to change obviously. The belt of bed-load transport changes in the direction of the opposite side of spur dyke, this action is in favor of the continuous regulation effect of the spur dyke.The variation of flow field before and after dredging or damming regulation can be modeled by two-dimensional mathematical model in Yanziqi gravel shoal, and the regulation effects also can be evaluated by measured data. The result of dredging modeling verified the conclusions of above generalized model tests. Although the local velocity in dredging zone is bigger than the starting velocity of bed-load, the flow structure don’t change fundamentally, the dredging zone is in the belt of bed-load transport, and there will be deposition in the dredging zone possibly; The variation of flow field and riverbed morphology in the damming regulation method is in agreement with the result of model tests, this phenomenon proves that the damming regulation method is in favor of the continuous regulation effect of gravel shoal.This paper puts forward the regulation water level determination method that in case of the determination of the position of spur dyke or other regulation structures, the regulation discharge is the discharge with the biggest scour effect, namely the second bed-building discharge, and the corresponding water level is the regulation water level. This paper shows the application example of this regulation water level determination method by Yanziqi gravel shoal regulation project.更多还原