黄河大柳树河段水沙运移规律及水温特性研究
发布时间：2018-11-15 22:53
【摘要】：黄河为举世闻名的高含沙河流,在自然演变过程中,不仅沿垂向发生冲淤变化,在平面上也发生明显的横向摆动。本文选取黄河大柳树河段为研究对象,该河段属于随来水来沙变化的弯曲性河道,主流摆动,冲淤变化大。拟建的大柳树水库位于甘肃与宁夏回族自治区交界处黄河干流黑山峡的出口处,是一项对西北经济欠发达地区和民族地区的工农业生产和经济社会发展都具有十分重要意义的工程。结合河岸冲刷力学模式建立适合黄河大柳树河段的三维水沙冲淤数学模型,对该河段建库前的水流运动、泥沙冲淤及河岸摆动进行实测和数值模拟研究。利用一维、二维水温数值模型模拟了黄河大柳树水库建成后坝下游河段及宁蒙河段冬季水温分布情况和结冰点位置。其研究成果对大柳树水库的合理运行、减少淤积及对宁蒙河段的防凌提供可靠的理论依据,具有重要的理论意义和工程应用价值。建立基于非结构网格下的三维紊流数值模型,利用非结构网格有限体积法离散控制方程,并采用非结构同位网格中的SIMPLE算法进行求解。对黄河沙坡头河段连续弯道段的水流运动进行数值模拟,得到了平面流场分布、纵向流速沿垂线分布及横向流速(二次流)的数值模拟结果,并与实测结果对比符合良好。验证了该模型能够较好地模拟具有复杂边界的天然河流中弯道水流运动情况。在三维紊流模型的基础上,综合考虑河岸冲刷力学机理和河岸形态修正技术,建立河床冲刷变化的三维水沙数学模型,利用该模型对黄河大柳树河段的河势变化情况进行了数值模拟研究。结果表明:模拟结果与实测结果吻合较好,说明本文建立的水沙数学模型能较好地反映黄河大柳树河段的水流运动情况及河床变化规律。由于上游来水来沙条件不同,黄河大柳树河段在2011年11月到2012年10月期间冲刷的同时还伴有横向摆动。最大冲深可达2.5m左右,在弯道区域,凹岸冲刷较凸岸严重,深槽向凹岸摆动。表明弯道环流是河道横向演变赖以实现的重要因素。建立了适合黄河大柳树坝址下游及宁蒙河段的一维、二维水温数学模型,模拟了冬季不同气象条件下坝下游河段水温分布情况及结冰点位置。预计黄河大柳树水库建成后,宁夏河段冬季各旬水温均在0℃以上,零温断面位置将下移到石嘴山至磴口之间,距大柳树坝址约320km。石嘴山至乌海段冰塞问题基本缓解,石嘴山至巴彦高勒河段将成为不稳定封冻河段,巴彦高勒以下河段为稳定封冻河段,昭君坟及以下河段冰情不会有明显变化。大柳树水库的运用,对缓解宁蒙河段的凌情有着显著的作用。
[Abstract]:The Yellow River is one of the most famous high sand bearing rivers in the world. In the process of natural evolution, not only the erosion and siltation along the vertical direction occurred, but also the lateral wobble occurred in the plane. In this paper, the Daliushu reach of the Yellow River is selected as the research object, which belongs to the curved channel with the change of incoming water and sediment, the main stream swinging and the scouring and silting changing greatly. The proposed Daliushu Reservoir is located at the exit of Heishan Gorge, the main Yellow River at the junction between Gansu and Ningxia Hui Autonomous region. It is a project of great significance to the industrial and agricultural production and economic and social development in the underdeveloped areas and ethnic areas of northwest China. Combined with the riverbank scour mechanics model, a 3D model of water and sediment scouring and silting was established for the Daliushu reach of the Yellow River. The flow movement, sediment scour and silt and riverbank swinging were measured and numerically simulated before the construction of the reservoir. Using one dimensional and two dimensional water temperature numerical model, the distribution of water temperature and the location of freezing point in the lower reaches of the dam and the Ningmeng reach after the completion of the Daliushu Reservoir on the Yellow River in winter were simulated. The research results provide a reliable theoretical basis for the rational operation of Daliushu Reservoir, reduce siltation and prevent the formation of the Ning-Meng River reach, and have important theoretical significance and engineering application value. A three-dimensional turbulent numerical model based on unstructured meshes is established. The control equations are discretized by the finite volume method of unstructured meshes and solved by SIMPLE algorithm in unstructured in-situ meshes. The numerical simulation of the flow movement in the continuous bend section of Shapotou reach of the Yellow River is carried out, and the numerical simulation results of the plane flow field, the vertical velocity along the vertical line and the transverse velocity (secondary flow) are obtained, which are in good agreement with the measured results. It is verified that the model can well simulate the movement of curved flow in natural rivers with complex boundaries. On the basis of three-dimensional turbulent model and considering the mechanism of riverbank scour mechanics and the technique of riverbank shape correction, a three-dimensional water-sediment mathematical model of riverbed scour change is established. The model is used to simulate the river regime variation in the Daliushu reach of the Yellow River. The results show that the simulation results are in good agreement with the measured results, which indicates that the mathematical model of water and sediment established in this paper can better reflect the flow movement of the Daliushu reach of the Yellow River and the variation law of the river bed. Due to the different conditions of water and sediment coming from the upper reaches of the Yellow River, the Daliushu reach of the Yellow River was washed from November, 2011 to October, 2012, and accompanied by lateral wobble at the same time. The maximum impact depth can reach about 2.5 m. In the bend area, the erosion of the concave bank is more serious than that of the convex bank, and the deep trough wobbles toward the concave bank. It is shown that the curved circulation is an important factor for the lateral evolution of the channel. A one-dimensional and two-dimensional water temperature mathematical model suitable for the lower reaches of Daliushu dam site and the Ningmeng reach of the Yellow River is established. The distribution of water temperature and the location of freezing point in the lower reaches of the dam under different weather conditions in winter are simulated. It is estimated that after the completion of the Daliushu Reservoir of the Yellow River, the water temperature of every ten days in the Ningxia reach will be above 0 鈩，
本文编号：2334646
[Abstract]:The Yellow River is one of the most famous high sand bearing rivers in the world. In the process of natural evolution, not only the erosion and siltation along the vertical direction occurred, but also the lateral wobble occurred in the plane. In this paper, the Daliushu reach of the Yellow River is selected as the research object, which belongs to the curved channel with the change of incoming water and sediment, the main stream swinging and the scouring and silting changing greatly. The proposed Daliushu Reservoir is located at the exit of Heishan Gorge, the main Yellow River at the junction between Gansu and Ningxia Hui Autonomous region. It is a project of great significance to the industrial and agricultural production and economic and social development in the underdeveloped areas and ethnic areas of northwest China. Combined with the riverbank scour mechanics model, a 3D model of water and sediment scouring and silting was established for the Daliushu reach of the Yellow River. The flow movement, sediment scour and silt and riverbank swinging were measured and numerically simulated before the construction of the reservoir. Using one dimensional and two dimensional water temperature numerical model, the distribution of water temperature and the location of freezing point in the lower reaches of the dam and the Ningmeng reach after the completion of the Daliushu Reservoir on the Yellow River in winter were simulated. The research results provide a reliable theoretical basis for the rational operation of Daliushu Reservoir, reduce siltation and prevent the formation of the Ning-Meng River reach, and have important theoretical significance and engineering application value. A three-dimensional turbulent numerical model based on unstructured meshes is established. The control equations are discretized by the finite volume method of unstructured meshes and solved by SIMPLE algorithm in unstructured in-situ meshes. The numerical simulation of the flow movement in the continuous bend section of Shapotou reach of the Yellow River is carried out, and the numerical simulation results of the plane flow field, the vertical velocity along the vertical line and the transverse velocity (secondary flow) are obtained, which are in good agreement with the measured results. It is verified that the model can well simulate the movement of curved flow in natural rivers with complex boundaries. On the basis of three-dimensional turbulent model and considering the mechanism of riverbank scour mechanics and the technique of riverbank shape correction, a three-dimensional water-sediment mathematical model of riverbed scour change is established. The model is used to simulate the river regime variation in the Daliushu reach of the Yellow River. The results show that the simulation results are in good agreement with the measured results, which indicates that the mathematical model of water and sediment established in this paper can better reflect the flow movement of the Daliushu reach of the Yellow River and the variation law of the river bed. Due to the different conditions of water and sediment coming from the upper reaches of the Yellow River, the Daliushu reach of the Yellow River was washed from November, 2011 to October, 2012, and accompanied by lateral wobble at the same time. The maximum impact depth can reach about 2.5 m. In the bend area, the erosion of the concave bank is more serious than that of the convex bank, and the deep trough wobbles toward the concave bank. It is shown that the curved circulation is an important factor for the lateral evolution of the channel. A one-dimensional and two-dimensional water temperature mathematical model suitable for the lower reaches of Daliushu dam site and the Ningmeng reach of the Yellow River is established. The distribution of water temperature and the location of freezing point in the lower reaches of the dam under different weather conditions in winter are simulated. It is estimated that after the completion of the Daliushu Reservoir of the Yellow River, the water temperature of every ten days in the Ningxia reach will be above 0 鈩，
本文编号：2334646
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