河道采沙对长江河床稳定的影响及其控制

As a hot focus of the public voices that the illegal sand mining in river courses could not be forbidden absolutely, which has harmful effects on the riverbed stability directly. The illegal sand mining in the riverbed in mess makes harm badly to the sustainable development in the area of the middle- lower reach of the Yangtze River. The effects of sand mining on the riverbed deformation have been studied experimentally by using micro scale models and close-range photogrammetry. Some results concerning sandpit positions and sand mining direction favorable to riverbed stability are analyzed. The case study on Zhenjiang stretch shows us that sand mining cosmically could modify the riverbed evolvement of a river stretch evidently, so the sand mining in scientific and orderly way can lead the river situation in the trend favorable to riverbed stability. The above-mentioned results are based on the idea of turning the harms of sedimentation into benefits, and can be taken as the references in the management and control of sand mining in riverbeds for the authorities concerned..The bank stability of the Yangtze River has been studied, and a Computational Early Warning Model has been presented based on the study results. A 3-D anisotropic Algebraic Stress Model (ASM) getting over the shortcoming of isotropic model is established to simulate turbulence-driven secondary motion in straight channel flow, which could be powerful means to study riverbed stability and deformations.The analyses on the similarity of hydraulic rigid models could be quantized as the comparability between their similitude grades. The effects of the deformation ratios and geometry scale on the similitude grades are analyzed based on a series of case studies on hydraulic rigid models. It is pointed by the study results that small-scale models or the microscale models should be taken more popularly. The quantization of model similarities is beneficial to the design and selection of hydraulic rigid models..The effects of sand mining on the riverbed deformation have been studied experimentally in the case study of the Zhenjiang stretch by using micro scale models and close-range photogrammetry. It has been demonstrated that the microscale models could be used in the experimental study of riverbed deformation, especially for the qualitative analyses and comparisons of different schemes. On the other hand, close-range photogrammetry will have broad prospects in the digital experimental studies..

河床稳定受水流和泥沙等因素的影响，长江亦有局部泥沙淤积需要疏浚。河流泥沙本身是宝贵的矿产资源，但盲目采沙危及堤岸的稳定和安全。考虑以长江具体河段为对象，采用原型调查、模型试验和计算机数值模拟相结合的方法，研究河道采沙对河床稳定与河流形态的影响及河床稳定所允许的河道采沙。将除害与兴利相结合，为河道采沙的管理提供决策依据。